/*
* Read a visibility map page.
*
* If the page doesn't exist, InvalidBuffer is returned, or if 'extend' is
* true, the visibility map file is extended.
*/
static Buffer
vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
{
Buffer buf;
/*
* We might not have opened the relation at the smgr level yet, or we
* might have been forced to close it by a sinval message. The code below
* won't necessarily notice relation extension immediately when extend =
* false, so we rely on sinval messages to ensure that our ideas about the
* size of the map aren't too far out of date.
*/
RelationOpenSmgr(rel);
/*
* If we haven't cached the size of the visibility map fork yet, check it
* first.
*/
if (rel->rd_smgr->smgr_vm_nblocks == InvalidBlockNumber)
{
if (smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
rel->rd_smgr->smgr_vm_nblocks = smgrnblocks(rel->rd_smgr,
VISIBILITYMAP_FORKNUM);
else
rel->rd_smgr->smgr_vm_nblocks = 0;
}
/* Handle requests beyond EOF */
if (blkno >= rel->rd_smgr->smgr_vm_nblocks)
{
if (extend)
vm_extend(rel, blkno + 1);
else
return InvalidBuffer;
}
/*
* 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.
*/
buf = ReadBufferExtended(rel, VISIBILITYMAP_FORKNUM, blkno,
RBM_ZERO_ON_ERROR, NULL);
if (PageIsNew(BufferGetPage(buf)))
PageInit(BufferGetPage(buf), BLCKSZ, 0);
return buf;
}
/*
* Read a visibility map page.
*
* If the page doesn't exist, InvalidBuffer is returned, or if 'extend' is
* true, the visibility map file is extended.
*/
static Buffer
vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
{
Buffer buf;
RelationOpenSmgr(rel);
/*
* If we haven't cached the size of the visibility map fork yet, check it
* first. Also recheck if the requested block seems to be past end, since
* our cached value might be stale. (We send smgr inval messages on
* truncation, but not on extension.)
*/
if (rel->rd_smgr->smgr_vm_nblocks == InvalidBlockNumber ||
blkno >= rel->rd_smgr->smgr_vm_nblocks)
{
if (smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
rel->rd_smgr->smgr_vm_nblocks = smgrnblocks(rel->rd_smgr,
VISIBILITYMAP_FORKNUM);
else
rel->rd_smgr->smgr_vm_nblocks = 0;
}
/* Handle requests beyond EOF */
if (blkno >= rel->rd_smgr->smgr_vm_nblocks)
{
if (extend)
vm_extend(rel, blkno + 1);
else
return InvalidBuffer;
}
/*
* 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.
*/
buf = ReadBufferExtended(rel, VISIBILITYMAP_FORKNUM, blkno,
RBM_ZERO_ON_ERROR, NULL);
if (PageIsNew(BufferGetPage(buf)))
PageInit(BufferGetPage(buf), BLCKSZ, 0);
return buf;
}
/*
* Read a visibility map page.
*
* If the page doesn't exist, InvalidBuffer is returned, or if 'extend' is
* true, the visibility map file is extended.
*/
static Buffer
vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
{
Buffer buf;
RelationOpenSmgr(rel);
/*
* The current size of the visibility map fork is kept in relcache, to
* avoid reading beyond EOF. If we haven't cached the size of the map yet,
* do that first.
*/
if (rel->rd_vm_nblocks == InvalidBlockNumber)
{
if (smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
rel->rd_vm_nblocks = smgrnblocks(rel->rd_smgr,
VISIBILITYMAP_FORKNUM);
else
rel->rd_vm_nblocks = 0;
}
/* Handle requests beyond EOF */
if (blkno >= rel->rd_vm_nblocks)
{
if (extend)
vm_extend(rel, blkno + 1);
else
return InvalidBuffer;
}
/*
* 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.
*/
buf = ReadBufferExtended(rel, VISIBILITYMAP_FORKNUM, blkno,
RBM_ZERO_ON_ERROR, NULL);
if (PageIsNew(BufferGetPage(buf)))
PageInit(BufferGetPage(buf), BLCKSZ, 0);
return buf;
}
