Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1680 insertions, 0 deletions

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
new file mode 100644
index 000000000..09ae0e73e
--- /dev/null
+++ b/fs/btrfs/extent-io-tree.c
@@ -0,0 +1,1680 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/slab.h>
+#include <trace/events/btrfs.h>
+#include "ctree.h"
+#include "extent-io-tree.h"
+#include "btrfs_inode.h"
+#include "misc.h"
+
+static struct kmem_cache *extent_state_cache;
+
+static inline bool extent_state_in_tree(const struct extent_state *state)
+{
+	return !RB_EMPTY_NODE(&state->rb_node);
+}
+
+#ifdef CONFIG_BTRFS_DEBUG
+static LIST_HEAD(states);
+static DEFINE_SPINLOCK(leak_lock);
+
+static inline void btrfs_leak_debug_add_state(struct extent_state *state)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&leak_lock, flags);
+	list_add(&state->leak_list, &states);
+	spin_unlock_irqrestore(&leak_lock, flags);
+}
+
+static inline void btrfs_leak_debug_del_state(struct extent_state *state)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&leak_lock, flags);
+	list_del(&state->leak_list);
+	spin_unlock_irqrestore(&leak_lock, flags);
+}
+
+static inline void btrfs_extent_state_leak_debug_check(void)
+{
+	struct extent_state *state;
+
+	while (!list_empty(&states)) {
+		state = list_entry(states.next, struct extent_state, leak_list);
+		pr_err("BTRFS: state leak: start %llu end %llu state %u in tree %d refs %d\n",
+		       state->start, state->end, state->state,
+		       extent_state_in_tree(state),
+		       refcount_read(&state->refs));
+		list_del(&state->leak_list);
+		kmem_cache_free(extent_state_cache, state);
+	}
+}
+
+#define btrfs_debug_check_extent_io_range(tree, start, end)		\
+	__btrfs_debug_check_extent_io_range(__func__, (tree), (start), (end))
+static inline void __btrfs_debug_check_extent_io_range(const char *caller,
+						       struct extent_io_tree *tree,
+						       u64 start, u64 end)
+{
+	struct inode *inode = tree->private_data;
+	u64 isize;
+
+	if (!inode)
+		return;
+
+	isize = i_size_read(inode);
+	if (end >= PAGE_SIZE && (end % 2) == 0 && end != isize - 1) {
+		btrfs_debug_rl(BTRFS_I(inode)->root->fs_info,
+		    "%s: ino %llu isize %llu odd range [%llu,%llu]",
+			caller, btrfs_ino(BTRFS_I(inode)), isize, start, end);
+	}
+}
+#else
+#define btrfs_leak_debug_add_state(state)		do {} while (0)
+#define btrfs_leak_debug_del_state(state)		do {} while (0)
+#define btrfs_extent_state_leak_debug_check()		do {} while (0)
+#define btrfs_debug_check_extent_io_range(c, s, e)	do {} while (0)
+#endif
+
+/*
+ * For the file_extent_tree, we want to hold the inode lock when we lookup and
+ * update the disk_i_size, but lockdep will complain because our io_tree we hold
+ * the tree lock and get the inode lock when setting delalloc.  These two things
+ * are unrelated, so make a class for the file_extent_tree so we don't get the
+ * two locking patterns mixed up.
+ */
+static struct lock_class_key file_extent_tree_class;
+
+struct tree_entry {
+	u64 start;
+	u64 end;
+	struct rb_node rb_node;
+};
+
+void extent_io_tree_init(struct btrfs_fs_info *fs_info,
+			 struct extent_io_tree *tree, unsigned int owner,
+			 void *private_data)
+{
+	tree->fs_info = fs_info;
+	tree->state = RB_ROOT;
+	spin_lock_init(&tree->lock);
+	tree->private_data = private_data;
+	tree->owner = owner;
+	if (owner == IO_TREE_INODE_FILE_EXTENT)
+		lockdep_set_class(&tree->lock, &file_extent_tree_class);
+}
+
+void extent_io_tree_release(struct extent_io_tree *tree)
+{
+	spin_lock(&tree->lock);
+	/*
+	 * Do a single barrier for the waitqueue_active check here, the state
+	 * of the waitqueue should not change once extent_io_tree_release is
+	 * called.
+	 */
+	smp_mb();
+	while (!RB_EMPTY_ROOT(&tree->state)) {
+		struct rb_node *node;
+		struct extent_state *state;
+
+		node = rb_first(&tree->state);
+		state = rb_entry(node, struct extent_state, rb_node);
+		rb_erase(&state->rb_node, &tree->state);
+		RB_CLEAR_NODE(&state->rb_node);
+		/*
+		 * btree io trees aren't supposed to have tasks waiting for
+		 * changes in the flags of extent states ever.
