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![Linus Torvalds](/assets/img/avatar_default.png)
We do not want to dirty the dentry->d_flags cacheline in dput() just to set the DCACHE_REFERENCED flag when it is already set in the common case anyway. This way the first cacheline of the dentry (which contains the RCU lookup information etc) can stay shared among multiple CPU's. This finishes off some of the details of all the scalability patches merged during the merge window. Also don't mark dentry_kill() for inlining, since it's the uncommon path and inlining it just makes the common path slower due to extra function entry/exit overhead. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3440 lines
88 KiB
C
3440 lines
88 KiB
C
/*
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* fs/dcache.c
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*
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* Complete reimplementation
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* (C) 1997 Thomas Schoebel-Theuer,
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* with heavy changes by Linus Torvalds
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*/
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/*
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* Notes on the allocation strategy:
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*
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* The dcache is a master of the icache - whenever a dcache entry
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* exists, the inode will always exist. "iput()" is done either when
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* the dcache entry is deleted or garbage collected.
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*/
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#include <linux/syscalls.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/fsnotify.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/hash.h>
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#include <linux/cache.h>
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#include <linux/export.h>
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#include <linux/mount.h>
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#include <linux/file.h>
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#include <asm/uaccess.h>
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#include <linux/security.h>
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#include <linux/seqlock.h>
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#include <linux/swap.h>
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#include <linux/bootmem.h>
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#include <linux/fs_struct.h>
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#include <linux/hardirq.h>
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#include <linux/bit_spinlock.h>
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#include <linux/rculist_bl.h>
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#include <linux/prefetch.h>
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#include <linux/ratelimit.h>
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#include <linux/list_lru.h>
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#include "internal.h"
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#include "mount.h"
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/*
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* Usage:
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* dcache->d_inode->i_lock protects:
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* - i_dentry, d_alias, d_inode of aliases
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* dcache_hash_bucket lock protects:
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* - the dcache hash table
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* s_anon bl list spinlock protects:
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* - the s_anon list (see __d_drop)
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* dentry->d_sb->s_dentry_lru_lock protects:
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* - the dcache lru lists and counters
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* d_lock protects:
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* - d_flags
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* - d_name
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* - d_lru
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* - d_count
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* - d_unhashed()
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* - d_parent and d_subdirs
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* - childrens' d_child and d_parent
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* - d_alias, d_inode
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*
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* Ordering:
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* dentry->d_inode->i_lock
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* dentry->d_lock
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* dentry->d_sb->s_dentry_lru_lock
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* dcache_hash_bucket lock
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* s_anon lock
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*
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* If there is an ancestor relationship:
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* dentry->d_parent->...->d_parent->d_lock
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* ...
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* dentry->d_parent->d_lock
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* dentry->d_lock
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*
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* If no ancestor relationship:
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* if (dentry1 < dentry2)
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* dentry1->d_lock
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* dentry2->d_lock
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*/
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int sysctl_vfs_cache_pressure __read_mostly = 100;
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EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
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__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
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EXPORT_SYMBOL(rename_lock);
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static struct kmem_cache *dentry_cache __read_mostly;
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/**
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* read_seqbegin_or_lock - begin a sequence number check or locking block
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* @lock: sequence lock
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* @seq : sequence number to be checked
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*
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* First try it once optimistically without taking the lock. If that fails,
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* take the lock. The sequence number is also used as a marker for deciding
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* whether to be a reader (even) or writer (odd).
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* N.B. seq must be initialized to an even number to begin with.
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*/
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static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq)
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{
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if (!(*seq & 1)) /* Even */
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*seq = read_seqbegin(lock);
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else /* Odd */
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read_seqlock_excl(lock);
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}
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static inline int need_seqretry(seqlock_t *lock, int seq)
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{
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return !(seq & 1) && read_seqretry(lock, seq);
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}
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static inline void done_seqretry(seqlock_t *lock, int seq)
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{
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if (seq & 1)
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read_sequnlock_excl(lock);
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}
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/*
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* This is the single most critical data structure when it comes
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* to the dcache: the hashtable for lookups. Somebody should try
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* to make this good - I've just made it work.
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*
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* This hash-function tries to avoid losing too many bits of hash
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* information, yet avoid using a prime hash-size or similar.
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*/
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#define D_HASHBITS d_hash_shift
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#define D_HASHMASK d_hash_mask
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static unsigned int d_hash_mask __read_mostly;
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static unsigned int d_hash_shift __read_mostly;
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static struct hlist_bl_head *dentry_hashtable __read_mostly;
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static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
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unsigned int hash)
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{
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hash += (unsigned long) parent / L1_CACHE_BYTES;
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hash = hash + (hash >> D_HASHBITS);
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return dentry_hashtable + (hash & D_HASHMASK);
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}
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/* Statistics gathering. */
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struct dentry_stat_t dentry_stat = {
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.age_limit = 45,
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};
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static DEFINE_PER_CPU(long, nr_dentry);
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static DEFINE_PER_CPU(long, nr_dentry_unused);
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#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
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/*
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* Here we resort to our own counters instead of using generic per-cpu counters
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* for consistency with what the vfs inode code does. We are expected to harvest
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* better code and performance by having our own specialized counters.
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*
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* Please note that the loop is done over all possible CPUs, not over all online
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* CPUs. The reason for this is that we don't want to play games with CPUs going
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* on and off. If one of them goes off, we will just keep their counters.
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*
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* glommer: See cffbc8a for details, and if you ever intend to change this,
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* please update all vfs counters to match.
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*/
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static long get_nr_dentry(void)
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{
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int i;
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long sum = 0;
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for_each_possible_cpu(i)
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sum += per_cpu(nr_dentry, i);
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return sum < 0 ? 0 : sum;
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}
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static long get_nr_dentry_unused(void)
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{
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int i;
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long sum = 0;
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for_each_possible_cpu(i)
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sum += per_cpu(nr_dentry_unused, i);
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return sum < 0 ? 0 : sum;
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}
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int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
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size_t *lenp, loff_t *ppos)
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{
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dentry_stat.nr_dentry = get_nr_dentry();
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dentry_stat.nr_unused = get_nr_dentry_unused();
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return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
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}
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#endif
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/*
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* Compare 2 name strings, return 0 if they match, otherwise non-zero.
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* The strings are both count bytes long, and count is non-zero.
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*/
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#ifdef CONFIG_DCACHE_WORD_ACCESS
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#include <asm/word-at-a-time.h>
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/*
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* NOTE! 'cs' and 'scount' come from a dentry, so it has a
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* aligned allocation for this particular component. We don't
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* strictly need the load_unaligned_zeropad() safety, but it
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* doesn't hurt either.
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*
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* In contrast, 'ct' and 'tcount' can be from a pathname, and do
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* need the careful unaligned handling.
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*/
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static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
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{
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unsigned long a,b,mask;
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for (;;) {
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a = *(unsigned long *)cs;
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b = load_unaligned_zeropad(ct);
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if (tcount < sizeof(unsigned long))
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break;
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if (unlikely(a != b))
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return 1;
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cs += sizeof(unsigned long);
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ct += sizeof(unsigned long);
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tcount -= sizeof(unsigned long);
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if (!tcount)
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return 0;
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}
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mask = ~(~0ul << tcount*8);
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return unlikely(!!((a ^ b) & mask));
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}
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#else
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static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
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{
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do {
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if (*cs != *ct)
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return 1;
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cs++;
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ct++;
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tcount--;
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} while (tcount);
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return 0;
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}
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#endif
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static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount)
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{
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const unsigned char *cs;
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/*
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* Be careful about RCU walk racing with rename:
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* use ACCESS_ONCE to fetch the name pointer.
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*
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* NOTE! Even if a rename will mean that the length
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* was not loaded atomically, we don't care. The
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* RCU walk will check the sequence count eventually,
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* and catch it. And we won't overrun the buffer,
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* because we're reading the name pointer atomically,
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* and a dentry name is guaranteed to be properly
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* terminated with a NUL byte.
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*
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* End result: even if 'len' is wrong, we'll exit
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* early because the data cannot match (there can
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* be no NUL in the ct/tcount data)
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*/
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cs = ACCESS_ONCE(dentry->d_name.name);
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smp_read_barrier_depends();
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return dentry_string_cmp(cs, ct, tcount);
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}
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static void __d_free(struct rcu_head *head)
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{
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struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
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WARN_ON(!hlist_unhashed(&dentry->d_alias));
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if (dname_external(dentry))
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kfree(dentry->d_name.name);
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kmem_cache_free(dentry_cache, dentry);
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}
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/*
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* no locks, please.
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*/
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static void d_free(struct dentry *dentry)
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{
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BUG_ON((int)dentry->d_lockref.count > 0);
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this_cpu_dec(nr_dentry);
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if (dentry->d_op && dentry->d_op->d_release)
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dentry->d_op->d_release(dentry);
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/* if dentry was never visible to RCU, immediate free is OK */
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if (!(dentry->d_flags & DCACHE_RCUACCESS))
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__d_free(&dentry->d_u.d_rcu);
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else
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call_rcu(&dentry->d_u.d_rcu, __d_free);
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}
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/**
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* dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
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* @dentry: the target dentry
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* After this call, in-progress rcu-walk path lookup will fail. This
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* should be called after unhashing, and after changing d_inode (if
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* the dentry has not already been unhashed).
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*/
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static inline void dentry_rcuwalk_barrier(struct dentry *dentry)
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{
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assert_spin_locked(&dentry->d_lock);
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/* Go through a barrier */
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write_seqcount_barrier(&dentry->d_seq);
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}
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/*
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* Release the dentry's inode, using the filesystem
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* d_iput() operation if defined. Dentry has no refcount
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* and is unhashed.
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*/
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static void dentry_iput(struct dentry * dentry)
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__releases(dentry->d_lock)
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__releases(dentry->d_inode->i_lock)
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{
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struct inode *inode = dentry->d_inode;
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if (inode) {
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dentry->d_inode = NULL;
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hlist_del_init(&dentry->d_alias);
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spin_unlock(&dentry->d_lock);
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spin_unlock(&inode->i_lock);
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if (!inode->i_nlink)
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fsnotify_inoderemove(inode);
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if (dentry->d_op && dentry->d_op->d_iput)
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dentry->d_op->d_iput(dentry, inode);
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else
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iput(inode);
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} else {
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spin_unlock(&dentry->d_lock);
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}
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}
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/*
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* Release the dentry's inode, using the filesystem
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* d_iput() operation if defined. dentry remains in-use.
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*/
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static void dentry_unlink_inode(struct dentry * dentry)
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__releases(dentry->d_lock)
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__releases(dentry->d_inode->i_lock)
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{
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struct inode *inode = dentry->d_inode;
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dentry->d_inode = NULL;
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hlist_del_init(&dentry->d_alias);
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dentry_rcuwalk_barrier(dentry);
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spin_unlock(&dentry->d_lock);
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spin_unlock(&inode->i_lock);
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if (!inode->i_nlink)
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fsnotify_inoderemove(inode);
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if (dentry->d_op && dentry->d_op->d_iput)
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dentry->d_op->d_iput(dentry, inode);
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else
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iput(inode);
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}
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/*
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* The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
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* is in use - which includes both the "real" per-superblock
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* LRU list _and_ the DCACHE_SHRINK_LIST use.
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*
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* The DCACHE_SHRINK_LIST bit is set whenever the dentry is
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* on the shrink list (ie not on the superblock LRU list).
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*
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* The per-cpu "nr_dentry_unused" counters are updated with
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* the DCACHE_LRU_LIST bit.
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*
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* These helper functions make sure we always follow the
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* rules. d_lock must be held by the caller.
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*/
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#define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
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static void d_lru_add(struct dentry *dentry)
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{
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D_FLAG_VERIFY(dentry, 0);
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dentry->d_flags |= DCACHE_LRU_LIST;
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this_cpu_inc(nr_dentry_unused);
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WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
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}
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static void d_lru_del(struct dentry *dentry)
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{
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D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
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dentry->d_flags &= ~DCACHE_LRU_LIST;
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this_cpu_dec(nr_dentry_unused);
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WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
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}
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static void d_shrink_del(struct dentry *dentry)
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{
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D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
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list_del_init(&dentry->d_lru);
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dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
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this_cpu_dec(nr_dentry_unused);
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}
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static void d_shrink_add(struct dentry *dentry, struct list_head *list)
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{
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D_FLAG_VERIFY(dentry, 0);
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list_add(&dentry->d_lru, list);
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dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST;
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this_cpu_inc(nr_dentry_unused);
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}
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/*
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* These can only be called under the global LRU lock, ie during the
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* callback for freeing the LRU list. "isolate" removes it from the
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* LRU lists entirely, while shrink_move moves it to the indicated
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* private list.
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*/
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static void d_lru_isolate(struct dentry *dentry)
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{
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D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
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dentry->d_flags &= ~DCACHE_LRU_LIST;
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this_cpu_dec(nr_dentry_unused);
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list_del_init(&dentry->d_lru);
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}
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static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list)
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{
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D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
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dentry->d_flags |= DCACHE_SHRINK_LIST;
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list_move_tail(&dentry->d_lru, list);
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}
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/*
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* dentry_lru_(add|del)_list) must be called with d_lock held.
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*/
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static void dentry_lru_add(struct dentry *dentry)
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{
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if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
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d_lru_add(dentry);
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}
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/*
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* Remove a dentry with references from the LRU.
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*
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* If we are on the shrink list, then we can get to try_prune_one_dentry() and
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* lose our last reference through the parent walk. In this case, we need to
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* remove ourselves from the shrink list, not the LRU.
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*/
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static void dentry_lru_del(struct dentry *dentry)
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{
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if (dentry->d_flags & DCACHE_LRU_LIST) {
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if (dentry->d_flags & DCACHE_SHRINK_LIST)
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return d_shrink_del(dentry);
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d_lru_del(dentry);
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}
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}
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|
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/**
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* d_kill - kill dentry and return parent
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* @dentry: dentry to kill
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* @parent: parent dentry
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*
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* The dentry must already be unhashed and removed from the LRU.
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*
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* If this is the root of the dentry tree, return NULL.
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*
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* dentry->d_lock and parent->d_lock must be held by caller, and are dropped by
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* d_kill.
