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![Arnd Bergmann](/assets/img/avatar_default.png)
In some randconfig builds, kernfs ends up being disabled, so there is no prototype for kernfs_generic_poll() In file included from kernel/sched/build_utility.c:97: kernel/sched/psi.c:1479:3: error: implicit declaration of function 'kernfs_generic_poll' is invalid in C99 [-Werror,-Wimplicit-function-declaration] kernfs_generic_poll(t->of, wait); ^ Add a stub helper for it, as we have it for other kernfs functions. Fixes:aff037078e
("sched/psi: use kernfs polling functions for PSI trigger polling") Fixes:147e1a97c4
("fs: kernfs: add poll file operation") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com> Link: https://lore.kernel.org/r/20230724121823.1357562-1-arnd@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
632 lines
19 KiB
C
632 lines
19 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* kernfs.h - pseudo filesystem decoupled from vfs locking
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*/
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#ifndef __LINUX_KERNFS_H
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#define __LINUX_KERNFS_H
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#include <linux/err.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/idr.h>
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#include <linux/lockdep.h>
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#include <linux/rbtree.h>
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#include <linux/atomic.h>
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#include <linux/bug.h>
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#include <linux/types.h>
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#include <linux/uidgid.h>
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#include <linux/wait.h>
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#include <linux/rwsem.h>
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#include <linux/cache.h>
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struct file;
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struct dentry;
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struct iattr;
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struct seq_file;
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struct vm_area_struct;
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struct vm_operations_struct;
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struct super_block;
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struct file_system_type;
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struct poll_table_struct;
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struct fs_context;
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struct kernfs_fs_context;
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struct kernfs_open_node;
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struct kernfs_iattrs;
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/*
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* NR_KERNFS_LOCK_BITS determines size (NR_KERNFS_LOCKS) of hash
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* table of locks.
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* Having a small hash table would impact scalability, since
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* more and more kernfs_node objects will end up using same lock
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* and having a very large hash table would waste memory.
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*
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* At the moment size of hash table of locks is being set based on
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* the number of CPUs as follows:
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*
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* NR_CPU NR_KERNFS_LOCK_BITS NR_KERNFS_LOCKS
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* 1 1 2
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* 2-3 2 4
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* 4-7 4 16
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* 8-15 6 64
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* 16-31 8 256
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* 32 and more 10 1024
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*
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* The above relation between NR_CPU and number of locks is based
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* on some internal experimentation which involved booting qemu
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* with different values of smp, performing some sysfs operations
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* on all CPUs and observing how increase in number of locks impacts
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* completion time of these sysfs operations on each CPU.
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*/
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#ifdef CONFIG_SMP
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#define NR_KERNFS_LOCK_BITS (2 * (ilog2(NR_CPUS < 32 ? NR_CPUS : 32)))
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#else
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#define NR_KERNFS_LOCK_BITS 1
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#endif
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#define NR_KERNFS_LOCKS (1 << NR_KERNFS_LOCK_BITS)
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/*
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* There's one kernfs_open_file for each open file and one kernfs_open_node
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* for each kernfs_node with one or more open files.
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*
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* filp->private_data points to seq_file whose ->private points to
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* kernfs_open_file.
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*
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* kernfs_open_files are chained at kernfs_open_node->files, which is
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* protected by kernfs_global_locks.open_file_mutex[i].
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*
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* To reduce possible contention in sysfs access, arising due to single
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* locks, use an array of locks (e.g. open_file_mutex) and use kernfs_node
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* object address as hash keys to get the index of these locks.
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*
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* Hashed mutexes are safe to use here because operations using these don't
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* rely on global exclusion.
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*
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* In future we intend to replace other global locks with hashed ones as well.
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* kernfs_global_locks acts as a holder for all such hash tables.
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*/
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struct kernfs_global_locks {
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struct mutex open_file_mutex[NR_KERNFS_LOCKS];
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};
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enum kernfs_node_type {
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KERNFS_DIR = 0x0001,
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KERNFS_FILE = 0x0002,
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KERNFS_LINK = 0x0004,
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};
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#define KERNFS_TYPE_MASK 0x000f
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#define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
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#define KERNFS_MAX_USER_XATTRS 128
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#define KERNFS_USER_XATTR_SIZE_LIMIT (128 << 10)
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enum kernfs_node_flag {
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KERNFS_ACTIVATED = 0x0010,
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KERNFS_NS = 0x0020,
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KERNFS_HAS_SEQ_SHOW = 0x0040,
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KERNFS_HAS_MMAP = 0x0080,
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KERNFS_LOCKDEP = 0x0100,
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KERNFS_HIDDEN = 0x0200,
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KERNFS_SUICIDAL = 0x0400,
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KERNFS_SUICIDED = 0x0800,
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KERNFS_EMPTY_DIR = 0x1000,
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KERNFS_HAS_RELEASE = 0x2000,
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KERNFS_REMOVING = 0x4000,
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};
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/* @flags for kernfs_create_root() */
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enum kernfs_root_flag {
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/*
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* kernfs_nodes are created in the deactivated state and invisible.
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* They require explicit kernfs_activate() to become visible. This
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* can be used to make related nodes become visible atomically
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* after all nodes are created successfully.
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*/
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KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001,
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/*
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* For regular files, if the opener has CAP_DAC_OVERRIDE, open(2)
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* succeeds regardless of the RW permissions. sysfs had an extra
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* layer of enforcement where open(2) fails with -EACCES regardless
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* of CAP_DAC_OVERRIDE if the permission doesn't have the
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* respective read or write access at all (none of S_IRUGO or
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* S_IWUGO) or the respective operation isn't implemented. The
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* following flag enables that behavior.
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*/
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KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK = 0x0002,
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/*
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* The filesystem supports exportfs operation, so userspace can use
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* fhandle to access nodes of the fs.
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*/
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KERNFS_ROOT_SUPPORT_EXPORTOP = 0x0004,
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/*
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* Support user xattrs to be written to nodes rooted at this root.
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*/
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KERNFS_ROOT_SUPPORT_USER_XATTR = 0x0008,
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};
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/* type-specific structures for kernfs_node union members */
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struct kernfs_elem_dir {
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unsigned long subdirs;
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/* children rbtree starts here and goes through kn->rb */
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struct rb_root children;
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/*
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* The kernfs hierarchy this directory belongs to. This fits
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* better directly in kernfs_node but is here to save space.
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*/
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struct kernfs_root *root;
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/*
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* Monotonic revision counter, used to identify if a directory
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* node has changed during negative dentry revalidation.
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*/
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unsigned long rev;
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};
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struct kernfs_elem_symlink {
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struct kernfs_node *target_kn;
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};
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struct kernfs_elem_attr {
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const struct kernfs_ops *ops;
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struct kernfs_open_node __rcu *open;
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loff_t size;
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struct kernfs_node *notify_next; /* for kernfs_notify() */
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};
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/*
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* kernfs_node - the building block of kernfs hierarchy. Each and every
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* kernfs node is represented by single kernfs_node. Most fields are
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* private to kernfs and shouldn't be accessed directly by kernfs users.
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*
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* As long as count reference is held, the kernfs_node itself is
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* accessible. Dereferencing elem or any other outer entity requires
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* active reference.
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*/
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struct kernfs_node {
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atomic_t count;
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atomic_t active;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif
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/*
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* Use kernfs_get_parent() and kernfs_name/path() instead of
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* accessing the following two fields directly. If the node is
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* never moved to a different parent, it is safe to access the
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* parent directly.
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*/
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struct kernfs_node *parent;
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const char *name;
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struct rb_node rb;
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const void *ns; /* namespace tag */
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unsigned int hash; /* ns + name hash */
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union {
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struct kernfs_elem_dir dir;
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struct kernfs_elem_symlink symlink;
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struct kernfs_elem_attr attr;
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};
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void *priv;
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/*
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* 64bit unique ID. On 64bit ino setups, id is the ino. On 32bit,
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* the low 32bits are ino and upper generation.
