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btrfs-progs: lowmem check: Fix function call stack overflow caused by wrong tree reloc tree detection

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For reloc tree root, its backref points to itself.  So for such case,
we should finish the lookup.

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

However the @root passed can be another tree, e.g. other tree reloc root
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 uses
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: 54c8f9152f ("btrfs-progs: check: Fix lowmem mode stack overflow caused by fsck/023")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2017-11-22 17:03:21 +08:00 committed by David Sterba
parent e6055097d1
commit 77d47b4a3d
1 changed files with 5 additions and 5 deletions
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10
cmds-check.c
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@ -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 {
/*