+		 */
+		ASSERT(!waitqueue_active(&state->wq));
+		free_extent_state(state);
+
+		cond_resched_lock(&tree->lock);
+	}
+	spin_unlock(&tree->lock);
+}
+
+static struct extent_state *alloc_extent_state(gfp_t mask)
+{
+	struct extent_state *state;
+
+	/*
+	 * The given mask might be not appropriate for the slab allocator,
+	 * drop the unsupported bits
+	 */
+	mask &= ~(__GFP_DMA32|__GFP_HIGHMEM);
+	state = kmem_cache_alloc(extent_state_cache, mask);
+	if (!state)
+		return state;
+	state->state = 0;
+	RB_CLEAR_NODE(&state->rb_node);
+	btrfs_leak_debug_add_state(state);
+	refcount_set(&state->refs, 1);
+	init_waitqueue_head(&state->wq);
+	trace_alloc_extent_state(state, mask, _RET_IP_);
+	return state;
+}
+
+static struct extent_state *alloc_extent_state_atomic(struct extent_state *prealloc)
+{
+	if (!prealloc)
+		prealloc = alloc_extent_state(GFP_ATOMIC);
+
+	return prealloc;
+}
+
+void free_extent_state(struct extent_state *state)
+{
+	if (!state)
+		return;
+	if (refcount_dec_and_test(&state->refs)) {
+		WARN_ON(extent_state_in_tree(state));
+		btrfs_leak_debug_del_state(state);
+		trace_free_extent_state(state, _RET_IP_);
+		kmem_cache_free(extent_state_cache, state);
+	}
+}
+
+static int add_extent_changeset(struct extent_state *state, u32 bits,
+				 struct extent_changeset *changeset,
+				 int set)
+{
+	int ret;
+
+	if (!changeset)
+		return 0;
+	if (set && (state->state & bits) == bits)
+		return 0;
+	if (!set && (state->state & bits) == 0)
+		return 0;
+	changeset->bytes_changed += state->end - state->start + 1;
+	ret = ulist_add(&changeset->range_changed, state->start, state->end,
+			GFP_ATOMIC);
+	return ret;
+}
+
+static inline struct extent_state *next_state(struct extent_state *state)
+{
+	struct rb_node *next = rb_next(&state->rb_node);
+
+	if (next)
+		return rb_entry(next, struct extent_state, rb_node);
+	else
+		return NULL;
+}
+
+static inline struct extent_state *prev_state(struct extent_state *state)
+{
+	struct rb_node *next = rb_prev(&state->rb_node);
+
+	if (next)
+		return rb_entry(next, struct extent_state, rb_node);
+	else
+		return NULL;
+}
+
+/*
+ * Search @tree for an entry that contains @offset. Such entry would have
+ * entry->start <= offset && entry->end >= offset.
+ *
+ * @tree:       the tree to search
+ * @offset:     offset that should fall within an entry in @tree
+ * @node_ret:   pointer where new node should be anchored (used when inserting an
+ *	        entry in the tree)
+ * @parent_ret: points to entry which would have been the parent of the entry,
+ *               containing @offset
+ *
+ * Return a pointer to the entry that contains @offset byte address and don't change
+ * @node_ret and @parent_ret.
+ *
+ * If no such entry exists, return pointer to entry that ends before @offset
+ * and fill parameters @node_ret and @parent_ret, ie. does not return NULL.
+ */
+static inline struct extent_state *tree_search_for_insert(struct extent_io_tree *tree,
+							  u64 offset,
+							  struct rb_node ***node_ret,
+							  struct rb_node **parent_ret)
+{
+	struct rb_root *root = &tree->state;
+	struct rb_node **node = &root->rb_node;
+	struct rb_node *prev = NULL;
+	struct extent_state *entry = NULL;
+
+	while (*node) {
+		prev = *node;
+		entry = rb_entry(prev, struct extent_state, rb_node);
+
+		if (offset < entry->start)
+			node = &(*node)->rb_left;
+		else if (offset > entry->end)
+			node = &(*node)->rb_right;
+		else
+			return entry;
+	}
+
+	if (node_ret)
+		*node_ret = node;
+	if (parent_ret)
+		*parent_ret = prev;
+
+	/* Search neighbors until we find the first one past the end */
+	while (entry && offset > entry->end)
+		entry = next_state(entry);
+
+	return entry;
+}
+
+/*
+ * Search offset in the tree or fill neighbor rbtree node pointers.
+ *
+ * @tree:      the tree to search
+ * @offset:    offset that should fall within an entry in @tree
+ * @next_ret:  pointer to the first entry whose range ends after @offset
+ * @prev_ret:  pointer to the first entry whose range begins before @offset
+ *
+ * Return a pointer to the entry that contains @offset byte address. If no
+ * such entry exists, then return NULL and fill @prev_ret and @next_ret.
+ * Otherwise return the found entry and other pointers are left untouched.
+ */
+static struct extent_state *tree_search_prev_next(struct extent_io_tree *tree,
+						  u64 offset,
+						  struct extent_state **prev_ret,
+						  struct extent_state **next_ret)
+{
+	struct rb_root *root = &tree->state;
+	struct rb_node **node = &root->rb_node;
+	struct extent_state *orig_prev;
+	struct extent_state *entry = NULL;
+
+	ASSERT(prev_ret);
+	ASSERT(next_ret);
+
+	while (*node) {
+		entry = rb_entry(*node, struct extent_state, rb_node);
+
+		if (offset < entry->start)
+			node = &(*node)->rb_left;
+		else if (offset > entry->end)
+			node = &(*node)->rb_right;
+		else
+			return entry;
+	}
+
+	orig_prev = entry;
+	while (entry && offset > entry->end)
+		entry = next_state(entry);
+	*next_ret = entry;
+	entry = orig_prev;
+
+	while (entry && offset < entry->start)
+		entry = prev_state(entry);
+	*prev_ret = entry;
+
+	return NULL;
+}
+
+/*
+ * Inexact rb-tree search, return the next entry if @offset is not found
+ */
+static inline struct extent_state *tree_search(struct extent_io_tree *tree, u64 offset)
+{
+	return tree_search_for_insert(tree, offset, NULL, NULL);
+}
+
+static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
+{
+	btrfs_panic(tree->fs_info, err,
+	"locking error: extent tree was modified by another thread while locked");
+}
+
+/*
+ * Utility function to look for merge candidates inside a given range.  Any
+ * extents with matching state are merged together into a single extent in the
+ * tree.  Extents with EXTENT_IO in their state field are not merged because
+ * the end_io handlers need to be able to do operations on them without
+ * sleeping (or doing allocations/splits).
+ *
+ * This should be called with the tree lock held.
