From 826980424538cb149670f9c89eedf34387ff674f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 1 Sep 2018 15:27:13 -0400 Subject: [PATCH] Avoid using potentially-under-aligned page buffers. There's a project policy against using plain "char buf[BLCKSZ]" local or static variables as page buffers; preferred style is to palloc or malloc each buffer to ensure it is MAXALIGN'd. However, that policy's been ignored in an increasing number of places. We've apparently got away with it so far, probably because (a) relatively few people use platforms on which misalignment causes core dumps and/or (b) the variables chance to be sufficiently aligned anyway. But this is not something to rely on. Moreover, even if we don't get a core dump, we might be paying a lot of cycles for misaligned accesses. To fix, invent new union types PGAlignedBlock and PGAlignedXLogBlock that the compiler must allocate with sufficient alignment, and use those in place of plain char arrays. I used these types even for variables where there's no risk of a misaligned access, since ensuring proper alignment should make kernel data transfers faster. I also changed some places where we had been palloc'ing short-lived buffers, for coding style uniformity and to save palloc/pfree overhead. Since this seems to be a live portability hazard (despite the lack of field reports), back-patch to all supported versions. Patch by me; thanks to Michael Paquier for review. Discussion: https://postgr.es/m/1535618100.1286.3.camel@credativ.de --- contrib/bloom/blinsert.c | 12 ++++----- contrib/pg_prewarm/pg_prewarm.c | 4 +-- src/backend/access/gin/ginentrypage.c | 6 ++--- src/backend/access/gin/ginfast.c | 11 +++----- src/backend/access/hash/hashpage.c | 6 ++--- src/backend/access/heap/heapam.c | 16 +++--------- src/backend/access/heap/visibilitymap.c | 11 +++----- src/backend/access/transam/generic_xlog.c | 21 +++++++-------- src/backend/access/transam/xlog.c | 19 +++++--------- src/backend/access/transam/xloginsert.c | 14 +++++----- src/backend/access/transam/xlogreader.c | 6 ++--- src/backend/commands/tablecmds.c | 17 +++---------- src/backend/replication/walsender.c | 6 ++--- src/backend/storage/file/buffile.c | 10 ++++---- src/backend/storage/freespace/freespace.c | 11 +++----- src/bin/pg_basebackup/receivelog.c | 8 +++--- src/bin/pg_resetxlog/pg_resetxlog.c | 14 +++++----- src/bin/pg_rewind/copy_fetch.c | 6 ++--- src/bin/pg_upgrade/file.c | 31 ++++++++--------------- src/include/c.h | 26 +++++++++++++++++++ 20 files changed, 116 insertions(+), 139 deletions(-) diff --git a/contrib/bloom/blinsert.c b/contrib/bloom/blinsert.c index 946902a61d..3a6e99466a 100644 --- a/contrib/bloom/blinsert.c +++ b/contrib/bloom/blinsert.c @@ -36,7 +36,7 @@ typedef struct int64 indtuples; /* total number of tuples indexed */ MemoryContext tmpCtx; /* temporary memory context reset after each * tuple */ - char data[BLCKSZ]; /* cached page */ + PGAlignedBlock data; /* cached page */ int count; /* number of tuples in cached page */ } BloomBuildState; @@ -52,7 +52,7 @@ flushCachedPage(Relation index, BloomBuildState *buildstate) state = GenericXLogStart(index); page = GenericXLogRegisterBuffer(state, buffer, GENERIC_XLOG_FULL_IMAGE); - memcpy(page, buildstate->data, BLCKSZ); + memcpy(page, buildstate->data.data, BLCKSZ); GenericXLogFinish(state); UnlockReleaseBuffer(buffer); } @@ -63,8 +63,8 @@ flushCachedPage(Relation index, BloomBuildState *buildstate) static void initCachedPage(BloomBuildState *buildstate) { - memset(buildstate->data, 0, BLCKSZ); - BloomInitPage(buildstate->data, 0); + memset(buildstate->data.data, 0, BLCKSZ); + BloomInitPage(buildstate->data.data, 0); buildstate->count = 0; } @@ -84,7 +84,7 @@ bloomBuildCallback(Relation index, HeapTuple htup, Datum *values, itup = BloomFormTuple(&buildstate->blstate, &htup->t_self, values, isnull); /* Try to