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Don't forget about failed fsync() requests.

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If fsync() fails, md.c must keep the request in its bitmap, so that
future attempts will try again.

Back-patch to all supported releases.

Author: Thomas Munro
Reviewed-by: Amit Kapila
Reported-by: Andrew Gierth
Discussion: https://postgr.es/m/87y3i1ia4w.fsf%40news-spur.riddles.org.uk
This commit is contained in:
Thomas Munro 2018-11-19 13:30:58 +13:00
parent 74171f8c12
commit 1556cb2fc5
1 changed files with 18 additions and 5 deletions
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23
src/backend/storage/smgr/md.c
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@ -1123,10 +1123,8 @@ mdsync(void)
* The bitmap manipulations are slightly tricky, because we can call
* AbsorbFsyncRequests() inside the loop and that could result in
* bms_add_member() modifying and even re-palloc'ing the bitmapsets.
* This is okay because we unlink each bitmapset from the hashtable
* entry before scanning it. That means that any incoming fsync
* requests will be processed now if they reach the table before we
* begin to scan their fork.
* So we detach it, but if we fail we'll merge it with any new
* requests that have arrived in the meantime.
*/
for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
{
@ -1136,7 +1134,8 @@ mdsync(void)
entry->requests[forknum] = NULL;
entry->canceled[forknum] = false;
while ((segno = bms_first_member(requests)) >= 0)
segno = -1;
while ((segno = bms_next_member(requests, segno)) >= 0)
{
int failures;
@ -1217,6 +1216,7 @@ mdsync(void)
longest = elapsed;
total_elapsed += elapsed;
processed++;
requests = bms_del_member(requests, segno);
if (log_checkpoints)
elog(DEBUG1, "checkpoint sync: number=%d file=%s time=%.3f msec",
processed,
@ -1245,10 +1245,23 @@ mdsync(void)
*/
if (!FILE_POSSIBLY_DELETED(errno) ||
failures > 0)
{
Bitmapset *new_requests;
/*
* We need to merge these unsatisfied requests with
* any others that have arrived since we started.
*/
new_requests = entry->requests[forknum];
entry->requests[forknum] =
bms_join(new_requests, requests);
errno = save_errno;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m",
path)));
}
else
ereport(DEBUG1,
(errcode_for_file_access(),