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*/
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u64 id;
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unsigned short flags;
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umode_t mode;
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struct kernfs_iattrs *iattr;
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};
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/*
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* kernfs_syscall_ops may be specified on kernfs_create_root() to support
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* syscalls. These optional callbacks are invoked on the matching syscalls
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* and can perform any kernfs operations which don't necessarily have to be
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* the exact operation requested. An active reference is held for each
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* kernfs_node parameter.
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*/
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struct kernfs_syscall_ops {
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int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
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int (*mkdir)(struct kernfs_node *parent, const char *name,
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umode_t mode);
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int (*rmdir)(struct kernfs_node *kn);
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int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
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const char *new_name);
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int (*show_path)(struct seq_file *sf, struct kernfs_node *kn,
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struct kernfs_root *root);
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};
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struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root);
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struct kernfs_open_file {
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/* published fields */
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struct kernfs_node *kn;
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struct file *file;
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struct seq_file *seq_file;
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void *priv;
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/* private fields, do not use outside kernfs proper */
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struct mutex mutex;
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struct mutex prealloc_mutex;
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int event;
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struct list_head list;
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char *prealloc_buf;
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size_t atomic_write_len;
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bool mmapped:1;
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bool released:1;
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const struct vm_operations_struct *vm_ops;
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};
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struct kernfs_ops {
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/*
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* Optional open/release methods. Both are called with
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* @of->seq_file populated.
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*/
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int (*open)(struct kernfs_open_file *of);
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void (*release)(struct kernfs_open_file *of);
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/*
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* Read is handled by either seq_file or raw_read().
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*
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* If seq_show() is present, seq_file path is active. Other seq
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* operations are optional and if not implemented, the behavior is
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* equivalent to single_open(). @sf->private points to the
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* associated kernfs_open_file.
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*
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* read() is bounced through kernel buffer and a read larger than
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* PAGE_SIZE results in partial operation of PAGE_SIZE.
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*/
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int (*seq_show)(struct seq_file *sf, void *v);
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void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
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void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
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void (*seq_stop)(struct seq_file *sf, void *v);
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ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
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loff_t off);
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/*
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* write() is bounced through kernel buffer. If atomic_write_len
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* is not set, a write larger than PAGE_SIZE results in partial
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* operations of PAGE_SIZE chunks. If atomic_write_len is set,
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* writes upto the specified size are executed atomically but
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* larger ones are rejected with -E2BIG.
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*/
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size_t atomic_write_len;
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/*
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* "prealloc" causes a buffer to be allocated at open for
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* all read/write requests. As ->seq_show uses seq_read()
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* which does its own allocation, it is incompatible with
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* ->prealloc. Provide ->read and ->write with ->prealloc.
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*/
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bool prealloc;
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ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
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loff_t off);
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__poll_t (*poll)(struct kernfs_open_file *of,
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struct poll_table_struct *pt);
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int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
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};
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/*
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* The kernfs superblock creation/mount parameter context.
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*/
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struct kernfs_fs_context {
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struct kernfs_root *root; /* Root of the hierarchy being mounted */
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void *ns_tag; /* Namespace tag of the mount (or NULL) */
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unsigned long magic; /* File system specific magic number */
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/* The following are set/used by kernfs_mount() */
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bool new_sb_created; /* Set to T if we allocated a new sb */
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};
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#ifdef CONFIG_KERNFS
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static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
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{
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return kn->flags & KERNFS_TYPE_MASK;
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}
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static inline ino_t kernfs_id_ino(u64 id)
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{
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/* id is ino if ino_t is 64bit; otherwise, low 32bits */
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if (sizeof(ino_t) >= sizeof(u64))
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return id;
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else
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return (u32)id;
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}
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static inline u32 kernfs_id_gen(u64 id)
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{
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/* gen is fixed at 1 if ino_t is 64bit; otherwise, high 32bits */
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if (sizeof(ino_t) >= sizeof(u64))
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return 1;
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else
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return id >> 32;
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}
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static inline ino_t kernfs_ino(struct kernfs_node *kn)
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{
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return kernfs_id_ino(kn->id);
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}
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static inline ino_t kernfs_gen(struct kernfs_node *kn)
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{
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return kernfs_id_gen(kn->id);
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}
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/**
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* kernfs_enable_ns - enable namespace under a directory
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* @kn: directory of interest, should be empty
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*
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* This is to be called right after @kn is created to enable namespace
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* under it. All children of @kn must have non-NULL namespace tags and
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* only the ones which match the super_block's tag will be visible.
