/* 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);
/*
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
* 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);
* 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
* 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;
}
static BlockNumber fsm_logical_to_physical(FSMAddress addr);
static Buffer fsm_readbuf(Relation rel, FSMAddress addr, bool extend);
-static void fsm_extend(Relation rel, BlockNumber fsm_nblocks);
+static Buffer fsm_extend(Relation rel, BlockNumber fsm_nblocks);
/* functions to convert amount of free space to a FSM category */
static uint8 fsm_space_avail_to_cat(Size avail);
reln->smgr_cached_nblocks[FSM_FORKNUM] = 0;
}
- /* Handle requests beyond EOF */
+ /*
+ * For reading we use ZERO_ON_ERROR mode, and initialize the page if
+ * necessary. The FSM information is not accurate anyway, so it's better
+ * to clear corrupt pages than error out. Since the FSM changes are not
+ * WAL-logged, the so-called torn page problem on crash can lead to pages
+ * with corrupt headers, for example.
+ *
+ * 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[FSM_FORKNUM])
{
if (extend)
- fsm_extend(rel, blkno + 1);
+ buf = fsm_extend(rel, blkno + 1);
else
return InvalidBuffer;
}
+ else
+ buf = ReadBufferExtended(rel, FSM_FORKNUM, blkno, RBM_ZERO_ON_ERROR, NULL);
/*
- * Use ZERO_ON_ERROR mode, and initialize the page if necessary. The FSM
- * information is not accurate anyway, so it's better to clear corrupt
- * pages than error out. Since the FSM changes are not WAL-logged, the
- * so-called torn page problem on crash can lead to pages with corrupt
- * headers, for example.
- *
- * 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
* 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, FSM_FORKNUM, blkno, RBM_ZERO_ON_ERROR, NULL);
if (PageIsNew(BufferGetPage(buf)))
{
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
* it if necessary with empty pages. And by empty, I mean pages filled
* with zeros, meaning there's no free space.
*/
-static void
+static Buffer
fsm_extend(Relation rel, BlockNumber fsm_nblocks)
{
- BlockNumber fsm_nblocks_now;
- PGAlignedBlock pg = {0};
- SMgrRelation reln;
-
-
- /*
- * We use the relation extension lock to lock out other backends trying to
- * extend the FSM at the same time. It also locks out extension of the
- * main fork, unnecessarily, but extending the FSM 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 FSM file first if it doesn't exist. If
- * smgr_cached_nblocks[FSM_FORKNUM] is positive then it must exist, no
- * need for an smgrexists call.
- */
- if ((reln->smgr_cached_nblocks[FSM_FORKNUM] == 0 ||
- reln->smgr_cached_nblocks[FSM_FORKNUM] == InvalidBlockNumber) &&
- !smgrexists(reln, FSM_FORKNUM))
- smgrcreate(reln, FSM_FORKNUM, false);
-
- /* Invalidate cache so that smgrnblocks() asks the kernel. */
- reln->smgr_cached_nblocks[FSM_FORKNUM] = InvalidBlockNumber;
- fsm_nblocks_now = smgrnblocks(reln, FSM_FORKNUM);
-
- /* Extend as needed. */
- while (fsm_nblocks_now < fsm_nblocks)
- {
- smgrextend(reln, FSM_FORKNUM, fsm_nblocks_now,
- pg.data, false);
- fsm_nblocks_now++;
- }
-
- UnlockRelationForExtension(rel, ExclusiveLock);
+ return ExtendBufferedRelTo(EB_REL(rel), FSM_FORKNUM, NULL,
+ EB_CREATE_FORK_IF_NEEDED |
+ EB_CLEAR_SIZE_CACHE,
+ fsm_nblocks,
+ RBM_ZERO_ON_ERROR);
}
/*
projects / users / rhaas / postgres.git / commitdiff