diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 42509042ad..4f8058d8b1 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -6868,7 +6868,7 @@ FROM pg_stat_get_backend_idset() AS backendid;
arg5 is the ID of the backend which created the temporary relation for a
local buffer, or InvalidBackendId (-1) for a shared buffer.
arg6 is the number of bytes actually read, while arg7 is the number
- requested (if these are different it indicates trouble).
+ requested (if these are different it indicates a short read).
smgr-md-write-start
@@ -6890,7 +6890,7 @@ FROM pg_stat_get_backend_idset() AS backendid;
arg5 is the ID of the backend which created the temporary relation for a
local buffer, or InvalidBackendId (-1) for a shared buffer.
arg6 is the number of bytes actually written, while arg7 is the number
- requested (if these are different it indicates trouble).
+ requested (if these are different it indicates a short write).
sort-start
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index bbac3c8741..50e531d827 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -28,6 +28,7 @@
#include "access/xlog.h"
#include "access/xlogutils.h"
#include "commands/tablespace.h"
+#include "common/file_utils.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "pgstat.h"
@@ -754,138 +755,274 @@ mdprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
}
/*
- * mdread() -- Read the specified block from a relation.
+ * Convert an array of buffer address into an array of iovec objects, and
+ * return the number that were required. 'iov' must have enough space for up
+ * to 'nblocks' elements, but the number used may be less depending on
+ * merging. In the case of a run of fully contiguous buffers, a single iovec
+ * will be populated that can be handled as a plain non-vectored I/O.
+ */
+static int
+buffers_to_iovec(struct iovec *iov, void **buffers, int nblocks)
+{
+ struct iovec *iovp;
+ int iovcnt;
+
+ Assert(nblocks >= 1);
+
+ /* If this build supports direct I/O, buffers must be I/O aligned. */
+ for (int i = 0; i < nblocks; ++i)
+ {
+ if (PG_O_DIRECT != 0 && PG_IO_ALIGN_SIZE <= BLCKSZ)
+ Assert((uintptr_t) buffers[i] ==
+ TYPEALIGN(PG_IO_ALIGN_SIZE, buffers[i]));
+ }
+
+ /* Start the first iovec off with the first buffer. */
+ iovp = &iov[0];
+ iovp->iov_base = buffers[0];
+ iovp->iov_len = BLCKSZ;
+ iovcnt = 1;
+
+ /* Try to merge the rest. */
+ for (int i = 1; i < nblocks; ++i)
+ {
+ void *buffer = buffers[i];
+
+ if (((char *) iovp->iov_base + iovp->iov_len) == buffer)
+ {
+ /* Contiguous with the last iovec. */
+ iovp->iov_len += BLCKSZ;
+ }
+ else
+ {
+ /* Need a new iovec. */
+ iovp++;
+ iovp->iov_base = buffer;
+ iovp->iov_len = BLCKSZ;
+ iovcnt++;
+ }
+ }
+
+ return iovcnt;
+}
+
+/*
+ * mdreadv() -- Read the specified blocks from a relation.