add next item to cached page */ - if (BloomPageAddItem(&buildstate->blstate, buildstate->data, itup)) + if (BloomPageAddItem(&buildstate->blstate, buildstate->data.data, itup)) { /* Next item was added successfully */ buildstate->count++; @@ -98,7 +98,7 @@ bloomBuildCallback(Relation index, HeapTuple htup, Datum *values, initCachedPage(buildstate); - if (!BloomPageAddItem(&buildstate->blstate, buildstate->data, itup)) + if (!BloomPageAddItem(&buildstate->blstate, buildstate->data.data, itup)) { /* We shouldn't be here since we're inserting to the empty page */ elog(ERROR, "could not add new bloom tuple to empty page"); diff --git a/contrib/pg_prewarm/pg_prewarm.c b/contrib/pg_prewarm/pg_prewarm.c index c3a518cfc2..979e0b0d10 100644 --- a/contrib/pg_prewarm/pg_prewarm.c +++ b/contrib/pg_prewarm/pg_prewarm.c @@ -37,7 +37,7 @@ typedef enum PREWARM_BUFFER } PrewarmType; -static char blockbuffer[BLCKSZ]; +static PGAlignedBlock blockbuffer; /* * pg_prewarm(regclass, mode text, fork text, @@ -179,7 +179,7 @@ pg_prewarm(PG_FUNCTION_ARGS) for (block = first_block; block <= last_block; ++block) { CHECK_FOR_INTERRUPTS(); - smgrread(rel->rd_smgr, forkNumber, block, blockbuffer); + smgrread(rel->rd_smgr, forkNumber, block, blockbuffer.data); ++blocks_done; } } diff --git a/src/backend/access/gin/ginentrypage.c b/src/backend/access/gin/ginentrypage.c index 8c0bfe9fde..906a3fe761 100644 --- a/src/backend/access/gin/ginentrypage.c +++ b/src/backend/access/gin/ginentrypage.c @@ -615,7 +615,7 @@ entrySplitPage(GinBtree btree, Buffer origbuf, Page lpage = PageGetTempPageCopy(BufferGetPage(origbuf)); Page rpage = PageGetTempPageCopy(BufferGetPage(origbuf)); Size pageSize = PageGetPageSize(lpage); - char tupstore[2 * BLCKSZ]; + PGAlignedBlock tupstore[2]; /* could need 2 pages' worth of tuples */ entryPreparePage(btree, lpage, off, insertData, updateblkno); @@ -624,7 +624,7 @@ entrySplitPage(GinBtree btree, Buffer origbuf, * one after another in a temporary workspace. */ maxoff = PageGetMaxOffsetNumber(lpage); - ptr = tupstore; + ptr = tupstore[0].data; for (i = FirstOffsetNumber; i <= maxoff; i++) { if (i == off) @@ -657,7 +657,7 @@ entrySplitPage(GinBtree btree, Buffer origbuf, GinInitPage(rpage, GinPageGetOpaque(lpage)->flags, pageSize); GinInitPage(lpage, GinPageGetOpaque(rpage)->flags, pageSize); - ptr = tupstore; + ptr = tupstore[0].data; maxoff++; lsize = 0; diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c index 56a3ff590a..ec708136c0 100644 --- a/src/backend/access/gin/ginfast.c +++ b/src/backend/access/gin/ginfast.c @@ -61,18 +61,15 @@ writeListPage(Relation index, Buffer buffer, size = 0; OffsetNumber l, off; - char *workspace; + PGAlignedBlock workspace; char *ptr; - /* workspace could be a local array; we use palloc for alignment */ - workspace = palloc(BLCKSZ); - START_CRIT_SECTION(); GinInitBuffer(buffer, GIN_LIST); off = FirstOffsetNumber; - ptr = workspace; + ptr = workspace.data; for (i = 0; i < ntuples; i++) { @@ -124,7 +121,7 @@ writeListPage(Relation index, Buffer buffer, XLogRegisterData((char *) &data, sizeof(ginxlogInsertListPage)); XLogRegisterBuffer(0, buffer, REGBUF_WILL_INIT); - XLogRegisterBufData(0, workspace, size); + XLogRegisterBufData(0, workspace.data, size); recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_INSERT_LISTPAGE); PageSetLSN(page, recptr); @@ -137,8 +134,6 @@ writeListPage(Relation index, Buffer buffer, END_CRIT_SECTION(); - pfree(workspace); - return freesize; } diff --git a/src/backend/access/hash/hashpage.c b/src/backend/access/hash/hashpage.c index 178463fcb6..2d20ddc0d1 100644 --- a/src/backend/access/hash/hashpage.c +++ b/src/backend/access/hash/hashpage.c @@ -710,7 +710,7 @@ static bool _hash_alloc_buckets(Relation rel, BlockNumber firstblock, uint32 nblocks) { BlockNumber lastblock; - char zerobuf[BLCKSZ]; + PGAlignedBlock zerobuf; lastblock = firstblock + nblocks - 1; @@ -721,10 +721,10 @@ _hash_alloc_buckets(Relation rel, BlockNumber firstblock, uint32 nblocks) if (lastblock < firstblock || lastblock == InvalidBlockNumber) return false; - MemSet(zerobuf, 0, sizeof(zerobuf)); + MemSet(zerobuf.data, 0, sizeof(zerobuf)); RelationOpenSmgr(rel); - smgrextend(rel->rd_smgr, MAIN_FORKNUM, lastblock, zerobuf, false); + smgrextend(rel->rd_smgr, MAIN_FORKNUM, lastblock, zerobuf.data, false); return true; } diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 9fb68cd7b3..4109ce4e4f 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -2637,7 +2637,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples, HeapTuple *heaptuples; int i; int ndone; - char *scratch = NULL; + PGAlignedBlock scratch; Page page; bool needwal; Size saveFreeSpace; @@ -2654,14 +2654,6 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples, heaptuples[i] = heap_prepare_insert(relation, tuples[i], xid, cid, options); - /* - * Allocate some memory to use for constructing the WAL record. Using - * palloc() within a critical section is not safe, so we allocate this - * beforehand. - */ - if (needwal) - scratch = palloc(BLCKSZ); - /* * We're about to do the actual inserts -- but check for conflict first, * to minimize the possibility of having to roll back work we've just @@ -2754,7 +2746,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples, uint8 info = XLOG_HEAP2_MULTI_INSERT; char *tupledata; int totaldatalen; - char *scratchptr = scratch; + char *scratchptr = scratch.data; bool init; int bufflags = 0; @@ -2813,7 +2805,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples, scratchptr += datalen; } totaldatalen = scratchptr - tupledata; - Assert((scratchptr - scratch) < BLCKSZ); + Assert((scratchptr - scratch.data) < BLCKSZ); if (need_tuple_data) xlrec->flags |= XLH_INSERT_CONTAINS_NEW_TUPLE; @@ -2840,7 +2832,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples, bufflags |= REGBUF_KEEP_DATA; XLogBeginInsert(); - XLogRegisterData((char *) xlrec, tupledata - scratch); + XLogRegisterData((char *) xlrec, tupledata - scratch.data); XLogRegisterBuffer(0, buffer, REGBUF_STANDARD | bufflags); XLogRegisterBufData(0, tupledata, totaldatalen); diff --git a/src/backend/access/heap/visibilitymap.c b/src/backend/access/heap/visibilitymap.c index cd5c6d0e9a..7d7585850b 100644 --- a/src/backend/access/heap/visibilitymap.c +++ b/src/backend/access/heap/visibilitymap.c @@ -645,10 +645,9 @@ static void vm_extend(Relation rel, BlockNumber vm_nblocks) { BlockNumber vm_nblocks_now; - Page pg; + PGAlignedBlock pg; - pg = (Page) palloc(BLCKSZ); - PageInit(pg, BLCKSZ, 0); + PageInit((Page) pg.data, BLCKSZ, 0); /* * We use the relation extension lock to lock out other backends trying to @@ -679,10 +678,10 @@ vm_extend(Relation rel, BlockNumber vm_nblocks) /* Now extend the file */ while (vm_nblocks_now < vm_nblocks) { - PageSetChecksumInplace(pg, vm_nblocks_now); + PageSetChecksumInplace((Page) pg.data, vm_nblocks_now); smgrextend(rel->rd_smgr, VISIBILITYMAP_FORKNUM, vm_nblocks_now, - (char *) pg, false); + pg.data, false); vm_nblocks_now++; } @@ -699,6 +698,4 @@ vm_extend(Relation rel, BlockNumber vm_nblocks) rel->rd_smgr->smgr_vm_nblocks = vm_nblocks_now; UnlockRelationForExtension(rel, ExclusiveLock); - - pfree(pg); } diff --git a/src/backend/access/transam/generic_xlog.c b/src/backend/access/transam/generic_xlog.c index 1926d98de0..9cb9fb4884 100644 --- a/src/backend/access/transam/generic_xlog.c +++ b/src/backend/access/transam/generic_xlog.c @@ -60,14 +60,11 @@ typedef struct /* State of generic xlog record construction */ struct GenericXLogState { - /* - * page's images. Should be first in this struct to have MAXALIGN'ed - * images addresses, because some code working with pages directly aligns - * addresses, not offsets from beginning of page - */ - char