Linux-2.6.33.2/fs/inode.c
/*
* linux/fs/inode.c
*
* (C) 1997 Linus Torvalds
*/
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/dcache.h>
#include <linux/init.h>
#include <linux/quotaops.h>
#include <linux/slab.h>
#include <linux/writeback.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>
#include <linux/rwsem.h>
#include <linux/hash.h>
#include <linux/swap.h>
#include <linux/security.h>
#include <linux/pagemap.h>
#include <linux/cdev.h>
#include <linux/bootmem.h>
#include <linux/inotify.h>
#include <linux/fsnotify.h>
#include <linux/mount.h>
#include <linux/async.h>
#include <linux/posix_acl.h>
/*
* This is needed for the following functions:
* - inode_has_buffers
* - invalidate_inode_buffers
* - invalidate_bdev
*
* FIXME: remove all knowledge of the buffer layer from this file
*/
#include <linux/buffer_head.h>
/*
* New inode.c implementation.
*
* This implementation has the basic premise of trying
* to be extremely low-overhead and SMP-safe, yet be
* simple enough to be "obviously correct".
*
* Famous last words.
*/
/* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */
/* #define INODE_PARANOIA 1 */
/* #define INODE_DEBUG 1 */
/*
* Inode lookup is no longer as critical as it used to be:
* most of the lookups are going to be through the dcache.
*/
#define I_HASHBITS i_hash_shift
#define I_HASHMASK i_hash_mask
static unsigned int i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;
/*
* Each inode can be on two separate lists. One is
* the hash list of the inode, used for lookups. The
* other linked list is the "type" list:
* "in_use" - valid inode, i_count > 0, i_nlink > 0
* "dirty" - as "in_use" but also dirty
* "unused" - valid inode, i_count = 0
*
* A "dirty" list is maintained for each super block,
* allowing for low-overhead inode sync() operations.
*/
LIST_HEAD(inode_in_use);
LIST_HEAD(inode_unused);
static struct hlist_head *inode_hashtable __read_mostly;
/*
* A simple spinlock to protect the list manipulations.
*
* NOTE! You also have to own the lock if you change
* the i_state of an inode while it is in use..
*/
DEFINE_SPINLOCK(inode_lock);
/*
* iprune_sem provides exclusion between the kswapd or try_to_free_pages
* icache shrinking path, and the umount path. Without this exclusion,
* by the time prune_icache calls iput for the inode whose pages it has
* been invalidating, or by the time it calls clear_inode & destroy_inode
* from its final dispose_list, the struct super_block they refer to
* (for inode->i_sb->s_op) may already have been freed and reused.
*
* We make this an rwsem because the fastpath is icache shrinking. In
* some cases a filesystem may be doing a significant amount of work in
* its inode reclaim code, so this should improve parallelism.
*/
static DECLARE_RWSEM(iprune_sem);
/*
* Statistics gathering..
*/
struct inodes_stat_t inodes_stat;
static struct kmem_cache *inode_cachep __read_mostly;
static void wake_up_inode(struct inode *inode)
{
/*
* Prevent speculative execution through spin_unlock(&inode_lock);
*/
smp_mb();
wake_up_bit(&inode->i_state, __I_NEW);
}
/**
* inode_init_always - perform inode structure intialisation
* @sb: superblock inode belongs to
* @inode: inode to initialise
*
* These are initializations that need to be done on every inode
* allocation as the fields are not initialised by slab allocation.
*/
int inode_init_always(struct super_block *sb, struct inode *inode)
{
static const struct address_space_operations empty_aops;
static const struct inode_operations empty_iops;
static const struct file_operations empty_fops;
struct address_space *const mapping = &inode->i_data;
inode->i_sb = sb;
inode->i_blkbits = sb->s_blocksize_bits;
inode->i_flags = 0;
atomic_set(&inode->i_count, 1);
inode->i_op = &empty_iops;
inode->i_fop = &empty_fops;
inode->i_nlink = 1;
inode->i_uid = 0;
inode->i_gid = 0;
atomic_set(&inode->i_writecount, 0);
inode->i_size = 0;
inode->i_blocks = 0;
inode->i_bytes = 0;
inode->i_generation = 0;
#ifdef CONFIG_QUOTA
memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
#endif
inode->i_pipe = NULL;
inode->i_bdev = NULL;
inode->i_cdev = NULL;
inode->i_rdev = 0;
inode->dirtied_when = 0;
if (security_inode_alloc(inode))
goto out;
spin_lock_init(&inode->i_lock);
lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
mutex_init(&inode->i_mutex);
lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
init_rwsem(&inode->i_alloc_sem);
lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);
mapping->a_ops = &empty_aops;
mapping->host = inode;
mapping->flags = 0;
mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
mapping->assoc_mapping = NULL;
mapping->backing_dev_info = &default_backing_dev_info;
mapping->writeback_index = 0;
/*
* If the block_device provides a backing_dev_info for client
* inodes then use that. Otherwise the inode share the bdev's
* backing_dev_info.