+ */
+static void merge_state(struct extent_io_tree *tree, struct extent_state *state)
+{
+	struct extent_state *other;
+
+	if (state->state & (EXTENT_LOCKED | EXTENT_BOUNDARY))
+		return;
+
+	other = prev_state(state);
+	if (other && other->end == state->start - 1 &&
+	    other->state == state->state) {
+		if (tree->private_data)
+			btrfs_merge_delalloc_extent(tree->private_data,
+						    state, other);
+		state->start = other->start;
+		rb_erase(&other->rb_node, &tree->state);
+		RB_CLEAR_NODE(&other->rb_node);
+		free_extent_state(other);
+	}
+	other = next_state(state);
+	if (other && other->start == state->end + 1 &&
+	    other->state == state->state) {
+		if (tree->private_data)
+			btrfs_merge_delalloc_extent(tree->private_data, state,
+						    other);
+		state->end = other->end;
+		rb_erase(&other->rb_node, &tree->state);
+		RB_CLEAR_NODE(&other->rb_node);
+		free_extent_state(other);
+	}
+}
+
+static void set_state_bits(struct extent_io_tree *tree,
+			   struct extent_state *state,
+			   u32 bits, struct extent_changeset *changeset)
+{
+	u32 bits_to_set = bits & ~EXTENT_CTLBITS;
+	int ret;
+
+	if (tree->private_data)
+		btrfs_set_delalloc_extent(tree->private_data, state, bits);
+
+	ret = add_extent_changeset(state, bits_to_set, changeset, 1);
+	BUG_ON(ret < 0);
+	state->state |= bits_to_set;
+}
+
+/*
+ * Insert an extent_state struct into the tree.  'bits' are set on the
+ * struct before it is inserted.
+ *
+ * This may return -EEXIST if the extent is already there, in which case the
+ * state struct is freed.
+ *
+ * The tree lock is not taken internally.  This is a utility function and
+ * probably isn't what you want to call (see set/clear_extent_bit).
+ */
+static int insert_state(struct extent_io_tree *tree,
+			struct extent_state *state,
+			u32 bits, struct extent_changeset *changeset)
+{
+	struct rb_node **node;
+	struct rb_node *parent = NULL;
+	const u64 end = state->end;
+
+	set_state_bits(tree, state, bits, changeset);
+
+	node = &tree->state.rb_node;
+	while (*node) {
+		struct extent_state *entry;
+
+		parent = *node;
+		entry = rb_entry(parent, struct extent_state, rb_node);
+
+		if (end < entry->start) {
+			node = &(*node)->rb_left;
+		} else if (end > entry->end) {
+			node = &(*node)->rb_right;
+		} else {
+			btrfs_err(tree->fs_info,
+			       "found node %llu %llu on insert of %llu %llu",
+			       entry->start, entry->end, state->start, end);
+			return -EEXIST;
+		}
+	}
+
+	rb_link_node(&state->rb_node, parent, node);
+	rb_insert_color(&state->rb_node, &tree->state);
+
+	merge_state(tree, state);
+	return 0;
+}
+
+/*
+ * Insert state to @tree to the location given by @node and @parent.
+ */
+static void insert_state_fast(struct extent_io_tree *tree,
+			      struct extent_state *state, struct rb_node **node,
+			      struct rb_node *parent, unsigned bits,
+			      struct extent_changeset *changeset)
+{
+	set_state_bits(tree, state, bits, changeset);
+	rb_link_node(&state->rb_node, parent, node);
+	rb_insert_color(&state->rb_node, &tree->state);
+	merge_state(tree, state);
+}
+
+/*
+ * Split a given extent state struct in two, inserting the preallocated
+ * struct 'prealloc' as the newly created second half.  'split' indicates an
+ * offset inside 'orig' where it should be split.
+ *
+ * Before calling,
+ * the tree has 'orig' at [orig->start, orig->end].  After calling, there
+ * are two extent state structs in the tree:
+ * prealloc: [orig->start, split - 1]
+ * orig: [ split, orig->end ]
+ *
+ * The tree locks are not taken by this function. They need to be held
+ * by the caller.
+ */
+static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
+		       struct extent_state *prealloc, u64 split)
+{
+	struct rb_node *parent = NULL;
+	struct rb_node **node;
+
+	if (tree->private_data)
+		btrfs_split_delalloc_extent(tree->private_data, orig, split);
+
+	prealloc->start = orig->start;
+	prealloc->end = split - 1;
+	prealloc->state = orig->state;
+	orig->start = split;
+
+	parent = &orig->rb_node;
+	node = &parent;
+	while (*node) {
+		struct extent_state *entry;
+
+		parent = *node;
+		entry = rb_entry(parent, struct extent_state, rb_node);
+
+		if (prealloc->end < entry->start) {
+			node = &(*node)->rb_left;
+		} else if (prealloc->end > entry->end) {
+			node = &(*node)->rb_right;
+		} else {
+			free_extent_state(prealloc);
+			return -EEXIST;
+		}
+	}
+
+	rb_link_node(&prealloc->rb_node, parent, node);
+	rb_insert_color(&prealloc->rb_node, &tree->state);
+
+	return 0;
+}
+
+/*
+ * Utility function to clear some bits in an extent state struct.  It will
+ * optionally wake up anyone waiting on this state (wake == 1).
+ *
+ * If no bits are set on the state struct after clearing things, the
+ * struct is freed and removed from the tree
+ */
+static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
+					    struct extent_state *state,
+					    u32 bits, int wake,
+					    struct extent_changeset *changeset)
+{
+	struct extent_state *next;
+	u32 bits_to_clear = bits & ~EXTENT_CTLBITS;
+	int ret;
+
+	if (tree->private_data)
+		btrfs_clear_delalloc_extent(tree->private_data, state, bits);
+
+	ret = add_extent_changeset(state, bits_to_clear, changeset, 0);
+	BUG_ON(ret < 0);
+	state->state &= ~bits_to_clear;
+	if (wake)
+		wake_up(&state->wq);
+	if (state->state == 0) {
+		next = next_state(state);
+		if (extent_state_in_tree(state)) {
+			rb_erase(&state->rb_node, &tree->state);
+			RB_CLEAR_NODE(&state->rb_node);
+			free_extent_state(state);
+		} else {
+			WARN_ON(1);
+		}
+	} else {
+		merge_state(tree, state);
+		next = next_state(state);
+	}
+	return next;
+}
+
+/*
+ * Clear some bits on a range in the tree.  This may require splitting or
+ * inserting elements in the tree, so the gfp mask is used to indicate which
+ * allocations or sleeping are allowed.
+ *
+ * Pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove the given
+ * range from the tree regardless of state (ie for truncate).
+ *
+ * The range [start, end] is inclusive.
+ *
+ * This takes the tree lock, and returns 0 on success and < 0 on error.
