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Fix unlinking of SLRU segments.

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Commit dee663f7 intended to drop any queued up fsync requests before
unlinking segment files, but missed a code path.  Fix, by centralizing
the forget-and-unlink code into a single function.

Reported-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Discussion: https://postgr.es/m/20201104013205.icogbi773przyny5%40development
This commit is contained in:
Thomas Munro 2020-11-05 13:45:32 +13:00
parent fac83dbd6f
commit c732c3f8c1
1 changed files with 18 additions and 26 deletions
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44
src/backend/access/transam/slru.c
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@ -145,7 +145,7 @@ static int SlruSelectLRUPage(SlruCtl ctl, int pageno);
static bool SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename, static bool SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename,
int segpage, void *data); int segpage, void *data);
static void SlruInternalDeleteSegment(SlruCtl ctl, char *filename); static void SlruInternalDeleteSegment(SlruCtl ctl, int segno);
/* /*
* Initialization of shared memory * Initialization of shared memory
@ -1298,19 +1298,28 @@ restart:;
} }
/* /*
* Delete an individual SLRU segment, identified by the filename. * Delete an individual SLRU segment.
* *
* NB: This does not touch the SLRU buffers themselves, callers have to ensure * NB: This does not touch the SLRU buffers themselves, callers have to ensure
* they either can't yet contain anything, or have already been cleaned out. * they either can't yet contain anything, or have already been cleaned out.
*/ */
static void static void
SlruInternalDeleteSegment(SlruCtl ctl, char *filename) SlruInternalDeleteSegment(SlruCtl ctl, int segno)
{ {
char path[MAXPGPATH]; char path[MAXPGPATH];
snprintf(path, MAXPGPATH, "%s/%s", ctl->Dir, filename); /* Forget any fsync requests queued for this segment. */
ereport(DEBUG2, if (ctl->sync_handler != SYNC_HANDLER_NONE)
(errmsg("removing file \"%s\"", path))); {
FileTag tag;
INIT_SLRUFILETAG(tag, ctl->sync_handler, segno);
RegisterSyncRequest(&tag, SYNC_FORGET_REQUEST, true);
}
/* Unlink the file. */
SlruFileName(ctl, path, segno);
ereport(DEBUG2, (errmsg("removing file \"%s\"", path)));
unlink(path); unlink(path);
} }
@ -1322,7 +1331,6 @@ SlruDeleteSegment(SlruCtl ctl, int segno)
{ {
SlruShared shared = ctl->shared; SlruShared shared = ctl->shared;
int slotno; int slotno;
char path[MAXPGPATH];
bool did_write; bool did_write;
/* Clean out any possibly existing references to the segment. */ /* Clean out any possibly existing references to the segment. */
@ -1364,23 +1372,7 @@ restart:
if (did_write) if (did_write)
goto restart; goto restart;
snprintf(path, MAXPGPATH, "%s/%04X", ctl->Dir, segno); SlruInternalDeleteSegment(ctl, segno);
ereport(DEBUG2,
(errmsg("removing file \"%s\"", path)));
/*
* Tell the checkpointer to forget any sync requests, before we unlink the
* file.
*/
if (ctl->sync_handler != SYNC_HANDLER_NONE)
{
FileTag tag;
INIT_SLRUFILETAG(tag, ctl->sync_handler, segno);
RegisterSyncRequest(&tag, SYNC_FORGET_REQUEST, true);
}
unlink(path);
LWLockRelease(shared->ControlLock); LWLockRelease(shared->ControlLock);
} }
@ -1413,7 +1405,7 @@ SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename, int segpage, void *data)
int cutoffPage = *(int *) data; int cutoffPage = *(int *) data;
if (ctl->PagePrecedes(segpage, cutoffPage)) if (ctl->PagePrecedes(segpage, cutoffPage))
SlruInternalDeleteSegment(ctl, filename); SlruInternalDeleteSegment(ctl, segpage / SLRU_PAGES_PER_SEGMENT);
return false; /* keep going */ return false; /* keep going */
} }
@ -1425,7 +1417,7 @@ SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename, int segpage, void *data)
bool bool
SlruScanDirCbDeleteAll(SlruCtl ctl, char *filename, int segpage, void *data) SlruScanDirCbDeleteAll(SlruCtl ctl, char *filename, int segpage, void *data)
{ {
SlruInternalDeleteSegment(ctl, filename); SlruInternalDeleteSegment(ctl, segpage / SLRU_PAGES_PER_SEGMENT);
return false; /* keep going */ return false; /* keep going */
} }