*/
if (sb->s_bdev) {
struct backing_dev_info *bdi;
bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
mapping->backing_dev_info = bdi;
}
inode->i_private = NULL;
inode->i_mapping = mapping;
#ifdef CONFIG_FS_POSIX_ACL
inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif
#ifdef CONFIG_FSNOTIFY
inode->i_fsnotify_mask = 0;
#endif
return 0;
out:
return -ENOMEM;
}
EXPORT_SYMBOL(inode_init_always);
static struct inode *alloc_inode(struct super_block *sb)
{
struct inode *inode;
if (sb->s_op->alloc_inode)
inode = sb->s_op->alloc_inode(sb);
else
inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
if (!inode)
return NULL;
if (unlikely(inode_init_always(sb, inode))) {
if (inode->i_sb->s_op->destroy_inode)
inode->i_sb->s_op->destroy_inode(inode);
else
kmem_cache_free(inode_cachep, inode);
return NULL;
}
return inode;
}
void __destroy_inode(struct inode *inode)
{
BUG_ON(inode_has_buffers(inode));
security_inode_free(inode);
fsnotify_inode_delete(inode);
#ifdef CONFIG_FS_POSIX_ACL
if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
posix_acl_release(inode->i_acl);
if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
posix_acl_release(inode->i_default_acl);
#endif
}
EXPORT_SYMBOL(__destroy_inode);
void destroy_inode(struct inode *inode)
{
__destroy_inode(inode);
if (inode->i_sb->s_op->destroy_inode)
inode->i_sb->s_op->destroy_inode(inode);
else
kmem_cache_free(inode_cachep, (inode));
}
/*
* These are initializations that only need to be done
* once, because the fields are idempotent across use
* of the inode, so let the slab aware of that.
*/
void inode_init_once(struct inode *inode)
{
memset(inode, 0, sizeof(*inode));
INIT_HLIST_NODE(&inode->i_hash);
INIT_LIST_HEAD(&inode->i_dentry);
INIT_LIST_HEAD(&inode->i_devices);
INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
spin_lock_init(&inode->i_data.tree_lock);
spin_lock_init(&inode->i_data.i_mmap_lock);
INIT_LIST_HEAD(&inode->i_data.private_list);
spin_lock_init(&inode->i_data.private_lock);
INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
i_size_ordered_init(inode);
#ifdef CONFIG_INOTIFY
INIT_LIST_HEAD(&inode->inotify_watches);
mutex_init(&inode->inotify_mutex);
#endif
#ifdef CONFIG_FSNOTIFY
INIT_HLIST_HEAD(&inode->i_fsnotify_mark_entries);
#endif
}
EXPORT_SYMBOL(inode_init_once);
static void init_once(void *foo)
{
struct inode *inode = (struct inode *) foo;
inode_init_once(inode);
}
/*
* inode_lock must be held
*/
void __iget(struct inode *inode)
{
if (atomic_read(&inode->i_count)) {
atomic_inc(&inode->i_count);
return;
}
atomic_inc(&inode->i_count);
if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_in_use);
inodes_stat.nr_unused--;
}
/**
* clear_inode - clear an inode
* @inode: inode to clear
*
* This is called by the filesystem to tell us
* that the inode is no longer useful. We just
* terminate it with extreme prejudice.
*/
void clear_inode(struct inode *inode)
{
might_sleep();
invalidate_inode_buffers(inode);
BUG_ON(inode->i_data.nrpages);
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);
inode_sync_wait(inode);
vfs_dq_drop(inode);
if (inode->i_sb->s_op->clear_inode)
inode->i_sb->s_op->clear_inode(inode);
if (S_ISBLK(inode->i_mode) && inode->i_bdev)
bd_forget(inode);
if (S_ISCHR(inode->i_mode) && inode->i_cdev)
cd_forget(inode);
inode->i_state = I_CLEAR;
}
EXPORT_SYMBOL(clear_inode);
/*
* dispose_list - dispose of the contents of a local list
* @head: the head of the list to free
*
* Dispose-list gets a local list with local inodes in it, so it doesn't
* need to worry about list corruption and SMP locks.
*/
static void dispose_list(struct list_head *head)
{
int nr_disposed = 0;
while (!list_empty(head)) {
struct inode *inode;
inode = list_first_entry(head, struct inode, i_list);
list_del(&inode->i_list);
if (inode->i_data.nrpages)
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);
spin_lock(&inode_lock);
hlist_del_init(&inode->i_hash);
list_del_init(&inode->i_sb_list);
spin_unlock(&inode_lock);
wake_up_inode(inode);
destroy_inode(inode);
nr_disposed++;
}
spin_lock(&inode_lock);
inodes_stat.nr_inodes -= nr_disposed;
spin_unlock(&inode_lock);
}
/*
* Invalidate all inodes for a device.
*/
static int invalidate_list(struct list_head *head, struct list_head *dispose)
{
struct list_head *next;
int busy = 0, count = 0;
next = head->next;
for (;;) {
struct list_head *tmp = next;
struct inode *inode;
/*
* We can reschedule here without worrying about the list's
* consistency because the per-sb list of inodes must not
* change during umount anymore, and because iprune_sem keeps
* shrink_icache_memory() away.
*/
cond_resched_lock(&inode_lock);
next = next->next;
if (tmp == head)
break;
inode = list_entry(tmp, struct inode, i_sb_list);
if (inode->i_state & I_NEW)
continue;
invalidate_inode_buffers(inode);
if (!atomic_read(&inode->i_count)) {
list_move(&inode->i_list, dispose);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
count++;
continue;
}
busy = 1;
}
/* only unused inodes may be cached with i_count zero */
inodes_stat.nr_unused -= count;
return busy;
}
/**
* invalidate_inodes - discard the inodes on a device
* @sb: superblock
*
* Discard all of the inodes for a given superblock. If the discard
* fails because there are busy inodes then a non zero value is returned.
* If the discard is successful all the inodes have been discarded.
*/
int invalidate_inodes(struct super_block *sb)
{
int busy;
LIST_HEAD(throw_away);
down_write(&iprune_sem);
spin_lock(&inode_lock);
inotify_unmount_inodes(&sb->s_inodes);
fsnotify_unmount_inodes(&sb->s_inodes);
busy = invalidate_list(&sb->s_inodes, &throw_away);
spin_unlock(&inode_lock);
dispose_list(&throw_away);
up_write(&iprune_sem);
return busy;
}
EXPORT_SYMBOL(invalidate_inodes);
static int can_unuse(struct inode *inode)
{
if (inode->i_state)
return 0;
if (inode_has_buffers(inode))
return 0;
if (atomic_read(&inode->i_count))
return 0;
if (inode->i_data.nrpages)
return 0;
return 1;
}
/*
* Scan `goal' inodes on the unused list for freeable ones. They are moved to
* a temporary list and then are freed outside inode_lock by dispose_list().
*
* Any inodes which are pinned purely because of attached pagecache have their
* pagecache removed. We expect the final iput() on that inode to add it to
* the front of the inode_unused list. So look for it there and if the
* inode is still freeable, proceed. The right inode is found 99.9% of the
* time in testing on a 4-way.
*
* If the inode has metadata buffers attached to mapping->private_list then
* try to remove them.
*/
static void prune_icache(int nr_to_scan)
{
LIST_HEAD(freeable);
int nr_pruned = 0;
int nr_scanned;
unsigned long reap = 0;
down_read(&iprune_sem);
spin_lock(&inode_lock);
for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
struct inode *inode;
if (list_empty(&inode_unused))
break;
inode = list_entry(inode_unused.prev, struct inode, i_list);
if (inode->i_state || atomic_read(&inode->i_count)) {
list_move(&inode->i_list, &inode_unused);
continue;
}
if (inode_has_buffers(inode) || inode->i_data.nrpages) {
__iget(inode);
spin_unlock(&inode_lock);
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
0, -1);
iput(inode);
spin_lock(&inode_lock);
if (inode != list_entry(inode_unused.next,
struct inode, i_list))
continue; /* wrong inode or list_empty */
if (!can_unuse(inode))
continue;
}
list_move(&inode->i_list, &freeable);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
nr_pruned++;
}
inodes_stat.nr_unused -= nr_pruned;
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
__count_vm_events(PGINODESTEAL, reap);
spin_unlock(&inode_lock);
dispose_list(&freeable);
up_read(&iprune_sem);
}
/*
* shrink_icache_memory() will attempt to reclaim some unused inodes. Here,
* "unused" means that no dentries are referring to the inodes: the files are
* not open and the dcache references to those inodes have already been
* reclaimed.
*
* This function is passed the number of inodes to scan, and it returns the
* total number of remaining possibly-reclaimable inodes.
*/
static int shrink_icache_memory(int nr, gfp_t gfp_mask)
{
if (nr) {
/*
* Nasty deadlock avoidance. We may hold various FS locks,
* and we don't want to recurse into the FS that called us
* in clear_inode() and friends..
*/
if (!(gfp_mask & __GFP_FS))
return -1;
prune_icache(nr);
}
return (inodes_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
}
static struct shrinker icache_shrinker = {
.shrink = shrink_icache_memory,
.seeks = DEFAULT_SEEKS,
};
static void __wait_on_freeing_inode(struct inode *inode);
/*
* Called with the inode lock held.
* NOTE: we are not increasing the inode-refcount, you must call __iget()
* by hand after calling find_inode now! This simplifies iunique and won't
* add any additional branch in the common code.
*/
static struct inode *find_inode(struct super_block *sb,
struct hlist_head *head,
int (*test)(struct inode *, void *),
void *data)
{
struct hlist_node *node;
struct inode *inode = NULL;
repeat:
hlist_for_each_entry(inode, node, head, i_hash) {
if (inode->i_sb != sb)
continue;
if (!test(inode, data))
continue;
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
__wait_on_freeing_inode(inode);
goto repeat;
}
break;
}
return node ? inode : NULL;
}
/*
* find_inode_fast is the fast path version of find_inode, see the comment at
* iget_locked for details.
