From: Ye Bin yebin10@huawei.com
commit 1da18e38cb97e9521e93d63034521a9649524f64 upstream.
When bigalloc is enabled, reserved cluster accounting for delayed allocation is handled in extent_status.c. With a corrupted file system, it's possible for this accounting to be incorrect, dsicovered by Syzbot:
EXT4-fs error (device loop0): ext4_validate_block_bitmap:398: comm rep: bg 0: block 5: invalid block bitmap EXT4-fs (loop0): Delayed block allocation failed for inode 18 at logical offset 0 with max blocks 32 with error 28 EXT4-fs (loop0): This should not happen!! Data will be lost
EXT4-fs (loop0): Total free blocks count 0 EXT4-fs (loop0): Free/Dirty block details EXT4-fs (loop0): free_blocks=0 EXT4-fs (loop0): dirty_blocks=32 EXT4-fs (loop0): Block reservation details EXT4-fs (loop0): i_reserved_data_blocks=2 EXT4-fs (loop0): Inode 18 (00000000845cd634): i_reserved_data_blocks (1) not cleared!
Above issue happens as follows: Assume: sbi->s_cluster_ratio = 16 Step1: Insert delay block [0, 31] -> ei->i_reserved_data_blocks=2 Step2: ext4_writepages mpage_map_and_submit_extent -> return failed mpage_release_unused_pages -> to release [0, 30] ext4_es_remove_extent -> remove lblk=0 end=30 __es_remove_extent -> len1=0 len2=31-30=1 __es_remove_extent: ... if (len2 > 0) { ... if (len1 > 0) { ... } else { es->es_lblk = end + 1; es->es_len = len2; ... } if (count_reserved) count_rsvd(inode, lblk, ...); goto out; -> will return but didn't calculate 'reserved' ... Step3: ext4_destroy_inode -> trigger "i_reserved_data_blocks (1) not cleared!"
To solve above issue if 'len2>0' call 'get_rsvd()' before goto out.
Reported-by: syzbot+05a0f0ccab4a25626e38@syzkaller.appspotmail.com Fixes: 8fcc3a580651 ("ext4: rework reserved cluster accounting when invalidating pages") Signed-off-by: Ye Bin yebin10@huawei.com Reviewed-by: Eric Whitney enwlinux@gmail.com Link: https://lore.kernel.org/r/20221208033426.1832460-2-yebin@huaweicloud.com Signed-off-by: Theodore Ts'o tytso@mit.edu Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/extents_status.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -1371,7 +1371,7 @@ retry: if (count_reserved) count_rsvd(inode, lblk, orig_es.es_len - len1 - len2, &orig_es, &rc); - goto out; + goto out_get_reserved; }
if (len1 > 0) { @@ -1413,6 +1413,7 @@ retry: } }
+out_get_reserved: if (count_reserved) *reserved = get_rsvd(inode, end, es, &rc); out: