diff options
| author | Raghavendra G <rgowdapp@redhat.com> | 2017-12-22 12:02:09 +0530 |
|---|---|---|
| committer | Raghavendra G <rgowdapp@redhat.com> | 2017-12-26 10:37:43 +0000 |
| commit | 466e24dcb19de95dd22c76aeb54861e902954d86 (patch) | |
| tree | d19a88de7d0dc5bdd427fcf81a0a5ec4829a6d0d | |
| parent | c1052342b2527f360e8f5d825431da015f973c56 (diff) | |
performance/write-behind: fix bug while handling short writes
The variabled "fulfilled" in wb_fulfill_short_write is not reset to 0
while handling every member of the list.
This has some interesting consequences:
* If we break from the loop while processing last member of the list
head->winds, req is reset to head as the list is a circular
one. However, head is already fulfilled and can potentially be
freed. So, we end up adding a freed request to wb_inode->todo
list. This is the RCA for the crash tracked by the bug associated
with this patch (Note that we saw "holder" which is freed in todo
list).
* If we break from the loop while processing any of the last but one
member of the list head->winds, req is set to next member in the
list, skipping the current request, even though it is not entirely
synced. This can lead to data corruption.
The fix is very simple and we've to change the code to make sure
"fulfilled" reflects whether the current request is fulfilled or not
and it doesn't carry history of previous requests in the list.
>Change-Id: Ia3d6988175a51c9e08efdb521a7b7938b01f93c8
>BUG: 1528558
>Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
(cherry picked from commit 0bc22bef7f3c24663aadfb3548b348aa121e3047)
Change-Id: Ia3d6988175a51c9e08efdb521a7b7938b01f93c8
BUG: 1529094
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
| -rw-r--r-- | xlators/performance/write-behind/src/write-behind.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/xlators/performance/write-behind/src/write-behind.c b/xlators/performance/write-behind/src/write-behind.c index d1a95c97d7a..7104eb908b5 100644 --- a/xlators/performance/write-behind/src/write-behind.c +++ b/xlators/performance/write-behind/src/write-behind.c @@ -964,6 +964,7 @@ __wb_fulfill_short_write (wb_request_t *req, int size, gf_boolean_t *fulfilled) } else { accounted_size = size; __wb_modify_write_request (req, size); + *fulfilled = 0; } out: @@ -1005,7 +1006,7 @@ wb_fulfill_short_write (wb_request_t *head, int size) size -= accounted_size; if (size == 0) { - if (fulfilled) + if (fulfilled && (next != head)) req = next; goto done; @@ -1017,7 +1018,7 @@ wb_fulfill_short_write (wb_request_t *head, int size) size -= accounted_size; if (size == 0) { - if (fulfilled) + if (fulfilled && (next != head)) req = next; break; } |