+ */
+int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		       u32 bits, struct extent_state **cached_state,
+		       gfp_t mask, struct extent_changeset *changeset)
+{
+	struct extent_state *state;
+	struct extent_state *cached;
+	struct extent_state *prealloc = NULL;
+	u64 last_end;
+	int err;
+	int clear = 0;
+	int wake;
+	int delete = (bits & EXTENT_CLEAR_ALL_BITS);
+
+	btrfs_debug_check_extent_io_range(tree, start, end);
+	trace_btrfs_clear_extent_bit(tree, start, end - start + 1, bits);
+
+	if (delete)
+		bits |= ~EXTENT_CTLBITS;
+
+	if (bits & EXTENT_DELALLOC)
+		bits |= EXTENT_NORESERVE;
+
+	wake = (bits & EXTENT_LOCKED) ? 1 : 0;
+	if (bits & (EXTENT_LOCKED | EXTENT_BOUNDARY))
+		clear = 1;
+again:
+	if (!prealloc) {
+		/*
+		 * Don't care for allocation failure here because we might end
+		 * up not needing the pre-allocated extent state at all, which
+		 * is the case if we only have in the tree extent states that
+		 * cover our input range and don't cover too any other range.
+		 * If we end up needing a new extent state we allocate it later.
+		 */
+		prealloc = alloc_extent_state(mask);
+	}
+
+	spin_lock(&tree->lock);
+	if (cached_state) {
+		cached = *cached_state;
+
+		if (clear) {
+			*cached_state = NULL;
+			cached_state = NULL;
+		}
+
+		if (cached && extent_state_in_tree(cached) &&
+		    cached->start <= start && cached->end > start) {
+			if (clear)
+				refcount_dec(&cached->refs);
+			state = cached;
+			goto hit_next;
+		}
+		if (clear)
+			free_extent_state(cached);
+	}
+
+	/* This search will find the extents that end after our range starts. */
+	state = tree_search(tree, start);
+	if (!state)
+		goto out;
+hit_next:
+	if (state->start > end)
+		goto out;
+	WARN_ON(state->end < start);
+	last_end = state->end;
+
+	/* The state doesn't have the wanted bits, go ahead. */
+	if (!(state->state & bits)) {
+		state = next_state(state);
+		goto next;
+	}
+
+	/*
+	 *     | ---- desired range ---- |
+	 *  | state | or
+	 *  | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip bits on second
+	 * half.
+	 *
+	 * If the extent we found extends past our range, we just split and
+	 * search again.  It'll get split again the next time though.
+	 *
+	 * If the extent we found is inside our range, we clear the desired bit
+	 * on it.
+	 */
+
+	if (state->start < start) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc)
+			goto search_again;
+		err = split_state(tree, state, prealloc, start);
+		if (err)
+			extent_io_tree_panic(tree, err);
+
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			state = clear_state_bit(tree, state, bits, wake, changeset);
+			goto next;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *                        | state |
+	 * We need to split the extent, and clear the bit on the first half.
+	 */
+	if (state->start <= end && state->end > end) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc)
+			goto search_again;
+		err = split_state(tree, state, prealloc, end + 1);
+		if (err)
+			extent_io_tree_panic(tree, err);
+
+		if (wake)
+			wake_up(&state->wq);
+
+		clear_state_bit(tree, prealloc, bits, wake, changeset);
+
+		prealloc = NULL;
+		goto out;
+	}
+
+	state = clear_state_bit(tree, state, bits, wake, changeset);
+next:
+	if (last_end == (u64)-1)
+		goto out;
+	start = last_end + 1;
+	if (start <= end && state && !need_resched())
+		goto hit_next;
+
+search_again:
+	if (start > end)
+		goto out;
+	spin_unlock(&tree->lock);
+	if (gfpflags_allow_blocking(mask))
+		cond_resched();
+	goto again;
+
+out:
+	spin_unlock(&tree->lock);
+	if (prealloc)
+		free_extent_state(prealloc);
+
+	return 0;
+
+}
+
+static void wait_on_state(struct extent_io_tree *tree,
+			  struct extent_state *state)
+		__releases(tree->lock)
+		__acquires(tree->lock)
+{
+	DEFINE_WAIT(wait);
+	prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
+	spin_unlock(&tree->lock);
+	schedule();
+	spin_lock(&tree->lock);
+	finish_wait(&state->wq, &wait);
+}
+
+/*
+ * Wait for one or more bits to clear on a range in the state tree.
+ * The range [start, end] is inclusive.
+ * The tree lock is taken by this function
+ */
+void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, u32 bits)
+{
+	struct extent_state *state;
+
+	btrfs_debug_check_extent_io_range(tree, start, end);
+
+	spin_lock(&tree->lock);
+again:
+	while (1) {
+		/*
+		 * This search will find all the extents that end after our
+		 * range starts.
+		 */
+		state = tree_search(tree, start);
+process_node:
+		if (!state)
+			break;
+		if (state->start > end)
+			goto out;
+
+		if (state->state & bits) {
+			start = state->start;
+			refcount_inc(&state->refs);
+			wait_on_state(tree, state);
+			free_extent_state(state);
+			goto again;
+		}
+		start = state->end + 1;
+
+		if (start > end)
+			break;
+
+		if (!cond_resched_lock(&tree->lock)) {
+			state = next_state(state);
+			goto process_node;
+		}
+	}
+out:
+	spin_unlock(&tree->lock);
+}
+
+static void cache_state_if_flags(struct extent_state *state,
+				 struct extent_state **cached_ptr,
+				 unsigned flags)
+{
+	if (cached_ptr && !(*cached_ptr)) {
+		if (!flags || (state->state & flags)) {
+			*cached_ptr = state;
+			refcount_inc(&state->refs);
+		}
+	}
+}
+
+static void cache_state(struct extent_state *state,
+			struct extent_state **cached_ptr)
+{
+	return cache_state_if_flags(state, cached_ptr,
+				    EXTENT_LOCKED | EXTENT_BOUNDARY);
+}
+
+/*
+ * Find the first state struct with 'bits' set after 'start', and return it.
+ * tree->lock must be held.  NULL will returned if nothing was found after
+ * 'start'.