images[MAX_GENERIC_XLOG_PAGES * BLCKSZ]; + /* Info about each page, see above */ PageData pages[MAX_GENERIC_XLOG_PAGES]; bool isLogged; + /* Page images (properly aligned) */ + PGAlignedBlock images[MAX_GENERIC_XLOG_PAGES]; }; static void writeFragment(PageData *pageData, OffsetNumber offset, @@ -250,12 +247,12 @@ computeDelta(PageData *pageData, Page curpage, Page targetpage) #ifdef WAL_DEBUG if (XLOG_DEBUG) { - char tmp[BLCKSZ]; + PGAlignedBlock tmp; - memcpy(tmp, curpage, BLCKSZ); - applyPageRedo(tmp, pageData->delta, pageData->deltaLen); - if (memcmp(tmp, targetpage, targetLower) != 0 || - memcmp(tmp + targetUpper, targetpage + targetUpper, + memcpy(tmp.data, curpage, BLCKSZ); + applyPageRedo(tmp.data, pageData->delta, pageData->deltaLen); + if (memcmp(tmp.data, targetpage, targetLower) != 0 || + memcmp(tmp.data + targetUpper, targetpage + targetUpper, BLCKSZ - targetUpper) != 0) elog(ERROR, "result of generic xlog apply does not match"); } @@ -276,7 +273,7 @@ GenericXLogStart(Relation relation) for (i = 0; i < MAX_GENERIC_XLOG_PAGES; i++) { - state->pages[i].image = state->images + BLCKSZ * i; + state->pages[i].image = state->images[i].data; state->pages[i].buffer = InvalidBuffer; } diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 47fe5a9290..724ff17a3f 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -3029,8 +3029,7 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock) { char path[MAXPGPATH]; char tmppath[MAXPGPATH]; - char zbuffer_raw[XLOG_BLCKSZ + MAXIMUM_ALIGNOF]; - char *zbuffer; + PGAlignedXLogBlock zbuffer; XLogSegNo installed_segno; XLogSegNo max_segno; int fd; @@ -3084,16 +3083,12 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock) * fsync below) that all the indirect blocks are down on disk. Therefore, * fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the * log file. - * - * Note: ensure the buffer is reasonably well-aligned; this may save a few - * cycles transferring data to the kernel. */ - zbuffer = (char *) MAXALIGN(zbuffer_raw); - memset(zbuffer, 0, XLOG_BLCKSZ); + memset(zbuffer.data, 0, XLOG_BLCKSZ); for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ) { errno = 0; - if ((int) write(fd, zbuffer, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ) + if ((int) write(fd, zbuffer.data, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ) { int save_errno = errno; @@ -3198,7 +3193,7 @@ XLogFileCopy(XLogSegNo destsegno, TimeLineID srcTLI, XLogSegNo srcsegno, { char path[MAXPGPATH]; char tmppath[MAXPGPATH]; - char buffer[XLOG_BLCKSZ]; + PGAlignedXLogBlock buffer; int srcfd; int fd; int nbytes; @@ -3242,14 +3237,14 @@ XLogFileCopy(XLogSegNo destsegno, TimeLineID srcTLI, XLogSegNo srcsegno, * zeros. */ if (nread < sizeof(buffer)) - memset(buffer, 0, sizeof(buffer)); + memset(buffer.data, 0, sizeof(buffer)); if (nread > 0) { if (nread > sizeof(buffer)) nread = sizeof(buffer); errno = 0; - if (read(srcfd, buffer, nread) != nread) + if (read(srcfd, buffer.data, nread) != nread) { if (errno != 0) ereport(ERROR, @@ -3263,7 +3258,7 @@ XLogFileCopy(XLogSegNo destsegno, TimeLineID srcTLI, XLogSegNo srcsegno, } } errno = 0; - if ((int) write(fd, buffer, sizeof(buffer)) != (int) sizeof(buffer)) + if ((int) write(fd, buffer.data, sizeof(buffer)) != (int) sizeof(buffer)) { int save_errno = errno; diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c index a92534e225..d141944133 100644 --- a/src/backend/access/transam/xloginsert.c +++ b/src/backend/access/transam/xloginsert.c @@ -774,12 +774,12 @@ XLogCompressBackupBlock(char *page, uint16 hole_offset, uint16 hole_length, int32 len; int32 extra_bytes = 0; char *source; - char tmp[BLCKSZ]; + PGAlignedBlock tmp; if (hole_length != 0) { /* must skip the hole */ - source = tmp; + source = tmp.data; memcpy(source, page, hole_offset); memcpy(source + hole_offset, page + (hole_offset + hole_length), @@ -882,7 +882,7 @@ XLogSaveBufferForHint(Buffer buffer, bool buffer_std) if (lsn <= RedoRecPtr) { int flags; - char copied_buffer[BLCKSZ]; + PGAlignedBlock copied_buffer; char *origdata = (char *) BufferGetBlock(buffer); RelFileNode rnode; ForkNumber forkno; @@ -900,11 +900,11 @@ XLogSaveBufferForHint(Buffer buffer, bool buffer_std) uint16 lower = ((PageHeader) page)->pd_lower; uint16 upper = ((PageHeader) page)->pd_upper; - memcpy(copied_buffer, origdata, lower); - memcpy(copied_buffer + upper, origdata + upper, BLCKSZ - upper); + memcpy(copied_buffer.data, origdata, lower); + memcpy(copied_buffer.data + upper, origdata + upper, BLCKSZ - upper); } else - memcpy(copied_buffer, origdata, BLCKSZ); + memcpy(copied_buffer.data, origdata, BLCKSZ); XLogBeginInsert(); @@ -913,7 +913,7 @@ XLogSaveBufferForHint(Buffer buffer, bool buffer_std) flags |= REGBUF_STANDARD; BufferGetTag(buffer, &rnode, &forkno, &blkno); - XLogRegisterBlock(0, &rnode, forkno, blkno, copied_buffer, flags); + XLogRegisterBlock(0, &rnode, forkno, blkno, copied_buffer.data, flags); recptr = XLogInsert(RM_XLOG_ID, XLOG_FPI_FOR_HINT); } diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c index 8e0d17d0f5..522f758581 100644 --- a/src/backend/access/transam/xlogreader.c +++ b/src/backend/access/transam/xlogreader.c @@ -1395,7 +1395,7 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page) { DecodedBkpBlock *bkpb; char *ptr; - char tmp[BLCKSZ]; + PGAlignedBlock tmp; if (!record->blocks[block_id].in_use) return false; @@ -1408,7 +1408,7 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page) if (bkpb->bimg_info & BKPIMAGE_IS_COMPRESSED) { /* If a backup block image is compressed, decompress it */ - if (pglz_decompress(ptr, bkpb->bimg_len, tmp, + if (pglz_decompress(ptr, bkpb->bimg_len, tmp.data, BLCKSZ - bkpb->hole_length) < 0) { report_invalid_record(record, "invalid compressed image at %X/%X, block %d", @@ -1417,7 +1417,7 @@ RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page) block_id); return false; } - ptr = tmp; + ptr = tmp.data; } /* generate page, taking into account hole if necessary */ diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 9a82313e2f..29e648bdae 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -10001,21 +10001,14 @@ static void copy_relation_data(SMgrRelation src, SMgrRelation dst, ForkNumber forkNum, char relpersistence) { - char *buf; + PGAlignedBlock buf; Page page; bool use_wal; bool copying_initfork; BlockNumber nblocks; BlockNumber blkno; - /* - * palloc the buffer so that it's MAXALIGN'd. If it were just a local - * char[] array, the compiler might align it on any byte boundary, which - * can seriously hurt transfer speed to and from the kernel; not to - * mention possibly making log_newpage's accesses to the page header fail. - */ - buf = (char *) palloc(BLCKSZ); - page = (Page) buf; + page = (Page) buf.data; /* * The init fork for an unlogged relation in many respects has to be @@ -10039,7 +10032,7 @@ copy_relation_data(SMgrRelation src, SMgrRelation dst, /* If we got a cancel signal during the copy of the data, quit */ CHECK_FOR_INTERRUPTS(); - smgrread(src, forkNum, blkno, buf); + smgrread(src, forkNum, blkno, buf.data); if (!PageIsVerified(page, blkno)) ereport(ERROR, @@ -10065,11 +10058,9 @@ copy_relation_data(SMgrRelation src, SMgrRelation dst, * rel, because there's no need for smgr to schedule an fsync for this * write; we'll do it ourselves below. */ - smgrextend(dst, forkNum, blkno, buf, true); + smgrextend(dst, forkNum, blkno, buf.data, true); } - pfree(buf); - /* * If the rel is WAL-logged, must fsync before commit. We use heap_sync * to ensure that the toast table gets fsync'd too. (For a temp or diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index 6645ed8608..0447136cc5 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -497,16 +497,16 