*/
static struct inode *find_inode_fast(struct super_block *sb,
struct hlist_head *head, unsigned long ino)
{
struct hlist_node *node;
struct inode *inode = NULL;
repeat:
hlist_for_each_entry(inode, node, head, i_hash) {
if (inode->i_ino != ino)
continue;
if (inode->i_sb != sb)
continue;
if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)) {
__wait_on_freeing_inode(inode);
goto repeat;
}
break;
}
return node ? inode : NULL;
}
static unsigned long hash(struct super_block *sb, unsigned long hashval)
{
unsigned long tmp;
tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
L1_CACHE_BYTES;
tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> I_HASHBITS);
return tmp & I_HASHMASK;
}
static inline void
__inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
struct inode *inode)
{
inodes_stat.nr_inodes++;
list_add(&inode->i_list, &inode_in_use);
list_add(&inode->i_sb_list, &sb->s_inodes);
if (head)
hlist_add_head(&inode->i_hash, head);
}
/**
* inode_add_to_lists - add a new inode to relevant lists
* @sb: superblock inode belongs to
* @inode: inode to mark in use
*
* When an inode is allocated it needs to be accounted for, added to the in use
* list, the owning superblock and the inode hash. This needs to be done under
* the inode_lock, so export a function to do this rather than the inode lock
* itself. We calculate the hash list to add to here so it is all internal
* which requires the caller to have already set up the inode number in the
* inode to add.
*/
void inode_add_to_lists(struct super_block *sb, struct inode *inode)
{
struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);
spin_lock(&inode_lock);
__inode_add_to_lists(sb, head, inode);
spin_unlock(&inode_lock);
}
EXPORT_SYMBOL_GPL(inode_add_to_lists);
/**
* new_inode - obtain an inode
* @sb: superblock
*
* Allocates a new inode for given superblock. The default gfp_mask
* for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
* If HIGHMEM pages are unsuitable or it is known that pages allocated
* for the page cache are not reclaimable or migratable,
* mapping_set_gfp_mask() must be called with suitable flags on the
* newly created inode's mapping
*
*/
struct inode *new_inode(struct super_block *sb)
{
/*
* On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
* error if st_ino won't fit in target struct field. Use 32bit counter
* here to attempt to avoid that.
*/
static unsigned int last_ino;
struct inode *inode;
spin_lock_prefetch(&inode_lock);
inode = alloc_inode(sb);
if (inode) {
spin_lock(&inode_lock);
__inode_add_to_lists(sb, NULL, inode);
inode->i_ino = ++last_ino;
inode->i_state = 0;
spin_unlock(&inode_lock);
}
return inode;
}
EXPORT_SYMBOL(new_inode);
void unlock_new_inode(struct inode *inode)
{
#ifdef CONFIG_DEBUG_LOCK_ALLOC
if (inode->i_mode & S_IFDIR) {
struct file_system_type *type = inode->i_sb->s_type;
/* Set new key only if filesystem hasn't already changed it */
if (!lockdep_match_class(&inode->i_mutex,
&type->i_mutex_key)) {
/*
* ensure nobody is actually holding i_mutex
*/
mutex_destroy(&inode->i_mutex);
mutex_init(&inode->i_mutex);
lockdep_set_class(&inode->i_mutex,
&type->i_mutex_dir_key);
}
}
#endif
/*
* This is special! We do not need the spinlock when clearing I_NEW,
* because we're guaranteed that nobody else tries to do anything about
* the state of the inode when it is locked, as we just created it (so
* there can be no old holders that haven't tested I_NEW).
* However we must emit the memory barrier so that other CPUs reliably
* see the clearing of I_NEW after the other inode initialisation has
* completed.
*/
smp_mb();
WARN_ON(!(inode->i_state & I_NEW));
inode->i_state &= ~I_NEW;
wake_up_inode(inode);
}
EXPORT_SYMBOL(unlock_new_inode);
/*
* This is called without the inode lock held.. Be careful.
*
* We no longer cache the sb_flags in i_flags - see fs.h
* -- rmk@arm.uk.linux.org
*/
static struct inode *get_new_inode(struct super_block *sb,
struct hlist_head *head,
int (*test)(struct inode *, void *),
int (*set)(struct inode *, void *),
void *data)
{
struct inode *inode;
inode = alloc_inode(sb);
if (inode) {
struct inode *old;
spin_lock(&inode_lock);
/* We released the lock, so.. */
old = find_inode(sb, head, test, data);
if (!old) {
if (set(inode, data))
goto set_failed;
__inode_add_to_lists(sb, head, inode);
inode->i_state = I_NEW;
spin_unlock(&inode_lock);
/* Return the locked inode with I_NEW set, the
* caller is responsible for filling in the contents
*/
return inode;
}
/*
* Uhhuh, somebody else created the same inode under
* us. Use the old inode instead of the one we just
* allocated.
*/
__iget(old);
spin_unlock(&inode_lock);
destroy_inode(inode);
inode = old;
wait_on_inode(inode);
}
return inode;
set_failed:
spin_unlock(&inode_lock);
destroy_inode(inode);
return NULL;
}
/*
* get_new_inode_fast is the fast path version of get_new_inode, see the
* comment at iget_locked for details.
*/
static struct inode *get_new_inode_fast(struct super_block *sb,
struct hlist_head *head, unsigned long ino)
{
struct inode *inode;
inode = alloc_inode(sb);
if (inode) {
struct inode *old;
spin_lock(&inode_lock);
/* We released the lock, so.. */
old = find_inode_fast(sb, head, ino);
if (!old) {
inode->i_ino = ino;
__inode_add_to_lists(sb, head, inode);
inode->i_state = I_NEW;
spin_unlock(&inode_lock);
/* Return the locked inode with I_NEW set, the
* caller is responsible for filling in the contents
*/
return inode;
}
/*
* Uhhuh, somebody else created the same inode under
* us. Use the old inode instead of the one we just
* allocated.
