On sudden f2fs shutdown, zoned block device status and f2fs meta data can be inconsistent. When f2fs shutdown happens during write operations, write pointers on the device go forward but the f2fs meta data does not reflect the write pointer progress. This inconsistency will eventually cause "Unaligned write command" error when restarting write operation after the next mount.
This error is observed with xfstests test case generic/388, which enforces sudden shutdown during write operation and checks the file system recovery. This patch series adds a feature to f2fs to check and fix the write pointer consistency when zoned block devices get mounted. Per discussion on the list, implement two checks: a check for open zones and a check for non-open zones. The first patch add the check for open zones that current segments point to. Check write pointer consistency with current segment positions recorded in CP, and if they are inconsistent, assign a new zone to the current segment. When fsync data exists, check and fix the consistency after fsync data recovery. The second patch adds the check for non-open zones that current segments do not point to. Compare write pointers with valid block maps in SIT, and if they are inconsistent, report the failure. Even if fixes are required, do not have kernel fix because SIT consistency with CP is not guaranteed because of hardware failure or software bug possibility. In such check failure cases, fail the mount to ask users to run fsck. Corresponding patch series is being posted for fsck.f2fs to add the write pointer consistency check feature. Thank goes to Chao Yu for the detailed discussion on the list. Shin'ichiro Kawasaki (2): f2fs: Check write pointer consistency of open zones f2fs: Check write pointer consistency of non-open zones fs/f2fs/f2fs.h | 4 + fs/f2fs/recovery.c | 6 + fs/f2fs/segment.c | 271 +++++++++++++++++++++++++++++++++++++++++++++ fs/f2fs/super.c | 17 ++- 4 files changed, 295 insertions(+), 3 deletions(-) -- 2.21.0 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