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd) bytesleft = histfilelen; while (bytesleft > 0) { - char rbuf[BLCKSZ]; + PGAlignedBlock rbuf; int nread; - nread = read(fd, rbuf, sizeof(rbuf)); + nread = read(fd, rbuf.data, sizeof(rbuf)); if (nread <= 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", path))); - pq_sendbytes(&buf, rbuf, nread); + pq_sendbytes(&buf, rbuf.data, nread); bytesleft -= nread; } CloseTransientFile(fd); diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c index 042be79440..5d95d5c45d 100644 --- a/src/backend/storage/file/buffile.c +++ b/src/backend/storage/file/buffile.c @@ -86,7 +86,7 @@ struct BufFile off_t curOffset; /* offset part of current pos */ int pos; /* next read/write position in buffer */ int nbytes; /* total # of valid bytes in buffer */ - char buffer[BLCKSZ]; + PGAlignedBlock buffer; }; static BufFile *makeBufFile(File firstfile); @@ -254,7 +254,7 @@ BufFileLoadBuffer(BufFile *file) /* * Read whatever we can get, up to a full bufferload. */ - file->nbytes = FileRead(thisfile, file->buffer, sizeof(file->buffer)); + file->nbytes = FileRead(thisfile, file->buffer.data, sizeof(file->buffer)); if (file->nbytes < 0) file->nbytes = 0; file->offsets[file->curFile] += file->nbytes; @@ -317,7 +317,7 @@ BufFileDumpBuffer(BufFile *file) return; /* seek failed, give up */ file->offsets[file->curFile] = file->curOffset; } - bytestowrite = FileWrite(thisfile, file->buffer + wpos, bytestowrite); + bytestowrite = FileWrite(thisfile, file->buffer.data + wpos, bytestowrite); if (bytestowrite <= 0) return; /* failed to write */ file->offsets[file->curFile] += bytestowrite; @@ -385,7 +385,7 @@ BufFileRead(BufFile *file, void *ptr, size_t size) nthistime = size; Assert(nthistime > 0); - memcpy(ptr, file->buffer + file->pos, nthistime); + memcpy(ptr, file->buffer.data + file->pos, nthistime); file->pos += nthistime; ptr = (void *) ((char *) ptr + nthistime); @@ -432,7 +432,7 @@ BufFileWrite(BufFile *file, void *ptr, size_t size) nthistime = size; Assert(nthistime > 0); - memcpy(file->buffer + file->pos, ptr, nthistime); + memcpy(file->buffer.data + file->pos, ptr, nthistime); file->dirty = true; file->pos += nthistime; diff --git a/src/backend/storage/freespace/freespace.c b/src/backend/storage/freespace/freespace.c index 9c7f325ab3..45d1d6333f 100644 --- a/src/backend/storage/freespace/freespace.c +++ b/src/backend/storage/freespace/freespace.c @@ -628,10 +628,9 @@ static void fsm_extend(Relation rel, BlockNumber fsm_nblocks) { BlockNumber fsm_nblocks_now; - Page pg; + PGAlignedBlock pg; - pg = (Page) palloc(BLCKSZ); - PageInit(pg, BLCKSZ, 0); + PageInit((Page) pg.data, BLCKSZ, 0); /* * We use the relation extension lock to lock out other backends trying to @@ -661,10 +660,10 @@ fsm_extend(Relation rel, BlockNumber fsm_nblocks) while (fsm_nblocks_now < fsm_nblocks) { - PageSetChecksumInplace(pg, fsm_nblocks_now); + PageSetChecksumInplace((Page) pg.data, fsm_nblocks_now); smgrextend(rel->rd_smgr, FSM_FORKNUM, fsm_nblocks_now, - (char *) pg, false); + pg.data, false); fsm_nblocks_now++; } @@ -672,8 +671,6 @@ fsm_extend(Relation rel, BlockNumber fsm_nblocks) rel->rd_smgr->smgr_fsm_nblocks = fsm_nblocks_now; UnlockRelationForExtension(rel, ExclusiveLock); - - pfree(pg); } /* diff --git a/src/bin/pg_basebackup/receivelog.c b/src/bin/pg_basebackup/receivelog.c index 79072a7939..d127355c31 100644 --- a/src/bin/pg_basebackup/receivelog.c +++ b/src/bin/pg_basebackup/receivelog.c @@ -98,7 +98,7 @@ open_walfile(StreamCtl *stream, XLogRecPtr startpoint) int f; char fn[MAXPGPATH]; struct stat statbuf; - char *zerobuf; + PGAlignedXLogBlock zerobuf; int bytes; XLogSegNo segno; @@ -144,11 +144,11 @@ open_walfile(StreamCtl *stream, XLogRecPtr startpoint) } /* New, empty, file. So pad it to 16Mb with zeroes */ - zerobuf = pg_malloc0(XLOG_BLCKSZ); + memset(zerobuf.data, 0, XLOG_BLCKSZ); for (bytes = 