+ */
+static struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree,
+							u64 start, u32 bits)
+{
+	struct extent_state *state;
+
+	/*
+	 * This search will find all the extents that end after our range
+	 * starts.
+	 */
+	state = tree_search(tree, start);
+	while (state) {
+		if (state->end >= start && (state->state & bits))
+			return state;
+		state = next_state(state);
+	}
+	return NULL;
+}
+
+/*
+ * Find the first offset in the io tree with one or more @bits set.
+ *
+ * Note: If there are multiple bits set in @bits, any of them will match.
+ *
+ * Return 0 if we find something, and update @start_ret and @end_ret.
+ * Return 1 if we found nothing.
+ */
+int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
+			  u64 *start_ret, u64 *end_ret, u32 bits,
+			  struct extent_state **cached_state)
+{
+	struct extent_state *state;
+	int ret = 1;
+
+	spin_lock(&tree->lock);
+	if (cached_state && *cached_state) {
+		state = *cached_state;
+		if (state->end == start - 1 && extent_state_in_tree(state)) {
+			while ((state = next_state(state)) != NULL) {
+				if (state->state & bits)
+					goto got_it;
+			}
+			free_extent_state(*cached_state);
+			*cached_state = NULL;
+			goto out;
+		}
+		free_extent_state(*cached_state);
+		*cached_state = NULL;
+	}
+
+	state = find_first_extent_bit_state(tree, start, bits);
+got_it:
+	if (state) {
+		cache_state_if_flags(state, cached_state, 0);
+		*start_ret = state->start;
+		*end_ret = state->end;
+		ret = 0;
+	}
+out:
+	spin_unlock(&tree->lock);
+	return ret;
+}
+
+/*
+ * Find a contiguous area of bits
+ *
+ * @tree:      io tree to check
+ * @start:     offset to start the search from
+ * @start_ret: the first offset we found with the bits set
+ * @end_ret:   the final contiguous range of the bits that were set
+ * @bits:      bits to look for
+ *
+ * set_extent_bit and clear_extent_bit can temporarily split contiguous ranges
+ * to set bits appropriately, and then merge them again.  During this time it
+ * will drop the tree->lock, so use this helper if you want to find the actual
+ * contiguous area for given bits.  We will search to the first bit we find, and
+ * then walk down the tree until we find a non-contiguous area.  The area
+ * returned will be the full contiguous area with the bits set.
+ */
+int find_contiguous_extent_bit(struct extent_io_tree *tree, u64 start,
+			       u64 *start_ret, u64 *end_ret, u32 bits)
+{
+	struct extent_state *state;
+	int ret = 1;
+
+	spin_lock(&tree->lock);
+	state = find_first_extent_bit_state(tree, start, bits);
+	if (state) {
+		*start_ret = state->start;
+		*end_ret = state->end;
+		while ((state = next_state(state)) != NULL) {
+			if (state->start > (*end_ret + 1))
+				break;
+			*end_ret = state->end;
+		}
+		ret = 0;
+	}
+	spin_unlock(&tree->lock);
+	return ret;
+}
+
+/*
+ * Find a contiguous range of bytes in the file marked as delalloc, not more
+ * than 'max_bytes'.  start and end are used to return the range,
+ *
+ * True is returned if we find something, false if nothing was in the tree.
+ */
+bool btrfs_find_delalloc_range(struct extent_io_tree *tree, u64 *start,
+			       u64 *end, u64 max_bytes,
+			       struct extent_state **cached_state)
+{
+	struct extent_state *state;
+	u64 cur_start = *start;
+	bool found = false;
+	u64 total_bytes = 0;
+
+	spin_lock(&tree->lock);
+
+	/*
+	 * This search will find all the extents that end after our range
+	 * starts.
+	 */
+	state = tree_search(tree, cur_start);
+	if (!state) {
+		*end = (u64)-1;
+		goto out;
+	}
+
+	while (state) {
+		if (found && (state->start != cur_start ||
+			      (state->state & EXTENT_BOUNDARY))) {
+			goto out;
+		}
+		if (!(state->state & EXTENT_DELALLOC)) {
+			if (!found)
+				*end = state->end;
+			goto out;
+		}
+		if (!found) {
+			*start = state->start;
+			*cached_state = state;
+			refcount_inc(&state->refs);
+		}
+		found = true;
+		*end = state->end;
+		cur_start = state->end + 1;
+		total_bytes += state->end - state->start + 1;
+		if (total_bytes >= max_bytes)
+			break;
+		state = next_state(state);
+	}
+out:
+	spin_unlock(&tree->lock);
+	return found;
+}
+
+/*
+ * Set some bits on a range in the tree.  This may require allocations or
+ * sleeping, so the gfp mask is used to indicate what is allowed.
+ *
+ * If any of the exclusive bits are set, this will fail with -EEXIST if some
+ * part of the range already has the desired bits set.  The start of the
+ * existing range is returned in failed_start in this case.
+ *
+ * [start, end] is inclusive This takes the tree lock.
+ */
+static int __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+			    u32 bits, u64 *failed_start,
+			    struct extent_state **cached_state,
+			    struct extent_changeset *changeset, gfp_t mask)
+{
+	struct extent_state *state;
+	struct extent_state *prealloc = NULL;
+	struct rb_node **p;
+	struct rb_node *parent;
+	int err = 0;
+	u64 last_start;
+	u64 last_end;
+	u32 exclusive_bits = (bits & EXTENT_LOCKED);
+
+	btrfs_debug_check_extent_io_range(tree, start, end);
+	trace_btrfs_set_extent_bit(tree, start, end - start + 1, bits);
+
+	if (exclusive_bits)
+		ASSERT(failed_start);
+	else
+		ASSERT(failed_start == NULL);
+again:
+	if (!prealloc) {
+		/*
+		 * Don't care for allocation failure here because we might end
+		 * up not needing the pre-allocated extent state at all, which
+		 * is the case if we only have in the tree extent states that
+		 * cover our input range and don't cover too any other range.
+		 * If we end up needing a new extent state we allocate it later.