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*/
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static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
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__releases(dentry->d_lock)
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__releases(parent->d_lock)
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__releases(dentry->d_inode->i_lock)
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{
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list_del(&dentry->d_u.d_child);
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/*
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* Inform try_to_ascend() that we are no longer attached to the
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* dentry tree
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*/
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|
dentry->d_flags |= DCACHE_DENTRY_KILLED;
|
|
if (parent)
|
|
spin_unlock(&parent->d_lock);
|
|
dentry_iput(dentry);
|
|
/*
|
|
* dentry_iput drops the locks, at which point nobody (except
|
|
* transient RCU lookups) can reach this dentry.
|
|
*/
|
|
d_free(dentry);
|
|
return parent;
|
|
}
|
|
|
|
/*
|
|
* Unhash a dentry without inserting an RCU walk barrier or checking that
|
|
* dentry->d_lock is locked. The caller must take care of that, if
|
|
* appropriate.
|
|
*/
|
|
static void __d_shrink(struct dentry *dentry)
|
|
{
|
|
if (!d_unhashed(dentry)) {
|
|
struct hlist_bl_head *b;
|
|
if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
|
|
b = &dentry->d_sb->s_anon;
|
|
else
|
|
b = d_hash(dentry->d_parent, dentry->d_name.hash);
|
|
|
|
hlist_bl_lock(b);
|
|
__hlist_bl_del(&dentry->d_hash);
|
|
dentry->d_hash.pprev = NULL;
|
|
hlist_bl_unlock(b);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* d_drop - drop a dentry
|
|
* @dentry: dentry to drop
|
|
*
|
|
* d_drop() unhashes the entry from the parent dentry hashes, so that it won't
|
|
* be found through a VFS lookup any more. Note that this is different from
|
|
* deleting the dentry - d_delete will try to mark the dentry negative if
|
|
* possible, giving a successful _negative_ lookup, while d_drop will
|
|
* just make the cache lookup fail.
|
|
*
|
|
* d_drop() is used mainly for stuff that wants to invalidate a dentry for some
|
|
* reason (NFS timeouts or autofs deletes).
|
|
*
|
|
* __d_drop requires dentry->d_lock.
|
|
*/
|
|
void __d_drop(struct dentry *dentry)
|
|
{
|
|
if (!d_unhashed(dentry)) {
|
|
__d_shrink(dentry);
|
|
dentry_rcuwalk_barrier(dentry);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__d_drop);
|
|
|
|
void d_drop(struct dentry *dentry)
|
|
{
|
|
spin_lock(&dentry->d_lock);
|
|
__d_drop(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
EXPORT_SYMBOL(d_drop);
|
|
|
|
/*
|
|
* Finish off a dentry we've decided to kill.
|
|
* dentry->d_lock must be held, returns with it unlocked.
|
|
* If ref is non-zero, then decrement the refcount too.
|
|
* Returns dentry requiring refcount drop, or NULL if we're done.
|
|
*/
|
|
static struct dentry *
|
|
dentry_kill(struct dentry *dentry, int unlock_on_failure)
|
|
__releases(dentry->d_lock)
|
|
{
|
|
struct inode *inode;
|
|
struct dentry *parent;
|
|
|
|
inode = dentry->d_inode;
|
|
if (inode && !spin_trylock(&inode->i_lock)) {
|
|
relock:
|
|
if (unlock_on_failure) {
|
|
spin_unlock(&dentry->d_lock);
|
|
cpu_relax();
|
|
}
|
|
return dentry; /* try again with same dentry */
|
|
}
|
|
if (IS_ROOT(dentry))
|
|
parent = NULL;
|
|
else
|
|
parent = dentry->d_parent;
|
|
if (parent && !spin_trylock(&parent->d_lock)) {
|
|
if (inode)
|
|
spin_unlock(&inode->i_lock);
|
|
goto relock;
|
|
}
|
|
|
|
/*
|
|
* The dentry is now unrecoverably dead to the world.
|
|
*/
|
|
lockref_mark_dead(&dentry->d_lockref);
|
|
|
|
/*
|
|
* inform the fs via d_prune that this dentry is about to be
|
|
* unhashed and destroyed.
|
|
*/
|
|
if ((dentry->d_flags & DCACHE_OP_PRUNE) && !d_unhashed(dentry))
|
|
dentry->d_op->d_prune(dentry);
|
|
|
|
dentry_lru_del(dentry);
|
|
/* if it was on the hash then remove it */
|
|
__d_drop(dentry);
|
|
return d_kill(dentry, parent);
|
|
}
|
|
|
|
/*
|
|
* This is dput
|
|
*
|
|
* This is complicated by the fact that we do not want to put
|
|
* dentries that are no longer on any hash chain on the unused
|
|
* list: we'd much rather just get rid of them immediately.
|
|
*
|
|
* However, that implies that we have to traverse the dentry
|
|
* tree upwards to the parents which might _also_ now be
|
|
* scheduled for deletion (it may have been only waiting for
|
|
* its last child to go away).
|
|
*
|
|
* This tail recursion is done by hand as we don't want to depend
|
|
* on the compiler to always get this right (gcc generally doesn't).
|
|
* Real recursion would eat up our stack space.
|
|
*/
|
|
|
|
/*
|
|
* dput - release a dentry
|
|
* @dentry: dentry to release
|
|
*
|
|
* Release a dentry. This will drop the usage count and if appropriate
|
|
* call the dentry unlink method as well as removing it from the queues and
|
|
* releasing its resources. If the parent dentries were scheduled for release
|
|
* they too may now get deleted.
|
|
*/
|
|
void dput(struct dentry *dentry)
|
|
{
|
|
if (unlikely(!dentry))
|
|
return;
|
|
|
|
repeat:
|
|
if (lockref_put_or_lock(&dentry->d_lockref))
|
|
return;
|
|
|
|
/* Unreachable? Get rid of it */
|
|
if (unlikely(d_unhashed(dentry)))
|
|
goto kill_it;
|
|
|
|
if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
|
|
if (dentry->d_op->d_delete(dentry))
|
|
goto kill_it;
|
|
}
|
|
|
|
if (!(dentry->d_flags & DCACHE_REFERENCED))
|
|
dentry->d_flags |= DCACHE_REFERENCED;
|
|
dentry_lru_add(dentry);
|
|
|
|
dentry->d_lockref.count--;
|
|
spin_unlock(&dentry->d_lock);
|
|
return;
|
|
|
|
kill_it:
|
|
dentry = dentry_kill(dentry, 1);
|
|
if (dentry)
|
|
goto repeat;
|
|
}
|
|
EXPORT_SYMBOL(dput);
|
|
|
|
/**
|
|
* d_invalidate - invalidate a dentry
|
|
* @dentry: dentry to invalidate
|
|
*
|
|
* Try to invalidate the dentry if it turns out to be
|
|
* possible. If there are other dentries that can be
|
|
* reached through this one we can't delete it and we
|
|
* return -EBUSY. On success we return 0.
|
|
*
|
|
* no dcache lock.
|
|
*/
|
|
|
|
int d_invalidate(struct dentry * dentry)
|
|
{
|
|
/*
|
|
* If it's already been dropped, return OK.
|
|
*/
|
|
spin_lock(&dentry->d_lock);
|
|
if (d_unhashed(dentry)) {
|
|
spin_unlock(&dentry->d_lock);
|
|
return 0;
|
|
}
|
|
/*
|
|
* Check whether to do a partial shrink_dcache
|
|
* to get rid of unused child entries.
|
|
*/
|
|
if (!list_empty(&dentry->d_subdirs)) {
|
|
spin_unlock(&dentry->d_lock);
|
|
shrink_dcache_parent(dentry);
|
|
spin_lock(&dentry->d_lock);
|
|
}
|
|
|
|
/*
|
|
* Somebody else still using it?
|
|
*
|
|
* If it's a directory, we can't drop it
|
|
* for fear of somebody re-populating it
|
|
* with children (even though dropping it
|
|
* would make it unreachable from the root,
|
|
* we might still populate it if it was a
|
|
* working directory or similar).
|
|
* We also need to leave mountpoints alone,
|
|
* directory or not.
|
|
*/
|
|
if (dentry->d_lockref.count > 1 && dentry->d_inode) {
|
|
if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) {
|
|
spin_unlock(&dentry->d_lock);
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
|
|
__d_drop(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(d_invalidate);
|
|
|
|
/* This must be called with d_lock held */
|
|
static inline void __dget_dlock(struct dentry *dentry)
|
|
{
|
|
dentry->d_lockref.count++;
|
|
}
|
|
|
|
static inline void __dget(struct dentry *dentry)
|
|
{
|
|
lockref_get(&dentry->d_lockref);
|
|
}
|
|
|
|
struct dentry *dget_parent(struct dentry *dentry)
|
|
{
|
|
int gotref;
|
|
struct dentry *ret;
|
|
|
|
/*
|
|
* Do optimistic parent lookup without any
|
|
* locking.
|
|
*/
|
|
rcu_read_lock();
|
|
ret = ACCESS_ONCE(dentry->d_parent);
|
|
gotref = lockref_get_not_zero(&ret->d_lockref);
|
|
rcu_read_unlock();
|
|
if (likely(gotref)) {
|
|
if (likely(ret == ACCESS_ONCE(dentry->d_parent)))
|
|
return ret;
|
|
dput(ret);
|
|
}
|
|
|
|
repeat:
|
|
/*
|
|
* Don't need rcu_dereference because we re-check it was correct under
|
|
* the lock.
|
|
*/
|
|
rcu_read_lock();
|
|
ret = dentry->d_parent;
|
|
spin_lock(&ret->d_lock);
|
|
if (unlikely(ret != dentry->d_parent)) {
|
|
spin_unlock(&ret->d_lock);
|
|
rcu_read_unlock();
|
|
goto repeat;
|
|
}
|
|
rcu_read_unlock();
|
|
BUG_ON(!ret->d_lockref.count);
|
|
ret->d_lockref.count++;
|
|
spin_unlock(&ret->d_lock);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(dget_parent);
|
|
|
|
/**
|
|
* d_find_alias - grab a hashed alias of inode
|
|
* @inode: inode in question
|
|
* @want_discon: flag, used by d_splice_alias, to request
|
|
* that only a DISCONNECTED alias be returned.
|
|
*
|
|
* If inode has a hashed alias, or is a directory and has any alias,
|
|
* acquire the reference to alias and return it. Otherwise return NULL.
|
|
* Notice that if inode is a directory there can be only one alias and
|
|
* it can be unhashed only if it has no children, or if it is the root
|
|
* of a filesystem.
|
|
*
|
|
* If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
|
|
* any other hashed alias over that one unless @want_discon is set,
|
|
* in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
|
|
*/
|
|
static struct dentry *__d_find_alias(struct inode *inode, int want_discon)
|
|
{
|
|
struct dentry *alias, *discon_alias;
|
|
|
|
again:
|
|
discon_alias = NULL;
|
|
hlist_for_each_entry(alias, &inode->i_dentry, d_alias) {
|
|
spin_lock(&alias->d_lock);
|
|
if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
|
|
if (IS_ROOT(alias) &&
|
|
(alias->d_flags & DCACHE_DISCONNECTED)) {
|
|
discon_alias = alias;
|
|
} else if (!want_discon) {
|
|
__dget_dlock(alias);
|
|
spin_unlock(&alias->d_lock);
|
|
return alias;
|
|
}
|
|
}
|
|
spin_unlock(&alias->d_lock);
|
|
}
|
|
if (discon_alias) {
|
|
alias = discon_alias;
|
|
spin_lock(&alias->d_lock);
|
|
if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
|
|
if (IS_ROOT(alias) &&
|
|
(alias->d_flags & DCACHE_DISCONNECTED)) {
|
|
__dget_dlock(alias);
|
|
spin_unlock(&alias->d_lock);
|
|
return alias;
|
|
}
|
|
}
|
|
spin_unlock(&alias->d_lock);
|
|
goto again;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
struct dentry *d_find_alias(struct inode *inode)
|
|
{
|
|
struct dentry *de = NULL;
|
|
|
|
if (!hlist_empty(&inode->i_dentry)) {
|
|
spin_lock(&inode->i_lock);
|
|
de = __d_find_alias(inode, 0);
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
return de;
|
|
}
|
|
EXPORT_SYMBOL(d_find_alias);
|
|
|
|
/*
|
|
* Try to kill dentries associated with this inode.
|
|
* WARNING: you must own a reference to inode.
|
|
*/
|
|
void d_prune_aliases(struct inode *inode)
|
|
{
|
|
struct dentry *dentry;
|
|
restart:
|
|
spin_lock(&inode->i_lock);
|
|
hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
|
|
spin_lock(&dentry->d_lock);
|
|
if (!dentry->d_lockref.count) {
|
|
/*
|
|
* inform the fs via d_prune that this dentry
|
|
* is about to be unhashed and destroyed.
|
|
*/
|
|
if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
|
|
!d_unhashed(dentry))
|
|
dentry->d_op->d_prune(dentry);
|
|
|
|
__dget_dlock(dentry);
|
|
__d_drop(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
spin_unlock(&inode->i_lock);
|
|
dput(dentry);
|
|
goto restart;
|
|
}
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
EXPORT_SYMBOL(d_prune_aliases);
|
|
|
|
/*
|
|
* Try to throw away a dentry - free the inode, dput the parent.
|
|
* Requires dentry->d_lock is held, and dentry->d_count == 0.
|
|
* Releases dentry->d_lock.
|
|
*
|
|
* This may fail if locks cannot be acquired no problem, just try again.
|
|
*/
|
|
static struct dentry * try_prune_one_dentry(struct dentry *dentry)
|
|
__releases(dentry->d_lock)
|
|
{
|
|
struct dentry *parent;
|
|
|
|
parent = dentry_kill(dentry, 0);
|
|
/*
|
|
* If dentry_kill returns NULL, we have nothing more to do.
|
|
* if it returns the same dentry, trylocks failed. In either
|
|
* case, just loop again.
|
|
*
|
|
* Otherwise, we need to prune ancestors too. This is necessary
|
|
* to prevent quadratic behavior of shrink_dcache_parent(), but
|
|
* is also expected to be beneficial in reducing dentry cache
|
|
* fragmentation.
|
|
*/
|
|
if (!parent)
|
|
return NULL;
|
|
if (parent == dentry)
|
|
return dentry;
|
|
|
|
/* Prune ancestors. */
|
|
dentry = parent;
|
|
while (dentry) {
|
|
if (lockref_put_or_lock(&dentry->d_lockref))
|
|
return NULL;
|
|
dentry = dentry_kill(dentry, 1);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static void shrink_dentry_list(struct list_head *list)
|
|
{
|
|
struct dentry *dentry;
|
|
|
|
rcu_read_lock();
|
|
for (;;) {
|
|
dentry = list_entry_rcu(list->prev, struct dentry, d_lru);
|
|
if (&dentry->d_lru == list)
|
|
break; /* empty */
|
|
|
|
/*
|
|
* Get the dentry lock, and re-verify that the dentry is
|
|
* this on the shrinking list. If it is, we know that
|
|
* DCACHE_SHRINK_LIST and DCACHE_LRU_LIST are set.
