[2/3] Btrfs: fix to search previous metadata extent item since skinny metadata

Commit Message

Wang Shilong Jan. 12, 2014, 1:38 p.m. UTC

From: Wang Shilong <[e-mail]>

There is a bug that using btrfs_previous_item() to search metadata extent item.
This is because in btrfs_previous_item(), we need type match, however, since
skinny metada was introduced by josef, we may mix this two types. So just
use btrfs_previous_item() is not working right.

To keep btrfs_previous_item() like normal tree search, i introduce another
function btrfs_previous_extent_item().

Signed-off-by: Wang Shilong <[e-mail]>
---
 fs/btrfs/backref.c |  3 +--
 fs/btrfs/ctree.c   | 43 +++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/ctree.h   |  2 ++
 fs/btrfs/scrub.c   |  3 +--
 4 files changed, 47 insertions(+), 4 deletions(-)

Patch

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 835b6c9..964679c 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1303,8 +1303,7 @@  int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
 	ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
 	if (ret < 0)
 		return ret;
-	ret = btrfs_previous_item(fs_info->extent_root, path,
-					0, BTRFS_EXTENT_ITEM_KEY);
+	ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0);
 	if (ret < 0)
 		return ret;
 
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 9e9de68..30f5b11 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5955,3 +5955,46 @@  int btrfs_previous_item(struct btrfs_root *root,
 	}
 	return 1;
 }
+
+/*
+ * search in extent tree to find a previous Metadata/Data extent item with
+ * min objecitd.
+ *
+ * returns 0 if something is found, 1 if nothing was found and < 0 on error
+ */
+int btrfs_previous_extent_item(struct btrfs_root *root,
+			struct btrfs_path *path, u64 min_objectid)
+{
+	struct btrfs_key found_key;
+	struct extent_buffer *leaf;
+	u32 nritems;
+	int ret;
+
+	while (1) {
+		if (path->slots[0] == 0) {
+			btrfs_set_path_blocking(path);
+			ret = btrfs_prev_leaf(root, path);
+			if (ret != 0)
+				return ret;
+		} else {
+			path->slots[0]--;
+		}
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		if (nritems == 0)
+			return 1;
+		if (path->slots[0] == nritems)
+			path->slots[0]--;
+
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.objectid < min_objectid)
+			break;
+		if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
+		    found_key.type == BTRFS_METADATA_ITEM_KEY)
+			return 0;
+		if (found_key.objectid == min_objectid &&
+		    found_key.type < BTRFS_EXTENT_ITEM_KEY)
+			break;
+	}
+	return 1;
+}
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3cebb4a..81f8190 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3331,6 +3331,8 @@  int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2);
 int btrfs_previous_item(struct btrfs_root *root,
 			struct btrfs_path *path, u64 min_objectid,
 			int type);
+int btrfs_previous_extent_item(struct btrfs_root *root,
+			struct btrfs_path *path, u64 min_objectid);
 void btrfs_set_item_key_safe(struct btrfs_root *root, struct btrfs_path *path,
 			     struct btrfs_key *new_key);
 struct extent_buffer *btrfs_root_node(struct btrfs_root *root);
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index e0677e4..51c342b 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -2385,8 +2385,7 @@  static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 			goto out;
 
 		if (ret > 0) {
-			ret = btrfs_previous_item(root, path, 0,
-						  BTRFS_EXTENT_ITEM_KEY);
+			ret = btrfs_previous_extent_item(root, path, 0);
 			if (ret < 0)
 				goto out;
 			if (ret > 0) {