*/
__iget(old);
spin_unlock(&inode_lock);
destroy_inode(inode);
inode = old;
wait_on_inode(inode);
}
return inode;
}
/**
* iunique - get a unique inode number
* @sb: superblock
* @max_reserved: highest reserved inode number
*
* Obtain an inode number that is unique on the system for a given
* superblock. This is used by file systems that have no natural
* permanent inode numbering system. An inode number is returned that
* is higher than the reserved limit but unique.
*
* BUGS:
* With a large number of inodes live on the file system this function
* currently becomes quite slow.
*/
ino_t iunique(struct super_block *sb, ino_t max_reserved)
{
/*
* On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
* error if st_ino won't fit in target struct field. Use 32bit counter
* here to attempt to avoid that.
*/
static unsigned int counter;
struct inode *inode;
struct hlist_head *head;
ino_t res;
spin_lock(&inode_lock);
do {
if (counter <= max_reserved)
counter = max_reserved + 1;
res = counter++;
head = inode_hashtable + hash(sb, res);
inode = find_inode_fast(sb, head, res);
} while (inode != NULL);
spin_unlock(&inode_lock);
return res;
}
EXPORT_SYMBOL(iunique);
struct inode *igrab(struct inode *inode)
{
spin_lock(&inode_lock);
if (!(inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE)))
__iget(inode);
else
/*
* Handle the case where s_op->clear_inode is not been
* called yet, and somebody is calling igrab
* while the inode is getting freed.
*/
inode = NULL;
spin_unlock(&inode_lock);
return inode;
}
EXPORT_SYMBOL(igrab);
/**
* ifind - internal function, you want ilookup5() or iget5().
* @sb: super block of file system to search
* @head: the head of the list to search
* @test: callback used for comparisons between inodes
* @data: opaque data pointer to pass to @test
* @wait: if true wait for the inode to be unlocked, if false do not
*
* ifind() searches for the inode specified by @data in the inode
* cache. This is a generalized version of ifind_fast() for file systems where
* the inode number is not sufficient for unique identification of an inode.
*
* If the inode is in the cache, the inode is returned with an incremented
* reference count.
*
* Otherwise NULL is returned.
*
* Note, @test is called with the inode_lock held, so can't sleep.
*/
static struct inode *ifind(struct super_block *sb,
struct hlist_head *head, int (*test)(struct inode *, void *),
void *data, const int wait)
{
struct inode *inode;
spin_lock(&inode_lock);
inode = find_inode(sb, head, test, data);
if (inode) {
__iget(inode);
spin_unlock(&inode_lock);
if (likely(wait))
wait_on_inode(inode);
return inode;
}
spin_unlock(&inode_lock);
return NULL;
}
/**
* ifind_fast - internal function, you want ilookup() or iget().
* @sb: super block of file system to search
* @head: head of the list to search
* @ino: inode number to search for
*
* ifind_fast() searches for the inode @ino in the inode cache. This is for
* file systems where the inode number is sufficient for unique identification
* of an inode.
*
* If the inode is in the cache, the inode is returned with an incremented
* reference count.
*
* Otherwise NULL is returned.
*/
static struct inode *ifind_fast(struct super_block *sb,
struct hlist_head *head, unsigned long ino)
{
struct inode *inode;
spin_lock(&inode_lock);
inode = find_inode_fast(sb, head, ino);
if (inode) {
__iget(inode);
spin_unlock(&inode_lock);
wait_on_inode(inode);
return inode;
}
spin_unlock(&inode_lock);
return NULL;
}
/**
* ilookup5_nowait - search for an inode in the inode cache
* @sb: super block of file system to search
* @hashval: hash value (usually inode number) to search for
* @test: callback used for comparisons between inodes
* @data: opaque data pointer to pass to @test
*
* ilookup5() uses ifind() to search for the inode specified by @hashval and
* @data in the inode cache. This is a generalized version of ilookup() for
* file systems where the inode number is not sufficient for unique
* identification of an inode.
*
* If the inode is in the cache, the inode is returned with an incremented
* reference count. Note, the inode lock is not waited upon so you have to be
* very careful what you do with the returned inode. You probably should be
* using ilookup5() instead.
*
* Otherwise NULL is returned.
*
* Note, @test is called with the inode_lock held, so can't sleep.
*/
struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
{
struct hlist_head *head = inode_hashtable + hash(sb, hashval);
return ifind(sb, head, test, data, 0);
}
EXPORT_SYMBOL(ilookup5_nowait);
/**
* ilookup5 - search for an inode in the inode cache
* @sb: super block of file system to search
* @hashval: hash value (usually inode number) to search for
* @test: callback used for comparisons between inodes
* @data: opaque data pointer to pass to @test
*
* ilookup5() uses ifind() to search for the inode specified by @hashval and
* @data in the inode cache. This is a generalized version of ilookup() for
* file systems where the inode number is not sufficient for unique
* identification of an inode.
*
* If the inode is in the cache, the inode lock is waited upon and the inode is
* returned with an incremented reference count.
*
* Otherwise NULL is returned.
*
* Note, @test is called with the inode_lock held, so can't sleep.
