md.h File Reference

#include "storage/block.h"
#include "storage/relfilelocator.h"
#include "storage/smgr.h"
#include "storage/sync.h"

Include dependency graph for md.h:

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Functions
void	mdinit (void)
void	mdopen (SMgrRelation reln)
void	mdclose (SMgrRelation reln, ForkNumber forknum)
void	mdcreate (SMgrRelation reln, ForkNumber forknum, bool isRedo)
bool	mdexists (SMgrRelation reln, ForkNumber forknum)
void	mdunlink (RelFileLocatorBackend rlocator, ForkNumber forknum, bool isRedo)
void	mdextend (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, const void *buffer, bool skipFsync)
bool	mdprefetch (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum)
void	mdread (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, void *buffer)
void	mdwrite (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, const void *buffer, bool skipFsync)
void	mdwriteback (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, BlockNumber nblocks)
BlockNumber	mdnblocks (SMgrRelation reln, ForkNumber forknum)
void	mdtruncate (SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
void	mdimmedsync (SMgrRelation reln, ForkNumber forknum)
void	ForgetDatabaseSyncRequests (Oid dbid)
void	DropRelationFiles (RelFileLocator *delrels, int ndelrels, bool isRedo)
int	mdsyncfiletag (const FileTag *ftag, char *path)
int	mdunlinkfiletag (const FileTag *ftag, char *path)
bool	mdfiletagmatches (const FileTag *ftag, const FileTag *candidate)

Function Documentation

DropRelationFiles()

void DropRelationFiles	(	RelFileLocator *	delrels,
		int	ndelrels,
		bool	isRedo
	)

Definition at line 1110 of file md.c.

{
    SMgrRelation *srels;
    int         i;
 
    srels = palloc(sizeof(SMgrRelation) * ndelrels);
    for (i = 0; i < ndelrels; i++)
    {
        SMgrRelation srel = smgropen(delrels[i], InvalidBackendId);
 
        if (isRedo)
        {
            ForkNumber  fork;
 
            for (fork = 0; fork <= MAX_FORKNUM; fork++)
                XLogDropRelation(delrels[i], fork);
        }
        srels[i] = srel;
    }
 
    smgrdounlinkall(srels, ndelrels, isRedo);
 
    for (i = 0; i < ndelrels; i++)
        smgrclose(srels[i]);
    pfree(srels);
}

References i, InvalidBackendId, MAX_FORKNUM, palloc(), pfree(), smgrclose(), smgrdounlinkall(), smgropen(), and XLogDropRelation().

Referenced by FinishPreparedTransaction(), xact_redo_abort(), and xact_redo_commit().

ForgetDatabaseSyncRequests()

void ForgetDatabaseSyncRequests

(

Oid

dbid

)

Definition at line 1092 of file md.c.

{
    FileTag     tag;
    RelFileLocator rlocator;
 
    rlocator.dbOid = dbid;
    rlocator.spcOid = 0;
    rlocator.relNumber = 0;
 
    INIT_MD_FILETAG(tag, rlocator, InvalidForkNumber, InvalidBlockNumber);
 
    RegisterSyncRequest(&tag, SYNC_FILTER_REQUEST, true /* retryOnError */ );
}

References RelFileLocator::dbOid, INIT_MD_FILETAG, InvalidBlockNumber, InvalidForkNumber, RegisterSyncRequest(), RelFileLocator::relNumber, RelFileLocator::spcOid, and SYNC_FILTER_REQUEST.

Referenced by createdb_failure_callback(), dbase_redo(), and dropdb().

mdclose()

void mdclose	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 568 of file md.c.

{
    int         nopensegs = reln->md_num_open_segs[forknum];
 
    /* No work if already closed */
    if (nopensegs == 0)
        return;
 
    /* close segments starting from the end */
    while (nopensegs > 0)
    {
        MdfdVec    *v = &reln->md_seg_fds[forknum][nopensegs - 1];
 
        FileClose(v->mdfd_vfd);
        _fdvec_resize(reln, forknum, nopensegs - 1);
        nopensegs--;
    }
}

References _fdvec_resize(), FileClose(), SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, and _MdfdVec::mdfd_vfd.

Referenced by mdexists().

mdcreate()

void mdcreate	(	SMgrRelation	reln,
		ForkNumber	forknum,
		bool	isRedo
	)

Definition at line 182 of file md.c.