|
|
*/
|
|
spin_lock(&dentry->d_lock);
|
|
if (dentry != list_entry(list->prev, struct dentry, d_lru)) {
|
|
spin_unlock(&dentry->d_lock);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The dispose list is isolated and dentries are not accounted
|
|
* to the LRU here, so we can simply remove it from the list
|
|
* here regardless of whether it is referenced or not.
|
|
*/
|
|
d_shrink_del(dentry);
|
|
|
|
/*
|
|
* We found an inuse dentry which was not removed from
|
|
* the LRU because of laziness during lookup. Do not free it.
|
|
*/
|
|
if (dentry->d_lockref.count) {
|
|
spin_unlock(&dentry->d_lock);
|
|
continue;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* If 'try_to_prune()' returns a dentry, it will
|
|
* be the same one we passed in, and d_lock will
|
|
* have been held the whole time, so it will not
|
|
* have been added to any other lists. We failed
|
|
* to get the inode lock.
|
|
*
|
|
* We just add it back to the shrink list.
|
|
*/
|
|
dentry = try_prune_one_dentry(dentry);
|
|
|
|
rcu_read_lock();
|
|
if (dentry) {
|
|
d_shrink_add(dentry, list);
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static enum lru_status
|
|
dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg)
|
|
{
|
|
struct list_head *freeable = arg;
|
|
struct dentry *dentry = container_of(item, struct dentry, d_lru);
|
|
|
|
|
|
/*
|
|
* we are inverting the lru lock/dentry->d_lock here,
|
|
* so use a trylock. If we fail to get the lock, just skip
|
|
* it
|
|
*/
|
|
if (!spin_trylock(&dentry->d_lock))
|
|
return LRU_SKIP;
|
|
|
|
/*
|
|
* Referenced dentries are still in use. If they have active
|
|
* counts, just remove them from the LRU. Otherwise give them
|
|
* another pass through the LRU.
|
|
*/
|
|
if (dentry->d_lockref.count) {
|
|
d_lru_isolate(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
return LRU_REMOVED;
|
|
}
|
|
|
|
if (dentry->d_flags & DCACHE_REFERENCED) {
|
|
dentry->d_flags &= ~DCACHE_REFERENCED;
|
|
spin_unlock(&dentry->d_lock);
|
|
|
|
/*
|
|
* The list move itself will be made by the common LRU code. At
|
|
* this point, we've dropped the dentry->d_lock but keep the
|
|
* lru lock. This is safe to do, since every list movement is
|
|
* protected by the lru lock even if both locks are held.
|
|
*
|
|
* This is guaranteed by the fact that all LRU management
|
|
* functions are intermediated by the LRU API calls like
|
|
* list_lru_add and list_lru_del. List movement in this file
|
|
* only ever occur through this functions or through callbacks
|
|
* like this one, that are called from the LRU API.
|
|
*
|
|
* The only exceptions to this are functions like
|
|
* shrink_dentry_list, and code that first checks for the
|
|
* DCACHE_SHRINK_LIST flag. Those are guaranteed to be
|
|
* operating only with stack provided lists after they are
|
|
* properly isolated from the main list. It is thus, always a
|
|
* local access.
|
|
*/
|
|
return LRU_ROTATE;
|
|
}
|
|
|
|
d_lru_shrink_move(dentry, freeable);
|
|
spin_unlock(&dentry->d_lock);
|
|
|
|
return LRU_REMOVED;
|
|
}
|
|
|
|
/**
|
|
* prune_dcache_sb - shrink the dcache
|
|
* @sb: superblock
|
|
* @nr_to_scan : number of entries to try to free
|
|
* @nid: which node to scan for freeable entities
|
|
*
|
|
* Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
|
|
* done when we need more memory an called from the superblock shrinker
|
|
* function.
|
|
*
|
|
* This function may fail to free any resources if all the dentries are in
|
|
* use.
|
|
*/
|
|
long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan,
|
|
int nid)
|
|
{
|
|
LIST_HEAD(dispose);
|
|
long freed;
|
|
|
|
freed = list_lru_walk_node(&sb->s_dentry_lru, nid, dentry_lru_isolate,
|
|
&dispose, &nr_to_scan);
|
|
shrink_dentry_list(&dispose);
|
|
return freed;
|
|
}
|
|
|
|
static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
|
|
spinlock_t *lru_lock, void *arg)
|
|
{
|
|
struct list_head *freeable = arg;
|
|
struct dentry *dentry = container_of(item, struct dentry, d_lru);
|
|
|
|
/*
|
|
* we are inverting the lru lock/dentry->d_lock here,
|
|
* so use a trylock. If we fail to get the lock, just skip
|
|
* it
|
|
*/
|
|
if (!spin_trylock(&dentry->d_lock))
|
|
return LRU_SKIP;
|
|
|
|
d_lru_shrink_move(dentry, freeable);
|
|
spin_unlock(&dentry->d_lock);
|
|
|
|
return LRU_REMOVED;
|
|
}
|
|
|
|
|
|
/**
|
|
* shrink_dcache_sb - shrink dcache for a superblock
|
|
* @sb: superblock
|
|
*
|
|
* Shrink the dcache for the specified super block. This is used to free
|
|
* the dcache before unmounting a file system.
|
|
*/
|
|
void shrink_dcache_sb(struct super_block *sb)
|
|
{
|
|
long freed;
|
|
|
|
do {
|
|
LIST_HEAD(dispose);
|
|
|
|
freed = list_lru_walk(&sb->s_dentry_lru,
|
|
dentry_lru_isolate_shrink, &dispose, UINT_MAX);
|
|
|
|
this_cpu_sub(nr_dentry_unused, freed);
|
|
shrink_dentry_list(&dispose);
|
|
} while (freed > 0);
|
|
}
|
|
EXPORT_SYMBOL(shrink_dcache_sb);
|
|
|
|
/*
|
|
* destroy a single subtree of dentries for unmount
|
|
* - see the comments on shrink_dcache_for_umount() for a description of the
|
|
* locking
|
|
*/
|
|
static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
|
|
{
|
|
struct dentry *parent;
|
|
|
|
BUG_ON(!IS_ROOT(dentry));
|
|
|
|
for (;;) {
|
|
/* descend to the first leaf in the current subtree */
|
|
while (!list_empty(&dentry->d_subdirs))
|
|
dentry = list_entry(dentry->d_subdirs.next,
|
|
struct dentry, d_u.d_child);
|
|
|
|
/* consume the dentries from this leaf up through its parents
|
|
* until we find one with children or run out altogether */
|
|
do {
|
|
struct inode *inode;
|
|
|
|
/*
|
|
* inform the fs that this dentry is about to be
|
|
* unhashed and destroyed.
|
|
*/
|
|
if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
|
|
!d_unhashed(dentry))
|
|
dentry->d_op->d_prune(dentry);
|
|
|
|
dentry_lru_del(dentry);
|
|
__d_shrink(dentry);
|
|
|
|
if (dentry->d_lockref.count != 0) {
|
|
printk(KERN_ERR
|
|
"BUG: Dentry %p{i=%lx,n=%s}"
|
|
" still in use (%d)"
|
|
" [unmount of %s %s]\n",
|
|
dentry,
|
|
dentry->d_inode ?
|
|
dentry->d_inode->i_ino : 0UL,
|
|
dentry->d_name.name,
|
|
dentry->d_lockref.count,
|
|
dentry->d_sb->s_type->name,
|
|
dentry->d_sb->s_id);
|
|
BUG();
|
|
}
|
|
|
|
if (IS_ROOT(dentry)) {
|
|
parent = NULL;
|
|
list_del(&dentry->d_u.d_child);
|
|
} else {
|
|
parent = dentry->d_parent;
|
|
parent->d_lockref.count--;
|
|
list_del(&dentry->d_u.d_child);
|
|
}
|
|
|
|
inode = dentry->d_inode;
|
|
if (inode) {
|
|
dentry->d_inode = NULL;
|
|
hlist_del_init(&dentry->d_alias);
|
|
if (dentry->d_op && dentry->d_op->d_iput)
|
|
dentry->d_op->d_iput(dentry, inode);
|
|
else
|
|
iput(inode);
|
|
}
|
|
|
|
d_free(dentry);
|
|
|
|
/* finished when we fall off the top of the tree,
|
|
* otherwise we ascend to the parent and move to the
|
|
* next sibling if there is one */
|
|
if (!parent)
|
|
return;
|
|
dentry = parent;
|
|
} while (list_empty(&dentry->d_subdirs));
|
|
|
|
dentry = list_entry(dentry->d_subdirs.next,
|
|
struct dentry, d_u.d_child);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* destroy the dentries attached to a superblock on unmounting
|
|
* - we don't need to use dentry->d_lock because:
|
|
* - the superblock is detached from all mountings and open files, so the
|
|
* dentry trees will not be rearranged by the VFS
|
|
* - s_umount is write-locked, so the memory pressure shrinker will ignore
|
|
* any dentries belonging to this superblock that it comes across
|
|
* - the filesystem itself is no longer permitted to rearrange the dentries
|
|
* in this superblock
|
|
*/
|
|
void shrink_dcache_for_umount(struct super_block *sb)
|
|
{
|
|
struct dentry *dentry;
|
|
|
|
if (down_read_trylock(&sb->s_umount))
|
|
BUG();
|
|
|
|
dentry = sb->s_root;
|
|
sb->s_root = NULL;
|
|
dentry->d_lockref.count--;
|
|
shrink_dcache_for_umount_subtree(dentry);
|
|
|
|
while (!hlist_bl_empty(&sb->s_anon)) {
|
|
dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
|
|
shrink_dcache_for_umount_subtree(dentry);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This tries to ascend one level of parenthood, but
|
|
* we can race with renaming, so we need to re-check
|
|
* the parenthood after dropping the lock and check
|
|
* that the sequence number still matches.
|
|
*/
|
|
static struct dentry *try_to_ascend(struct dentry *old, unsigned seq)
|
|
{
|
|
struct dentry *new = old->d_parent;
|
|
|
|
rcu_read_lock();
|
|
spin_unlock(&old->d_lock);
|
|
spin_lock(&new->d_lock);
|
|
|
|
/*
|
|
* might go back up the wrong parent if we have had a rename
|
|
* or deletion
|
|
*/
|
|
if (new != old->d_parent ||
|
|
(old->d_flags & DCACHE_DENTRY_KILLED) ||
|
|
need_seqretry(&rename_lock, seq)) {
|
|
spin_unlock(&new->d_lock);
|
|
new = NULL;
|
|
}
|
|
rcu_read_unlock();
|
|
return new;
|
|
}
|
|
|
|
/**
|
|
* enum d_walk_ret - action to talke during tree walk
|
|
* @D_WALK_CONTINUE: contrinue walk
|
|
* @D_WALK_QUIT: quit walk
|
|
* @D_WALK_NORETRY: quit when retry is needed
|
|
* @D_WALK_SKIP: skip this dentry and its children
|
|
*/
|
|
enum d_walk_ret {
|
|
D_WALK_CONTINUE,
|
|
D_WALK_QUIT,
|
|
D_WALK_NORETRY,
|
|
D_WALK_SKIP,
|
|
};
|
|
|
|
/**
|
|
* d_walk - walk the dentry tree
|
|
* @parent: start of walk
|
|
* @data: data passed to @enter() and @finish()
|
|
* @enter: callback when first entering the dentry
|
|
* @finish: callback when successfully finished the walk
|
|
*
|
|
* The @enter() and @finish() callbacks are called with d_lock held.
|
|
*/
|
|
static void d_walk(struct dentry *parent, void *data,
|
|
enum d_walk_ret (*enter)(void *, struct dentry *),
|
|
void (*finish)(void *))
|
|
{
|
|
struct dentry *this_parent;
|
|
struct list_head *next;
|
|
unsigned seq = 0;
|
|
enum d_walk_ret ret;
|
|
bool retry = true;
|
|
|
|
again:
|
|
read_seqbegin_or_lock(&rename_lock, &seq);
|
|
this_parent = parent;
|
|
spin_lock(&this_parent->d_lock);
|
|
|
|
ret = enter(data, this_parent);
|
|
switch (ret) {
|
|
case D_WALK_CONTINUE:
|
|
break;
|
|
case D_WALK_QUIT:
|
|
case D_WALK_SKIP:
|
|
goto out_unlock;
|
|
case D_WALK_NORETRY:
|
|
retry = false;
|
|
break;
|
|
}
|
|
repeat:
|
|
next = this_parent->d_subdirs.next;
|
|
resume:
|
|
while (next != &this_parent->d_subdirs) {
|
|
struct list_head *tmp = next;
|
|
struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
|
|
next = tmp->next;
|
|
|
|
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
|
|
|
|
ret = enter(data, dentry);
|
|
switch (ret) {
|
|
case D_WALK_CONTINUE:
|
|
break;
|
|
case D_WALK_QUIT:
|
|
spin_unlock(&dentry->d_lock);
|
|
goto out_unlock;
|
|
case D_WALK_NORETRY:
|
|
retry = false;
|
|
break;
|
|
case D_WALK_SKIP:
|
|
spin_unlock(&dentry->d_lock);
|
|
continue;
|
|
}
|
|
|
|
if (!list_empty(&dentry->d_subdirs)) {
|
|
spin_unlock(&this_parent->d_lock);
|
|
spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
|
|
this_parent = dentry;
|
|
spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
|
|
goto repeat;
|
|
}
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
/*
|
|
* All done at this level ... ascend and resume the search.
|
|
*/
|
|
if (this_parent != parent) {
|
|
struct dentry *child = this_parent;
|
|
this_parent = try_to_ascend(this_parent, seq);
|
|
if (!this_parent)
|
|
goto rename_retry;
|
|
next = child->d_u.d_child.next;
|
|
goto resume;
|
|
}
|
|
if (need_seqretry(&rename_lock, seq)) {
|
|
spin_unlock(&this_parent->d_lock);
|
|
goto rename_retry;
|
|
}
|
|
if (finish)
|
|
finish(data);
|
|
|
|
out_unlock:
|
|
spin_unlock(&this_parent->d_lock);
|
|
done_seqretry(&rename_lock, seq);
|
|
return;
|
|
|
|
rename_retry:
|
|
if (!retry)
|
|
return;
|
|
seq = 1;
|
|
goto again;
|
|
}
|
|
|
|
/*
|
|
* Search for at least 1 mount point in the dentry's subdirs.