*/
void
-mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
- void *buffer)
+mdreadv(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ void **buffers, BlockNumber nblocks)
{
- off_t seekpos;
- int nbytes;
- MdfdVec *v;
-
- /* If this build supports direct I/O, the buffer must be I/O aligned. */
- if (PG_O_DIRECT != 0 && PG_IO_ALIGN_SIZE <= BLCKSZ)
- Assert((uintptr_t) buffer == TYPEALIGN(PG_IO_ALIGN_SIZE, buffer));
-
- TRACE_POSTGRESQL_SMGR_MD_READ_START(forknum, blocknum,
- reln->smgr_rlocator.locator.spcOid,
- reln->smgr_rlocator.locator.dbOid,
- reln->smgr_rlocator.locator.relNumber,
- reln->smgr_rlocator.backend);
-
- v = _mdfd_getseg(reln, forknum, blocknum, false,
- EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
-
- seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
-
- Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
-
- nbytes = FileRead(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_READ);
-
- TRACE_POSTGRESQL_SMGR_MD_READ_DONE(forknum, blocknum,
- reln->smgr_rlocator.locator.spcOid,
- reln->smgr_rlocator.locator.dbOid,
- reln->smgr_rlocator.locator.relNumber,
- reln->smgr_rlocator.backend,
- nbytes,
- BLCKSZ);
-
- if (nbytes != BLCKSZ)
+ while (nblocks > 0)
{
- if (nbytes < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not read block %u in file \"%s\": %m",
- blocknum, FilePathName(v->mdfd_vfd))));
+ struct iovec iov[PG_IOV_MAX];
+ int iovcnt;
+ off_t seekpos;
+ int nbytes;
+ MdfdVec *v;
+ BlockNumber nblocks_this_segment;
+ size_t transferred_this_segment;
+ size_t size_this_segment;
+
+ v = _mdfd_getseg(reln, forknum, blocknum, false,
+ EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
+
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
+
+ Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
+
+ nblocks_this_segment =
+ Min(nblocks,
+ RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE)));
+ nblocks_this_segment = Min(nblocks_this_segment, lengthof(iov));
+
+ iovcnt = buffers_to_iovec(iov, buffers, nblocks_this_segment);
+ size_this_segment = nblocks_this_segment * BLCKSZ;
+ transferred_this_segment = 0;
/*
- * Short read: we are at or past EOF, or we read a partial block at
- * EOF. Normally this is an error; upper levels should never try to
- * read a nonexistent block. However, if zero_damaged_pages is ON or
- * we are InRecovery, we should instead return zeroes without
- * complaining. This allows, for example, the case of trying to
- * update a block that was later truncated away.
+ * Inner loop to continue after a short read. We'll keep going until
+ * we hit EOF rather than assuming that a short read means we hit the
+ * end.
*/
- if (zero_damaged_pages || InRecovery)
- MemSet(buffer, 0, BLCKSZ);
- else
- ereport(ERROR,
- (errcode(ERRCODE_DATA_CORRUPTED),
- errmsg("could not read block %u in file \"%s\": read only %d of %d bytes",
- blocknum, FilePathName(v->mdfd_vfd),
- nbytes, BLCKSZ)));
+ for (;;)
+ {
+ TRACE_POSTGRESQL_SMGR_MD_READ_START(forknum, blocknum,
+ reln->smgr_rlocator.locator.spcOid,
+ reln->smgr_rlocator.locator.dbOid,
+ reln->smgr_rlocator.locator.relNumber,
+ reln->smgr_rlocator.backend);
+ nbytes = FileReadV(v->mdfd_vfd, iov, iovcnt, seekpos,
+ WAIT_EVENT_DATA_FILE_READ);
+ TRACE_POSTGRESQL_SMGR_MD_READ_DONE(forknum, blocknum,
+ reln->smgr_rlocator.locator.spcOid,
+ reln->smgr_rlocator.locator.dbOid,
+ reln->smgr_rlocator.locator.relNumber,
+ reln->smgr_rlocator.backend,
+ nbytes,
+ size_this_segment - transferred_this_segment);
+
+#ifdef SIMULATE_SHORT_READ
+ nbytes = Min(nbytes, 4096);
+#endif
+
+ if (nbytes < 0)
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not read blocks %u..%u in file \"%s\": %m",
+ blocknum,
+ blocknum + nblocks_this_segment - 1,
+ FilePathName(v->mdfd_vfd))));
+
+ if (nbytes == 0)
+ {
+ /*
+ * We are at or past EOF, or we read a partial block at EOF.
+ * Normally this is an error; upper levels should never try to
+ * read a nonexistent block. However, if zero_damaged_pages
+ * is ON or we are InRecovery, we should instead return zeroes
+ * without complaining. This allows, for example, the case of
+ * trying to update a block that was later truncated away.