0; bytes < XLogSegSize; bytes += XLOG_BLCKSZ) { errno = 0; - if (write(f, zerobuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) + if (write(f, zerobuf.data, XLOG_BLCKSZ) != XLOG_BLCKSZ) { /* if write didn't set errno, assume problem is no disk space */ if (errno == 0) @@ -156,13 +156,11 @@ open_walfile(StreamCtl *stream, XLogRecPtr startpoint) fprintf(stderr, _("%s: could not pad transaction log file \"%s\": %s\n"), progname, fn, strerror(errno)); - free(zerobuf); close(f); unlink(fn); return false; } } - free(zerobuf); if (lseek(f, SEEK_SET, 0) != 0) { diff --git a/src/bin/pg_resetxlog/pg_resetxlog.c b/src/bin/pg_resetxlog/pg_resetxlog.c index fdd75044de..3e79482ca2 100644 --- a/src/bin/pg_resetxlog/pg_resetxlog.c +++ b/src/bin/pg_resetxlog/pg_resetxlog.c @@ -1133,7 +1133,7 @@ KillExistingArchiveStatus(void) static void WriteEmptyXLOG(void) { - char *buffer; + PGAlignedXLogBlock buffer; XLogPageHeader page; XLogLongPageHeader longpage; XLogRecord *record; @@ -1143,12 +1143,10 @@ WriteEmptyXLOG(void) int nbytes; char *recptr; - /* Use malloc() to ensure buffer is MAXALIGNED */ - buffer = (char *) pg_malloc(XLOG_BLCKSZ); - page = (XLogPageHeader) buffer; - memset(buffer, 0, XLOG_BLCKSZ); + memset(buffer.data, 0, XLOG_BLCKSZ); /* Set up the XLOG page header */ + page = (XLogPageHeader) buffer.data; page->xlp_magic = XLOG_PAGE_MAGIC; page->xlp_info = XLP_LONG_HEADER; page->xlp_tli = ControlFile.checkPointCopy.ThisTimeLineID; @@ -1194,7 +1192,7 @@ WriteEmptyXLOG(void) } errno = 0; - if (write(fd, buffer, XLOG_BLCKSZ) != XLOG_BLCKSZ) + if (write(fd, buffer.data, XLOG_BLCKSZ) != XLOG_BLCKSZ) { /* if write didn't set errno, assume problem is no disk space */ if (errno == 0) @@ -1205,11 +1203,11 @@ WriteEmptyXLOG(void) } /* Fill the rest of the file with zeroes */ - memset(buffer, 0, XLOG_BLCKSZ); + memset(buffer.data, 0, XLOG_BLCKSZ); for (nbytes = XLOG_BLCKSZ; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ) { errno = 0; - if (write(fd, buffer, XLOG_BLCKSZ) != XLOG_BLCKSZ) + if (write(fd, buffer.data, XLOG_BLCKSZ) != XLOG_BLCKSZ) { if (errno == 0) errno = ENOSPC; diff --git a/src/bin/pg_rewind/copy_fetch.c b/src/bin/pg_rewind/copy_fetch.c index d7a31c16f4..47f4f41952 100644 --- a/src/bin/pg_rewind/copy_fetch.c +++ b/src/bin/pg_rewind/copy_fetch.c @@ -160,7 +160,7 @@ recurse_dir(const char *datadir, const char *parentpath, static void rewind_copy_file_range(const char *path, off_t begin, off_t end, bool trunc) { - char buf[BLCKSZ]; + PGAlignedBlock buf; char srcpath[MAXPGPATH]; int srcfd; @@ -186,7 +186,7 @@ rewind_copy_file_range(const char *path, off_t begin, off_t end, bool trunc) else len = end - begin; - readlen = read(srcfd, buf, len); + readlen = read(srcfd, buf.data, len); if (readlen < 0) pg_fatal("could not read file \"%s\": %s\n", @@ -194,7 +194,7 @@ rewind_copy_file_range(const char *path, off_t begin, off_t end, bool trunc) else if (readlen == 0) pg_fatal("unexpected EOF while reading file \"%s\"\n", srcpath); - write_target_range(buf, begin, readlen); + write_target_range(buf.data, begin, readlen); begin += readlen; } diff --git a/src/bin/pg_upgrade/file.c b/src/bin/pg_upgrade/file.c index 6bb811be69..628784e32b 100644 --- a/src/bin/pg_upgrade/file.c +++ b/src/bin/pg_upgrade/file.c @@ -131,8 +131,8 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, { int src_fd; int dst_fd; - char *buffer; - char *new_vmbuf; + PGAlignedBlock buffer; + PGAlignedBlock new_vmbuf; ssize_t totalBytesRead = 0; ssize_t src_filesize; int rewriteVmBytesPerPage; @@ -158,13 +158,6 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, /* Save old file size */ src_filesize = statbuf.st_size; - /* - * Malloc the work buffers, rather than making them local arrays, to - * ensure adequate alignment. - */ - buffer = (char *) pg_malloc(BLCKSZ); - new_vmbuf = (char *) pg_malloc(BLCKSZ); - /* * Turn each visibility map page into 2 pages one by one. Each new page * has the same page header as the old one. If the last section of the @@ -180,7 +173,7 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, PageHeaderData pageheader; bool old_lastblk; - if ((bytesRead = read(src_fd, buffer, BLCKSZ)) != BLCKSZ) + if ((bytesRead = read(src_fd, buffer.data, BLCKSZ)) != BLCKSZ) { if (bytesRead < 0) pg_fatal("error while copying relation \"%s.