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

[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
Show Stats 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);
}

27
fs/btrfs/tree-checker.c
View File

@ -242,7 +242,8 @@ static int check_leaf_item(struct btrfs_root *root,
return ret;
}
int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf)
static int check_leaf(struct btrfs_root *root, struct extent_buffer *leaf,
bool check_item_data)
{
struct btrfs_fs_info *fs_info = root->fs_info;
/* No valid key type is 0, so all key should be larger than this key */
@ -361,10 +362,15 @@ int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf)
return -EUCLEAN;
}
/* Check if the item size and content meet other criteria */
ret = check_leaf_item(root, leaf, &key, slot);
if (ret < 0)
return ret;
if (check_item_data) {
/*
* Check if the item size and content meet other
* criteria
*/
ret = check_leaf_item(root, leaf, &key, slot);
if (ret < 0)
return ret;
}
prev_key.objectid = key.objectid;
prev_key.type = key.type;
@ -374,6 +380,17 @@ int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf)
return 0;
}
int btrfs_check_leaf_full(struct btrfs_root *root, struct extent_buffer *leaf)
{
return check_leaf(root, leaf, true);
}
int btrfs_check_leaf_relaxed(struct btrfs_root *root,
struct extent_buffer *leaf)
{
return check_leaf(root, leaf, false);
}
int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node)
{
unsigned long nr = btrfs_header_nritems(node);

14
fs/btrfs/tree-checker.h
View File

@ -20,7 +20,19 @@
#include "ctree.h"
#include "extent_io.h"
int btrfs_check_leaf(struct btrfs_root *root, struct extent_buffer *leaf);
/*
* Comprehensive leaf checker.
* Will check not only the item pointers, but also every possible member
* in item data.
*/
int btrfs_check_leaf_full(struct btrfs_root *root, struct extent_buffer *leaf);
/*
* Less strict leaf checker.
* Will only check item pointers, not reading item data.
*/
int btrfs_check_leaf_relaxed(struct btrfs_root *root,
struct extent_buffer *leaf);
int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node);
#endif