+ */
+ if (zero_damaged_pages || InRecovery)
+ {
+ for (BlockNumber i = transferred_this_segment / BLCKSZ;
+ i < nblocks_this_segment;
+ ++i)
+ memset(buffers[i], 0, BLCKSZ);
+ break;
+ }
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_CORRUPTED),
+ errmsg("could not read blocks %u..%u in file \"%s\": read only %zu of %zu bytes",
+ blocknum,
+ blocknum + nblocks_this_segment - 1,
+ FilePathName(v->mdfd_vfd),
+ transferred_this_segment,
+ size_this_segment)));
+ }
+
+ /* One loop should usually be enough. */
+ transferred_this_segment += nbytes;
+ Assert(transferred_this_segment <= size_this_segment);
+ if (transferred_this_segment == size_this_segment)
+ break;
+
+ /* Adjust position and vectors after a short read. */
+ seekpos += nbytes;
+ iovcnt = compute_remaining_iovec(iov, iov, iovcnt, nbytes);
+ }
+
+ nblocks -= nblocks_this_segment;
+ buffers += nblocks_this_segment;
+ blocknum += nblocks_this_segment;
}
}
/*
- * mdwrite() -- Write the supplied block at the appropriate location.
+ * mdwritev() -- Write the supplied blocks at the appropriate location.
*
* This is to be used only for updating already-existing blocks of a
* relation (ie, those before the current EOF). To extend a relation,
* use mdextend().
*/
void
-mdwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
- const void *buffer, bool skipFsync)
+mdwritev(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ const void **buffers, BlockNumber nblocks, bool skipFsync)
{
- off_t seekpos;
- int nbytes;
- MdfdVec *v;
-
- /* If this build supports direct I/O, the buffer must be I/O aligned. */
- if (PG_O_DIRECT != 0 && PG_IO_ALIGN_SIZE <= BLCKSZ)
- Assert((uintptr_t) buffer == TYPEALIGN(PG_IO_ALIGN_SIZE, buffer));
-
/* This assert is too expensive to have on normally ... */
#ifdef CHECK_WRITE_VS_EXTEND
Assert(blocknum < mdnblocks(reln, forknum));
#endif
- TRACE_POSTGRESQL_SMGR_MD_WRITE_START(forknum, blocknum,
- reln->smgr_rlocator.locator.spcOid,
- reln->smgr_rlocator.locator.dbOid,
- reln->smgr_rlocator.locator.relNumber,
- reln->smgr_rlocator.backend);
-
- v = _mdfd_getseg(reln, forknum, blocknum, skipFsync,
- EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
-
- seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
-
- Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
-
- nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_WRITE);
-
- TRACE_POSTGRESQL_SMGR_MD_WRITE_DONE(forknum, blocknum,
- reln->smgr_rlocator.locator.spcOid,
- reln->smgr_rlocator.locator.dbOid,
- reln->smgr_rlocator.locator.relNumber,
- reln->smgr_rlocator.backend,
- nbytes,
- BLCKSZ);
-
- if (nbytes != BLCKSZ)
+ while (nblocks > 0)
{
- if (nbytes < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not write block %u in file \"%s\": %m",
- blocknum, FilePathName(v->mdfd_vfd))));
- /* short write: complain appropriately */
- ereport(ERROR,
- (errcode(ERRCODE_DISK_FULL),
- errmsg("could not write block %u in file \"%s\": wrote only %d of %d bytes",
- blocknum,
- FilePathName(v->mdfd_vfd),
- nbytes, BLCKSZ),
- errhint("Check free disk space.")));
- }
+ struct iovec iov[PG_IOV_MAX];
+ int iovcnt;
+ off_t seekpos;
+ int nbytes;
+ MdfdVec *v;
+ BlockNumber nblocks_this_segment;
+ size_t transferred_this_segment;
+ size_t size_this_segment;
- if (!skipFsync && !SmgrIsTemp(reln))
- register_dirty_segment(reln, forknum, v);
+ v = _mdfd_getseg(reln, forknum, blocknum, skipFsync,
+ EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
+
+ seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
+
+ Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
+
+ nblocks_this_segment =
+ Min(nblocks,
+ RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE)));
+ nblocks_this_segment = Min(nblocks_this_segment, lengthof(iov));
+
+ iovcnt = buffers_to_iovec(iov, (void **) buffers, nblocks_this_segment);
+ size_this_segment = nblocks_this_segment * BLCKSZ;
+ transferred_this_segment = 0;
+
+ /*
+ * Inner loop to continue after a short write. If the reason is that
+ * we're out of disk space, a future attempt should get an ENOSPC
+ * error from the kernel.
