diff options
Diffstat (limited to 'fs/inode.c')
| -rw-r--r-- | fs/inode.c | 1377 |
1 files changed, 1377 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c new file mode 100644 index 0000000..af8fd78 --- /dev/null +++ b/fs/inode.c @@ -0,0 +1,1377 @@ +/* + * linux/fs/inode.c + * + * (C) 1997 Linus Torvalds + */ + +#include <linux/config.h> +#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> + +/* + * This is needed for the following functions: + * - inode_has_buffers + * - invalidate_inode_buffers + * - fsync_bdev + * - 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; +static unsigned int i_hash_shift; + +/* + * 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; + +/* + * 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. + */ +DECLARE_MUTEX(iprune_sem); + +/* + * Statistics gathering.. + */ +struct inodes_stat_t inodes_stat; + +static kmem_cache_t * inode_cachep; + +static struct inode *alloc_inode(struct super_block *sb) +{ + static struct address_space_operations empty_aops; + static struct inode_operations empty_iops; + static 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, SLAB_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->i_security = NULL; + 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; + } + memset(&inode->u, 0, sizeof(inode->u)); + inode->i_mapping = mapping; + } + return inode; +} + +void destroy_inode(struct inode *inode) +{ + if (inode_has_buffers(inode)) + BUG(); + 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); + sema_init(&inode->i_sem, 1); + 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); +} + +EXPORT_SYMBOL(inode_init_once); + +static void init_once(void * foo, kmem_cache_t * 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); + + if (inode->i_data.nrpages) + BUG(); + if (!(inode->i_state & I_FREEING)) + BUG(); + if (inode->i_state & I_CLEAR) + BUG(); + 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 (inode->i_bdev) + bd_forget(inode); + if (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); + 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); + invalidate_inode_buffers(inode); + if (!atomic_read(&inode->i_count)) { + hlist_del_init(&inode->i_hash); + list_del(&inode->i_sb_list); + 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; +} + +/* + * This is a two-stage process. First we collect all + * offending inodes onto the throw-away list, and in + * the second stage we actually dispose of them. This + * is because we don't want to sleep while messing + * with the global lists.. + */ + +/** + * 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(&iprune_sem); + spin_lock(&inode_lock); + busy = invalidate_list(&sb->s_inodes, &throw_away); + spin_unlock(&inode_lock); + + dispose_list(&throw_away); + up(&iprune_sem); + + return busy; +} + +EXPORT_SYMBOL(invalidate_inodes); + +int __invalidate_device(struct block_device *bdev, int do_sync) +{ + struct super_block *sb; + int res; + + if (do_sync) + fsync_bdev(bdev); + + res = 0; + sb = get_super(bdev); + if (sb) { + /* + * no need to lock the super, get_super holds the + * read semaphore so the filesystem cannot go away + * under us (->put_super runs with the write lock + * hold). + */ + shrink_dcache_sb(sb); + res = invalidate_inodes(sb); + drop_super(sb); + } + invalidate_bdev(bdev, 0); + return res; +} + +EXPORT_SYMBOL(__invalidate_device); + +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(&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_inode_pages(&inode->i_data); + 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; + } + hlist_del_init(&inode->i_hash); + list_del_init(&inode->i_sb_list); + list_move(&inode->i_list, &freeable); + inode->i_state |= I_FREEING; + nr_pruned++; + } + inodes_stat.nr_unused -= nr_pruned; + spin_unlock(&inode_lock); + + dispose_list(&freeable); + up(&iprune_sem); + + if (current_is_kswapd()) + mod_page_state(kswapd_inodesteal, reap); + else + mod_page_state(pginodesteal, reap); +} + +/* + * 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, unsigned int 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)) { + __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)) { + __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 inline 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)) + __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 + * + * 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 inline struct