6.15-stable review patch. If anyone has any objections, please let me know.
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From: Sun YangKai sunk67188@gmail.com
[ Upstream commit 27260dd1904bb409cf84709928ba9bc5506fbe8e ]
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 original purpose was just to do some leaf node 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 handles the non-leaf nodes when path->lowest_level is nonzero, which is wrong. However 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 was originally used to handle non-leaf node (calling btrfs_node_key_to_cpu()) when lowest_level is not zero, dead code.
Since btrfs_search_forward() is never called for a path with a lowest_level different from zero, just completely remove the partial support for a non-zero lowest_level, simplifying a bit the code, and assert that lowest_level is zero at the start of the function.
Suggested-by: Qu Wenruo wqu@suse.com Fixes: 323ac95bce44 ("Btrfs: don't read leaf blocks containing only checksums during truncate") Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Sun YangKai sunk67188@gmail.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/ctree.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index a2e7979372cc..648531fe0900 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -4585,16 +4585,13 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
/* * A helper function to walk down the tree starting at min_key, and looking - * for nodes or leaves that are have a minimum transaction id. + * for leaves that have a minimum transaction id. * This is used by the btree defrag code, and tree logging * * This does not cow, but it does stuff the starting key it finds back * into min_key, so you can call btrfs_search_slot with cow=1 on the * key and get a writable path. * - * This honors path->lowest_level to prevent descent past a given level - * of the tree. - * * min_trans indicates the oldest transaction that you are interested * in walking through. Any nodes or leaves older than min_trans are * skipped over (without reading them). @@ -4615,6 +4612,7 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, int keep_locks = path->keep_locks;
ASSERT(!path->nowait); + ASSERT(path->lowest_level == 0); path->keep_locks = 1; again: cur = btrfs_read_lock_root_node(root); @@ -4636,8 +4634,8 @@ 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) { + /* At level 0 we're done, setup the path and exit. */ + if (level == 0) { if (slot >= nritems) goto find_next_key; ret = 0; @@ -4678,12 +4676,6 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, goto out; } } - if (level == path->lowest_level) { - ret = 0; - /* Save our key for returning back. */ - btrfs_node_key_to_cpu(cur, min_key, slot); - goto out; - } cur = btrfs_read_node_slot(cur, slot); if (IS_ERR(cur)) { ret = PTR_ERR(cur); @@ -4699,7 +4691,7 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, out: path->keep_locks = keep_locks; if (ret == 0) - btrfs_unlock_up_safe(path, path->lowest_level + 1); + btrfs_unlock_up_safe(path, 1); return ret; }