+ */
+ for (;;)
+ {
+ TRACE_POSTGRESQL_SMGR_MD_WRITE_START(forknum, blocknum,
+ reln->smgr_rlocator.locator.spcOid,
+ reln->smgr_rlocator.locator.dbOid,
+ reln->smgr_rlocator.locator.relNumber,
+ reln->smgr_rlocator.backend);
+ nbytes = FileWriteV(v->mdfd_vfd, iov, iovcnt, seekpos,
+ WAIT_EVENT_DATA_FILE_WRITE);
+ TRACE_POSTGRESQL_SMGR_MD_WRITE_DONE(forknum, blocknum,
+ reln->smgr_rlocator.locator.spcOid,
+ reln->smgr_rlocator.locator.dbOid,
+ reln->smgr_rlocator.locator.relNumber,
+ reln->smgr_rlocator.backend,
+ nbytes,
+ size_this_segment - transferred_this_segment);
+
+#ifdef SIMULATE_SHORT_WRITE
+ nbytes = Min(nbytes, 4096);
+#endif
+
+ if (nbytes < 0)
+ {
+ bool enospc = errno == ENOSPC;
+
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not write blocks %u..%u in file \"%s\": %m",
+ blocknum,
+ blocknum + nblocks_this_segment - 1,
+ FilePathName(v->mdfd_vfd)),
+ enospc ? errhint("Check free disk space.") : 0));
+ }
+
+ /* One loop should usually be enough. */
+ transferred_this_segment += nbytes;
+ Assert(transferred_this_segment <= size_this_segment);
+ if (transferred_this_segment == size_this_segment)
+ break;
+
+ /* Adjust position and iovecs after a short write. */
+ seekpos += nbytes;
+ iovcnt = compute_remaining_iovec(iov, iov, iovcnt, nbytes);
+ }
+
+ if (!skipFsync && !SmgrIsTemp(reln))
+ register_dirty_segment(reln, forknum, v);
+
+ nblocks -= nblocks_this_segment;
+ buffers += nblocks_this_segment;
+ blocknum += nblocks_this_segment;
+ }
}
+
/*
* mdwriteback() -- Tell the kernel to write pages back to storage.
*
diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index 003a55a592..7ce31fd30a 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -55,10 +55,13 @@ typedef struct f_smgr
BlockNumber blocknum, int nblocks, bool skipFsync);
bool (*smgr_prefetch) (SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks);
- void (*smgr_read) (SMgrRelation reln, ForkNumber forknum,
- BlockNumber blocknum, void *buffer);
- void (*smgr_write) (SMgrRelation reln, ForkNumber forknum,
- BlockNumber blocknum, const void *buffer, bool skipFsync);
+ void (*smgr_readv) (SMgrRelation reln, ForkNumber forknum,
+ BlockNumber blocknum,
+ void **buffers, BlockNumber nblocks);
+ void (*smgr_writev) (SMgrRelation reln, ForkNumber forknum,
+ BlockNumber blocknum,
+ const void **buffers, BlockNumber nblocks,
+ bool skipFsync);
void (*smgr_writeback) (SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, BlockNumber nblocks);
BlockNumber (*smgr_nblocks) (SMgrRelation reln, ForkNumber forknum);
@@ -80,8 +83,8 @@ static const f_smgr smgrsw[] = {
.smgr_extend = mdextend,
.smgr_zeroextend = mdzeroextend,
.smgr_prefetch = mdprefetch,
- .smgr_read = mdread,
- .smgr_write = mdwrite,
+ .smgr_readv = mdreadv,
+ .smgr_writev = mdwritev,
.smgr_writeback = mdwriteback,
.smgr_nblocks = mdnblocks,
.smgr_truncate = mdtruncate,
@@ -554,22 +557,23 @@ smgrprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
}
/*
- * smgrread() -- read a particular block from a relation into the supplied
- * buffer.