{
    MdfdVec    *mdfd;
    char       *path;
    File        fd;
 
    if (isRedo && reln->md_num_open_segs[forknum] > 0)
        return;                 /* created and opened already... */
 
    Assert(reln->md_num_open_segs[forknum] == 0);
 
    /*
     * We may be using the target table space for the first time in this
     * database, so create a per-database subdirectory if needed.
     *
     * XXX this is a fairly ugly violation of module layering, but this seems
     * to be the best place to put the check.  Maybe TablespaceCreateDbspace
     * should be here and not in commands/tablespace.c?  But that would imply
     * importing a lot of stuff that smgr.c oughtn't know, either.
     */
    TablespaceCreateDbspace(reln->smgr_rlocator.locator.spcOid,
                            reln->smgr_rlocator.locator.dbOid,
                            isRedo);
 
    path = relpath(reln->smgr_rlocator, forknum);
 
    fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY);
 
    if (fd < 0)
    {
        int         save_errno = errno;
 
        if (isRedo)
            fd = PathNameOpenFile(path, O_RDWR | PG_BINARY);
        if (fd < 0)
        {
            /* be sure to report the error reported by create, not open */
            errno = save_errno;
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not create file \"%s\": %m", path)));
        }
    }
 
    pfree(path);
 
    _fdvec_resize(reln, forknum, 1);
    mdfd = &reln->md_seg_fds[forknum][0];
    mdfd->mdfd_vfd = fd;
    mdfd->mdfd_segno = 0;
}

References _fdvec_resize(), Assert(), RelFileLocator::dbOid, ereport, errcode_for_file_access(), errmsg(), ERROR, fd(), RelFileLocatorBackend::locator, SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_segno, _MdfdVec::mdfd_vfd, PathNameOpenFile(), pfree(), PG_BINARY, relpath, SMgrRelationData::smgr_rlocator, RelFileLocator::spcOid, and TablespaceCreateDbspace().

mdexists()

bool mdexists	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 163 of file md.c.

{
    /*
     * Close it first, to ensure that we notice if the fork has been unlinked
     * since we opened it.  As an optimization, we can skip that in recovery,
     * which already closes relations when dropping them.
     */
    if (!InRecovery)
        mdclose(reln, forknum);
 
    return (mdopenfork(reln, forknum, EXTENSION_RETURN_NULL) != NULL);
}

References EXTENSION_RETURN_NULL, InRecovery, mdclose(), and mdopenfork().

mdextend()

void mdextend	(	SMgrRelation	reln,
		ForkNumber	forknum,
		BlockNumber	blocknum,
		const void *	buffer,
		bool	skipFsync
	)

Definition at line 449 of file md.c.

{
    off_t       seekpos;
    int         nbytes;
    MdfdVec    *v;
 
    /* This assert is too expensive to have on normally ... */
#ifdef CHECK_WRITE_VS_EXTEND
    Assert(blocknum >= mdnblocks(reln, forknum));
#endif
 
    /*
     * If a relation manages to grow to 2^32-1 blocks, refuse to extend it any
     * more --- we mustn't create a block whose number actually is
     * InvalidBlockNumber.  (Note that this failure should be unreachable
     * because of upstream checks in bufmgr.c.)
     */
    if (blocknum == InvalidBlockNumber)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("cannot extend file \"%s\" beyond %u blocks",
                        relpath(reln->smgr_rlocator, forknum),
                        InvalidBlockNumber)));
 
    v = _mdfd_getseg(reln, forknum, blocknum, skipFsync, EXTENSION_CREATE);
 
    seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
 
    Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
 
    if ((nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_EXTEND)) != BLCKSZ)
    {
        if (nbytes < 0)
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not extend file \"%s\": %m",
                            FilePathName(v->mdfd_vfd)),
                     errhint("Check free disk space.")));
        /* short write: complain appropriately */
        ereport(ERROR,
                (errcode(ERRCODE_DISK_FULL),
                 errmsg("could not extend file \"%s\": wrote only %d of %d bytes at block %u",
                        FilePathName(v->mdfd_vfd),
                        nbytes, BLCKSZ, blocknum),
                 errhint("Check free disk space.")));
    }
 
    if (!skipFsync && !SmgrIsTemp(reln))
        register_dirty_segment(reln, forknum, v);
 
    Assert(_mdnblocks(reln, forknum, v) <= ((BlockNumber) RELSEG_SIZE));
}

References _mdfd_getseg(), _mdnblocks(), Assert(), ereport, errcode(), errcode_for_file_access(), errhint(), errmsg(), ERROR, EXTENSION_CREATE, FilePathName(), FileWrite(), InvalidBlockNumber, _MdfdVec::mdfd_vfd, mdnblocks(), register_dirty_segment(), relpath, SMgrRelationData::smgr_rlocator, SmgrIsTemp, and WAIT_EVENT_DATA_FILE_EXTEND.

