From: Tom Rini <trini@konsulko.com>
Date: Sat, 27 Apr 2019 15:34:55 +0000 (-0400)
Subject: Revert "fs: btrfs: fix false negatives in ROOT_ITEM search"
X-Git-Tag: v2019.07-rc1~3
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=6aebc0d11a10f48a54146c5e71bbef15a1a458fc;p=oweals%2Fu-boot.git

Revert "fs: btrfs: fix false negatives in ROOT_ITEM search"

Per Pierre this change shouldn't have been applied as it was superseded
by "fs: btrfs: fix btrfs_search_tree invalid results" which is also
applied now as 1627e5e5985d.

This reverts commit 633967f9818cb6a0e87ffa8cba33148a5bcc6edb.

Signed-off-by: Tom Rini <trini@konsulko.com>
---

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ca44a2404d..65c152a52f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -292,52 +292,20 @@ btrfs_search_tree_key_type(const struct btrfs_root *root, u64 objectid,
 {
 	struct btrfs_key key, *res;
 
-	/*
-	 * In some cases (e.g. tree roots), we need to look for a given
-	 * objectid and type without knowing the offset value (3rd element of a
-	 * btrfs tree node key). We can rely on the fact that btrfs_search_tree
-	 * returns the first element with key >= search_key, and then perform
-	 * our own comparison between the returned element and the search key.
-	 *
-	 * It is tempting to use a search key with offset 0 to perform this
-	 * "fuzzy search". This would return the first item with the (objectid,
-	 * type) we're looking for. However, using offset 0 has the wrong
-	 * behavior when the wanted item is the first in a leaf: since our
-	 * search key will be lower than the wanted item, the recursive search
-	 * will explore the wrong branch of the tree.
-	 *
-	 * Instead, use the largest possible offset (-1). The result of this
-	 * search will either be:
-	 *   1. An element with the (objectid, type) we're looking for, if it
-	 *      has offset -1 or if it is the last element in its leaf.
-	 *   2. The first element *after* an element with the (objectid, type)
-	 */
 	key.objectid = objectid;
 	key.type = type;
-	key.offset = -1;
+	key.offset = 0;
 
 	if (btrfs_search_tree(root, &key, path))
 		return NULL;
 
-	/*
-	 * Compare with the previous element first -- this is the likely case
-	 * since the result of the search is only what we want if it had offset
-	 * == -1 or if it was last in its leaf.
-	 */
-	if (path->slots[0] > 0) {
-		path->slots[0]--;
-		res = btrfs_path_leaf_key(path);
-		if (!btrfs_comp_keys_type(&key, res))
-			return res;
-		path->slots[0]++;
-	}
-
 	res = btrfs_path_leaf_key(path);
-	if (!btrfs_comp_keys_type(&key, res))
-		return res;
+	if (btrfs_comp_keys_type(&key, res)) {
+		btrfs_free_path(path);
+		return NULL;
+	}
 
-	btrfs_free_path(path);
-	return NULL;
+	return res;
 }
 
 static inline u32 btrfs_path_item_size(struct btrfs_path *p)