|
|
* We descend to the next level whenever the d_subdirs
|
|
* list is non-empty and continue searching.
|
|
*/
|
|
|
|
static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
|
|
{
|
|
int *ret = data;
|
|
if (d_mountpoint(dentry)) {
|
|
*ret = 1;
|
|
return D_WALK_QUIT;
|
|
}
|
|
return D_WALK_CONTINUE;
|
|
}
|
|
|
|
/**
|
|
* have_submounts - check for mounts over a dentry
|
|
* @parent: dentry to check.
|
|
*
|
|
* Return true if the parent or its subdirectories contain
|
|
* a mount point
|
|
*/
|
|
int have_submounts(struct dentry *parent)
|
|
{
|
|
int ret = 0;
|
|
|
|
d_walk(parent, &ret, check_mount, NULL);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(have_submounts);
|
|
|
|
/*
|
|
* Called by mount code to set a mountpoint and check if the mountpoint is
|
|
* reachable (e.g. NFS can unhash a directory dentry and then the complete
|
|
* subtree can become unreachable).
|
|
*
|
|
* Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For
|
|
* this reason take rename_lock and d_lock on dentry and ancestors.
|
|
*/
|
|
int d_set_mounted(struct dentry *dentry)
|
|
{
|
|
struct dentry *p;
|
|
int ret = -ENOENT;
|
|
write_seqlock(&rename_lock);
|
|
for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
|
|
/* Need exclusion wrt. check_submounts_and_drop() */
|
|
spin_lock(&p->d_lock);
|
|
if (unlikely(d_unhashed(p))) {
|
|
spin_unlock(&p->d_lock);
|
|
goto out;
|
|
}
|
|
spin_unlock(&p->d_lock);
|
|
}
|
|
spin_lock(&dentry->d_lock);
|
|
if (!d_unlinked(dentry)) {
|
|
dentry->d_flags |= DCACHE_MOUNTED;
|
|
ret = 0;
|
|
}
|
|
spin_unlock(&dentry->d_lock);
|
|
out:
|
|
write_sequnlock(&rename_lock);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Search the dentry child list of the specified parent,
|
|
* and move any unused dentries to the end of the unused
|
|
* list for prune_dcache(). We descend to the next level
|
|
* whenever the d_subdirs list is non-empty and continue
|
|
* searching.
|
|
*
|
|
* It returns zero iff there are no unused children,
|
|
* otherwise it returns the number of children moved to
|
|
* the end of the unused list. This may not be the total
|
|
* number of unused children, because select_parent can
|
|
* drop the lock and return early due to latency
|
|
* constraints.
|
|
*/
|
|
|
|
struct select_data {
|
|
struct dentry *start;
|
|
struct list_head dispose;
|
|
int found;
|
|
};
|
|
|
|
static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
|
|
{
|
|
struct select_data *data = _data;
|
|
enum d_walk_ret ret = D_WALK_CONTINUE;
|
|
|
|
if (data->start == dentry)
|
|
goto out;
|
|
|
|
/*
|
|
* move only zero ref count dentries to the dispose list.
|
|
*
|
|
* Those which are presently on the shrink list, being processed
|
|
* by shrink_dentry_list(), shouldn't be moved. Otherwise the
|
|
* loop in shrink_dcache_parent() might not make any progress
|
|
* and loop forever.
|
|
*/
|
|
if (dentry->d_lockref.count) {
|
|
dentry_lru_del(dentry);
|
|
} else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
|
|
/*
|
|
* We can't use d_lru_shrink_move() because we
|
|
* need to get the global LRU lock and do the
|
|
* LRU accounting.
|
|
*/
|
|
d_lru_del(dentry);
|
|
d_shrink_add(dentry, &data->dispose);
|
|
data->found++;
|
|
ret = D_WALK_NORETRY;
|
|
}
|
|
/*
|
|
* We can return to the caller if we have found some (this
|
|
* ensures forward progress). We'll be coming back to find
|
|
* the rest.
|
|
*/
|
|
if (data->found && need_resched())
|
|
ret = D_WALK_QUIT;
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* shrink_dcache_parent - prune dcache
|
|
* @parent: parent of entries to prune
|
|
*
|
|
* Prune the dcache to remove unused children of the parent dentry.
|
|
*/
|
|
void shrink_dcache_parent(struct dentry *parent)
|
|
{
|
|
for (;;) {
|
|
struct select_data data;
|
|
|
|
INIT_LIST_HEAD(&data.dispose);
|
|
data.start = parent;
|
|
data.found = 0;
|
|
|
|
d_walk(parent, &data, select_collect, NULL);
|
|
if (!data.found)
|
|
break;
|
|
|
|
shrink_dentry_list(&data.dispose);
|
|
cond_resched();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(shrink_dcache_parent);
|
|
|
|
static enum d_walk_ret check_and_collect(void *_data, struct dentry *dentry)
|
|
{
|
|
struct select_data *data = _data;
|
|
|
|
if (d_mountpoint(dentry)) {
|
|
data->found = -EBUSY;
|
|
return D_WALK_QUIT;
|
|
}
|
|
|
|
return select_collect(_data, dentry);
|
|
}
|
|
|
|
static void check_and_drop(void *_data)
|
|
{
|
|
struct select_data *data = _data;
|
|
|
|
if (d_mountpoint(data->start))
|
|
data->found = -EBUSY;
|
|
if (!data->found)
|
|
__d_drop(data->start);
|
|
}
|
|
|
|
/**
|
|
* check_submounts_and_drop - prune dcache, check for submounts and drop
|
|
*
|
|
* All done as a single atomic operation relative to has_unlinked_ancestor().
|
|
* Returns 0 if successfully unhashed @parent. If there were submounts then
|
|
* return -EBUSY.
|
|
*
|
|
* @dentry: dentry to prune and drop
|
|
*/
|
|
int check_submounts_and_drop(struct dentry *dentry)
|
|
{
|
|
int ret = 0;
|
|
|
|
/* Negative dentries can be dropped without further checks */
|
|
if (!dentry->d_inode) {
|
|
d_drop(dentry);
|
|
goto out;
|
|
}
|
|
|
|
for (;;) {
|
|
struct select_data data;
|
|
|
|
INIT_LIST_HEAD(&data.dispose);
|
|
data.start = dentry;
|
|
data.found = 0;
|
|
|
|
d_walk(dentry, &data, check_and_collect, check_and_drop);
|
|
ret = data.found;
|
|
|
|
if (!list_empty(&data.dispose))
|
|
shrink_dentry_list(&data.dispose);
|
|
|
|
if (ret <= 0)
|
|
break;
|
|
|
|
cond_resched();
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(check_submounts_and_drop);
|
|
|
|
/**
|
|
* __d_alloc - allocate a dcache entry
|
|
* @sb: filesystem it will belong to
|
|
* @name: qstr of the name
|
|
*
|
|
* Allocates a dentry. It returns %NULL if there is insufficient memory
|
|
* available. On a success the dentry is returned. The name passed in is
|
|
* copied and the copy passed in may be reused after this call.
|
|
*/
|
|
|
|
struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
|
|
{
|
|
struct dentry *dentry;
|
|
char *dname;
|
|
|
|
dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
|
|
if (!dentry)
|
|
return NULL;
|
|
|
|
/*
|
|
* We guarantee that the inline name is always NUL-terminated.
|
|
* This way the memcpy() done by the name switching in rename
|
|
* will still always have a NUL at the end, even if we might
|
|
* be overwriting an internal NUL character
|
|
*/
|
|
dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
|
|
if (name->len > DNAME_INLINE_LEN-1) {
|
|
dname = kmalloc(name->len + 1, GFP_KERNEL);
|
|
if (!dname) {
|
|
kmem_cache_free(dentry_cache, dentry);
|
|
return NULL;
|
|
}
|
|
} else {
|
|
dname = dentry->d_iname;
|
|
}
|
|
|
|
dentry->d_name.len = name->len;
|
|
dentry->d_name.hash = name->hash;
|
|
memcpy(dname, name->name, name->len);
|
|
dname[name->len] = 0;
|
|
|
|
/* Make sure we always see the terminating NUL character */
|
|
smp_wmb();
|
|
dentry->d_name.name = dname;
|
|
|
|
dentry->d_lockref.count = 1;
|
|
dentry->d_flags = 0;
|
|
spin_lock_init(&dentry->d_lock);
|
|
seqcount_init(&dentry->d_seq);
|
|
dentry->d_inode = NULL;
|
|
dentry->d_parent = dentry;
|
|
dentry->d_sb = sb;
|
|
dentry->d_op = NULL;
|
|
dentry->d_fsdata = NULL;
|
|
INIT_HLIST_BL_NODE(&dentry->d_hash);
|
|
INIT_LIST_HEAD(&dentry->d_lru);
|
|
INIT_LIST_HEAD(&dentry->d_subdirs);
|
|
INIT_HLIST_NODE(&dentry->d_alias);
|
|
INIT_LIST_HEAD(&dentry->d_u.d_child);
|
|
d_set_d_op(dentry, dentry->d_sb->s_d_op);
|
|
|
|
this_cpu_inc(nr_dentry);
|
|
|
|
return dentry;
|
|
}
|
|
|
|
/**
|
|
* d_alloc - allocate a dcache entry
|
|
* @parent: parent of entry to allocate
|
|
* @name: qstr of the name
|
|
*
|
|
* Allocates a dentry. It returns %NULL if there is insufficient memory
|
|
* available. On a success the dentry is returned. The name passed in is
|
|
* copied and the copy passed in may be reused after this call.
|
|
*/
|
|
struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
|
|
{
|
|
struct dentry *dentry = __d_alloc(parent->d_sb, name);
|
|
if (!dentry)
|
|
return NULL;
|
|
|
|
spin_lock(&parent->d_lock);
|
|
/*
|
|
* don't need child lock because it is not subject
|
|
* to concurrency here
|
|
*/
|
|
__dget_dlock(parent);
|
|
dentry->d_parent = parent;
|
|
list_add(&dentry->d_u.d_child, &parent->d_subdirs);
|
|
spin_unlock(&parent->d_lock);
|
|
|
|
return dentry;
|
|
}
|
|
EXPORT_SYMBOL(d_alloc);
|
|
|
|
struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
|
|
{
|
|
struct dentry *dentry = __d_alloc(sb, name);
|
|
if (dentry)
|
|
dentry->d_flags |= DCACHE_DISCONNECTED;
|
|
return dentry;
|
|
}
|
|
EXPORT_SYMBOL(d_alloc_pseudo);
|
|
|
|
struct dentry *d_alloc_name(struct dentry *parent, const char *name)
|
|
{
|
|
struct qstr q;
|
|
|
|
q.name = name;
|
|
q.len = strlen(name);
|
|
q.hash = full_name_hash(q.name, q.len);
|
|
return d_alloc(parent, &q);
|
|
}
|
|
EXPORT_SYMBOL(d_alloc_name);
|
|
|
|
void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
|
|
{
|
|
WARN_ON_ONCE(dentry->d_op);
|
|
WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
|
|
DCACHE_OP_COMPARE |
|
|
DCACHE_OP_REVALIDATE |
|
|
DCACHE_OP_WEAK_REVALIDATE |
|
|
DCACHE_OP_DELETE ));
|
|
dentry->d_op = op;
|
|
if (!op)
|
|
return;
|
|
if (op->d_hash)
|
|
dentry->d_flags |= DCACHE_OP_HASH;
|
|
if (op->d_compare)
|
|
dentry->d_flags |= DCACHE_OP_COMPARE;
|
|
if (op->d_revalidate)
|
|
dentry->d_flags |= DCACHE_OP_REVALIDATE;
|
|
if (op->d_weak_revalidate)
|
|
dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE;
|
|
if (op->d_delete)
|
|
dentry->d_flags |= DCACHE_OP_DELETE;
|
|
if (op->d_prune)
|
|
dentry->d_flags |= DCACHE_OP_PRUNE;
|
|
|
|
}
|
|
EXPORT_SYMBOL(d_set_d_op);
|
|
|
|
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
|
|
{
|
|
spin_lock(&dentry->d_lock);
|
|
if (inode) {
|
|
if (unlikely(IS_AUTOMOUNT(inode)))
|
|
dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
|
|
hlist_add_head(&dentry->d_alias, &inode->i_dentry);
|
|
}
|
|
dentry->d_inode = inode;
|
|
dentry_rcuwalk_barrier(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
fsnotify_d_instantiate(dentry, inode);
|
|
}
|
|
|
|
/**
|
|
* d_instantiate - fill in inode information for a dentry
|
|
* @entry: dentry to complete
|
|
* @inode: inode to attach to this dentry
|
|
*
|
|
* Fill in inode information in the entry.
|
|
*
|
|
* This turns negative dentries into productive full members
|
|
* of society.
|
|
*
|
|
* NOTE! This assumes that the inode count has been incremented
|
|
* (or otherwise set) by the caller to indicate that it is now
|
|
* in use by the dcache.
|
|
*/
|
|
|
|
void d_instantiate(struct dentry *entry, struct inode * inode)
|
|
{
|
|
BUG_ON(!hlist_unhashed(&entry->d_alias));
|
|
if (inode)
|
|
spin_lock(&inode->i_lock);
|
|
__d_instantiate(entry, inode);
|
|
if (inode)
|
|
spin_unlock(&inode->i_lock);
|
|
security_d_instantiate(entry, inode);
|
|
}
|
|
EXPORT_SYMBOL(d_instantiate);
|
|
|
|
/**
|
|
* d_instantiate_unique - instantiate a non-aliased dentry
|
|
* @entry: dentry to instantiate
|
|
* @inode: inode to attach to this dentry
|
|
*
|
|
* Fill in inode information in the entry. On success, it returns NULL.
|
|
* If an unhashed alias of "entry" already exists, then we return the
|
|
* aliased dentry instead and drop one reference to inode.
|
|
*
|
|
* Note that in order to avoid conflicts with rename() etc, the caller
|
|
* had better be holding the parent directory semaphore.
|
|
*
|
|
* This also assumes that the inode count has been incremented
|
|
* (or otherwise set) by the caller to indicate that it is now
|
|
* in use by the dcache.