+		 */
+		prealloc = alloc_extent_state(mask);
+	}
+
+	spin_lock(&tree->lock);
+	if (cached_state && *cached_state) {
+		state = *cached_state;
+		if (state->start <= start && state->end > start &&
+		    extent_state_in_tree(state))
+			goto hit_next;
+	}
+	/*
+	 * This search will find all the extents that end after our range
+	 * starts.
+	 */
+	state = tree_search_for_insert(tree, start, &p, &parent);
+	if (!state) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc)
+			goto search_again;
+		prealloc->start = start;
+		prealloc->end = end;
+		insert_state_fast(tree, prealloc, p, parent, bits, changeset);
+		cache_state(prealloc, cached_state);
+		prealloc = NULL;
+		goto out;
+	}
+hit_next:
+	last_start = state->start;
+	last_end = state->end;
+
+	/*
+	 * | ---- desired range ---- |
+	 * | state |
+	 *
+	 * Just lock what we found and keep going
+	 */
+	if (state->start == start && state->end <= end) {
+		if (state->state & exclusive_bits) {
+			*failed_start = state->start;
+			err = -EEXIST;
+			goto out;
+		}
+
+		set_state_bits(tree, state, bits, changeset);
+		cache_state(state, cached_state);
+		merge_state(tree, state);
+		if (last_end == (u64)-1)
+			goto out;
+		start = last_end + 1;
+		state = next_state(state);
+		if (start < end && state && state->start == start &&
+		    !need_resched())
+			goto hit_next;
+		goto search_again;
+	}
+
+	/*
+	 *     | ---- desired range ---- |
+	 * | state |
+	 *   or
+	 * | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip bits on second
+	 * half.
+	 *
+	 * If the extent we found extends past our range, we just split and
+	 * search again.  It'll get split again the next time though.
+	 *
+	 * If the extent we found is inside our range, we set the desired bit
+	 * on it.
+	 */
+	if (state->start < start) {
+		if (state->state & exclusive_bits) {
+			*failed_start = start;
+			err = -EEXIST;
+			goto out;
+		}
+
+		/*
+		 * If this extent already has all the bits we want set, then
+		 * skip it, not necessary to split it or do anything with it.
+		 */
+		if ((state->state & bits) == bits) {
+			start = state->end + 1;
+			cache_state(state, cached_state);
+			goto search_again;
+		}
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc)
+			goto search_again;
+		err = split_state(tree, state, prealloc, start);
+		if (err)
+			extent_io_tree_panic(tree, err);
+
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			set_state_bits(tree, state, bits, changeset);
+			cache_state(state, cached_state);
+			merge_state(tree, state);
+			if (last_end == (u64)-1)
+				goto out;
+			start = last_end + 1;
+			state = next_state(state);
+			if (start < end && state && state->start == start &&
+			    !need_resched())
+				goto hit_next;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *     | state | or               | state |
+	 *
+	 * There's a hole, we need to insert something in it and ignore the
+	 * extent we found.
+	 */
+	if (state->start > start) {
+		u64 this_end;
+		if (end < last_start)
+			this_end = end;
+		else
+			this_end = last_start - 1;
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc)
+			goto search_again;
+
+		/*
+		 * Avoid to free 'prealloc' if it can be merged with the later
+		 * extent.
+		 */
+		prealloc->start = start;
+		prealloc->end = this_end;
+		err = insert_state(tree, prealloc, bits, changeset);
+		if (err)
+			extent_io_tree_panic(tree, err);
+
+		cache_state(prealloc, cached_state);
+		prealloc = NULL;
+		start = this_end + 1;
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *                        | state |
+	 *
+	 * We need to split the extent, and set the bit on the first half
+	 */
+	if (state->start <= end && state->end > end) {
+		if (state->state & exclusive_bits) {
+			*failed_start = start;
+			err = -EEXIST;
+			goto out;
+		}
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc)
+			goto search_again;
+		err = split_state(tree, state, prealloc, end + 1);
+		if (err)
+			extent_io_tree_panic(tree, err);
+
+		set_state_bits(tree, prealloc, bits, changeset);
+		cache_state(prealloc, cached_state);
+		merge_state(tree, prealloc);
+		prealloc = NULL;
+		goto out;
+	}
+
+search_again:
+	if (start > end)
+		goto out;
+	spin_unlock(&tree->lock);
+	if (gfpflags_allow_blocking(mask))
+		cond_resched();
+	goto again;
+
+out:
+	spin_unlock(&tree->lock);
+	if (prealloc)
+		free_extent_state(prealloc);
+
+	return err;
+
+}
+
+int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		   u32 bits, struct extent_state **cached_state, gfp_t mask)
+{
+	return __set_extent_bit(tree, start, end, bits, NULL, cached_state,
+				NULL, mask);
+}
+
+/*
+ * Convert all bits in a given range from one bit to another
+ *
+ * @tree:	the io tree to search
+ * @start:	the start offset in bytes
+ * @end:	the end offset in bytes (inclusive)
+ * @bits:	the bits to set in this range
+ * @clear_bits:	the bits to clear in this range
+ * @cached_state:	state that we're going to cache
+ *
+ * This will go through and set bits for the given range.  If any states exist
+ * already in this range they are set with the given bit and cleared of the
+ * clear_bits.  This is only meant to be used by things that are mergeable, ie.
+ * converting from say DELALLOC to DIRTY.  This is not meant to be used with
+ * boundary bits like LOCK.
+ *
+ * All allocations are done with GFP_NOFS.
+ */
+int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		       u32 bits, u32 clear_bits,
+		       struct extent_state **cached_state)
+{
+	struct extent_state *state;
+	struct extent_state *prealloc = NULL;
+	struct rb_node **p;
+	struct rb_node *parent;
+	int err = 0;
+	u64 last_start;
+	u64 last_end;
+	bool first_iteration = true;
+
+	btrfs_debug_check_extent_io_range(tree, start, end);
+	trace_btrfs_convert_extent_bit(tree, start, end - start + 1, bits,
+				       clear_bits);
+
+again:
+	if (!prealloc) {
+		/*
+		 * Best effort, don't worry if extent state allocation fails
+		 * here for the first iteration. We might have a cached state
+		 * that matches exactly the target range, in which case no
+		 * extent state allocations are needed. We'll only know this
+		 * after locking the tree.