*/
struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
{
struct hlist_head *head = inode_hashtable + hash(sb, hashval);
return ifind(sb, head, test, data, 1);
}
EXPORT_SYMBOL(ilookup5);
/**
* ilookup - search for an inode in the inode cache
* @sb: super block of file system to search
* @ino: inode number to search for
*
* ilookup() uses ifind_fast() to search for the inode @ino in the inode cache.
* This is for file systems where the inode number is sufficient for unique
* identification of an inode.
*
* If the inode is in the cache, the inode is returned with an incremented
* reference count.
*
* Otherwise NULL is returned.
*/
struct inode *ilookup(struct super_block *sb, unsigned long ino)
{
struct hlist_head *head = inode_hashtable + hash(sb, ino);
return ifind_fast(sb, head, ino);
}
EXPORT_SYMBOL(ilookup);
/**
* iget5_locked - obtain an inode from a mounted file system
* @sb: super block of file system
* @hashval: hash value (usually inode number) to get
* @test: callback used for comparisons between inodes
* @set: callback used to initialize a new struct inode
* @data: opaque data pointer to pass to @test and @set
*
* iget5_locked() uses ifind() to search for the inode specified by @hashval
* and @data in the inode cache and if present it is returned with an increased
* reference count. This is a generalized version of iget_locked() for file
* systems where the inode number is not sufficient for unique identification
* of an inode.
*
* If the inode is not in cache, get_new_inode() is called to allocate a new
* inode and this is returned locked, hashed, and with the I_NEW flag set. The
* file system gets to fill it in before unlocking it via unlock_new_inode().
*
* Note both @test and @set are called with the inode_lock held, so can't sleep.
*/
struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *),
int (*set)(struct inode *, void *), void *data)
{
struct hlist_head *head = inode_hashtable + hash(sb, hashval);
struct inode *inode;
inode = ifind(sb, head, test, data, 1);
if (inode)
return inode;
/*
* get_new_inode() will do the right thing, re-trying the search
* in case it had to block at any point.
*/
return get_new_inode(sb, head, test, set, data);
}
EXPORT_SYMBOL(iget5_locked);
/**
* iget_locked - obtain an inode from a mounted file system
* @sb: super block of file system
* @ino: inode number to get
*
* iget_locked() uses ifind_fast() to search for the inode specified by @ino in
* the inode cache and if present it is returned with an increased reference
* count. This is for file systems where the inode number is sufficient for
* unique identification of an inode.
*
* If the inode is not in cache, get_new_inode_fast() is called to allocate a
* new inode and this is returned locked, hashed, and with the I_NEW flag set.
* The file system gets to fill it in before unlocking it via
* unlock_new_inode().
*/
struct inode *iget_locked(struct super_block *sb, unsigned long ino)
{
struct hlist_head *head = inode_hashtable + hash(sb, ino);
struct inode *inode;
inode = ifind_fast(sb, head, ino);
if (inode)
return inode;
/*
* get_new_inode_fast() will do the right thing, re-trying the search
* in case it had to block at any point.
*/
return get_new_inode_fast(sb, head, ino);
}
EXPORT_SYMBOL(iget_locked);
int insert_inode_locked(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
ino_t ino = inode->i_ino;
struct hlist_head *head = inode_hashtable + hash(sb, ino);
inode->i_state |= I_NEW;
while (1) {
struct hlist_node *node;
struct inode *old = NULL;
spin_lock(&inode_lock);
hlist_for_each_entry(old, node, head, i_hash) {
if (old->i_ino != ino)
continue;
if (old->i_sb != sb)
continue;
if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
continue;
break;
}
if (likely(!node)) {
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode_lock);
return 0;
}
__iget(old);
spin_unlock(&inode_lock);
wait_on_inode(old);
if (unlikely(!hlist_unhashed(&old->i_hash))) {
iput(old);
return -EBUSY;
}
iput(old);
}
}
EXPORT_SYMBOL(insert_inode_locked);
int insert_inode_locked4(struct inode *inode, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
{
struct super_block *sb = inode->i_sb;
struct hlist_head *head = inode_hashtable + hash(sb, hashval);
inode->i_state |= I_NEW;
while (1) {
struct hlist_node *node;
struct inode *old = NULL;
spin_lock(&inode_lock);
hlist_for_each_entry(old, node, head, i_hash) {
if (old->i_sb != sb)
continue;
if (!test(old, data))
continue;
if (old->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE))
continue;
break;
}
if (likely(!node)) {
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode_lock);
return 0;
}
__iget(old);
spin_unlock(&inode_lock);
wait_on_inode(old);
if (unlikely(!hlist_unhashed(&old->i_hash))) {
iput(old);
return -EBUSY;
}
iput(old);
}
}
EXPORT_SYMBOL(insert_inode_locked4);
/**
* __insert_inode_hash - hash an inode
* @inode: unhashed inode
* @hashval: unsigned long value used to locate this object in the
* inode_hashtable.
*
* Add an inode to the inode hash for this superblock.
*/
void __insert_inode_hash(struct inode *inode, unsigned long hashval)
{
struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);
spin_lock(&inode_lock);
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode_lock);
}
EXPORT_SYMBOL(__insert_inode_hash);
/**
* remove_inode_hash - remove an inode from the hash
* @inode: inode to unhash
*
* Remove an inode from the superblock.
