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Use ExtendBufferedRelTo() in {vm,fsm}_extend()

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This uses ExtendBufferedRelTo(), introduced in 31966b151e, to extend the
visibilitymap and freespacemap to the size needed.

It also happens to fix a warning introduced in 3d6a98457d, reported by Tom
Lane.

Discussion: https://postgr.es/m/20221029025420.eplyow6k7tgu6he3@awork3.anarazel.de
Discussion: https://postgr.es/m/2194723.1680736788@sss.pgh.pa.us
This commit is contained in:
Andres Freund
2023-04-05 17:29:57 -07:00
parent bccd6908ca
commit fcdda1e4b5
2 changed files with 48 additions and 115 deletions
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80
src/backend/access/heap/visibilitymap.c
View File

@@ -126,7 +126,7 @@
/* prototypes for internal routines */
static Buffer vm_readbuf(Relation rel, BlockNumber blkno, bool extend);
static void vm_extend(Relation rel, BlockNumber vm_nblocks);
static Buffer vm_extend(Relation rel, BlockNumber vm_nblocks);
/*
@@ -574,22 +574,29 @@ vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = 0;
}
/* Handle requests beyond EOF */
/*
* For reading we use ZERO_ON_ERROR mode, and initialize the page if
* necessary. It's always safe to clear bits, so it's better to clear
* corrupt pages than error out.
*
* We use the same path below to initialize pages when extending the
* relation, as a concurrent extension can end up with vm_extend()
* returning an already-initialized page.
*/
if (blkno >= reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM])
{
if (extend)
vm_extend(rel, blkno + 1);
buf = vm_extend(rel, blkno + 1);
else
return InvalidBuffer;
}
else
buf = ReadBufferExtended(rel, VISIBILITYMAP_FORKNUM, blkno,
RBM_ZERO_ON_ERROR, NULL);
/*
* Use ZERO_ON_ERROR mode, and initialize the page if necessary. It's
* always safe to clear bits, so it's better to clear corrupt pages than
* error out.
*
* The initialize-the-page part is trickier than it looks, because of the
* possibility of multiple backends doing this concurrently, and our
* Initializing the page when needed is trickier than it looks, because of
* the possibility of multiple backends doing this concurrently, and our
* desire to not uselessly take the buffer lock in the normal path where
* the page is OK. We must take the lock to initialize the page, so
* recheck page newness after we have the lock, in case someone else
@@ -602,8 +609,6 @@ vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
* long as it doesn't depend on the page header having correct contents.
* Current usage is safe because PageGetContents() does not require that.
*/
buf = ReadBufferExtended(rel, VISIBILITYMAP_FORKNUM, blkno,
RBM_ZERO_ON_ERROR, NULL);
if (PageIsNew(BufferGetPage(buf)))
{
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
@@ -618,51 +623,16 @@ vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
* Ensure that the visibility map fork is at least vm_nblocks long, extending
* it if necessary with zeroed pages.
*/
static void
static Buffer
vm_extend(Relation rel, BlockNumber vm_nblocks)
{
BlockNumber vm_nblocks_now;
PGAlignedBlock pg = {0};
SMgrRelation reln;
Buffer buf;
/*
* We use the relation extension lock to lock out other backends trying to
* extend the visibility map at the same time. It also locks out extension
* of the main fork, unnecessarily, but extending the visibility map
* happens seldom enough that it doesn't seem worthwhile to have a
* separate lock tag type for it.
*
* Note that another backend might have extended or created the relation
* by the time we get the lock.
*/
LockRelationForExtension(rel, ExclusiveLock);
/*
* Caution: re-using this smgr pointer could fail if the relcache entry
* gets closed. It's safe as long as we only do smgr-level operations
* between here and the last use of the pointer.
*/
reln = RelationGetSmgr(rel);
/*
* Create the file first if it doesn't exist. If smgr_vm_nblocks is
* positive then it must exist, no need for an smgrexists call.
*/
if ((reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == 0 ||
reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == InvalidBlockNumber) &&
!smgrexists(reln, VISIBILITYMAP_FORKNUM))
smgrcreate(reln, VISIBILITYMAP_FORKNUM, false);
/* Invalidate cache so that smgrnblocks() asks the kernel. */
reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = InvalidBlockNumber;
vm_nblocks_now = smgrnblocks(reln, VISIBILITYMAP_FORKNUM);
/* Now extend the file */
while (vm_nblocks_now < vm_nblocks)
{
smgrextend(reln, VISIBILITYMAP_FORKNUM, vm_nblocks_now, pg.data, false);
vm_nblocks_now++;
}
buf = ExtendBufferedRelTo(EB_REL(rel), VISIBILITYMAP_FORKNUM, NULL,
EB_CREATE_FORK_IF_NEEDED |
EB_CLEAR_SIZE_CACHE,
vm_nblocks,
RBM_ZERO_ON_ERROR);
/*
* Send a shared-inval message to force other backends to close any smgr
@@ -671,7 +641,7 @@ vm_extend(Relation rel, BlockNumber vm_nblocks)
* to keep checking for creation or extension of the file, which happens
* infrequently.
*/
CacheInvalidateSmgr(reln->smgr_rlocator);
CacheInvalidateSmgr(RelationGetSmgr(rel)->smgr_rlocator);
UnlockRelationForExtension(rel, ExclusiveLock);
return buf;
}