Referenced by _mdfd_getseg().

mdfiletagmatches()

bool mdfiletagmatches	(	const FileTag *	ftag,
		const FileTag *	candidate
	)

Definition at line 1467 of file md.c.

{
    /*
     * For now we only use filter requests as a way to drop all scheduled
     * callbacks relating to a given database, when dropping the database.
     * We'll return true for all candidates that have the same database OID as
     * the ftag from the SYNC_FILTER_REQUEST request, so they're forgotten.
     */
    return ftag->rlocator.dbOid == candidate->rlocator.dbOid;
}

References RelFileLocator::dbOid, and FileTag::rlocator.

mdimmedsync()

void mdimmedsync	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 960 of file md.c.

{
    int         segno;
    int         min_inactive_seg;
 
    /*
     * NOTE: mdnblocks makes sure we have opened all active segments, so that
     * fsync loop will get them all!
     */
    mdnblocks(reln, forknum);
 
    min_inactive_seg = segno = reln->md_num_open_segs[forknum];
 
    /*
     * Temporarily open inactive segments, then close them after sync.  There
     * may be some inactive segments left opened after fsync() error, but that
     * is harmless.  We don't bother to clean them up and take a risk of
     * further trouble.  The next mdclose() will soon close them.
     */
    while (_mdfd_openseg(reln, forknum, segno, 0) != NULL)
        segno++;
 
    while (segno > 0)
    {
        MdfdVec    *v = &reln->md_seg_fds[forknum][segno - 1];
 
        /*
         * fsyncs done through mdimmedsync() should be tracked in a separate
         * IOContext than those done through mdsyncfiletag() to differentiate
         * between unavoidable client backend fsyncs (e.g. those done during
         * index build) and those which ideally would have been done by the
         * checkpointer. Since other IO operations bypassing the buffer
         * manager could also be tracked in such an IOContext, wait until
         * these are also tracked to track immediate fsyncs.
         */
        if (FileSync(v->mdfd_vfd, WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC) < 0)
            ereport(data_sync_elevel(ERROR),
                    (errcode_for_file_access(),
                     errmsg("could not fsync file \"%s\": %m",
                            FilePathName(v->mdfd_vfd))));
 
        /* Close inactive segments immediately */
        if (segno > min_inactive_seg)
        {
            FileClose(v->mdfd_vfd);
            _fdvec_resize(reln, forknum, segno - 1);
        }
 
        segno--;
    }
}

References _fdvec_resize(), _mdfd_openseg(), data_sync_elevel(), ereport, errcode_for_file_access(), errmsg(), ERROR, FileClose(), FilePathName(), FileSync(), SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_vfd, mdnblocks(), and WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC.

mdinit()

void mdinit

(

void

)

Definition at line 150 of file md.c.

{
    MdCxt = AllocSetContextCreate(TopMemoryContext,
                                  "MdSmgr",
                                  ALLOCSET_DEFAULT_SIZES);
}

References ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, MdCxt, and TopMemoryContext.

mdnblocks()

BlockNumber mdnblocks	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 801 of file md.c.

{
    MdfdVec    *v;
    BlockNumber nblocks;
    BlockNumber segno;
 
    mdopenfork(reln, forknum, EXTENSION_FAIL);
 
    /* mdopen has opened the first segment */
    Assert(reln->md_num_open_segs[forknum] > 0);
 
    /*
     * Start from the last open segments, to avoid redundant seeks.  We have
     * previously verified that these segments are exactly RELSEG_SIZE long,
     * and it's useless to recheck that each time.
     *
     * NOTE: this assumption could only be wrong if another backend has
     * truncated the relation.  We rely on higher code levels to handle that
     * scenario by closing and re-opening the md fd, which is handled via
     * relcache flush.  (Since the checkpointer doesn't participate in
     * relcache flush, it could have segment entries for inactive segments;
     * that's OK because the checkpointer never needs to compute relation
     * size.)
     */
    segno = reln->md_num_open_segs[forknum] - 1;
    v = &reln->md_seg_fds[forknum][segno];
 
    for (;;)
    {
        nblocks = _mdnblocks(reln, forknum, v);
        if (nblocks > ((BlockNumber) RELSEG_SIZE))
            elog(FATAL, "segment too big");
        if (nblocks < ((BlockNumber) RELSEG_SIZE))
            return (segno * ((BlockNumber) RELSEG_SIZE)) + nblocks;
 
