fs: dcache per-bucket dcache hash locking
We can turn the dcache hash locking from a global dcache_hash_lock into per-bucket locking. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin
parent
626d607435
commit
ceb5bdc2d2
133
fs/dcache.c
133
fs/dcache.c
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@ -33,14 +33,18 @@
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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 "internal.h"
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/*
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* Usage:
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* dcache_inode_lock protects:
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* - i_dentry, d_alias, d_inode
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* dcache_hash_lock protects:
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* - the dcache hash table, s_anon lists
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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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* dcache_lru_lock protects:
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* - the dcache lru lists and counters
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* d_lock protects:
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@ -57,7 +61,8 @@
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* dcache_inode_lock
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* dentry->d_lock
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* dcache_lru_lock
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* dcache_hash_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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@ -74,7 +79,6 @@ 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_SPINLOCK(dcache_inode_lock);
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static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock);
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static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
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__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
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@ -96,7 +100,29 @@ static struct kmem_cache *dentry_cache __read_mostly;
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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_head *dentry_hashtable __read_mostly;
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struct dcache_hash_bucket {
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struct hlist_bl_head head;
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};
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static struct dcache_hash_bucket *dentry_hashtable __read_mostly;
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static inline struct dcache_hash_bucket *d_hash(struct dentry *parent,
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unsigned long hash)
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{
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hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
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hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
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return dentry_hashtable + (hash & D_HASHMASK);
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}
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static inline void spin_lock_bucket(struct dcache_hash_bucket *b)
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{
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bit_spin_lock(0, (unsigned long *)&b->head.first);
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}
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static inline void spin_unlock_bucket(struct dcache_hash_bucket *b)
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{
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__bit_spin_unlock(0, (unsigned long *)&b->head.first);
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}
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/* Statistics gathering. */
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struct dentry_stat_t dentry_stat = {
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@ -144,7 +170,7 @@ static void d_free(struct dentry *dentry)
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dentry->d_op->d_release(dentry);
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/* if dentry was never inserted into hash, immediate free is OK */
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if (hlist_unhashed(&dentry->d_hash))
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if (hlist_bl_unhashed(&dentry->d_hash))
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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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@ -302,11 +328,27 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
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void __d_drop(struct dentry *dentry)
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{
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if (!(dentry->d_flags & DCACHE_UNHASHED)) {
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dentry->d_flags |= DCACHE_UNHASHED;
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spin_lock(&dcache_hash_lock);
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hlist_del_rcu(&dentry->d_hash);
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spin_unlock(&dcache_hash_lock);
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dentry_rcuwalk_barrier(dentry);
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if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) {
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bit_spin_lock(0,
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(unsigned long *)&dentry->d_sb->s_anon.first);
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dentry->d_flags |= DCACHE_UNHASHED;
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hlist_bl_del_init(&dentry->d_hash);
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__bit_spin_unlock(0,
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(unsigned long *)&dentry->d_sb->s_anon.first);
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} else {
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struct dcache_hash_bucket *b;
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b = d_hash(dentry->d_parent, dentry->d_name.hash);
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spin_lock_bucket(b);
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/*
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* We may not actually need to put DCACHE_UNHASHED
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* manipulations under the hash lock, but follow
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* the principle of least surprise.