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*/
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static inline void kernfs_enable_ns(struct kernfs_node *kn)
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{
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WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
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WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
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kn->flags |= KERNFS_NS;
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}
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/**
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* kernfs_ns_enabled - test whether namespace is enabled
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* @kn: the node to test
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*
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* Test whether namespace filtering is enabled for the children of @ns.
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*/
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static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
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{
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return kn->flags & KERNFS_NS;
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}
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int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen);
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int kernfs_path_from_node(struct kernfs_node *root_kn, struct kernfs_node *kn,
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char *buf, size_t buflen);
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void pr_cont_kernfs_name(struct kernfs_node *kn);
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void pr_cont_kernfs_path(struct kernfs_node *kn);
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struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn);
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struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
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const char *name, const void *ns);
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struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
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const char *path, const void *ns);
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void kernfs_get(struct kernfs_node *kn);
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void kernfs_put(struct kernfs_node *kn);
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struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry);
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struct kernfs_root *kernfs_root_from_sb(struct super_block *sb);
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struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
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struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
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struct super_block *sb);
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struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
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unsigned int flags, void *priv);
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void kernfs_destroy_root(struct kernfs_root *root);
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struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
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const char *name, umode_t mode,
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kuid_t uid, kgid_t gid,
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void *priv, const void *ns);
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struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
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const char *name);
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struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
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const char *name, umode_t mode,
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kuid_t uid, kgid_t gid,
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loff_t size,
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const struct kernfs_ops *ops,
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void *priv, const void *ns,
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struct lock_class_key *key);
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struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
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const char *name,
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struct kernfs_node *target);
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void kernfs_activate(struct kernfs_node *kn);
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void kernfs_show(struct kernfs_node *kn, bool show);
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void kernfs_remove(struct kernfs_node *kn);
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void kernfs_break_active_protection(struct kernfs_node *kn);
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void kernfs_unbreak_active_protection(struct kernfs_node *kn);
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bool kernfs_remove_self(struct kernfs_node *kn);
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int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
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const void *ns);
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int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
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const char *new_name, const void *new_ns);
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int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
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__poll_t kernfs_generic_poll(struct kernfs_open_file *of,
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struct poll_table_struct *pt);
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void kernfs_notify(struct kernfs_node *kn);
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int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
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void *value, size_t size);
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int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
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const void *value, size_t size, int flags);
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const void *kernfs_super_ns(struct super_block *sb);
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int kernfs_get_tree(struct fs_context *fc);
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void kernfs_free_fs_context(struct fs_context *fc);
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void kernfs_kill_sb(struct super_block *sb);
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void kernfs_init(void);
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struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
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u64 id);
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#else /* CONFIG_KERNFS */
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static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
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{ return 0; } /* whatever */
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static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
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static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
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{ return false; }
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static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
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{ return -ENOSYS; }
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static inline int kernfs_path_from_node(struct kernfs_node *root_kn,
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struct kernfs_node *kn,
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char *buf, size_t buflen)
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{ return -ENOSYS; }
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static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { }
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static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { }
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static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
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{ return NULL; }
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static inline struct kernfs_node *
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kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
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const void *ns)
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{ return NULL; }
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static inline struct kernfs_node *
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kernfs_walk_and_get_ns(struct kernfs_node *parent, const char *path,
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const void *ns)
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{ return NULL; }
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static inline void kernfs_get(struct kernfs_node *kn) { }
