Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

1 files changed, 1448 insertions, 0 deletions

diff --git a/fs/inode.c b/fs/inode.c
new file mode 100644
index 0000000..7b2acc1
--- /dev/null
+++ b/fs/inode.c
@@ -0,0 +1,1448 @@
+/*
+ * 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 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 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;
+		}
+
+		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_PAGECACHE);
+		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_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);
+	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
+}
+
+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);
+	DQUOT_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_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);
+			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);
+
+	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);
+		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);
+	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 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;
+}
+
+/**
+ *	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_PAGECACHE.
+ *	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);
+		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)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (inode->i_mode & S_IFDIR) {
+		struct file_system_type *type = inode->i_sb->s_type;
+
+		/*
+		 * 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_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).
+	 */
+	WARN_ON((inode->i_state & (I_LOCK|I_NEW)) != (I_LOCK|I_NEW));
+	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)
+{
+	/*
+	 * 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);
+
+/**
+ *	__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))
+			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_SYNC)))
+			list_move(&inode->i_list, &inode_unused);
+		inodes_stat.nr_unused++;
+		if (sb->s_flags & MS_ACTIVE) {
+			spin_unlock(&inode_lock);
+			return;
+		}
+		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);
+	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);
+
+/**
+ *	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 (mnt_want_write(mnt))
+		return;
+	if (inode->i_flags & S_NOATIME)
+		goto out;
+	if (IS_NOATIME(inode))
+		goto out;
+	if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
+		goto out;
+
+	if (mnt->mnt_flags & MNT_NOATIME)
+		goto out;
+	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
+		goto out;
+	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)
+			goto out;
+	}
+
+	now = current_fs_time(inode->i_sb);
+	if (timespec_equal(&inode->i_atime, &now))
+		goto out;
+
+	inode->i_atime = now;
+	mark_inode_dirty_sync(inode);
+out:
+	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_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;
+	int err;
+
+	if (IS_NOCMTIME(inode))
+		return;
+
+	err = mnt_want_write(file->f_path.mnt);
+	if (err)
+		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 (IS_I_VERSION(inode)) {
+		inode_inc_iversion(inode);
+		sync_it = 1;
+	}
+
+	if (sync_it)
+		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;
+}
+
+/*
+ * 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);
+}
+
+/*
+ * 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(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)\n",
+		       mode);
+}
+EXPORT_SYMBOL(init_special_inode);