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*/
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dentry->d_flags |= DCACHE_UNHASHED;
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hlist_bl_del_rcu(&dentry->d_hash);
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spin_unlock_bucket(b);
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dentry_rcuwalk_barrier(dentry);
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}
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}
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}
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EXPORT_SYMBOL(__d_drop);
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@ -961,8 +1003,8 @@ void shrink_dcache_for_umount(struct super_block *sb)
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spin_unlock(&dentry->d_lock);
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shrink_dcache_for_umount_subtree(dentry);
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while (!hlist_empty(&sb->s_anon)) {
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dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash);
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while (!hlist_bl_empty(&sb->s_anon)) {
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dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
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shrink_dcache_for_umount_subtree(dentry);
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}
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}
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@ -1263,7 +1305,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
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dentry->d_sb = NULL;
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dentry->d_op = NULL;
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dentry->d_fsdata = NULL;
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INIT_HLIST_NODE(&dentry->d_hash);
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INIT_HLIST_BL_NODE(&dentry->d_hash);
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INIT_LIST_HEAD(&dentry->d_lru);
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INIT_LIST_HEAD(&dentry->d_subdirs);
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INIT_LIST_HEAD(&dentry->d_alias);
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@ -1459,14 +1501,6 @@ struct dentry * d_alloc_root(struct inode * root_inode)
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}
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EXPORT_SYMBOL(d_alloc_root);
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static inline struct hlist_head *d_hash(struct dentry *parent,
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unsigned long hash)
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{
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hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES;
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hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS);
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return dentry_hashtable + (hash & D_HASHMASK);
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}
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/**
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* d_obtain_alias - find or allocate a dentry for a given inode
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* @inode: inode to allocate the dentry for
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@ -1521,11 +1555,11 @@ struct dentry *d_obtain_alias(struct inode *inode)
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tmp->d_sb = inode->i_sb;
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tmp->d_inode = inode;
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tmp->d_flags |= DCACHE_DISCONNECTED;
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tmp->d_flags &= ~DCACHE_UNHASHED;
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list_add(&tmp->d_alias, &inode->i_dentry);
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spin_lock(&dcache_hash_lock);
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hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
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spin_unlock(&dcache_hash_lock);
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bit_spin_lock(0, (unsigned long *)&tmp->d_sb->s_anon.first);
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tmp->d_flags &= ~DCACHE_UNHASHED;
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hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
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__bit_spin_unlock(0, (unsigned long *)&tmp->d_sb->s_anon.first);
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spin_unlock(&tmp->d_lock);
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spin_unlock(&dcache_inode_lock);
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@ -1567,7 +1601,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
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d_move(new, dentry);
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iput(inode);
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} else {
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/* already taking dcache_inode_lock, so d_add() by hand */
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/* already got dcache_inode_lock, so d_add() by hand */
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__d_instantiate(dentry, inode);
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spin_unlock(&dcache_inode_lock);
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security_d_instantiate(dentry, inode);
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@ -1702,8 +1736,8 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
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unsigned int len = name->len;
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unsigned int hash = name->hash;
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const unsigned char *str = name->name;
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struct hlist_head *head = d_hash(parent, hash);
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struct hlist_node *node;
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struct dcache_hash_bucket *b = d_hash(parent, hash);
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struct hlist_bl_node *node;
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struct dentry *dentry;
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/*
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@ -1726,7 +1760,7 @@ struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
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*
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* See Documentation/vfs/dcache-locking.txt for more details.
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*/
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hlist_for_each_entry_rcu(dentry, node, head, d_hash) {
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hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) {
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struct inode *i;
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const char *tname;
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int tlen;
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@ -1820,8 +1854,8 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
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unsigned int len = name->len;
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unsigned int hash = name->hash;
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const unsigned char *str = name->name;
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struct hlist_head *head = d_hash(parent,hash);
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struct hlist_node *node;
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struct dcache_hash_bucket *b = d_hash(parent, hash);
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struct hlist_bl_node *node;
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struct dentry *found = NULL;
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struct dentry *dentry;
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@ -1847,7 +1881,7 @@ struct dentry *__d_lookup(struct dentry *parent, struct qstr *name)
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*/
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rcu_read_lock();
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hlist_for_each_entry_rcu(dentry, node, head, d_hash) {
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hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) {
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const char *tname;
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int tlen;
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@ -1998,11 +2032,13 @@ again:
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}
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EXPORT_SYMBOL(d_delete);
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static void __d_rehash(struct dentry * entry, struct hlist_head *list)
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static void __d_rehash(struct dentry * entry, struct dcache_hash_bucket *b)
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{
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BUG_ON(!d_unhashed(entry));
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spin_lock_bucket(b);
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entry->d_flags &= ~DCACHE_UNHASHED;
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hlist_add_head_rcu(&entry->d_hash, list);
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hlist_bl_add_head_rcu(&entry->d_hash, &b->head);
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spin_unlock_bucket(b);
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}
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static void _d_rehash(struct dentry * entry)
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@ -2020,9 +2056,7 @@ static void _d_rehash(struct dentry * entry)
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void d_rehash(struct dentry * entry)
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{
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spin_lock(&entry->d_lock);
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spin_lock(&dcache_hash_lock);
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_d_rehash(entry);
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spin_unlock(&dcache_hash_lock);
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spin_unlock(&entry->d_lock);
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}
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EXPORT_SYMBOL(d_rehash);
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@ -2165,15 +2199,16 @@ void d_move(struct dentry * dentry, struct dentry * target)
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write_seqcount_begin(&dentry->d_seq);
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write_seqcount_begin(&target->d_seq);
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/* Move the dentry to the target hash queue, if on different bucket */
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spin_lock(&dcache_hash_lock);
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if (!d_unhashed(dentry))
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hlist_del_rcu(&dentry->d_hash);
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/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
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/*
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* Move the dentry to the target hash queue. Don't bother checking
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* for the same hash queue because of how unlikely it is.