inode *ifind(struct super_block *sb, + struct hlist_head *head, int (*test)(struct inode *, void *), + void *data) +{ + struct inode *inode; + + spin_lock(&inode_lock); + inode = find_inode(sb, head, test, data); + if (inode) { + __iget(inode); + spin_unlock(&inode_lock); + 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 inline 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 - 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. + * + * 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); +} + +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); + 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); + + if (inode->i_data.nrpages) + truncate_inode_pages(&inode->i_data, 0); + + security_inode_delete(inode); + + if (op->delete_inode) { + void (*delete)(struct inode *) = op->delete_inode; + if (!is_bad_inode(inode)) + DQUOT_INIT(inode); + /* s_op->delete_inode internally recalls clear_inode() */ + delete(inode); + } else + clear_inode(inode); + spin_lock(&inode_lock); + hlist_del_init(&inode->i_hash); + spin_unlock(&inode_lock); + wake_up_inode(inode); + if (inode->i_state != I_CLEAR) + BUG(); + 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++; + spin_unlock(&inode_lock); + if (!sb || (sb->s_flags & MS_ACTIVE)) + return; + write_inode_now(inode, 1); + spin_lock(&inode_lock); + 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); + destroy_inode(inode); +} + +/* + * Normal UNIX filesystem behaviour: delete the + * inode when the usage count drops to zero, and + * i_nlink is zero. + */ +static void generic_drop_inode(struct inode *inode) +{ + if (!inode->i_nlink) + generic_delete_inode(inode); + else + generic_forget_inode(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); + +/** + * update_atime - update the access time + * @inode: inode 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 update_atime(struct inode *inode) +{ + struct timespec now; + + if (IS_NOATIME(inode)) + return; + if (IS_NODIRATIME(inode) && S_ISDIR(inode->i_mode)) + return; + if (IS_RDONLY(inode)) + return; + + now = current_fs_time(inode->i_sb); + if (!timespec_equal(&inode->i_atime, &now)) { + inode->i_atime = now; + mark_inode_dirty_sync(inode); + } else { + if (!timespec_equal(&inode->i_atime, &now)) + inode->i_atime = now; + } +} + +EXPORT_SYMBOL(update_atime); + +/** + * inode_update_time - update mtime and ctime time + * @inode: inode accessed + * @ctime_too: update ctime too + * + * Update the mtime time on an inode and mark it for writeback. + * When ctime_too is specified update the ctime too. + */ + +void inode_update_time(struct inode *inode, int ctime_too) +{ + 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)) + sync_it = 1; + inode->i_mtime = now; + + if (ctime_too) { + if (!timespec_equal(&inode->i_ctime, &now)) + sync_it = 1; + inode->i_ctime = now; + } + if (sync_it) + mark_inode_dirty_sync(inode); +} + +EXPORT_SYMBOL(inode_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); + +/* + * Quota functions that want to walk the inode lists.. + */ +#ifdef CONFIG_QUOTA + +/* Function back in dquot.c */ +int remove_inode_dquot_ref(struct inode *, int, struct list_head *); + +void remove_dquot_ref(struct super_block *sb, int type, + struct list_head *tofree_head) +{ + struct inode *inode; + + if (!sb->dq_op) + return; /* nothing to do */ + spin_lock(&inode_lock); /* This lock is for inodes code */ + + /* + * We don't have to lock against quota code - test IS_QUOTAINIT is + * just for speedup... + */ + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) + if (!IS_NOQUOTA(inode)) + remove_inode_dquot_ref(inode, type, tofree_head); + + spin_unlock(&inode_lock); +} + +#endif + +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 is because iget will immediately call + * ->read_inode, and we want to be sure that evidence of the deletion is found + * by ->read_inode. + * 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); + + /* + * I_FREEING and I_CLEAR are cleared in process context under + * inode_lock, so we have to give the tasks who would clear them + * a chance to run and acquire inode_lock. + */ + if (!(inode->i_state & I_LOCK)) { + spin_unlock(&inode_lock); + yield(); + spin_lock(&inode_lock); + return; + } + 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); +} + +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_PANIC, 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); |
