/* * 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/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/mount.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_mutex 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. */ static DEFINE_MUTEX(iprune_mutex); /* * Statistics gathering.. */ struct inodes_stat_t inodes_stat; static struct kmem_cache * inode_cachep __read_mostly; static struct inode *alloc_inode(struct super_block *sb) { static const struct address_space_operations empty_aops; static struct inode_operations empty_iops; static const struct file_operations empty_fops; struct inode *inode; if (sb->s_op->alloc_inode) inode = sb->s_op->alloc_inode(sb); else inode = (struct inode *) kmem_cache_alloc(inode_cachep, GFP_KERNEL); if (inode) { 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; 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)) { 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; } mapping->a_ops = &empty_aops; mapping->host = inode; mapping->flags = 0; mapping_set_gfp_mask(mapping, GFP_HIGHUSER); mapping->assoc_mapping = NULL; mapping->backing_dev_info = &default_backing_dev_info; /* * 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_backing_dev_info; if (!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; } return inode; } void destroy_inode(struct inode *inode) { BUG_ON(inode_has_buffers(inode)); security_inode_free(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); mutex_init(&inode->i_mutex); init_rwsem(&inode->i_alloc_sem); INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC); rwlock_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); spin_lock_init(&inode->i_lock); i_size_ordered_init(inode); #ifdef CONFIG_INOTIFY INIT_LIST_HEAD(&inode->inotify_watches); mutex_init(&inode->inotify_mutex); #endif } EXPORT_SYMBOL(inode_init_once); static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags) { struct inode * inode = (struct inode *) foo; if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) 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_LOCK))) 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); wait_on_inode(inode); DQUOT_DROP(inode); if (inode->i_sb && 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_entry(head->next, 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_mutex 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); invalidate_inode_buffers(inode); if (!atomic_read(&inode->i_count)) { list_move(&inode->i_list, dispose); 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); mutex_lock(&iprune_mutex); spin_lock(&inode_lock); inotify_unmount_inodes(&sb->s_inodes); busy = invalidate_list(&sb->s_inodes, &throw_away); spin_unlock(&inode_lock); dispose_list(&throw_away); mutex_unlock(&iprune_mutex); 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; mutex_lock(&iprune_mutex); 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); 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); mutex_unlock(&iprune_mutex); } /* * 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 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 (node, head) { inode = hlist_entry(node, struct inode, 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 (node, head) { inode = hlist_entry(node, struct inode, 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; } /** * new_inode - obtain an inode * @sb: superblock * * Allocates a new inode for given superblock. */ struct inode *new_inode(struct super_block *sb) { static unsigned long last_ino; struct inode * inode; spin_lock_prefetch(&inode_lock); inode = alloc_inode(sb); if (inode) { spin_lock(&inode_lock); inodes_stat.nr_inodes++; list_add(&inode->i_list, &inode_in_use); list_add(&inode->i_sb_list, &sb->s_inodes); 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) { /* * This is special! We do not need the spinlock * when clearing I_LOCK, 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_LOCK). */ inode->i_state &= ~(I_LOCK|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; inodes_stat.nr_inodes++; list_add(&inode->i_list, &inode_in_use); list_add(&inode->i_sb_list, &sb->s_inodes); hlist_add_head(&inode->i_hash, head); inode->i_state = I_LOCK|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; inodes_stat.nr_inodes++; list_add(&inode->i_list, &inode_in_use); list_add(&inode->i_sb_list, &sb->s_inodes); hlist_add_head(&inode->i_hash, head); inode->i_state = I_LOCK|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; } 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; } /** * 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) { static ino_t counter; struct inode *inode; struct hlist_head * head; ino_t res; spin_lock(&inode_lock); retry: if (counter > max_reserved) { head = inode_hashtable + hash(sb,counter); res = counter++; inode = find_inode_fast(sb, head, res); if (!inode) { spin_unlock(&inode_lock); return res; } } else { counter = max_reserved + 1; } goto retry; } 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 * * This is iget() without the read_inode() portion of get_new_inode(). * * 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 * * This is iget() without the read_inode() portion of get_new_inode_fast(). * * 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); /** * __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) { struct super_operations *op = inode->i_sb->s_op; list_del_init(&inode->i_list); list_del_init(&inode->i_sb_list); 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)) DQUOT_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); static void generic_forget_inode(struct inode *inode) { struct super_block *sb = inode->i_sb; if (!hlist_unhashed(&inode->i_hash)) { if (!(inode->i_state & (I_DIRTY|I_LOCK))) list_move(&inode->i_list, &inode_unused); inodes_stat.nr_unused++; if (!sb || (sb->s_flags & MS_ACTIVE)) { spin_unlock(&inode_lock); return; } inode->i_state |= I_WILL_FREE; spin_unlock(&inode_lock); write_inode_now(inode, 1); spin_lock(&inode_lock); 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); inode->i_state |= I_FREEING; inodes_stat.nr_inodes--; spin_unlock(&inode_lock); 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) { 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) { struct super_operations *op = inode->i_sb->s_op; BUG_ON(inode->i_state == I_CLEAR); if (op && op->put_inode) op->put_inode(inode); 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); /** * 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; /* * We may have a NULL vfsmount when coming from NFSD */ if (mnt) { if (mnt->mnt_flags & MNT_NOATIME) return; if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)) return; if (mnt->mnt_flags & MNT_RELATIME) { /* * With relative atime, only update atime if the * previous atime is earlier than either the ctime or * mtime. */ if (timespec_compare(&inode->i_mtime, &inode->i_atime) < 0 && timespec_compare(&inode->i_ctime, &inode->i_atime) < 0) return; } } now = current_fs_time(inode->i_sb); if (timespec_equal(&inode->i_atime, &now)) return; inode->i_atime = now; mark_inode_dirty_sync(inode); } 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_NOCTIME 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; int sync_it = 0; if (IS_NOCMTIME(inode)) return; if (IS_RDONLY(inode)) return; now = current_fs_time(inode->i_sb); if (!timespec_equal(&inode->i_mtime, &now)) { inode->i_mtime = now; sync_it = 1; } if (!timespec_equal(&inode->i_ctime, &now)) { inode->i_ctime = now; sync_it = 1; } if (sync_it) mark_inode_dirty_sync(inode); } 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; } /* * 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_LOCK 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_LOCK); wq = bit_waitqueue(&inode->i_state, __I_LOCK); prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE); spin_unlock(&inode_lock); schedule(); finish_wait(wq, &wait.wait); spin_lock(&inode_lock); } void wake_up_inode(struct inode *inode) { /* * Prevent speculative execution through spin_unlock(&inode_lock); */ smp_mb(); wake_up_bit(&inode->i_state, __I_LOCK); } /* * We rarely want to lock two inodes that do not have a parent/child * relationship (such as directory, child inode) simultaneously. The * vast majority of file systems should be able to get along fine * without this. Do not use these functions except as a last resort. */ void inode_double_lock(struct inode *inode1, struct inode *inode2) { if (inode1 == NULL || inode2 == NULL || inode1 == inode2) { if (inode1) mutex_lock(&inode1->i_mutex); else if (inode2) mutex_lock(&inode2->i_mutex); return; } if (inode1 < inode2) { mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT); mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD); } else { mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT); mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD); } } EXPORT_SYMBOL(inode_double_lock); void inode_double_unlock(struct inode *inode1, struct inode *inode2) { if (inode1) mutex_unlock(&inode1->i_mutex); if (inode2 && inode2 != inode1) mutex_unlock(&inode2->i_mutex); } EXPORT_SYMBOL(inode_double_unlock); 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(unsigned long mempages) { 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, NULL); set_shrinker(DEFAULT_SEEKS, shrink_icache_memory); /* 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)\n", mode); } EXPORT_SYMBOL(init_special_inode);