*/
void remove_inode_hash(struct inode *inode)
{
spin_lock(&inode_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_lock);
}
EXPORT_SYMBOL(remove_inode_hash);
/*
* Tell the filesystem that this inode is no longer of any interest and should
* be completely destroyed.
*
* We leave the inode in the inode hash table until *after* the filesystem's
* ->delete_inode completes. This ensures that an iget (such as nfsd might
* instigate) will always find up-to-date information either in the hash or on
* disk.
*
* I_FREEING is set so that no-one will take a new reference to the inode while
* it is being deleted.
*/
void generic_delete_inode(struct inode *inode)
{
const struct super_operations *op = inode->i_sb->s_op;
list_del_init(&inode->i_list);
list_del_init(&inode->i_sb_list);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
inodes_stat.nr_inodes--;
spin_unlock(&inode_lock);
security_inode_delete(inode);
if (op->delete_inode) {
void (*delete)(struct inode *) = op->delete_inode;
if (!is_bad_inode(inode))
vfs_dq_init(inode);
/* Filesystems implementing their own
* s_op->delete_inode are required to call
* truncate_inode_pages and clear_inode()
* internally */
delete(inode);
} else {
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);
}
spin_lock(&inode_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_lock);
wake_up_inode(inode);
BUG_ON(inode->i_state != I_CLEAR);
destroy_inode(inode);
}
EXPORT_SYMBOL(generic_delete_inode);
/**
* generic_detach_inode - remove inode from inode lists
* @inode: inode to remove
*
* Remove inode from inode lists, write it if it's dirty. This is just an
* internal VFS helper exported for hugetlbfs. Do not use!
*
* Returns 1 if inode should be completely destroyed.
*/
int generic_detach_inode(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
if (!hlist_unhashed(&inode->i_hash)) {
if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_unused);
inodes_stat.nr_unused++;
if (sb->s_flags & MS_ACTIVE) {
spin_unlock(&inode_lock);
return 0;
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_WILL_FREE;
spin_unlock(&inode_lock);
write_inode_now(inode, 1);
spin_lock(&inode_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
inodes_stat.nr_unused--;
hlist_del_init(&inode->i_hash);
}
list_del_init(&inode->i_list);
list_del_init(&inode->i_sb_list);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
inodes_stat.nr_inodes--;
spin_unlock(&inode_lock);
return 1;
}
EXPORT_SYMBOL_GPL(generic_detach_inode);
static void generic_forget_inode(struct inode *inode)
{
if (!generic_detach_inode(inode))
return;
if (inode->i_data.nrpages)
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);
wake_up_inode(inode);
destroy_inode(inode);
}
/*
* Normal UNIX filesystem behaviour: delete the
* inode when the usage count drops to zero, and
* i_nlink is zero.
*/
void generic_drop_inode(struct inode *inode)
{
if (!inode->i_nlink)
generic_delete_inode(inode);
else
generic_forget_inode(inode);
}
EXPORT_SYMBOL_GPL(generic_drop_inode);
/*
* Called when we're dropping the last reference
* to an inode.
*
* Call the FS "drop()" function, defaulting to
* the legacy UNIX filesystem behaviour..
*
* NOTE! NOTE! NOTE! We're called with the inode lock
* held, and the drop function is supposed to release
* the lock!
*/
static inline void iput_final(struct inode *inode)
{
const struct super_operations *op = inode->i_sb->s_op;
void (*drop)(struct inode *) = generic_drop_inode;
if (op && op->drop_inode)
drop = op->drop_inode;
drop(inode);
}
/**
* iput - put an inode
* @inode: inode to put
*
* Puts an inode, dropping its usage count. If the inode use count hits
* zero, the inode is then freed and may also be destroyed.
*
* Consequently, iput() can sleep.
*/
void iput(struct inode *inode)
{
if (inode) {
BUG_ON(inode->i_state == I_CLEAR);
if (atomic_dec_and_lock(&inode->i_count, &inode_lock))
iput_final(inode);
}
}
EXPORT_SYMBOL(iput);
/**
* bmap - find a block number in a file
* @inode: inode of file
* @block: block to find
*
* Returns the block number on the device holding the inode that
* is the disk block number for the block of the file requested.
* That is, asked for block 4 of inode 1 the function will return the
* disk block relative to the disk start that holds that block of the
* file.
*/
sector_t bmap(struct inode *inode, sector_t block)
{
sector_t res = 0;
if (inode->i_mapping->a_ops->bmap)
res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
return res;
}
EXPORT_SYMBOL(bmap);
/*
* With relative atime, only update atime if the previous atime is
* earlier than either the ctime or mtime or if at least a day has
* passed since the last atime update.
*/
static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
struct timespec now)
{
if (!(mnt->mnt_flags & MNT_RELATIME))
return 1;
/*
* Is mtime younger than atime? If yes, update atime:
*/
if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
return 1;
/*
* Is ctime younger than atime? If yes, update atime:
*/
if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
return 1;
/*
* Is the previous atime value older than a day? If yes,
* update atime:
*/
if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
return 1;
/*
* Good, we can skip the atime update:
*/
return 0;
}
/**
* touch_atime - update the access time
* @mnt: mount the inode is accessed on
* @dentry: dentry accessed
*
* Update the accessed time on an inode and mark it for writeback.