+		 */
+		prealloc = alloc_extent_state(GFP_NOFS);
+		if (!prealloc && !first_iteration)
+			return -ENOMEM;
+	}
+
+	spin_lock(&tree->lock);
+	if (cached_state && *cached_state) {
+		state = *cached_state;
+		if (state->start <= start && state->end > start &&
+		    extent_state_in_tree(state))
+			goto hit_next;
+	}
+
+	/*
+	 * This search will find all the extents that end after our range
+	 * starts.
+	 */
+	state = tree_search_for_insert(tree, start, &p, &parent);
+	if (!state) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
+		prealloc->start = start;
+		prealloc->end = end;
+		insert_state_fast(tree, prealloc, p, parent, bits, NULL);
+		cache_state(prealloc, cached_state);
+		prealloc = NULL;
+		goto out;
+	}
+hit_next:
+	last_start = state->start;
+	last_end = state->end;
+
+	/*
+	 * | ---- desired range ---- |
+	 * | state |
+	 *
+	 * Just lock what we found and keep going.
+	 */
+	if (state->start == start && state->end <= end) {
+		set_state_bits(tree, state, bits, NULL);
+		cache_state(state, cached_state);
+		state = clear_state_bit(tree, state, clear_bits, 0, NULL);
+		if (last_end == (u64)-1)
+			goto out;
+		start = last_end + 1;
+		if (start < end && state && state->start == start &&
+		    !need_resched())
+			goto hit_next;
+		goto search_again;
+	}
+
+	/*
+	 *     | ---- desired range ---- |
+	 * | state |
+	 *   or
+	 * | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip bits on second
+	 * half.
+	 *
+	 * If the extent we found extends past our range, we just split and
+	 * search again.  It'll get split again the next time though.
+	 *
+	 * If the extent we found is inside our range, we set the desired bit
+	 * on it.
+	 */
+	if (state->start < start) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
+		err = split_state(tree, state, prealloc, start);
+		if (err)
+			extent_io_tree_panic(tree, err);
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			set_state_bits(tree, state, bits, NULL);
+			cache_state(state, cached_state);
+			state = clear_state_bit(tree, state, clear_bits, 0, NULL);
+			if (last_end == (u64)-1)
+				goto out;
+			start = last_end + 1;
+			if (start < end && state && state->start == start &&
+			    !need_resched())
+				goto hit_next;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *     | state | or               | state |
+	 *
+	 * There's a hole, we need to insert something in it and ignore the
+	 * extent we found.
+	 */
+	if (state->start > start) {
+		u64 this_end;
+		if (end < last_start)
+			this_end = end;
+		else
+			this_end = last_start - 1;
+
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
+
+		/*
+		 * Avoid to free 'prealloc' if it can be merged with the later
+		 * extent.
+		 */
+		prealloc->start = start;
+		prealloc->end = this_end;
+		err = insert_state(tree, prealloc, bits, NULL);
+		if (err)
+			extent_io_tree_panic(tree, err);
+		cache_state(prealloc, cached_state);
+		prealloc = NULL;
+		start = this_end + 1;
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *                        | state |
+	 *
+	 * We need to split the extent, and set the bit on the first half.
+	 */
+	if (state->start <= end && state->end > end) {
+		prealloc = alloc_extent_state_atomic(prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
+
+		err = split_state(tree, state, prealloc, end + 1);
+		if (err)
+			extent_io_tree_panic(tree, err);
+
+		set_state_bits(tree, prealloc, bits, NULL);
+		cache_state(prealloc, cached_state);
+		clear_state_bit(tree, prealloc, clear_bits, 0, NULL);
+		prealloc = NULL;
+		goto out;
+	}
+
+search_again:
+	if (start > end)
+		goto out;
+	spin_unlock(&tree->lock);
+	cond_resched();
+	first_iteration = false;
+	goto again;
+
+out:
+	spin_unlock(&tree->lock);
+	if (prealloc)
+		free_extent_state(prealloc);
+
+	return err;
+}
+
+/*
+ * Find the first range that has @bits not set. This range could start before
+ * @start.
+ *
+ * @tree:      the tree to search
+ * @start:     offset at/after which the found extent should start
+ * @start_ret: records the beginning of the range
+ * @end_ret:   records the end of the range (inclusive)
+ * @bits:      the set of bits which must be unset
+ *
+ * Since unallocated range is also considered one which doesn't have the bits
+ * set it's possible that @end_ret contains -1, this happens in case the range
+ * spans (last_range_end, end of device]. In this case it's up to the caller to
+ * trim @end_ret to the appropriate size.
+ */
+void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
+				 u64 *start_ret, u64 *end_ret, u32 bits)
+{
+	struct extent_state *state;
+	struct extent_state *prev = NULL, *next;
+
+	spin_lock(&tree->lock);
+
+	/* Find first extent with bits cleared */
+	while (1) {
+		state = tree_search_prev_next(tree, start, &prev, &next);
+		if (!state && !next && !prev) {
+			/*
+			 * Tree is completely empty, send full range and let
+			 * caller deal with it
+			 */
+			*start_ret = 0;
+			*end_ret = -1;
+			goto out;
+		} else if (!state && !next) {
+			/*
+			 * We are past the last allocated chunk, set start at
+			 * the end of the last extent.