        /*
         * If segment is exactly RELSEG_SIZE, advance to next one.
         */
        segno++;
 
        /*
         * We used to pass O_CREAT here, but that has the disadvantage that it
         * might create a segment which has vanished through some operating
         * system misadventure.  In such a case, creating the segment here
         * undermines _mdfd_getseg's attempts to notice and report an error
         * upon access to a missing segment.
         */
        v = _mdfd_openseg(reln, forknum, segno, 0);
        if (v == NULL)
            return segno * ((BlockNumber) RELSEG_SIZE);
    }
}

References _mdfd_openseg(), _mdnblocks(), Assert(), elog(), EXTENSION_FAIL, FATAL, SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, and mdopenfork().

Referenced by mdextend(), mdimmedsync(), mdtruncate(), and mdwrite().

mdopen()

void mdopen

(

SMgrRelation

reln

)

Definition at line 557 of file md.c.

{
    /* mark it not open */
    for (int forknum = 0; forknum <= MAX_FORKNUM; forknum++)
        reln->md_num_open_segs[forknum] = 0;
}

References MAX_FORKNUM, and SMgrRelationData::md_num_open_segs.

mdprefetch()

bool mdprefetch	(	SMgrRelation	reln,
		ForkNumber	forknum,
		BlockNumber	blocknum
	)

Definition at line 591 of file md.c.

{
#ifdef USE_PREFETCH
    off_t       seekpos;
    MdfdVec    *v;
 
    v = _mdfd_getseg(reln, forknum, blocknum, false,
                     InRecovery ? EXTENSION_RETURN_NULL : EXTENSION_FAIL);
    if (v == NULL)
        return false;
 
    seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
 
    Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
 
    (void) FilePrefetch(v->mdfd_vfd, seekpos, BLCKSZ, WAIT_EVENT_DATA_FILE_PREFETCH);
#endif                          /* USE_PREFETCH */
 
    return true;
}

References _mdfd_getseg(), Assert(), EXTENSION_FAIL, EXTENSION_RETURN_NULL, FilePrefetch(), InRecovery, _MdfdVec::mdfd_vfd, and WAIT_EVENT_DATA_FILE_PREFETCH.

mdread()

void mdread	(	SMgrRelation	reln,
		ForkNumber	forknum,
		BlockNumber	blocknum,
		void *	buffer
	)

Definition at line 671 of file md.c.

{
    off_t       seekpos;
    int         nbytes;
    MdfdVec    *v;
 
    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)
    {
        if (nbytes < 0)
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not read block %u in file \"%s\": %m",
                            blocknum, FilePathName(v->mdfd_vfd))));
 
        /*
         * 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.
         */
        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)));
    }
}

References _mdfd_getseg(), Assert(), RelFileLocatorBackend::backend, RelFileLocator::dbOid, ereport, errcode(), ERRCODE_DATA_CORRUPTED, errcode_for_file_access(), errmsg(), ERROR, EXTENSION_CREATE_RECOVERY, EXTENSION_FAIL, FilePathName(), FileRead(), InRecovery, RelFileLocatorBackend::locator, _MdfdVec::mdfd_vfd, MemSet, RelFileLocator::relNumber, SMgrRelationData::smgr_rlocator, RelFileLocator::spcOid, WAIT_EVENT_DATA_FILE_READ, and zero_damaged_pages.

mdsyncfiletag()

int mdsyncfiletag	(	const FileTag *	ftag,
		char *	path
	)

Definition at line 1399 of file md.c.