* This function automatically handles read only file systems and media,
* as well as the "noatime" flag and inode specific "noatime" markers.
*/
void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
struct timespec now;
if (inode->i_flags & S_NOATIME)
return;
if (IS_NOATIME(inode))
return;
if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
return;
if (mnt->mnt_flags & MNT_NOATIME)
return;
if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
return;
now = current_fs_time(inode->i_sb);
if (!relatime_need_update(mnt, inode, now))
return;
if (timespec_equal(&inode->i_atime, &now))
return;
if (mnt_want_write(mnt))
return;
inode->i_atime = now;
mark_inode_dirty_sync(inode);
mnt_drop_write(mnt);
}
EXPORT_SYMBOL(touch_atime);
/**
* file_update_time - update mtime and ctime time
* @file: file accessed
*
* Update the mtime and ctime members of an inode and mark the inode
* for writeback. Note that this function is meant exclusively for
* usage in the file write path of filesystems, and filesystems may
* choose to explicitly ignore update via this function with the
* S_NOCMTIME inode flag, e.g. for network filesystem where these
* timestamps are handled by the server.
*/
void file_update_time(struct file *file)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct timespec now;
enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
/* First try to exhaust all avenues to not sync */
if (IS_NOCMTIME(inode))
return;
now = current_fs_time(inode->i_sb);
if (!timespec_equal(&inode->i_mtime, &now))
sync_it = S_MTIME;
if (!timespec_equal(&inode->i_ctime, &now))
sync_it |= S_CTIME;
if (IS_I_VERSION(inode))
sync_it |= S_VERSION;
if (!sync_it)
return;
/* Finally allowed to write? Takes lock. */
if (mnt_want_write_file(file))
return;
/* Only change inode inside the lock region */
if (sync_it & S_VERSION)
inode_inc_iversion(inode);
if (sync_it & S_CTIME)
inode->i_ctime = now;
if (sync_it & S_MTIME)
inode->i_mtime = now;
mark_inode_dirty_sync(inode);
mnt_drop_write(file->f_path.mnt);
}
EXPORT_SYMBOL(file_update_time);
int inode_needs_sync(struct inode *inode)
{
if (IS_SYNC(inode))
return 1;
if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
return 1;
return 0;
}
EXPORT_SYMBOL(inode_needs_sync);
int inode_wait(void *word)
{
schedule();
return 0;
}
EXPORT_SYMBOL(inode_wait);
/*
* If we try to find an inode in the inode hash while it is being
* deleted, we have to wait until the filesystem completes its
* deletion before reporting that it isn't found. This function waits
* until the deletion _might_ have completed. Callers are responsible
* to recheck inode state.
*
* It doesn't matter if I_NEW is not set initially, a call to
* wake_up_inode() after removing from the hash list will DTRT.
*
* This is called with inode_lock held.
*/
static void __wait_on_freeing_inode(struct inode *inode)
{
wait_queue_head_t *wq;
DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
wq = bit_waitqueue(&inode->i_state, __I_NEW);
prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&inode_lock);
schedule();
finish_wait(wq, &wait.wait);
spin_lock(&inode_lock);
}
static __initdata unsigned long ihash_entries;
static int __init set_ihash_entries(char *str)
{
if (!str)
return 0;
ihash_entries = simple_strtoul(str, &str, 0);
return 1;
}
__setup("ihash_entries=", set_ihash_entries);
/*
* Initialize the waitqueues and inode hash table.
*/
void __init inode_init_early(void)
{
int loop;
/* If hashes are distributed across NUMA nodes, defer
* hash allocation until vmalloc space is available.
*/
if (hashdist)
return;
inode_hashtable =
alloc_large_system_hash("Inode-cache",
sizeof(struct hlist_head),
ihash_entries,
14,
HASH_EARLY,
&i_hash_shift,
&i_hash_mask,
0);
for (loop = 0; loop < (1 << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}
void __init inode_init(void)
{
int loop;
/* inode slab cache */
inode_cachep = kmem_cache_create("inode_cache",
sizeof(struct inode),
0,
(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
SLAB_MEM_SPREAD),
init_once);
register_shrinker(&icache_shrinker);
/* Hash may have been set up in inode_init_early */
if (!hashdist)
return;
inode_hashtable =
alloc_large_system_hash("Inode-cache",
sizeof(struct hlist_head),
ihash_entries,
14,
0,
&i_hash_shift,
&i_hash_mask,
0);
for (loop = 0; loop < (1 << i_hash_shift); loop++)
INIT_HLIST_HEAD(&inode_hashtable[loop]);
}
void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
{
inode->i_mode = mode;
if (S_ISCHR(mode)) {
inode->i_fop = &def_chr_fops;
inode->i_rdev = rdev;
} else if (S_ISBLK(mode)) {
inode->i_fop = &def_blk_fops;
inode->i_rdev = rdev;
} else if (S_ISFIFO(mode))
inode->i_fop = &def_fifo_fops;
else if (S_ISSOCK(mode))
inode->i_fop = &bad_sock_fops;
else
printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
" inode %s:%lu\n", mode, inode->i_sb->s_id,
inode->i_ino);
}
EXPORT_SYMBOL(init_special_inode);