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static inline void kernfs_put(struct kernfs_node *kn) { }
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static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
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{ return NULL; }
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static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
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{ return NULL; }
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static inline struct inode *
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kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
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{ return NULL; }
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static inline struct kernfs_root *
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kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
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void *priv)
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{ return ERR_PTR(-ENOSYS); }
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static inline void kernfs_destroy_root(struct kernfs_root *root) { }
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static inline struct kernfs_node *
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kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
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umode_t mode, kuid_t uid, kgid_t gid,
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void *priv, const void *ns)
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{ return ERR_PTR(-ENOSYS); }
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static inline struct kernfs_node *
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__kernfs_create_file(struct kernfs_node *parent, const char *name,
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umode_t mode, kuid_t uid, kgid_t gid,
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loff_t size, const struct kernfs_ops *ops,
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void *priv, const void *ns, struct lock_class_key *key)
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{ return ERR_PTR(-ENOSYS); }
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static inline struct kernfs_node *
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kernfs_create_link(struct kernfs_node *parent, const char *name,
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struct kernfs_node *target)
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{ return ERR_PTR(-ENOSYS); }
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static inline void kernfs_activate(struct kernfs_node *kn) { }
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static inline void kernfs_remove(struct kernfs_node *kn) { }
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static inline bool kernfs_remove_self(struct kernfs_node *kn)
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{ return false; }
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static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
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const char *name, const void *ns)
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{ return -ENOSYS; }
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static inline int kernfs_rename_ns(struct kernfs_node *kn,
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struct kernfs_node *new_parent,
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const char *new_name, const void *new_ns)
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{ return -ENOSYS; }
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static inline int kernfs_setattr(struct kernfs_node *kn,
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const struct iattr *iattr)
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{ return -ENOSYS; }
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static inline __poll_t kernfs_generic_poll(struct kernfs_open_file *of,
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struct poll_table_struct *pt)
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{ return -ENOSYS; }
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static inline void kernfs_notify(struct kernfs_node *kn) { }
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static inline int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
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void *value, size_t size)
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{ return -ENOSYS; }
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static inline int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
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const void *value, size_t size, int flags)
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{ return -ENOSYS; }
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static inline const void *kernfs_super_ns(struct super_block *sb)
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{ return NULL; }
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static inline int kernfs_get_tree(struct fs_context *fc)
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{ return -ENOSYS; }
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static inline void kernfs_free_fs_context(struct fs_context *fc) { }
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static inline void kernfs_kill_sb(struct super_block *sb) { }
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static inline void kernfs_init(void) { }
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#endif /* CONFIG_KERNFS */
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/**
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* kernfs_path - build full path of a given node
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* @kn: kernfs_node of interest
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* @buf: buffer to copy @kn's name into
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* @buflen: size of @buf
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*
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* If @kn is NULL result will be "(null)".
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*
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* Returns the length of the full path. If the full length is equal to or
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* greater than @buflen, @buf contains the truncated path with the trailing
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* '\0'. On error, -errno is returned.
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*/
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static inline int kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
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{
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return kernfs_path_from_node(kn, NULL, buf, buflen);
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}
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static inline struct kernfs_node *
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kernfs_find_and_get(struct kernfs_node *kn, const char *name)
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{
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return kernfs_find_and_get_ns(kn, name, NULL);
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}
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static inline struct kernfs_node *
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kernfs_walk_and_get(struct kernfs_node *kn, const char *path)
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{
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return kernfs_walk_and_get_ns(kn, path, NULL);
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}
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static inline struct kernfs_node *
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kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
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void *priv)
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{
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return kernfs_create_dir_ns(parent, name, mode,
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GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
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priv, NULL);
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}
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static inline int kernfs_remove_by_name(struct kernfs_node *parent,
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const char *name)
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{
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return kernfs_remove_by_name_ns(parent, name, NULL);
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}
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static inline int kernfs_rename(struct kernfs_node *kn,
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struct kernfs_node *new_parent,
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const char *new_name)
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{
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return kernfs_rename_ns(kn, new_parent, new_name, NULL);
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}
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#endif /* __LINUX_KERNFS_H */
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