diff options
| author | Raghavendra G <rgowdapp@redhat.com> | 2014-04-11 15:58:47 +0530 |
|---|---|---|
| committer | Raghavendra G <rgowdapp@redhat.com> | 2017-05-09 10:06:39 +0000 |
| commit | 2ff39c5cbea6fbda0d7a442f55e6dc2a72efb171 (patch) | |
| tree | 8fe676783e4fed824bfad390d20790da081f4100 /xlators/performance | |
| parent | af226d250bcced782d19412bd7de1ca32834c8eb (diff) | |
performance/read-ahead: prevent stale data being returned to application.
Assume that fd is shared by two application threads/processes.
T0 read is triggered from app-thread t1 and read call passes through
write-behind.
T1 app-thread t2 issues a write. The page on which read from t1 is
waiting is marked stale
T2 write-behind caches write and indicates to application as write
complete.
T3 app-thread t2 issues read to same region. Since, there is already a
page for that region (created as part of read at T0), this read
request waits on that page to be filled (though it is stale, which
is a bug).
T4 read (triggered at T0) completes from brick (with write still
pending). Now both read requests from t1 and t2 are served this data
(though data is stale from app-thread t2's perspective - which is a
bug)
T5 write is flushed to brick by write-behind.
Fix is to not to serve data from a stale page, but instead initiate a
fresh read to back-end.
Change-Id: Id6af733464fa41bb4e81fd29c7451c73d06453fb
BUG: 1414242
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: https://review.gluster.org/7447
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Csaba Henk <csaba@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Zhou Zhengping <johnzzpcrystal@gmail.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Diffstat (limited to 'xlators/performance')
| -rw-r--r-- | xlators/performance/read-ahead/src/page.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/xlators/performance/read-ahead/src/page.c b/xlators/performance/read-ahead/src/page.c index 216e327af74..17e346ec947 100644 --- a/xlators/performance/read-ahead/src/page.c +++ b/xlators/performance/read-ahead/src/page.c @@ -139,6 +139,7 @@ ra_fault_cbk (call_frame_t *frame, void *cookie, xlator_t *this, ra_waitq_t *waitq = NULL; fd_t *fd = NULL; uint64_t tmp_file = 0; + gf_boolean_t stale = _gf_false; GF_ASSERT (frame); @@ -174,6 +175,13 @@ ra_fault_cbk (call_frame_t *frame, void *cookie, xlator_t *this, goto unlock; } + if (page->stale) { + page->stale = 0; + page->ready = 0; + stale = 1; + goto unlock; + } + /* * "Dirty" means that the request was a pure read-ahead; it's * set for requests we issue ourselves, and cleared when user @@ -219,6 +227,16 @@ ra_fault_cbk (call_frame_t *frame, void *cookie, xlator_t *this, unlock: ra_file_unlock (file); + if (stale) { + STACK_WIND (frame, ra_fault_cbk, + FIRST_CHILD (frame->this), + FIRST_CHILD (frame->this)->fops->readv, + local->fd, local->pending_size, + local->pending_offset, 0, NULL); + + return 0; + } + ra_waitq_return (waitq); fd_unref (local->fd); |