5.4-stable review patch. If anyone has any objections, please let me know.
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From: Yongjian Sun sunyongjian1@huawei.com
commit 9d80eaa1a1d37539224982b76c9ceeee736510b9 upstream.
After running a stress test combined with fault injection, we performed fsck -a followed by fsck -fn on the filesystem image. During the second pass, fsck -fn reported:
Inode 131512, end of extent exceeds allowed value (logical block 405, physical block 1180540, len 2)
This inode was not in the orphan list. Analysis revealed the following call chain that leads to the inconsistency:
ext4_da_write_end() //does not update i_disksize ext4_punch_hole() //truncate folio, keep size ext4_page_mkwrite() ext4_block_page_mkwrite() ext4_block_write_begin() ext4_get_block() //insert written extent without update i_disksize journal commit echo 1 > /sys/block/xxx/device/delete
da-write path updates i_size but does not update i_disksize. Then ext4_punch_hole truncates the da-folio yet still leaves i_disksize unchanged(in the ext4_update_disksize_before_punch function, the condition offset + len < size is met). Then ext4_page_mkwrite sees ext4_nonda_switch return 1 and takes the nodioread_nolock path, the folio about to be written has just been punched out, and it’s offset sits beyond the current i_disksize. This may result in a written extent being inserted, but again does not update i_disksize. If the journal gets committed and then the block device is yanked, we might run into this. It should be noted that replacing ext4_punch_hole with ext4_zero_range in the call sequence may also trigger this issue, as neither will update i_disksize under these circumstances.
To fix this, we can modify ext4_update_disksize_before_punch to increase i_disksize to min(i_size, offset + len) when both i_size and (offset + len) are greater than i_disksize.
Cc: stable@kernel.org Signed-off-by: Yongjian Sun sunyongjian1@huawei.com Reviewed-by: Zhang Yi yi.zhang@huawei.com Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: Baokun Li libaokun1@huawei.com Message-ID: 20250911133024.1841027-1-sunyongjian@huaweicloud.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/inode.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4247,7 +4247,11 @@ int ext4_can_truncate(struct inode *inod * We have to make sure i_disksize gets properly updated before we truncate * page cache due to hole punching or zero range. Otherwise i_disksize update * can get lost as it may have been postponed to submission of writeback but - * that will never happen after we truncate page cache. + * that will never happen if we remove the folio containing i_size from the + * page cache. Also if we punch hole within i_size but above i_disksize, + * following ext4_page_mkwrite() may mistakenly allocate written blocks over + * the hole and thus introduce allocated blocks beyond i_disksize which is + * not allowed (e2fsck would complain in case of crash). */ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset, loff_t len) @@ -4256,9 +4260,11 @@ int ext4_update_disksize_before_punch(st loff_t size = i_size_read(inode);
WARN_ON(!inode_is_locked(inode)); - if (offset > size || offset + len < size) + if (offset > size) return 0;
+ if (offset + len < size) + size = offset + len; if (EXT4_I(inode)->i_disksize >= size) return 0;