+			 */
+			*start_ret = prev->end + 1;
+			*end_ret = -1;
+			goto out;
+		} else if (!state) {
+			state = next;
+		}
+
+		/*
+		 * At this point 'state' either contains 'start' or start is
+		 * before 'state'
+		 */
+		if (in_range(start, state->start, state->end - state->start + 1)) {
+			if (state->state & bits) {
+				/*
+				 * |--range with bits sets--|
+				 *    |
+				 *    start
+				 */
+				start = state->end + 1;
+			} else {
+				/*
+				 * 'start' falls within a range that doesn't
+				 * have the bits set, so take its start as the
+				 * beginning of the desired range
+				 *
+				 * |--range with bits cleared----|
+				 *      |
+				 *      start
+				 */
+				*start_ret = state->start;
+				break;
+			}
+		} else {
+			/*
+			 * |---prev range---|---hole/unset---|---node range---|
+			 *                          |
+			 *                        start
+			 *
+			 *                        or
+			 *
+			 * |---hole/unset--||--first node--|
+			 * 0   |
+			 *    start
+			 */
+			if (prev)
+				*start_ret = prev->end + 1;
+			else
+				*start_ret = 0;
+			break;
+		}
+	}
+
+	/*
+	 * Find the longest stretch from start until an entry which has the
+	 * bits set
+	 */
+	while (state) {
+		if (state->end >= start && !(state->state & bits)) {
+			*end_ret = state->end;
+		} else {
+			*end_ret = state->start - 1;
+			break;
+		}
+		state = next_state(state);
+	}
+out:
+	spin_unlock(&tree->lock);
+}
+
+/*
+ * Count the number of bytes in the tree that have a given bit(s) set.  This
+ * can be fairly slow, except for EXTENT_DIRTY which is cached.  The total
+ * number found is returned.
+ */
+u64 count_range_bits(struct extent_io_tree *tree,
+		     u64 *start, u64 search_end, u64 max_bytes,
+		     u32 bits, int contig)
+{
+	struct extent_state *state;
+	u64 cur_start = *start;
+	u64 total_bytes = 0;
+	u64 last = 0;
+	int found = 0;
+
+	if (WARN_ON(search_end < cur_start))
+		return 0;
+
+	spin_lock(&tree->lock);
+
+	/*
+	 * This search will find all the extents that end after our range
+	 * starts.
+	 */
+	state = tree_search(tree, cur_start);
+	while (state) {
+		if (state->start > search_end)
+			break;
+		if (contig && found && state->start > last + 1)
+			break;
+		if (state->end >= cur_start && (state->state & bits) == bits) {
+			total_bytes += min(search_end, state->end) + 1 -
+				       max(cur_start, state->start);
+			if (total_bytes >= max_bytes)
+				break;
+			if (!found) {
+				*start = max(cur_start, state->start);
+				found = 1;
+			}
+			last = state->end;
+		} else if (contig && found) {
+			break;
+		}
+		state = next_state(state);
+	}
+	spin_unlock(&tree->lock);
+	return total_bytes;
+}
+
+/*
+ * Searche a range in the state tree for a given mask.  If 'filled' == 1, this
+ * returns 1 only if every extent in the tree has the bits set.  Otherwise, 1
+ * is returned if any bit in the range is found set.
+ */
+int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		   u32 bits, int filled, struct extent_state *cached)
+{
+	struct extent_state *state = NULL;
+	int bitset = 0;
+
+	spin_lock(&tree->lock);
+	if (cached && extent_state_in_tree(cached) && cached->start <= start &&
+	    cached->end > start)
+		state = cached;
+	else
+		state = tree_search(tree, start);
+	while (state && start <= end) {
+		if (filled && state->start > start) {
+			bitset = 0;
+			break;
+		}
+
+		if (state->start > end)
+			break;
+
+		if (state->state & bits) {
+			bitset = 1;
+			if (!filled)
+				break;
+		} else if (filled) {
+			bitset = 0;
+			break;
+		}
+
+		if (state->end == (u64)-1)
+			break;
+
+		start = state->end + 1;
+		if (start > end)
+			break;
+		state = next_state(state);
+	}
+
+	/* We ran out of states and were still inside of our range. */
+	if (filled && !state)
+		bitset = 0;
+	spin_unlock(&tree->lock);
+	return bitset;
+}
+
+/* Wrappers around set/clear extent bit */
+int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
+			   u32 bits, struct extent_changeset *changeset)
+{
+	/*
+	 * We don't support EXTENT_LOCKED yet, as current changeset will
+	 * record any bits changed, so for EXTENT_LOCKED case, it will
+	 * either fail with -EEXIST or changeset will record the whole
+	 * range.
+	 */
+	ASSERT(!(bits & EXTENT_LOCKED));
+
+	return __set_extent_bit(tree, start, end, bits, NULL, NULL, changeset,
+				GFP_NOFS);
+}
+
+int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
+			     u32 bits, struct extent_changeset *changeset)
+{
+	/*
+	 * Don't support EXTENT_LOCKED case, same reason as
+	 * set_record_extent_bits().
+	 */
+	ASSERT(!(bits & EXTENT_LOCKED));
+
+	return __clear_extent_bit(tree, start, end, bits, NULL, GFP_NOFS,
+				  changeset);
+}
+
+int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	int err;
+	u64 failed_start;
+
+	err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, &failed_start,
+			       NULL, NULL, GFP_NOFS);
+	if (err == -EEXIST) {
+		if (failed_start > start)
+			clear_extent_bit(tree, start, failed_start - 1,
+					 EXTENT_LOCKED, NULL);
+		return 0;
+	}
+	return 1;
+}
+
+/*
+ * Either insert or lock state struct between start and end use mask to tell
+ * us if waiting is desired.
+ */
+int lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
+		struct extent_state **cached_state)
+{
+	int err;
+	u64 failed_start;
+
+	err = __set_extent_bit(tree, start, end, EXTENT_LOCKED, &failed_start,
+			       cached_state, NULL, GFP_NOFS);
+	while (err == -EEXIST) {
+		if (failed_start != start)
+			clear_extent_bit(tree, start, failed_start - 1,
+					 EXTENT_LOCKED, cached_state);
+
+		wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
+		err = __set_extent_bit(tree, start, end, EXTENT_LOCKED,
+				       &failed_start, cached_state, NULL,
+				       GFP_NOFS);
+	}
+	return err;
+}
+
+void __cold extent_state_free_cachep(void)
+{
+	btrfs_extent_state_leak_debug_check();
+	kmem_cache_destroy(extent_state_cache);
+}
+
+int __init extent_state_init_cachep(void)
+{
+	extent_state_cache = kmem_cache_create("btrfs_extent_state",
+			sizeof(struct extent_state), 0,
+			SLAB_MEM_SPREAD, NULL);
+	if (!extent_state_cache)
+		return -ENOMEM;
+
+	return 0;
+}