|
|
*/
|
|
static struct dentry *__d_instantiate_unique(struct dentry *entry,
|
|
struct inode *inode)
|
|
{
|
|
struct dentry *alias;
|
|
int len = entry->d_name.len;
|
|
const char *name = entry->d_name.name;
|
|
unsigned int hash = entry->d_name.hash;
|
|
|
|
if (!inode) {
|
|
__d_instantiate(entry, NULL);
|
|
return NULL;
|
|
}
|
|
|
|
hlist_for_each_entry(alias, &inode->i_dentry, d_alias) {
|
|
/*
|
|
* Don't need alias->d_lock here, because aliases with
|
|
* d_parent == entry->d_parent are not subject to name or
|
|
* parent changes, because the parent inode i_mutex is held.
|
|
*/
|
|
if (alias->d_name.hash != hash)
|
|
continue;
|
|
if (alias->d_parent != entry->d_parent)
|
|
continue;
|
|
if (alias->d_name.len != len)
|
|
continue;
|
|
if (dentry_cmp(alias, name, len))
|
|
continue;
|
|
__dget(alias);
|
|
return alias;
|
|
}
|
|
|
|
__d_instantiate(entry, inode);
|
|
return NULL;
|
|
}
|
|
|
|
struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
|
|
{
|
|
struct dentry *result;
|
|
|
|
BUG_ON(!hlist_unhashed(&entry->d_alias));
|
|
|
|
if (inode)
|
|
spin_lock(&inode->i_lock);
|
|
result = __d_instantiate_unique(entry, inode);
|
|
if (inode)
|
|
spin_unlock(&inode->i_lock);
|
|
|
|
if (!result) {
|
|
security_d_instantiate(entry, inode);
|
|
return NULL;
|
|
}
|
|
|
|
BUG_ON(!d_unhashed(result));
|
|
iput(inode);
|
|
return result;
|
|
}
|
|
|
|
EXPORT_SYMBOL(d_instantiate_unique);
|
|
|
|
struct dentry *d_make_root(struct inode *root_inode)
|
|
{
|
|
struct dentry *res = NULL;
|
|
|
|
if (root_inode) {
|
|
static const struct qstr name = QSTR_INIT("/", 1);
|
|
|
|
res = __d_alloc(root_inode->i_sb, &name);
|
|
if (res)
|
|
d_instantiate(res, root_inode);
|
|
else
|
|
iput(root_inode);
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(d_make_root);
|
|
|
|
static struct dentry * __d_find_any_alias(struct inode *inode)
|
|
{
|
|
struct dentry *alias;
|
|
|
|
if (hlist_empty(&inode->i_dentry))
|
|
return NULL;
|
|
alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias);
|
|
__dget(alias);
|
|
return alias;
|
|
}
|
|
|
|
/**
|
|
* d_find_any_alias - find any alias for a given inode
|
|
* @inode: inode to find an alias for
|
|
*
|
|
* If any aliases exist for the given inode, take and return a
|
|
* reference for one of them. If no aliases exist, return %NULL.
|
|
*/
|
|
struct dentry *d_find_any_alias(struct inode *inode)
|
|
{
|
|
struct dentry *de;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
de = __d_find_any_alias(inode);
|
|
spin_unlock(&inode->i_lock);
|
|
return de;
|
|
}
|
|
EXPORT_SYMBOL(d_find_any_alias);
|
|
|
|
/**
|
|
* d_obtain_alias - find or allocate a dentry for a given inode
|
|
* @inode: inode to allocate the dentry for
|
|
*
|
|
* Obtain a dentry for an inode resulting from NFS filehandle conversion or
|
|
* similar open by handle operations. The returned dentry may be anonymous,
|
|
* or may have a full name (if the inode was already in the cache).
|
|
*
|
|
* When called on a directory inode, we must ensure that the inode only ever
|
|
* has one dentry. If a dentry is found, that is returned instead of
|
|
* allocating a new one.
|
|
*
|
|
* On successful return, the reference to the inode has been transferred
|
|
* to the dentry. In case of an error the reference on the inode is released.
|
|
* To make it easier to use in export operations a %NULL or IS_ERR inode may
|
|
* be passed in and will be the error will be propagate to the return value,
|
|
* with a %NULL @inode replaced by ERR_PTR(-ESTALE).
|
|
*/
|
|
struct dentry *d_obtain_alias(struct inode *inode)
|
|
{
|
|
static const struct qstr anonstring = QSTR_INIT("/", 1);
|
|
struct dentry *tmp;
|
|
struct dentry *res;
|
|
|
|
if (!inode)
|
|
return ERR_PTR(-ESTALE);
|
|
if (IS_ERR(inode))
|
|
return ERR_CAST(inode);
|
|
|
|
res = d_find_any_alias(inode);
|
|
if (res)
|
|
goto out_iput;
|
|
|
|
tmp = __d_alloc(inode->i_sb, &anonstring);
|
|
if (!tmp) {
|
|
res = ERR_PTR(-ENOMEM);
|
|
goto out_iput;
|
|
}
|
|
|
|
spin_lock(&inode->i_lock);
|
|
res = __d_find_any_alias(inode);
|
|
if (res) {
|
|
spin_unlock(&inode->i_lock);
|
|
dput(tmp);
|
|
goto out_iput;
|
|
}
|
|
|
|
/* attach a disconnected dentry */
|
|
spin_lock(&tmp->d_lock);
|
|
tmp->d_inode = inode;
|
|
tmp->d_flags |= DCACHE_DISCONNECTED;
|
|
hlist_add_head(&tmp->d_alias, &inode->i_dentry);
|
|
hlist_bl_lock(&tmp->d_sb->s_anon);
|
|
hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
|
|
hlist_bl_unlock(&tmp->d_sb->s_anon);
|
|
spin_unlock(&tmp->d_lock);
|
|
spin_unlock(&inode->i_lock);
|
|
security_d_instantiate(tmp, inode);
|
|
|
|
return tmp;
|
|
|
|
out_iput:
|
|
if (res && !IS_ERR(res))
|
|
security_d_instantiate(res, inode);
|
|
iput(inode);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(d_obtain_alias);
|
|
|
|
/**
|
|
* d_splice_alias - splice a disconnected dentry into the tree if one exists
|
|
* @inode: the inode which may have a disconnected dentry
|
|
* @dentry: a negative dentry which we want to point to the inode.
|
|
*
|
|
* If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
|
|
* DCACHE_DISCONNECTED), then d_move that in place of the given dentry
|
|
* and return it, else simply d_add the inode to the dentry and return NULL.
|
|
*
|
|
* This is needed in the lookup routine of any filesystem that is exportable
|
|
* (via knfsd) so that we can build dcache paths to directories effectively.
|
|
*
|
|
* If a dentry was found and moved, then it is returned. Otherwise NULL
|
|
* is returned. This matches the expected return value of ->lookup.
|
|
*
|
|
* Cluster filesystems may call this function with a negative, hashed dentry.
|
|
* In that case, we know that the inode will be a regular file, and also this
|
|
* will only occur during atomic_open. So we need to check for the dentry
|
|
* being already hashed only in the final case.
|
|
*/
|
|
struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
|
|
{
|
|
struct dentry *new = NULL;
|
|
|
|
if (IS_ERR(inode))
|
|
return ERR_CAST(inode);
|
|
|
|
if (inode && S_ISDIR(inode->i_mode)) {
|
|
spin_lock(&inode->i_lock);
|
|
new = __d_find_alias(inode, 1);
|
|
if (new) {
|
|
BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
|
|
spin_unlock(&inode->i_lock);
|
|
security_d_instantiate(new, inode);
|
|
d_move(new, dentry);
|
|
iput(inode);
|
|
} else {
|
|
/* already taking inode->i_lock, so d_add() by hand */
|
|
__d_instantiate(dentry, inode);
|
|
spin_unlock(&inode->i_lock);
|
|
security_d_instantiate(dentry, inode);
|
|
d_rehash(dentry);
|
|
}
|
|
} else {
|
|
d_instantiate(dentry, inode);
|
|
if (d_unhashed(dentry))
|
|
d_rehash(dentry);
|
|
}
|
|
return new;
|
|
}
|
|
EXPORT_SYMBOL(d_splice_alias);
|
|
|
|
/**
|
|
* d_add_ci - lookup or allocate new dentry with case-exact name
|
|
* @inode: the inode case-insensitive lookup has found
|
|
* @dentry: the negative dentry that was passed to the parent's lookup func
|
|
* @name: the case-exact name to be associated with the returned dentry
|
|
*
|
|
* This is to avoid filling the dcache with case-insensitive names to the
|
|
* same inode, only the actual correct case is stored in the dcache for
|
|
* case-insensitive filesystems.
|
|
*
|
|
* For a case-insensitive lookup match and if the the case-exact dentry
|
|
* already exists in in the dcache, use it and return it.
|
|
*
|
|
* If no entry exists with the exact case name, allocate new dentry with
|
|
* the exact case, and return the spliced entry.
|
|
*/
|
|
struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
|
|
struct qstr *name)
|
|
{
|
|
struct dentry *found;
|
|
struct dentry *new;
|
|
|
|
/*
|
|
* First check if a dentry matching the name already exists,
|
|
* if not go ahead and create it now.
|
|
*/
|
|
found = d_hash_and_lookup(dentry->d_parent, name);
|
|
if (unlikely(IS_ERR(found)))
|
|
goto err_out;
|
|
if (!found) {
|
|
new = d_alloc(dentry->d_parent, name);
|
|
if (!new) {
|
|
found = ERR_PTR(-ENOMEM);
|
|
goto err_out;
|
|
}
|
|
|
|
found = d_splice_alias(inode, new);
|
|
if (found) {
|
|
dput(new);
|
|
return found;
|
|
}
|
|
return new;
|
|
}
|
|
|
|
/*
|
|
* If a matching dentry exists, and it's not negative use it.
|
|
*
|
|
* Decrement the reference count to balance the iget() done
|
|
* earlier on.
|
|
*/
|
|
if (found->d_inode) {
|
|
if (unlikely(found->d_inode != inode)) {
|
|
/* This can't happen because bad inodes are unhashed. */
|
|
BUG_ON(!is_bad_inode(inode));
|
|
BUG_ON(!is_bad_inode(found->d_inode));
|
|
}
|
|
iput(inode);
|
|
return found;
|
|
}
|
|
|
|
/*
|
|
* Negative dentry: instantiate it unless the inode is a directory and
|
|
* already has a dentry.
|
|
*/
|
|
new = d_splice_alias(inode, found);
|
|
if (new) {
|
|
dput(found);
|
|
found = new;
|
|
}
|
|
return found;
|
|
|
|
err_out:
|
|
iput(inode);
|
|
return found;
|
|
}
|
|
EXPORT_SYMBOL(d_add_ci);
|
|
|
|
/*
|
|
* Do the slow-case of the dentry name compare.
|
|
*
|
|
* Unlike the dentry_cmp() function, we need to atomically
|
|
* load the name and length information, so that the
|
|
* filesystem can rely on them, and can use the 'name' and
|
|
* 'len' information without worrying about walking off the
|
|
* end of memory etc.
|
|
*
|
|
* Thus the read_seqcount_retry() and the "duplicate" info
|
|
* in arguments (the low-level filesystem should not look
|
|
* at the dentry inode or name contents directly, since
|
|
* rename can change them while we're in RCU mode).
|
|
*/
|
|
enum slow_d_compare {
|
|
D_COMP_OK,
|
|
D_COMP_NOMATCH,
|
|
D_COMP_SEQRETRY,
|
|
};
|
|
|
|
static noinline enum slow_d_compare slow_dentry_cmp(
|
|
const struct dentry *parent,
|
|
struct dentry *dentry,
|
|
unsigned int seq,
|
|
const struct qstr *name)
|
|
{
|
|
int tlen = dentry->d_name.len;
|
|
const char *tname = dentry->d_name.name;
|
|
|
|
if (read_seqcount_retry(&dentry->d_seq, seq)) {
|
|
cpu_relax();
|
|
return D_COMP_SEQRETRY;
|
|
}
|
|
if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
|
|
return D_COMP_NOMATCH;
|
|
return D_COMP_OK;
|
|
}
|
|
|
|
/**
|
|
* __d_lookup_rcu - search for a dentry (racy, store-free)
|
|
* @parent: parent dentry
|
|
* @name: qstr of name we wish to find
|
|
* @seqp: returns d_seq value at the point where the dentry was found
|
|
* Returns: dentry, or NULL
|
|
*
|
|
* __d_lookup_rcu is the dcache lookup function for rcu-walk name
|
|
* resolution (store-free path walking) design described in
|
|
* Documentation/filesystems/path-lookup.txt.
|
|
*
|
|
* This is not to be used outside core vfs.
|
|
*
|
|
* __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
|
|
* held, and rcu_read_lock held. The returned dentry must not be stored into
|
|
* without taking d_lock and checking d_seq sequence count against @seq
|
|
* returned here.
|
|
*
|
|
* A refcount may be taken on the found dentry with the d_rcu_to_refcount
|
|
* function.
|
|
*
|
|
* Alternatively, __d_lookup_rcu may be called again to look up the child of
|
|
* the returned dentry, so long as its parent's seqlock is checked after the
|
|
* child is looked up. Thus, an interlocking stepping of sequence lock checks
|
|
* is formed, giving integrity down the path walk.
|
|
*
|
|
* NOTE! The caller *has* to check the resulting dentry against the sequence
|
|
* number we've returned before using any of the resulting dentry state!
|
|
*/
|
|
struct dentry *__d_lookup_rcu(const struct dentry *parent,
|
|
const struct qstr *name,
|
|
unsigned *seqp)
|
|
{
|
|
u64 hashlen = name->hash_len;
|
|
const unsigned char *str = name->name;
|
|
struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen));
|
|
struct hlist_bl_node *node;
|
|
struct dentry *dentry;
|
|
|
|
/*
|
|
* Note: There is significant duplication with __d_lookup_rcu which is
|
|
* required to prevent single threaded performance regressions
|
|
* especially on architectures where smp_rmb (in seqcounts) are costly.
|
|
* Keep the two functions in sync.
|
|
*/
|
|
|
|
/*
|
|
* The hash list is protected using RCU.
|
|
*
|
|
* Carefully use d_seq when comparing a candidate dentry, to avoid
|
|
* races with d_move().
|
|
*
|
|
* It is possible that concurrent renames can mess up our list
|
|
* walk here and result in missing our dentry, resulting in the
|
|
* false-negative result. d_lookup() protects against concurrent
|
|
* renames using rename_lock seqlock.
|
|
*
|
|
* See Documentation/filesystems/path-lookup.txt for more details.
