[PATCH v2 5/6] xfs: handle -EFSCORRUPTED during head/tail verification

Brian Foster
2017-07-10T13:28:02Z

Torn write and tail overwrite detection both trigger only on
-EFSBADCRC errors. While this is the most likely failure scenario
for each condition, -EFSCORRUPTED is still possible in certain cases
depending on what ends up on disk when a torn write or partial tail
overwrite occurs. For example, an invalid log record h_len can lead
to an -EFSCORRUPTED error when running the log recovery CRC pass.

Therefore, update log head and tail verification to trigger the
associated head/tail fixups in the event of -EFSCORRUPTED errors
along with -EFSBADCRC. Also, -EFSCORRUPTED can currently be returned
from xlog_do_recovery_pass() before rhead_blk is initialized if the
first record encountered happens to be corrupted. This leads to an
incorrect 'first_bad' return value. Initialize rhead_blk earlier in
the function to address that problem as well.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
fs/xfs/xfs_log_recover.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index d3bef45..2e34797 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1102,7 +1102,7 @@ xlog_verify_tail(
first_bad = 0;
error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
XLOG_RECOVER_CRCPASS, &first_bad);
- while (error == -EFSBADCRC && first_bad) {
+ while ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
int tail_distance;

/*
@@ -1188,7 +1188,7 @@ xlog_verify_head(
*/
error = xlog_do_recovery_pass(log, *head_blk, tmp_rhead_blk,
XLOG_RECOVER_CRCPASS, &first_bad);
- if (error == -EFSBADCRC) {
+ if ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
/*
* We've hit a potential torn write. Reset the error and warn
* about it.
@@ -5257,7 +5257,7 @@ xlog_do_recovery_pass(
LIST_HEAD (buffer_list);

ASSERT(head_blk != tail_blk);
- rhead_blk = 0;
+ blk_no = rhead_blk = tail_blk;

for (i = 0; i < XLOG_RHASH_SIZE; i++)
INIT_HLIST_HEAD(&rhash[i]);
@@ -5335,7 +5335,6 @@ xlog_do_recovery_pass(
}

memset(rhash, 0, sizeof(rhash));
- blk_no = rhead_blk = tail_blk;
if (tail_blk > head_blk) {
/*
* Perform recovery around the end of the physical log.
--
2.9.4