diff mbox

[07/11] btrfs-progs: lowmem check: Fix function call stack overflow caused by wrong tree reloc tree detection

Message ID 20171122090325.29458-8-wqu@suse.com (mailing list archive)
State New, archived
Headers show

Commit Message

Qu Wenruo Nov. 22, 2017, 9:03 a.m. UTC
For tree reloc tree root, its backref points to it self.
So for such case, we should finish the lookup.

Previous end condition is to ensure it's tree reloc tree *and* needs its
root bytenr to match the bytenr passed in.

However the @root passed in can be other tree, e.g. other tree reloc
tree which shares the node/leaf.
This makes any check based on @root passed in invalid.

The patch removes the unreliable root objectid detection, and only use
root->bytenr check.
For the possibility of invalid self-pointing backref, extent tree
checker should have already handled it, so we don't need to bother in
fs tree checker.

Fixes: 54c8f9152fd9 ("btrfs-progs: check: Fix lowmem mode stack overflow caused by fsck/023")
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 cmds-check.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox

Patch

diff --git a/cmds-check.c b/cmds-check.c
index 452e715bf245..7eb08b6cb962 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -11700,16 +11700,12 @@  static int check_tree_block_ref(struct btrfs_root *root,
 	u32 nodesize = root->fs_info->nodesize;
 	u32 item_size;
 	u64 offset;
-	int tree_reloc_root = 0;
 	int found_ref = 0;
 	int err = 0;
 	int ret;
 	int strict = 1;
 	int parent = 0;
 
-	if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
-	    btrfs_header_bytenr(root->node) == bytenr)
-		tree_reloc_root = 1;
 	btrfs_init_path(&path);
 	key.objectid = bytenr;
 	if (btrfs_fs_incompat(root->fs_info, SKINNY_METADATA))
@@ -11817,8 +11813,12 @@  static int check_tree_block_ref(struct btrfs_root *root,
 			/*
 			 * Backref of tree reloc root points to itself, no need
 			 * to check backref any more.
+			 *
+			 * This may be an error of loop backref, but extent tree
+			 * checker should have already handled it.
+			 * Here we only need to avoid infinite iteration.
 			 */
-			if (tree_reloc_root) {
+			if (offset == bytenr) {
 				found_ref = 1;
 			} else {
 				/*