|
|
*/
|
|
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
|
|
unsigned seq;
|
|
|
|
seqretry:
|
|
/*
|
|
* The dentry sequence count protects us from concurrent
|
|
* renames, and thus protects parent and name fields.
|
|
*
|
|
* The caller must perform a seqcount check in order
|
|
* to do anything useful with the returned dentry.
|
|
*
|
|
* NOTE! We do a "raw" seqcount_begin here. That means that
|
|
* we don't wait for the sequence count to stabilize if it
|
|
* is in the middle of a sequence change. If we do the slow
|
|
* dentry compare, we will do seqretries until it is stable,
|
|
* and if we end up with a successful lookup, we actually
|
|
* want to exit RCU lookup anyway.
|
|
*/
|
|
seq = raw_seqcount_begin(&dentry->d_seq);
|
|
if (dentry->d_parent != parent)
|
|
continue;
|
|
if (d_unhashed(dentry))
|
|
continue;
|
|
|
|
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
|
|
if (dentry->d_name.hash != hashlen_hash(hashlen))
|
|
continue;
|
|
*seqp = seq;
|
|
switch (slow_dentry_cmp(parent, dentry, seq, name)) {
|
|
case D_COMP_OK:
|
|
return dentry;
|
|
case D_COMP_NOMATCH:
|
|
continue;
|
|
default:
|
|
goto seqretry;
|
|
}
|
|
}
|
|
|
|
if (dentry->d_name.hash_len != hashlen)
|
|
continue;
|
|
*seqp = seq;
|
|
if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
|
|
return dentry;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* d_lookup - search for a dentry
|
|
* @parent: parent dentry
|
|
* @name: qstr of name we wish to find
|
|
* Returns: dentry, or NULL
|
|
*
|
|
* d_lookup searches the children of the parent dentry for the name in
|
|
* question. If the dentry is found its reference count is incremented and the
|
|
* dentry is returned. The caller must use dput to free the entry when it has
|
|
* finished using it. %NULL is returned if the dentry does not exist.
|
|
*/
|
|
struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name)
|
|
{
|
|
struct dentry *dentry;
|
|
unsigned seq;
|
|
|
|
do {
|
|
seq = read_seqbegin(&rename_lock);
|
|
dentry = __d_lookup(parent, name);
|
|
if (dentry)
|
|
break;
|
|
} while (read_seqretry(&rename_lock, seq));
|
|
return dentry;
|
|
}
|
|
EXPORT_SYMBOL(d_lookup);
|
|
|
|
/**
|
|
* __d_lookup - search for a dentry (racy)
|
|
* @parent: parent dentry
|
|
* @name: qstr of name we wish to find
|
|
* Returns: dentry, or NULL
|
|
*
|
|
* __d_lookup is like d_lookup, however it may (rarely) return a
|
|
* false-negative result due to unrelated rename activity.
|
|
*
|
|
* __d_lookup is slightly faster by avoiding rename_lock read seqlock,
|
|
* however it must be used carefully, eg. with a following d_lookup in
|
|
* the case of failure.
|
|
*
|
|
* __d_lookup callers must be commented.
|
|
*/
|
|
struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
|
|
{
|
|
unsigned int len = name->len;
|
|
unsigned int hash = name->hash;
|
|
const unsigned char *str = name->name;
|
|
struct hlist_bl_head *b = d_hash(parent, hash);
|
|
struct hlist_bl_node *node;
|
|
struct dentry *found = NULL;
|
|
struct dentry *dentry;
|
|
|
|
/*
|
|
* Note: There is significant duplication with __d_lookup_rcu which is
|
|
* required to prevent single threaded performance regressions
|
|
* especially on architectures where smp_rmb (in seqcounts) are costly.
|
|
* Keep the two functions in sync.
|
|
*/
|
|
|
|
/*
|
|
* The hash list is protected using RCU.
|
|
*
|
|
* Take d_lock when comparing a candidate dentry, to avoid races
|
|
* with d_move().
|
|
*
|
|
* It is possible that concurrent renames can mess up our list
|
|
* walk here and result in missing our dentry, resulting in the
|
|
* false-negative result. d_lookup() protects against concurrent
|
|
* renames using rename_lock seqlock.
|
|
*
|
|
* See Documentation/filesystems/path-lookup.txt for more details.
|
|
*/
|
|
rcu_read_lock();
|
|
|
|
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
|
|
|
|
if (dentry->d_name.hash != hash)
|
|
continue;
|
|
|
|
spin_lock(&dentry->d_lock);
|
|
if (dentry->d_parent != parent)
|
|
goto next;
|
|
if (d_unhashed(dentry))
|
|
goto next;
|
|
|
|
/*
|
|
* It is safe to compare names since d_move() cannot
|
|
* change the qstr (protected by d_lock).
|
|
*/
|
|
if (parent->d_flags & DCACHE_OP_COMPARE) {
|
|
int tlen = dentry->d_name.len;
|
|
const char *tname = dentry->d_name.name;
|
|
if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
|
|
goto next;
|
|
} else {
|
|
if (dentry->d_name.len != len)
|
|
goto next;
|
|
if (dentry_cmp(dentry, str, len))
|
|
goto next;
|
|
}
|
|
|
|
dentry->d_lockref.count++;
|
|
found = dentry;
|
|
spin_unlock(&dentry->d_lock);
|
|
break;
|
|
next:
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return found;
|
|
}
|
|
|
|
/**
|
|
* d_hash_and_lookup - hash the qstr then search for a dentry
|
|
* @dir: Directory to search in
|
|
* @name: qstr of name we wish to find
|
|
*
|
|
* On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
|
|
*/
|
|
struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
|
|
{
|
|
/*
|
|
* Check for a fs-specific hash function. Note that we must
|
|
* calculate the standard hash first, as the d_op->d_hash()
|
|
* routine may choose to leave the hash value unchanged.
|
|
*/
|
|
name->hash = full_name_hash(name->name, name->len);
|
|
if (dir->d_flags & DCACHE_OP_HASH) {
|
|
int err = dir->d_op->d_hash(dir, name);
|
|
if (unlikely(err < 0))
|
|
return ERR_PTR(err);
|
|
}
|
|
return d_lookup(dir, name);
|
|
}
|
|
EXPORT_SYMBOL(d_hash_and_lookup);
|
|
|
|
/**
|
|
* d_validate - verify dentry provided from insecure source (deprecated)
|
|
* @dentry: The dentry alleged to be valid child of @dparent
|
|
* @dparent: The parent dentry (known to be valid)
|
|
*
|
|
* An insecure source has sent us a dentry, here we verify it and dget() it.
|
|
* This is used by ncpfs in its readdir implementation.
|
|
* Zero is returned in the dentry is invalid.
|
|
*
|
|
* This function is slow for big directories, and deprecated, do not use it.
|
|
*/
|
|
int d_validate(struct dentry *dentry, struct dentry *dparent)
|
|
{
|
|
struct dentry *child;
|
|
|
|
spin_lock(&dparent->d_lock);
|
|
list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
|
|
if (dentry == child) {
|
|
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
|
|
__dget_dlock(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
spin_unlock(&dparent->d_lock);
|
|
return 1;
|
|
}
|
|
}
|
|
spin_unlock(&dparent->d_lock);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(d_validate);
|
|
|
|
/*
|
|
* When a file is deleted, we have two options:
|
|
* - turn this dentry into a negative dentry
|
|
* - unhash this dentry and free it.
|
|
*
|
|
* Usually, we want to just turn this into
|
|
* a negative dentry, but if anybody else is
|
|
* currently using the dentry or the inode
|
|
* we can't do that and we fall back on removing
|
|
* it from the hash queues and waiting for
|
|
* it to be deleted later when it has no users
|
|
*/
|
|
|
|
/**
|
|
* d_delete - delete a dentry
|
|
* @dentry: The dentry to delete
|
|
*
|
|
* Turn the dentry into a negative dentry if possible, otherwise
|
|
* remove it from the hash queues so it can be deleted later
|
|
*/
|
|
|
|
void d_delete(struct dentry * dentry)
|
|
{
|
|
struct inode *inode;
|
|
int isdir = 0;
|
|
/*
|
|
* Are we the only user?
|
|
*/
|
|
again:
|
|
spin_lock(&dentry->d_lock);
|
|
inode = dentry->d_inode;
|
|
isdir = S_ISDIR(inode->i_mode);
|
|
if (dentry->d_lockref.count == 1) {
|
|
if (!spin_trylock(&inode->i_lock)) {
|
|
spin_unlock(&dentry->d_lock);
|
|
cpu_relax();
|
|
goto again;
|
|
}
|
|
dentry->d_flags &= ~DCACHE_CANT_MOUNT;
|
|
dentry_unlink_inode(dentry);
|
|
fsnotify_nameremove(dentry, isdir);
|
|
return;
|
|
}
|
|
|
|
if (!d_unhashed(dentry))
|
|
__d_drop(dentry);
|
|
|
|
spin_unlock(&dentry->d_lock);
|
|
|
|
fsnotify_nameremove(dentry, isdir);
|
|
}
|
|
EXPORT_SYMBOL(d_delete);
|
|
|
|
static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
|
|
{
|
|
BUG_ON(!d_unhashed(entry));
|
|
hlist_bl_lock(b);
|
|
entry->d_flags |= DCACHE_RCUACCESS;
|
|
hlist_bl_add_head_rcu(&entry->d_hash, b);
|
|
hlist_bl_unlock(b);
|
|
}
|
|
|
|
static void _d_rehash(struct dentry * entry)
|
|
{
|
|
__d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
|
|
}
|
|
|
|
/**
|
|
* d_rehash - add an entry back to the hash
|
|
* @entry: dentry to add to the hash
|
|
*
|
|
* Adds a dentry to the hash according to its name.
|
|
*/
|
|
|
|
void d_rehash(struct dentry * entry)
|
|
{
|
|
spin_lock(&entry->d_lock);
|
|
_d_rehash(entry);
|
|
spin_unlock(&entry->d_lock);
|
|
}
|
|
EXPORT_SYMBOL(d_rehash);
|
|
|
|
/**
|
|
* dentry_update_name_case - update case insensitive dentry with a new name
|
|
* @dentry: dentry to be updated
|
|
* @name: new name
|
|
*
|
|
* Update a case insensitive dentry with new case of name.
|
|
*
|
|
* dentry must have been returned by d_lookup with name @name. Old and new
|
|
* name lengths must match (ie. no d_compare which allows mismatched name
|
|
* lengths).
|
|
*
|
|
* Parent inode i_mutex must be held over d_lookup and into this call (to
|
|
* keep renames and concurrent inserts, and readdir(2) away).
|
|
*/
|
|
void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
|
|
{
|
|
BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));
|
|
BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
|
|
|
|
spin_lock(&dentry->d_lock);
|
|
write_seqcount_begin(&dentry->d_seq);
|
|
memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
|
|
write_seqcount_end(&dentry->d_seq);
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
EXPORT_SYMBOL(dentry_update_name_case);
|
|
|
|
static void switch_names(struct dentry *dentry, struct dentry *target)
|
|
{
|
|
if (dname_external(target)) {
|
|
if (dname_external(dentry)) {
|
|
/*
|
|
* Both external: swap the pointers
|
|
*/
|
|
swap(target->d_name.name, dentry->d_name.name);
|
|
} else {
|
|
/*
|
|
* dentry:internal, target:external. Steal target's
|
|
* storage and make target internal.
|
|
*/
|
|
memcpy(target->d_iname, dentry->d_name.name,
|
|
dentry->d_name.len + 1);
|
|
dentry->d_name.name = target->d_name.name;
|
|
target->d_name.name = target->d_iname;
|
|
}
|
|
} else {
|
|
if (dname_external(dentry)) {
|
|
/*
|
|
* dentry:external, target:internal. Give dentry's
|
|
* storage to target and make dentry internal
|
|
*/
|
|
memcpy(dentry->d_iname, target->d_name.name,
|
|
target->d_name.len + 1);
|
|
target->d_name.name = dentry->d_name.name;
|
|
dentry->d_name.name = dentry->d_iname;
|
|
} else {
|
|
/*
|
|
* Both are internal. Just copy target to dentry
|
|
*/
|
|
memcpy(dentry->d_iname, target->d_name.name,
|
|
target->d_name.len + 1);
|
|
dentry->d_name.len = target->d_name.len;
|
|
return;
|
|
}
|
|
}
|
|
swap(dentry->d_name.len, target->d_name.len);
|
|
}
|
|
|
|
static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
|
|
{
|
|
/*
|
|
* XXXX: do we really need to take target->d_lock?
|
|
*/
|
|
if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
|
|
spin_lock(&target->d_parent->d_lock);
|
|
else {
|
|
if (d_ancestor(dentry->d_parent, target->d_parent)) {
|
|
spin_lock(&dentry->d_parent->d_lock);
|
|
spin_lock_nested(&target->d_parent->d_lock,
|
|
DENTRY_D_LOCK_NESTED);
|
|
} else {
|
|
spin_lock(&target->d_parent->d_lock);
|
|
spin_lock_nested(&dentry->d_parent->d_lock,
|
|
DENTRY_D_LOCK_NESTED);
|
|
}
|
|
}
|
|
if (target < dentry) {
|
|
spin_lock_nested(&target->d_lock, 2);
|
|
spin_lock_nested(&dentry->d_lock, 3);
|
|
} else {
|
|
spin_lock_nested(&dentry->d_lock, 2);
|
|
spin_lock_nested(&target->d_lock, 3);
|
|
}
|
|
}
|
|
|
|
static void dentry_unlock_parents_for_move(struct dentry *dentry,
|
|
struct dentry *target)
|
|
{
|
|
if (target->d_parent != dentry->d_parent)
|
|
spin_unlock(&dentry->d_parent->d_lock);
|
|
if (target->d_parent != target)
|
|
spin_unlock(&target->d_parent->d_lock);
|
|
}
|
|
|
|
/*
|
|
* When switching names, the actual string doesn't strictly have to
|
|
* be preserved in the target - because we're dropping the target
|
|
* anyway. As such, we can just do a simple memcpy() to copy over
|
|
* the new name before we switch.
|
|
*
|
|
* Note that we have to be a lot more careful about getting the hash
|
|
* switched - we have to switch the hash value properly even if it
|
|
* then no longer matches the actual (corrupted) string of the target.
|
|
* The hash value has to match the hash queue that the dentry is on..