{
    SMgrRelation reln = smgropen(ftag->rlocator, InvalidBackendId);
    File        file;
    bool        need_to_close;
    int         result,
                save_errno;
 
    /* See if we already have the file open, or need to open it. */
    if (ftag->segno < reln->md_num_open_segs[ftag->forknum])
    {
        file = reln->md_seg_fds[ftag->forknum][ftag->segno].mdfd_vfd;
        strlcpy(path, FilePathName(file), MAXPGPATH);
        need_to_close = false;
    }
    else
    {
        char       *p;
 
        p = _mdfd_segpath(reln, ftag->forknum, ftag->segno);
        strlcpy(path, p, MAXPGPATH);
        pfree(p);
 
        file = PathNameOpenFile(path, O_RDWR | PG_BINARY);
        if (file < 0)
            return -1;
        need_to_close = true;
    }
 
    /* Sync the file. */
    result = FileSync(file, WAIT_EVENT_DATA_FILE_SYNC);
    save_errno = errno;
 
    if (need_to_close)
        FileClose(file);
 
    pgstat_count_io_op(IOOBJECT_RELATION, IOCONTEXT_NORMAL, IOOP_FSYNC);
 
    errno = save_errno;
    return result;
}

References _mdfd_segpath(), FileClose(), FilePathName(), FileSync(), FileTag::forknum, InvalidBackendId, IOCONTEXT_NORMAL, IOOBJECT_RELATION, IOOP_FSYNC, MAXPGPATH, SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_vfd, PathNameOpenFile(), pfree(), PG_BINARY, pgstat_count_io_op(), FileTag::rlocator, FileTag::segno, smgropen(), strlcpy(), and WAIT_EVENT_DATA_FILE_SYNC.

mdtruncate()

void mdtruncate	(	SMgrRelation	reln,
		ForkNumber	forknum,
		BlockNumber	nblocks
	)

Definition at line 858 of file md.c.

{
    BlockNumber curnblk;
    BlockNumber priorblocks;
    int         curopensegs;
 
    /*
     * NOTE: mdnblocks makes sure we have opened all active segments, so that
     * truncation loop will get them all!
     */
    curnblk = mdnblocks(reln, forknum);
    if (nblocks > curnblk)
    {
        /* Bogus request ... but no complaint if InRecovery */
        if (InRecovery)
            return;
        ereport(ERROR,
                (errmsg("could not truncate file \"%s\" to %u blocks: it's only %u blocks now",
                        relpath(reln->smgr_rlocator, forknum),
                        nblocks, curnblk)));
    }
    if (nblocks == curnblk)
        return;                 /* no work */
 
    /*
     * Truncate segments, starting at the last one. Starting at the end makes
     * managing the memory for the fd array easier, should there be errors.
     */
    curopensegs = reln->md_num_open_segs[forknum];
    while (curopensegs > 0)
    {
        MdfdVec    *v;
 
        priorblocks = (curopensegs - 1) * RELSEG_SIZE;
 
        v = &reln->md_seg_fds[forknum][curopensegs - 1];
 
        if (priorblocks > nblocks)
        {
            /*
             * This segment is no longer active. We truncate the file, but do
             * not delete it, for reasons explained in the header comments.
             */
            if (FileTruncate(v->mdfd_vfd, 0, WAIT_EVENT_DATA_FILE_TRUNCATE) < 0)
                ereport(ERROR,
                        (errcode_for_file_access(),
                         errmsg("could not truncate file \"%s\": %m",
                                FilePathName(v->mdfd_vfd))));
 
            if (!SmgrIsTemp(reln))
                register_dirty_segment(reln, forknum, v);
 
            /* we never drop the 1st segment */
            Assert(v != &reln->md_seg_fds[forknum][0]);
 
            FileClose(v->mdfd_vfd);
            _fdvec_resize(reln, forknum, curopensegs - 1);
        }
        else if (priorblocks + ((BlockNumber) RELSEG_SIZE) > nblocks)
        {
            /*
             * This is the last segment we want to keep. Truncate the file to
             * the right length. NOTE: if nblocks is exactly a multiple K of
             * RELSEG_SIZE, we will truncate the K+1st segment to 0 length but
             * keep it. This adheres to the invariant given in the header
             * comments.
             */
            BlockNumber lastsegblocks = nblocks - priorblocks;
 
            if (FileTruncate(v->mdfd_vfd, (off_t) lastsegblocks * BLCKSZ, WAIT_EVENT_DATA_FILE_TRUNCATE) < 0)
                ereport(ERROR,
                        (errcode_for_file_access(),
                         errmsg("could not truncate file \"%s\" to %u blocks: %m",
                                FilePathName(v->mdfd_vfd),
                                nblocks)));
            if (!SmgrIsTemp(reln))
                register_dirty_segment(reln, forknum, v);
        }
        else
        {
            /*
             * We still need this segment, so nothing to do for this and any
             * earlier segment.
             */
            break;
        }
        curopensegs--;
    }
}

References _fdvec_resize(), Assert(), ereport, errcode_for_file_access(), errmsg(), ERROR, FileClose(), FilePathName(), FileTruncate(), InRecovery, SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_vfd, mdnblocks(), register_dirty_segment(), relpath, SMgrRelationData::smgr_rlocator, SmgrIsTemp, and WAIT_EVENT_DATA_FILE_TRUNCATE.

mdunlink()

void mdunlink	(	RelFileLocatorBackend	rlocator,
		ForkNumber	forknum,
		bool	isRedo
	)

Definition at line 296 of file md.c.