+ * smgrreadv() -- read a particular block range from a relation into the
+ * supplied buffers.
*
* This routine is called from the buffer manager in order to
* instantiate pages in the shared buffer cache. All storage managers
* return pages in the format that POSTGRES expects.
*/
void
-smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
- void *buffer)
+smgrreadv(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ void **buffers, BlockNumber nblocks)
{
- smgrsw[reln->smgr_which].smgr_read(reln, forknum, blocknum, buffer);
+ smgrsw[reln->smgr_which].smgr_readv(reln, forknum, blocknum, buffers,
+ nblocks);
}
/*
- * smgrwrite() -- Write the supplied buffer out.
+ * smgrwritev() -- Write the supplied buffers out.
*
* This is to be used only for updating already-existing blocks of a
* relation (ie, those before the current EOF). To extend a relation,
@@ -584,14 +588,13 @@ smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
* do not require fsync.
*/
void
-smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
- const void *buffer, bool skipFsync)
+smgrwritev(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ const void **buffers, BlockNumber nblocks, bool skipFsync)
{
- smgrsw[reln->smgr_which].smgr_write(reln, forknum, blocknum,
- buffer, skipFsync);
+ smgrsw[reln->smgr_which].smgr_writev(reln, forknum, blocknum,
+ buffers, nblocks, skipFsync);
}
-
/*
* smgrwriteback() -- Trigger kernel writeback for the supplied range of
* blocks.
diff --git a/src/include/storage/md.h b/src/include/storage/md.h
index 091784c171..3dc651ec17 100644
--- a/src/include/storage/md.h
+++ b/src/include/storage/md.h
@@ -32,10 +32,11 @@ extern void mdzeroextend(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks, bool skipFsync);
extern bool mdprefetch(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks);
-extern void mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
- void *buffer);
-extern void mdwrite(SMgrRelation reln, ForkNumber forknum,
- BlockNumber blocknum, const void *buffer, bool skipFsync);
+extern void mdreadv(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ void **buffers, BlockNumber nblocks);
+extern void mdwritev(SMgrRelation reln, ForkNumber forknum,
+ BlockNumber blocknum,
+ const void **buffers, BlockNumber nblocks, bool skipFsync);
extern void mdwriteback(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, BlockNumber nblocks);
extern BlockNumber mdnblocks(SMgrRelation reln, ForkNumber forknum);
diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h
index da7e7c5a2e..6e62dc053c 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -96,10 +96,13 @@ extern void smgrzeroextend(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks, bool skipFsync);
extern bool smgrprefetch(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks);
-extern void smgrread(SMgrRelation reln, ForkNumber forknum,
- BlockNumber blocknum, void *buffer);
-extern void smgrwrite(SMgrRelation reln, ForkNumber forknum,
- BlockNumber blocknum, const void *buffer, bool skipFsync);
+extern void smgrreadv(SMgrRelation reln, ForkNumber forknum,
+ BlockNumber blocknum,
+ void **buffer, BlockNumber nblocks);
+extern void smgrwritev(SMgrRelation reln, ForkNumber forknum,
+ BlockNumber blocknum,
+ const void **buffer, BlockNumber nblocks,
+ bool skipFsync);
extern void smgrwriteback(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, BlockNumber nblocks);
extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
@@ -110,4 +113,18 @@ extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
extern void AtEOXact_SMgr(void);
extern bool ProcessBarrierSmgrRelease(void);
+static inline void
+smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ void *buffer)
+{
+ smgrreadv(reln, forknum, blocknum, &buffer, 1);
+}
+
+static inline void
+smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
+ const void *buffer, bool skipFsync)
+{
+ smgrwritev(reln, forknum, blocknum, &buffer, 1, skipFsync);
+}
+
#endif /* SMGR_H */