|
|
*/
|
|
/*
|
|
* __d_move - move a dentry
|
|
* @dentry: entry to move
|
|
* @target: new dentry
|
|
*
|
|
* Update the dcache to reflect the move of a file name. Negative
|
|
* dcache entries should not be moved in this way. Caller must hold
|
|
* rename_lock, the i_mutex of the source and target directories,
|
|
* and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
|
|
*/
|
|
static void __d_move(struct dentry * dentry, struct dentry * target)
|
|
{
|
|
if (!dentry->d_inode)
|
|
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
|
|
|
|
BUG_ON(d_ancestor(dentry, target));
|
|
BUG_ON(d_ancestor(target, dentry));
|
|
|
|
dentry_lock_for_move(dentry, target);
|
|
|
|
write_seqcount_begin(&dentry->d_seq);
|
|
write_seqcount_begin(&target->d_seq);
|
|
|
|
/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
|
|
|
|
/*
|
|
* Move the dentry to the target hash queue. Don't bother checking
|
|
* for the same hash queue because of how unlikely it is.
|
|
*/
|
|
__d_drop(dentry);
|
|
__d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
|
|
|
|
/* Unhash the target: dput() will then get rid of it */
|
|
__d_drop(target);
|
|
|
|
list_del(&dentry->d_u.d_child);
|
|
list_del(&target->d_u.d_child);
|
|
|
|
/* Switch the names.. */
|
|
switch_names(dentry, target);
|
|
swap(dentry->d_name.hash, target->d_name.hash);
|
|
|
|
/* ... and switch the parents */
|
|
if (IS_ROOT(dentry)) {
|
|
dentry->d_parent = target->d_parent;
|
|
target->d_parent = target;
|
|
INIT_LIST_HEAD(&target->d_u.d_child);
|
|
} else {
|
|
swap(dentry->d_parent, target->d_parent);
|
|
|
|
/* And add them back to the (new) parent lists */
|
|
list_add(&target->d_u.d_child, &target->d_parent->d_subdirs);
|
|
}
|
|
|
|
list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
|
|
|
|
write_seqcount_end(&target->d_seq);
|
|
write_seqcount_end(&dentry->d_seq);
|
|
|
|
dentry_unlock_parents_for_move(dentry, target);
|
|
spin_unlock(&target->d_lock);
|
|
fsnotify_d_move(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
}
|
|
|
|
/*
|
|
* d_move - move a dentry
|
|
* @dentry: entry to move
|
|
* @target: new dentry
|
|
*
|
|
* Update the dcache to reflect the move of a file name. Negative
|
|
* dcache entries should not be moved in this way. See the locking
|
|
* requirements for __d_move.
|
|
*/
|
|
void d_move(struct dentry *dentry, struct dentry *target)
|
|
{
|
|
write_seqlock(&rename_lock);
|
|
__d_move(dentry, target);
|
|
write_sequnlock(&rename_lock);
|
|
}
|
|
EXPORT_SYMBOL(d_move);
|
|
|
|
/**
|
|
* d_ancestor - search for an ancestor
|
|
* @p1: ancestor dentry
|
|
* @p2: child dentry
|
|
*
|
|
* Returns the ancestor dentry of p2 which is a child of p1, if p1 is
|
|
* an ancestor of p2, else NULL.
|
|
*/
|
|
struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
struct dentry *p;
|
|
|
|
for (p = p2; !IS_ROOT(p); p = p->d_parent) {
|
|
if (p->d_parent == p1)
|
|
return p;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* This helper attempts to cope with remotely renamed directories
|
|
*
|
|
* It assumes that the caller is already holding
|
|
* dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
|
|
*
|
|
* Note: If ever the locking in lock_rename() changes, then please
|
|
* remember to update this too...
|
|
*/
|
|
static struct dentry *__d_unalias(struct inode *inode,
|
|
struct dentry *dentry, struct dentry *alias)
|
|
{
|
|
struct mutex *m1 = NULL, *m2 = NULL;
|
|
struct dentry *ret = ERR_PTR(-EBUSY);
|
|
|
|
/* If alias and dentry share a parent, then no extra locks required */
|
|
if (alias->d_parent == dentry->d_parent)
|
|
goto out_unalias;
|
|
|
|
/* See lock_rename() */
|
|
if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
|
|
goto out_err;
|
|
m1 = &dentry->d_sb->s_vfs_rename_mutex;
|
|
if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex))
|
|
goto out_err;
|
|
m2 = &alias->d_parent->d_inode->i_mutex;
|
|
out_unalias:
|
|
if (likely(!d_mountpoint(alias))) {
|
|
__d_move(alias, dentry);
|
|
ret = alias;
|
|
}
|
|
out_err:
|
|
spin_unlock(&inode->i_lock);
|
|
if (m2)
|
|
mutex_unlock(m2);
|
|
if (m1)
|
|
mutex_unlock(m1);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Prepare an anonymous dentry for life in the superblock's dentry tree as a
|
|
* named dentry in place of the dentry to be replaced.
|
|
* returns with anon->d_lock held!
|
|
*/
|
|
static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
|
|
{
|
|
struct dentry *dparent;
|
|
|
|
dentry_lock_for_move(anon, dentry);
|
|
|
|
write_seqcount_begin(&dentry->d_seq);
|
|
write_seqcount_begin(&anon->d_seq);
|
|
|
|
dparent = dentry->d_parent;
|
|
|
|
switch_names(dentry, anon);
|
|
swap(dentry->d_name.hash, anon->d_name.hash);
|
|
|
|
dentry->d_parent = dentry;
|
|
list_del_init(&dentry->d_u.d_child);
|
|
anon->d_parent = dparent;
|
|
list_move(&anon->d_u.d_child, &dparent->d_subdirs);
|
|
|
|
write_seqcount_end(&dentry->d_seq);
|
|
write_seqcount_end(&anon->d_seq);
|
|
|
|
dentry_unlock_parents_for_move(anon, dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
|
|
/* anon->d_lock still locked, returns locked */
|
|
anon->d_flags &= ~DCACHE_DISCONNECTED;
|
|
}
|
|
|
|
/**
|
|
* d_materialise_unique - introduce an inode into the tree
|
|
* @dentry: candidate dentry
|
|
* @inode: inode to bind to the dentry, to which aliases may be attached
|
|
*
|
|
* Introduces an dentry into the tree, substituting an extant disconnected
|
|
* root directory alias in its place if there is one. Caller must hold the
|
|
* i_mutex of the parent directory.
|
|
*/
|
|
struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
|
|
{
|
|
struct dentry *actual;
|
|
|
|
BUG_ON(!d_unhashed(dentry));
|
|
|
|
if (!inode) {
|
|
actual = dentry;
|
|
__d_instantiate(dentry, NULL);
|
|
d_rehash(actual);
|
|
goto out_nolock;
|
|
}
|
|
|
|
spin_lock(&inode->i_lock);
|
|
|
|
if (S_ISDIR(inode->i_mode)) {
|
|
struct dentry *alias;
|
|
|
|
/* Does an aliased dentry already exist? */
|
|
alias = __d_find_alias(inode, 0);
|
|
if (alias) {
|
|
actual = alias;
|
|
write_seqlock(&rename_lock);
|
|
|
|
if (d_ancestor(alias, dentry)) {
|
|
/* Check for loops */
|
|
actual = ERR_PTR(-ELOOP);
|
|
spin_unlock(&inode->i_lock);
|
|
} else if (IS_ROOT(alias)) {
|
|
/* Is this an anonymous mountpoint that we
|
|
* could splice into our tree? */
|
|
__d_materialise_dentry(dentry, alias);
|
|
write_sequnlock(&rename_lock);
|
|
__d_drop(alias);
|
|
goto found;
|
|
} else {
|
|
/* Nope, but we must(!) avoid directory
|
|
* aliasing. This drops inode->i_lock */
|
|
actual = __d_unalias(inode, dentry, alias);
|
|
}
|
|
write_sequnlock(&rename_lock);
|
|
if (IS_ERR(actual)) {
|
|
if (PTR_ERR(actual) == -ELOOP)
|
|
pr_warn_ratelimited(
|
|
"VFS: Lookup of '%s' in %s %s"
|
|
" would have caused loop\n",
|
|
dentry->d_name.name,
|
|
inode->i_sb->s_type->name,
|
|
inode->i_sb->s_id);
|
|
dput(alias);
|
|
}
|
|
goto out_nolock;
|
|
}
|
|
}
|
|
|
|
/* Add a unique reference */
|
|
actual = __d_instantiate_unique(dentry, inode);
|
|
if (!actual)
|
|
actual = dentry;
|
|
else
|
|
BUG_ON(!d_unhashed(actual));
|
|
|
|
spin_lock(&actual->d_lock);
|
|
found:
|
|
_d_rehash(actual);
|
|
spin_unlock(&actual->d_lock);
|
|
spin_unlock(&inode->i_lock);
|
|
out_nolock:
|
|
if (actual == dentry) {
|
|
security_d_instantiate(dentry, inode);
|
|
return NULL;
|
|
}
|
|
|
|
iput(inode);
|
|
return actual;
|
|
}
|
|
EXPORT_SYMBOL_GPL(d_materialise_unique);
|
|
|
|
static int prepend(char **buffer, int *buflen, const char *str, int namelen)
|
|
{
|
|
*buflen -= namelen;
|
|
if (*buflen < 0)
|
|
return -ENAMETOOLONG;
|
|
*buffer -= namelen;
|
|
memcpy(*buffer, str, namelen);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* prepend_name - prepend a pathname in front of current buffer pointer
|
|
* @buffer: buffer pointer
|
|
* @buflen: allocated length of the buffer
|
|
* @name: name string and length qstr structure
|
|
*
|
|
* With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to
|
|
* make sure that either the old or the new name pointer and length are
|
|
* fetched. However, there may be mismatch between length and pointer.
|
|
* The length cannot be trusted, we need to copy it byte-by-byte until
|
|
* the length is reached or a null byte is found. It also prepends "/" at
|
|
* the beginning of the name. The sequence number check at the caller will
|
|
* retry it again when a d_move() does happen. So any garbage in the buffer
|
|
* due to mismatched pointer and length will be discarded.
|
|
*/
|
|
static int prepend_name(char **buffer, int *buflen, struct qstr *name)
|
|
{
|
|
const char *dname = ACCESS_ONCE(name->name);
|
|
u32 dlen = ACCESS_ONCE(name->len);
|
|
char *p;
|
|
|
|
if (*buflen < dlen + 1)
|
|
return -ENAMETOOLONG;
|
|
*buflen -= dlen + 1;
|
|
p = *buffer -= dlen + 1;
|
|
*p++ = '/';
|
|
while (dlen--) {
|
|
char c = *dname++;
|
|
if (!c)
|
|
break;
|
|
*p++ = c;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* prepend_path - Prepend path string to a buffer
|
|
* @path: the dentry/vfsmount to report
|
|
* @root: root vfsmnt/dentry
|
|
* @buffer: pointer to the end of the buffer
|
|
* @buflen: pointer to buffer length
|
|
*
|
|
* The function will first try to write out the pathname without taking any
|
|
* lock other than the RCU read lock to make sure that dentries won't go away.
|
|
* It only checks the sequence number of the global rename_lock as any change
|
|
* in the dentry's d_seq will be preceded by changes in the rename_lock
|
|
* sequence number. If the sequence number had been changed, it will restart
|
|
* the whole pathname back-tracing sequence again by taking the rename_lock.
|
|
* In this case, there is no need to take the RCU read lock as the recursive
|
|
* parent pointer references will keep the dentry chain alive as long as no
|
|
* rename operation is performed.
|
|
*/
|
|
static int prepend_path(const struct path *path,
|
|
const struct path *root,
|
|
char **buffer, int *buflen)
|
|
{
|
|
struct dentry *dentry = path->dentry;
|
|
struct vfsmount *vfsmnt = path->mnt;
|
|
struct mount *mnt = real_mount(vfsmnt);
|
|
int error = 0;
|
|
unsigned seq = 0;
|
|
char *bptr;
|
|
int blen;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
bptr = *buffer;
|
|
blen = *buflen;
|
|
read_seqbegin_or_lock(&rename_lock, &seq);
|
|
while (dentry != root->dentry || vfsmnt != root->mnt) {
|
|
struct dentry * parent;
|
|
|
|
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
|
|
/* Global root? */
|
|
if (mnt_has_parent(mnt)) {
|
|
dentry = mnt->mnt_mountpoint;
|
|
mnt = mnt->mnt_parent;
|
|
vfsmnt = &mnt->mnt;
|
|
continue;
|
|
}
|
|
/*
|
|
* Filesystems needing to implement special "root names"
|
|
* should do so with ->d_dname()
|
|
*/
|
|
if (IS_ROOT(dentry) &&
|
|
(dentry->d_name.len != 1 ||
|
|
dentry->d_name.name[0] != '/')) {
|
|
WARN(1, "Root dentry has weird name <%.*s>\n",
|
|
(int) dentry->d_name.len,
|
|
dentry->d_name.name);
|
|
}
|
|
if (!error)
|
|
error = is_mounted(vfsmnt) ? 1 : 2;
|
|
break;
|
|
}
|
|
parent = dentry->d_parent;
|
|
prefetch(parent);
|
|
error = prepend_name(&bptr, &blen, &dentry->d_name);
|
|
if (error)
|
|
break;
|
|
|
|
dentry = parent;
|
|
}
|
|
if (!(seq & 1))
|
|
rcu_read_unlock();
|
|
if (need_seqretry(&rename_lock, seq)) {
|
|
seq = 1;
|
|
goto restart;
|
|
}
|
|
done_seqretry(&rename_lock, seq);
|
|
|
|
if (error >= 0 && bptr == *buffer) {
|
|
if (--blen < 0)
|
|
error = -ENAMETOOLONG;
|
|
else
|
|
*--bptr = '/';
|
|
}
|
|
*buffer = bptr;
|
|
*buflen = blen;
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* __d_path - return the path of a dentry
|
|
* @path: the dentry/vfsmount to report
|
|
* @root: root vfsmnt/dentry
|
|
* @buf: buffer to return value in
|
|
* @buflen: buffer length
|
|
*
|
|
* Convert a dentry into an ASCII path name.
|
|
*
|
|
* Returns a pointer into the buffer or an error code if the
|
|
* path was too long.
|
|
*
|
|
* "buflen" should be positive.
|
|
*
|
|
* If the path is not reachable from the supplied root, return %NULL.