{
    /* Now do the per-fork work */
    if (forknum == InvalidForkNumber)
    {
        for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
            mdunlinkfork(rlocator, forknum, isRedo);
    }
    else
        mdunlinkfork(rlocator, forknum, isRedo);
}

References InvalidForkNumber, MAX_FORKNUM, and mdunlinkfork().

mdunlinkfiletag()

int mdunlinkfiletag	(	const FileTag *	ftag,
		char *	path
	)

Definition at line 1448 of file md.c.

{
    char       *p;
 
    /* Compute the path. */
    p = relpathperm(ftag->rlocator, MAIN_FORKNUM);
    strlcpy(path, p, MAXPGPATH);
    pfree(p);
 
    /* Try to unlink the file. */
    return unlink(path);
}

References MAIN_FORKNUM, MAXPGPATH, pfree(), relpathperm, FileTag::rlocator, and strlcpy().

mdwrite()

void mdwrite	(	SMgrRelation	reln,
		ForkNumber	forknum,
		BlockNumber	blocknum,
		const void *	buffer,
		bool	skipFsync
	)

Definition at line 736 of file md.c.

{
    off_t       seekpos;
    int         nbytes;
    MdfdVec    *v;
 
    /* 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)
    {
        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.")));
    }
 
    if (!skipFsync && !SmgrIsTemp(reln))
        register_dirty_segment(reln, forknum, v);
}

References _mdfd_getseg(), Assert(), RelFileLocatorBackend::backend, RelFileLocator::dbOid, ereport, errcode(), errcode_for_file_access(), errhint(), errmsg(), ERROR, EXTENSION_CREATE_RECOVERY, EXTENSION_FAIL, FilePathName(), FileWrite(), RelFileLocatorBackend::locator, _MdfdVec::mdfd_vfd, mdnblocks(), register_dirty_segment(), RelFileLocator::relNumber, SMgrRelationData::smgr_rlocator, SmgrIsTemp, RelFileLocator::spcOid, and WAIT_EVENT_DATA_FILE_WRITE.

mdwriteback()

void mdwriteback	(	SMgrRelation	reln,
		ForkNumber	forknum,
		BlockNumber	blocknum,
		BlockNumber	nblocks
	)

Definition at line 619 of file md.c.

{
    /*
     * Issue flush requests in as few requests as possible; have to split at
     * segment boundaries though, since those are actually separate files.
     */
    while (nblocks > 0)
    {
        BlockNumber nflush = nblocks;
        off_t       seekpos;
        MdfdVec    *v;
        int         segnum_start,
                    segnum_end;
 
        v = _mdfd_getseg(reln, forknum, blocknum, true /* not used */ ,
                         EXTENSION_DONT_OPEN);
 
        /*
         * We might be flushing buffers of already removed relations, that's
         * ok, just ignore that case.  If the segment file wasn't open already
         * (ie from a recent mdwrite()), then we don't want to re-open it, to
         * avoid a race with PROCSIGNAL_BARRIER_SMGRRELEASE that might leave
         * us with a descriptor to a file that is about to be unlinked.
         */
        if (!v)
            return;
 
        /* compute offset inside the current segment */
        segnum_start = blocknum / RELSEG_SIZE;
 
        /* compute number of desired writes within the current segment */
        segnum_end = (blocknum + nblocks - 1) / RELSEG_SIZE;
        if (segnum_start != segnum_end)
            nflush = RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE));
 
        Assert(nflush >= 1);
        Assert(nflush <= nblocks);
 
        seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
 
        FileWriteback(v->mdfd_vfd, seekpos, (off_t) BLCKSZ * nflush, WAIT_EVENT_DATA_FILE_FLUSH);
 
        nblocks -= nflush;
        blocknum += nflush;
    }
}

References _mdfd_getseg(), Assert(), EXTENSION_DONT_OPEN, FileWriteback(), _MdfdVec::mdfd_vfd, and WAIT_EVENT_DATA_FILE_FLUSH.