@@ -4637,38 +4637,28 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
goto out;
}
- /* at the lowest level, we're done, setup the path and exit */
- if (level == path->lowest_level) {
- if (slot >= nritems)
- goto find_next_key;
- ret = 0;
- path->slots[level] = slot;
- /* Save our key for returning back. */
- btrfs_item_key_to_cpu(cur, min_key, slot);
- goto out;
- }
- if (sret && slot > 0)
+ /*
+ * Not at the lowest level and not a perfect match,
+ * go back a slot if possible to search lower level.
+ */
+ if (sret && slot > 0 && level > path->lowest_level)
slot--;
/*
- * check this node pointer against the min_trans parameters.
+ * Check this node pointer against the min_trans parameters.
* If it is too old, skip to the next one.
*/
- while (slot < nritems) {
- u64 gen;
-
- gen = btrfs_node_ptr_generation(cur, slot);
- if (gen < min_trans) {
+ if (level > 0) {
+ while (slot < nritems) {
+ if (btrfs_node_ptr_generation(cur, slot) >= min_trans)
+ break;
slot++;
- continue;
}
- break;
}
-find_next_key:
+ path->slots[level] = slot;
/*
- * we didn't find a candidate key in this node, walk forward
- * and find another one
+ * We didn't find a candidate key in this node, walk forward
+ * and find another one.
*/
- path->slots[level] = slot;
if (slot >= nritems) {
sret = btrfs_find_next_key(root, path, min_key, level,
min_trans);
@@ -4679,12 +4669,16 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
goto out;
}
}
+ /* At the lowest level, we're done. Set the key and exit. */
if (level == path->lowest_level) {
ret = 0;
- /* Save our key for returning back. */
- btrfs_node_key_to_cpu(cur, min_key, slot);
+ if (level == 0)
+ btrfs_item_key_to_cpu(cur, min_key, slot);
+ else
+ btrfs_node_key_to_cpu(cur, min_key, slot);
goto out;
}
+ /* Search down to a lower level. */
cur = btrfs_read_node_slot(cur, slot);
if (IS_ERR(cur)) {
ret = PTR_ERR(cur);
Commit 323ac95bce44 ("Btrfs: don't read leaf blocks containing only checksums during truncate") changed the condition from `level == 0` to `level == path->lowest_level`, while its origional purpose is just to do some leaf nodes handling (calling btrfs_item_key_to_cpu()) and skip some code that doesn't fit leaf nodes. After changing the condition, the code path 1. also handle the non-leaf nodes when path->lowest_level is nonzero, which is wrong. However, it seems that btrfs_search_forward() is never called with a nonzero path->lowest_level, which makes this bug not found before. 2. makes the later if block with the same condition, which is origionally used to handle non-leaf node (calling btrfs_node_key_to_cpu()) when lowest_level is not zero, dead code. So Use if conditions to skip the non-leaf handling code instead of using goto to make it more clear, and handle both leaf and non-leaf node in the lowest_level loop exit logic. This changes the behavior when btrfs_search_forward() is called with nonzero path->lowest_level. But this never happens in the current code base, and the previous behavior is wrong. So the change of behavior will not be a problem. Fix: commit 323ac95bce44 ("Btrfs: don't read leaf blocks containing only checksums during truncate") Signed-off-by: Sun YangKai <sunk67188@gmail.com> --- fs/btrfs/ctree.c | 44 +++++++++++++++++++------------------------- 1 file changed, 19 insertions(+), 25 deletions(-)