[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 some btrfs_mark_buffer_dirty() caller, like
setup_items_for_insert(), doesn'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.
[Fix]
The correct timing to check leaf validation should be before write IO or
after read IO.
Just like ee have already done the tree validation check at btree
readpage end io hook, this patch will move the write time tree checker to
csum_dirty_buffer().
As csum_dirty_buffer() is called just before submitting btree write bio, as
the call path shows:
btree_submit_bio_hook()
|- __btree_submit_bio_start()
|- btree_csum_one_bio()
|- csum_dirty_buffer()
|- btrfs_check_leaf()
By this we can ensure the leaf passed in is in consistent status, and
can check them without causing tons of false alert.
Reported-by: Lakshmipathi.G <lakshmipathi.g@xxxxxxxxx>
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/btrfs/disk-io.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index efce9a2fa9be..6c17bce2a05e 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -506,6 +506,7 @@ static int csum_dirty_buffer(struct btrfs_fs_info *fs_info, struct page *page)
u64 start = page_offset(page);
u64 found_start;
struct extent_buffer *eb;
+ int ret;
eb = (struct extent_buffer *)page->private;
if (page != eb->pages[0])
@@ -524,7 +525,24 @@ static int csum_dirty_buffer(struct btrfs_fs_info *fs_info, struct page *page)
ASSERT(memcmp_extent_buffer(eb, fs_info->fsid,
btrfs_header_fsid(), BTRFS_FSID_SIZE) == 0);
- return csum_tree_block(fs_info, eb, 0);
+ ret = csum_tree_block(fs_info, eb, 0);
+ if (ret)
+ return ret;
+
+#ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
+ /*
+ * Do extra check before we write the tree block into disk.
+ */
+ if (btrfs_header_level(eb) == 0) {
+ ret = btrfs_check_leaf(fs_info->tree_root, eb);
+ if (ret) {
+ btrfs_print_leaf(eb);
+ ASSERT(0);
+ return ret;
+ }
+ }
+#endif
+ return 0;
}
static int check_tree_block_fsid(struct btrfs_fs_info *fs_info,
@@ -3847,12 +3865,6 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
buf->len,
fs_info->dirty_metadata_batch);
-#ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
- if (btrfs_header_level(buf) == 0 && btrfs_check_leaf(root, buf)) {
- btrfs_print_leaf(buf);
- ASSERT(0);
- }
-#endif
}
static void __btrfs_btree_balance_dirty(struct btrfs_fs_info *fs_info,
--
2.14.3
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