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btrfs: tree-checker: Fix false panic for sanity test

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[BUG]
If we run btrfs with CONFIG_BTRFS_FS_RUN_SANITY_TESTS=y, it will
instantly cause kernel panic like:

------
...
assertion failed: 0, file: fs/btrfs/disk-io.c, line: 3853
...
Call Trace:
 btrfs_mark_buffer_dirty+0x187/0x1f0 [btrfs]
 setup_items_for_insert+0x385/0x650 [btrfs]
 __btrfs_drop_extents+0x129a/0x1870 [btrfs]
...
-----

[Cause]
Btrfs will call btrfs_check_leaf() in btrfs_mark_buffer_dirty() to check
if the leaf is valid with CONFIG_BTRFS_FS_RUN_SANITY_TESTS=y.

However quite some btrfs_mark_buffer_dirty() callers(*) don't really
initialize its item data but only initialize its item pointers, leaving
item data uninitialized.

This makes tree-checker catch uninitialized data as error, causing
such panic.

*: These callers include but not limited to
setup_items_for_insert()
btrfs_split_item()
btrfs_expand_item()

[Fix]
Add a new parameter @check_item_data to btrfs_check_leaf().
With @check_item_data set to false, item data check will be skipped and
fallback to old btrfs_check_leaf() behavior.

So we can still get early warning if we screw up item pointers, and
avoid false panic.

Cc: Filipe Manana <fdmanana@gmail.com>
Reported-by: Lakshmipathi.G <lakshmipathi.g@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo
2017-11-08 08:54:24 +08:00
committed by David Sterba
parent ebb70442cd
commit 69fc6cbbac
3 changed files with 43 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
fs/btrfs/disk-io.c
View File

@@ -610,7 +610,7 @@ static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
* that we don't try and read the other copies of this block, just
* return -EIO.
*/
if (found_level == 0 && btrfs_check_leaf(root, eb)) {
if (found_level == 0 && btrfs_check_leaf_full(root, eb)) {
set_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
ret = -EIO;
}
@@ -3848,7 +3848,13 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
buf->len,
fs_info->dirty_metadata_batch);
#ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
if (btrfs_header_level(buf) == 0 && btrfs_check_leaf(root, buf)) {
/*
* Since btrfs_mark_buffer_dirty() can be called with item pointer set
* but item data not updated.
* So here we should only check item pointers, not item data.
*/
if (btrfs_header_level(buf) == 0 &&
btrfs_check_leaf_relaxed(root, buf)) {
btrfs_print_leaf(buf);
ASSERT(0);
}