|
|
*/
|
|
char *__d_path(const struct path *path,
|
|
const struct path *root,
|
|
char *buf, int buflen)
|
|
{
|
|
char *res = buf + buflen;
|
|
int error;
|
|
|
|
prepend(&res, &buflen, "\0", 1);
|
|
br_read_lock(&vfsmount_lock);
|
|
error = prepend_path(path, root, &res, &buflen);
|
|
br_read_unlock(&vfsmount_lock);
|
|
|
|
if (error < 0)
|
|
return ERR_PTR(error);
|
|
if (error > 0)
|
|
return NULL;
|
|
return res;
|
|
}
|
|
|
|
char *d_absolute_path(const struct path *path,
|
|
char *buf, int buflen)
|
|
{
|
|
struct path root = {};
|
|
char *res = buf + buflen;
|
|
int error;
|
|
|
|
prepend(&res, &buflen, "\0", 1);
|
|
br_read_lock(&vfsmount_lock);
|
|
error = prepend_path(path, &root, &res, &buflen);
|
|
br_read_unlock(&vfsmount_lock);
|
|
|
|
if (error > 1)
|
|
error = -EINVAL;
|
|
if (error < 0)
|
|
return ERR_PTR(error);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* same as __d_path but appends "(deleted)" for unlinked files.
|
|
*/
|
|
static int path_with_deleted(const struct path *path,
|
|
const struct path *root,
|
|
char **buf, int *buflen)
|
|
{
|
|
prepend(buf, buflen, "\0", 1);
|
|
if (d_unlinked(path->dentry)) {
|
|
int error = prepend(buf, buflen, " (deleted)", 10);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
return prepend_path(path, root, buf, buflen);
|
|
}
|
|
|
|
static int prepend_unreachable(char **buffer, int *buflen)
|
|
{
|
|
return prepend(buffer, buflen, "(unreachable)", 13);
|
|
}
|
|
|
|
static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
|
|
{
|
|
unsigned seq;
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&fs->seq);
|
|
*root = fs->root;
|
|
} while (read_seqcount_retry(&fs->seq, seq));
|
|
}
|
|
|
|
/**
|
|
* d_path - return the path of a dentry
|
|
* @path: path to report
|
|
* @buf: buffer to return value in
|
|
* @buflen: buffer length
|
|
*
|
|
* Convert a dentry into an ASCII path name. If the entry has been deleted
|
|
* the string " (deleted)" is appended. Note that this is ambiguous.
|
|
*
|
|
* Returns a pointer into the buffer or an error code if the path was
|
|
* too long. Note: Callers should use the returned pointer, not the passed
|
|
* in buffer, to use the name! The implementation often starts at an offset
|
|
* into the buffer, and may leave 0 bytes at the start.
|
|
*
|
|
* "buflen" should be positive.
|
|
*/
|
|
char *d_path(const struct path *path, char *buf, int buflen)
|
|
{
|
|
char *res = buf + buflen;
|
|
struct path root;
|
|
int error;
|
|
|
|
/*
|
|
* We have various synthetic filesystems that never get mounted. On
|
|
* these filesystems dentries are never used for lookup purposes, and
|
|
* thus don't need to be hashed. They also don't need a name until a
|
|
* user wants to identify the object in /proc/pid/fd/. The little hack
|
|
* below allows us to generate a name for these objects on demand:
|
|
*/
|
|
if (path->dentry->d_op && path->dentry->d_op->d_dname)
|
|
return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
|
|
|
|
rcu_read_lock();
|
|
get_fs_root_rcu(current->fs, &root);
|
|
br_read_lock(&vfsmount_lock);
|
|
error = path_with_deleted(path, &root, &res, &buflen);
|
|
br_read_unlock(&vfsmount_lock);
|
|
rcu_read_unlock();
|
|
|
|
if (error < 0)
|
|
res = ERR_PTR(error);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(d_path);
|
|
|
|
/*
|
|
* Helper function for dentry_operations.d_dname() members
|
|
*/
|
|
char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
|
|
const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
char temp[64];
|
|
int sz;
|
|
|
|
va_start(args, fmt);
|
|
sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
|
|
va_end(args);
|
|
|
|
if (sz > sizeof(temp) || sz > buflen)
|
|
return ERR_PTR(-ENAMETOOLONG);
|
|
|
|
buffer += buflen - sz;
|
|
return memcpy(buffer, temp, sz);
|
|
}
|
|
|
|
char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
|
|
{
|
|
char *end = buffer + buflen;
|
|
/* these dentries are never renamed, so d_lock is not needed */
|
|
if (prepend(&end, &buflen, " (deleted)", 11) ||
|
|
prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) ||
|
|
prepend(&end, &buflen, "/", 1))
|
|
end = ERR_PTR(-ENAMETOOLONG);
|
|
return end;
|
|
}
|
|
|
|
/*
|
|
* Write full pathname from the root of the filesystem into the buffer.
|
|
*/
|
|
static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
|
|
{
|
|
char *end, *retval;
|
|
int len, seq = 0;
|
|
int error = 0;
|
|
|
|
rcu_read_lock();
|
|
restart:
|
|
end = buf + buflen;
|
|
len = buflen;
|
|
prepend(&end, &len, "\0", 1);
|
|
if (buflen < 1)
|
|
goto Elong;
|
|
/* Get '/' right */
|
|
retval = end-1;
|
|
*retval = '/';
|
|
read_seqbegin_or_lock(&rename_lock, &seq);
|
|
while (!IS_ROOT(dentry)) {
|
|
struct dentry *parent = dentry->d_parent;
|
|
int error;
|
|
|
|
prefetch(parent);
|
|
error = prepend_name(&end, &len, &dentry->d_name);
|
|
if (error)
|
|
break;
|
|
|
|
retval = end;
|
|
dentry = parent;
|
|
}
|
|
if (!(seq & 1))
|
|
rcu_read_unlock();
|
|
if (need_seqretry(&rename_lock, seq)) {
|
|
seq = 1;
|
|
goto restart;
|
|
}
|
|
done_seqretry(&rename_lock, seq);
|
|
if (error)
|
|
goto Elong;
|
|
return retval;
|
|
Elong:
|
|
return ERR_PTR(-ENAMETOOLONG);
|
|
}
|
|
|
|
char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
|
|
{
|
|
return __dentry_path(dentry, buf, buflen);
|
|
}
|
|
EXPORT_SYMBOL(dentry_path_raw);
|
|
|
|
char *dentry_path(struct dentry *dentry, char *buf, int buflen)
|
|
{
|
|
char *p = NULL;
|
|
char *retval;
|
|
|
|
if (d_unlinked(dentry)) {
|
|
p = buf + buflen;
|
|
if (prepend(&p, &buflen, "//deleted", 10) != 0)
|
|
goto Elong;
|
|
buflen++;
|
|
}
|
|
retval = __dentry_path(dentry, buf, buflen);
|
|
if (!IS_ERR(retval) && p)
|
|
*p = '/'; /* restore '/' overriden with '\0' */
|
|
return retval;
|
|
Elong:
|
|
return ERR_PTR(-ENAMETOOLONG);
|
|
}
|
|
|
|
static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root,
|
|
struct path *pwd)
|
|
{
|
|
unsigned seq;
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&fs->seq);
|
|
*root = fs->root;
|
|
*pwd = fs->pwd;
|
|
} while (read_seqcount_retry(&fs->seq, seq));
|
|
}
|
|
|
|
/*
|
|
* NOTE! The user-level library version returns a
|
|
* character pointer. The kernel system call just
|
|
* returns the length of the buffer filled (which
|
|
* includes the ending '\0' character), or a negative
|
|
* error value. So libc would do something like
|
|
*
|
|
* char *getcwd(char * buf, size_t size)
|
|
* {
|
|
* int retval;
|
|
*
|
|
* retval = sys_getcwd(buf, size);
|
|
* if (retval >= 0)
|
|
* return buf;
|
|
* errno = -retval;
|
|
* return NULL;
|
|
* }
|
|
*/
|
|
SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
|
|
{
|
|
int error;
|
|
struct path pwd, root;
|
|
char *page = __getname();
|
|
|
|
if (!page)
|
|
return -ENOMEM;
|
|
|
|
rcu_read_lock();
|
|
get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
|
|
|
|
error = -ENOENT;
|
|
br_read_lock(&vfsmount_lock);
|
|
if (!d_unlinked(pwd.dentry)) {
|
|
unsigned long len;
|
|
char *cwd = page + PATH_MAX;
|
|
int buflen = PATH_MAX;
|
|
|
|
prepend(&cwd, &buflen, "\0", 1);
|
|
error = prepend_path(&pwd, &root, &cwd, &buflen);
|
|
br_read_unlock(&vfsmount_lock);
|
|
rcu_read_unlock();
|
|
|
|
if (error < 0)
|
|
goto out;
|
|
|
|
/* Unreachable from current root */
|
|
if (error > 0) {
|
|
error = prepend_unreachable(&cwd, &buflen);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
|
|
error = -ERANGE;
|
|
len = PATH_MAX + page - cwd;
|
|
if (len <= size) {
|
|
error = len;
|
|
if (copy_to_user(buf, cwd, len))
|
|
error = -EFAULT;
|
|
}
|
|
} else {
|
|
br_read_unlock(&vfsmount_lock);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
out:
|
|
__putname(page);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Test whether new_dentry is a subdirectory of old_dentry.
|
|
*
|
|
* Trivially implemented using the dcache structure
|
|
*/
|
|
|
|
/**
|
|
* is_subdir - is new dentry a subdirectory of old_dentry
|
|
* @new_dentry: new dentry
|
|
* @old_dentry: old dentry
|
|
*
|
|
* Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
|
|
* Returns 0 otherwise.
|
|
* Caller must ensure that "new_dentry" is pinned before calling is_subdir()
|
|
*/
|
|
|
|
int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
|
|
{
|
|
int result;
|
|
unsigned seq;
|
|
|
|
if (new_dentry == old_dentry)
|
|
return 1;
|
|
|
|
do {
|
|
/* for restarting inner loop in case of seq retry */
|
|
seq = read_seqbegin(&rename_lock);
|
|
/*
|
|
* Need rcu_readlock to protect against the d_parent trashing
|
|
* due to d_move
|
|
*/
|
|
rcu_read_lock();
|
|
if (d_ancestor(old_dentry, new_dentry))
|
|
result = 1;
|
|
else
|
|
result = 0;
|
|
rcu_read_unlock();
|
|
} while (read_seqretry(&rename_lock, seq));
|
|
|
|
return result;
|
|
}
|
|
|
|
static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
|
|
{
|
|
struct dentry *root = data;
|
|
if (dentry != root) {
|
|
if (d_unhashed(dentry) || !dentry->d_inode)
|
|
return D_WALK_SKIP;
|
|
|
|
if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
|
|
dentry->d_flags |= DCACHE_GENOCIDE;
|
|
dentry->d_lockref.count--;
|
|
}
|
|
}
|
|
return D_WALK_CONTINUE;
|
|
}
|
|
|
|
void d_genocide(struct dentry *parent)
|
|
{
|
|
d_walk(parent, parent, d_genocide_kill, NULL);
|
|
}
|
|
|
|
void d_tmpfile(struct dentry *dentry, struct inode *inode)
|
|
{
|
|
inode_dec_link_count(inode);
|
|
BUG_ON(dentry->d_name.name != dentry->d_iname ||
|
|
!hlist_unhashed(&dentry->d_alias) ||
|
|
!d_unlinked(dentry));
|
|
spin_lock(&dentry->d_parent->d_lock);
|
|
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
|
|
dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
|
|
(unsigned long long)inode->i_ino);
|
|
spin_unlock(&dentry->d_lock);
|
|
spin_unlock(&dentry->d_parent->d_lock);
|
|
d_instantiate(dentry, inode);
|
|
}
|
|
EXPORT_SYMBOL(d_tmpfile);
|
|
|
|
static __initdata unsigned long dhash_entries;
|
|
static int __init set_dhash_entries(char *str)
|
|
{
|
|
if (!str)
|
|
return 0;
|
|
dhash_entries = simple_strtoul(str, &str, 0);
|
|
return 1;
|
|
}
|
|
__setup("dhash_entries=", set_dhash_entries);
|
|
|
|
static void __init dcache_init_early(void)
|
|
{
|
|
unsigned int loop;
|
|
|
|
/* If hashes are distributed across NUMA nodes, defer
|
|
* hash allocation until vmalloc space is available.
|
|
*/
|
|
if (hashdist)
|
|
return;
|
|
|
|
dentry_hashtable =
|
|
alloc_large_system_hash("Dentry cache",
|
|
sizeof(struct hlist_bl_head),
|
|
dhash_entries,
|
|
13,
|
|
HASH_EARLY,
|
|
&d_hash_shift,
|
|
&d_hash_mask,
|
|
0,
|
|
0);
|
|
|
|
for (loop = 0; loop < (1U << d_hash_shift); loop++)
|
|
INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
|
|
}
|
|
|
|
static void __init dcache_init(void)
|
|
{
|
|
unsigned int loop;
|
|
|
|
/*
|
|
* A constructor could be added for stable state like the lists,
|
|
* but it is probably not worth it because of the cache nature
|
|
* of the dcache.
|
|
*/
|
|
dentry_cache = KMEM_CACHE(dentry,
|
|
SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
|
|
|
|
/* Hash may have been set up in dcache_init_early */
|
|
if (!hashdist)
|
|
return;
|
|
|
|
dentry_hashtable =
|
|
alloc_large_system_hash("Dentry cache",
|
|
sizeof(struct hlist_bl_head),
|
|
dhash_entries,
|
|
13,
|
|
0,
|
|
&d_hash_shift,
|
|
&d_hash_mask,
|
|
0,
|
|
0);
|
|
|
|
for (loop = 0; loop < (1U << d_hash_shift); loop++)
|
|
INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
|
|
}
|
|
|
|
/* SLAB cache for __getname() consumers */
|
|
struct kmem_cache *names_cachep __read_mostly;
|
|
EXPORT_SYMBOL(names_cachep);
|
|
|
|
EXPORT_SYMBOL(d_genocide);
|
|
|
|
void __init vfs_caches_init_early(void)
|
|
{
|
|
dcache_init_early();
|
|
inode_init_early();
|
|
}
|
|
|
|
void __init vfs_caches_init(unsigned long mempages)
|
|
{
|
|
unsigned long reserve;
|
|
|
|
/* Base hash sizes on available memory, with a reserve equal to
|
|
150% of current kernel size */
|
|
|
|
reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1);
|
|
mempages -= reserve;
|
|
|
|
names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
|
|
|
|
dcache_init();
|
|
inode_init();
|
|
files_init(mempages);
|
|
mnt_init();
|
|
bdev_cache_init();
|
|
chrdev_init();
|
|
}
|