%s\": could not read file \"%s\": %s\n", @@ -194,7 +187,7 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, old_lastblk = (totalBytesRead == src_filesize); /* Save the page header data */ - memcpy(&pageheader, buffer, SizeOfPageHeaderData); + memcpy(&pageheader, buffer.data, SizeOfPageHeaderData); /* * These old_* variables point to old visibility map page. old_cur @@ -202,8 +195,8 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, * old block. old_break is the end+1 position on the old page for the * data that will be transferred to the current new page. */ - old_cur = buffer + SizeOfPageHeaderData; - old_blkend = buffer + bytesRead; + old_cur = buffer.data + SizeOfPageHeaderData; + old_blkend = buffer.data + bytesRead; old_break = old_cur + rewriteVmBytesPerPage; while (old_break <= old_blkend) @@ -213,12 +206,12 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, bool old_lastpart; /* First, copy old page header to new page */ - memcpy(new_vmbuf, &pageheader, SizeOfPageHeaderData); + memcpy(new_vmbuf.data, &pageheader, SizeOfPageHeaderData); /* Rewriting the last part of the last old page? */ old_lastpart = old_lastblk && (old_break == old_blkend); - new_cur = new_vmbuf + SizeOfPageHeaderData; + new_cur = new_vmbuf.data + SizeOfPageHeaderData; /* Process old page bytes one by one, and turn it into new page. */ while (old_cur < old_break) @@ -252,11 +245,11 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, /* Set new checksum for visibility map page, if enabled */ if (new_cluster.controldata.data_checksum_version != 0) - ((PageHeader) new_vmbuf)->pd_checksum = - pg_checksum_page(new_vmbuf, new_blkno); + ((PageHeader) new_vmbuf.data)->pd_checksum = + pg_checksum_page(new_vmbuf.data, new_blkno); errno = 0; - if (write(dst_fd, new_vmbuf, BLCKSZ) != BLCKSZ) + if (write(dst_fd, new_vmbuf.data, BLCKSZ) != BLCKSZ) { /* if write didn't set errno, assume problem is no disk space */ if (errno == 0) @@ -272,8 +265,6 @@ rewriteVisibilityMap(const char *fromfile, const char *tofile, } /* Clean up */ - pg_free(buffer); - pg_free(new_vmbuf); close(dst_fd); close(src_fd); } diff --git a/src/include/c.h b/src/include/c.h index 8633657aeb..81d8e642da 100644 --- a/src/include/c.h +++ b/src/include/c.h @@ -949,6 +949,32 @@ typedef NameData *Name; * ---------------------------------------------------------------- */ +/* + * Use this, not "char buf[BLCKSZ]", to declare a field or local variable + * holding a page buffer, if that page might be accessed as a page and not + * just a string of bytes. Otherwise the variable might be under-aligned, + * causing problems on alignment-picky hardware. (In some places, we use + * this to declare buffers even though we only pass them to read() and + * write(), because copying to/from aligned buffers is usually faster than + * using unaligned buffers.) We include both "double" and "int64" in the + * union to ensure that the compiler knows the value must be MAXALIGN'ed + * (cf. configure's computation of MAXIMUM_ALIGNOF). + */ +typedef union PGAlignedBlock +{ + char data[BLCKSZ]; + double force_align_d; + int64 force_align_i64; +} PGAlignedBlock; + +/* Same, but for an XLOG_BLCKSZ-sized buffer */ +typedef union PGAlignedXLogBlock +{ + char data[XLOG_BLCKSZ]; + double force_align_d; + int64 force_align_i64; +} PGAlignedXLogBlock; + /* msb for char */ #define HIGHBIT (0x80) #define IS_HIGHBIT_SET(ch) ((unsigned char)(ch) & HIGHBIT)