btrfs: pass a pointer to get_range_bits() to cache first search result

Allow get_range_bits() to take an extent state pointer to pointer argument
so that we can cache the first extent state record in the target range, so
that a caller can use it for subsequent operations without doing a full
tree search. Currently the only user is try_release_extent_state(), which
then does a call to __clear_extent_bit() which can use such a cached state
record.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

3 files changed, 26 insertions, 9 deletions

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
index 14510a71a8fd..7ae24a533404 100644
--- a/fs/btrfs/extent-io-tree.c
+++ b/fs/btrfs/extent-io-tree.c
@@ -1752,14 +1752,26 @@ bool test_range_bit_exists(struct extent_io_tree *tree, u64 start, u64 end, u32
 	return bitset;
 }
 
-void get_range_bits(struct extent_io_tree *tree, u64 start, u64 end, u32 *bits)
+void get_range_bits(struct extent_io_tree *tree, u64 start, u64 end, u32 *bits,
+		    struct extent_state **cached_state)
 {
 	struct extent_state *state;
 
+	/*
+	 * The cached state is currently mandatory and not used to start the
+	 * search, only to cache the first state record found in the range.
+	 */
+	ASSERT(cached_state != NULL);
+	ASSERT(*cached_state == NULL);
+
 	*bits = 0;
 
 	spin_lock(&tree->lock);
 	state = tree_search(tree, start);
+	if (state && state->start < end) {
+		*cached_state = state;
+		refcount_inc(&state->refs);
+	}
 	while (state) {
 		if (state->start > end)
 			break;
diff --git a/fs/btrfs/extent-io-tree.h b/fs/btrfs/extent-io-tree.h
index 9095e49e059c..6dfe8b097d93 100644
--- a/fs/btrfs/extent-io-tree.h
+++ b/fs/btrfs/extent-io-tree.h
@@ -170,7 +170,8 @@ void free_extent_state(struct extent_state *state);
 bool test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, u32 bit,
 		    struct extent_state *cached_state);
 bool test_range_bit_exists(struct extent_io_tree *tree, u64 start, u64 end, u32 bit);
-void get_range_bits(struct extent_io_tree *tree, u64 start, u64 end, u32 *bits);
+void get_range_bits(struct extent_io_tree *tree, u64 start, u64 end, u32 *bits,
+		    struct extent_state **cached_state);
 int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 			     u32 bits, struct extent_changeset *changeset);
 int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 8a544c6e65d9..a9ecf10debd9 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2621,13 +2621,15 @@ int extent_invalidate_folio(struct extent_io_tree *tree,
 static bool try_release_extent_state(struct extent_io_tree *tree,
 				     struct folio *folio)
 {
+	struct extent_state *cached_state = NULL;
 	u64 start = folio_pos(folio);
 	u64 end = start + folio_size(folio) - 1;
 	u32 range_bits;
 	u32 clear_bits;
-	int ret;
+	bool ret = false;
+	int ret2;
 
-	get_range_bits(tree, start, end, &range_bits);
+	get_range_bits(tree, start, end, &range_bits, &cached_state);
 
 	/*
 	 * We can release the folio if it's locked only for ordered extent
@@ -2635,7 +2637,7 @@ static bool try_release_extent_state(struct extent_io_tree *tree,
 	 */
 	if ((range_bits & EXTENT_LOCKED) &&
 	    !(range_bits & EXTENT_FINISHING_ORDERED))
-		return false;
+		goto out;
 
 	clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM | EXTENT_DELALLOC_NEW |
 		       EXTENT_CTLBITS | EXTENT_QGROUP_RESERVED |
@@ -2645,15 +2647,17 @@ static bool try_release_extent_state(struct extent_io_tree *tree,
 	 * nodatasum, delalloc new and finishing ordered bits. The delalloc new
 	 * bit will be cleared by ordered extent completion.
 	 */
-	ret = __clear_extent_bit(tree, start, end, clear_bits, NULL, NULL);
+	ret2 = __clear_extent_bit(tree, start, end, clear_bits, &cached_state, NULL);
 	/*
 	 * If clear_extent_bit failed for enomem reasons, we can't allow the
 	 * release to continue.
 	 */
-	if (ret < 0)
-		return false;
+	if (ret2 == 0)
+		ret = true;
+out:
+	free_extent_state(cached_state);
 
-	return true;
+	return ret;
 }
 
 /*