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*/
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__d_drop(dentry);
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__d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
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spin_unlock(&dcache_hash_lock);
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/* Unhash the target: dput() will then get rid of it */
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/* __d_drop does write_seqcount_barrier, but they're OK to nest. */
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__d_drop(target);
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list_del(&dentry->d_u.d_child);
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@ -2369,9 +2404,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
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spin_lock(&actual->d_lock);
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found:
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spin_lock(&dcache_hash_lock);
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_d_rehash(actual);
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spin_unlock(&dcache_hash_lock);
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spin_unlock(&actual->d_lock);
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spin_unlock(&dcache_inode_lock);
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out_nolock:
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@ -2953,7 +2986,7 @@ static void __init dcache_init_early(void)
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dentry_hashtable =
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alloc_large_system_hash("Dentry cache",
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sizeof(struct hlist_head),
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sizeof(struct dcache_hash_bucket),
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dhash_entries,
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13,
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HASH_EARLY,
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@ -2962,7 +2995,7 @@ static void __init dcache_init_early(void)
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0);
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for (loop = 0; loop < (1 << d_hash_shift); loop++)
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INIT_HLIST_HEAD(&dentry_hashtable[loop]);
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INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head);
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}
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static void __init dcache_init(void)
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@ -2985,7 +3018,7 @@ static void __init dcache_init(void)
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dentry_hashtable =
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alloc_large_system_hash("Dentry cache",
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sizeof(struct hlist_head),
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sizeof(struct dcache_hash_bucket),
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dhash_entries,
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13,
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0,
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@ -2994,7 +3027,7 @@ static void __init dcache_init(void)
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0);
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for (loop = 0; loop < (1 << d_hash_shift); loop++)
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INIT_HLIST_HEAD(&dentry_hashtable[loop]);
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INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head);
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}
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/* SLAB cache for __getname() consumers */
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@ -30,6 +30,7 @@
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#include <linux/idr.h>
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#include <linux/mutex.h>
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#include <linux/backing-dev.h>
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#include <linux/rculist_bl.h>
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#include "internal.h"
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@ -71,7 +72,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
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INIT_LIST_HEAD(&s->s_files);
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#endif
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INIT_LIST_HEAD(&s->s_instances);
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INIT_HLIST_HEAD(&s->s_anon);
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INIT_HLIST_BL_HEAD(&s->s_anon);
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INIT_LIST_HEAD(&s->s_inodes);
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INIT_LIST_HEAD(&s->s_dentry_lru);
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init_rwsem(&s->s_umount);
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@ -4,6 +4,7 @@
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#include <asm/atomic.h>
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#include <linux/list.h>
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#include <linux/rculist.h>
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#include <linux/rculist_bl.h>
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#include <linux/spinlock.h>
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#include <linux/seqlock.h>
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#include <linux/cache.h>
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@ -95,7 +96,7 @@ struct dentry {
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/* RCU lookup touched fields */
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unsigned int d_flags; /* protected by d_lock */
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seqcount_t d_seq; /* per dentry seqlock */
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struct hlist_node d_hash; /* lookup hash list */
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struct hlist_bl_node d_hash; /* lookup hash list */
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struct dentry *d_parent; /* parent directory */
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struct qstr d_name;
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struct inode *d_inode; /* Where the name belongs to - NULL is
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@ -392,6 +392,7 @@ struct inodes_stat_t {
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#include <linux/capability.h>
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#include <linux/semaphore.h>
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#include <linux/fiemap.h>
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#include <linux/rculist_bl.h>
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#include <asm/atomic.h>
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#include <asm/byteorder.h>
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@ -1377,7 +1378,7 @@ struct super_block {
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const struct xattr_handler **s_xattr;
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struct list_head s_inodes; /* all inodes */
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struct hlist_head s_anon; /* anonymous dentries for (nfs) exporting */
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struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */
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#ifdef CONFIG_SMP
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struct list_head __percpu *s_files;
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#else
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