md.c File Reference

#include "postgres.h"
#include <unistd.h>
#include <fcntl.h>
#include <sys/file.h>
#include "access/xlog.h"
#include "access/xlogutils.h"
#include "commands/tablespace.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "pgstat.h"
#include "postmaster/bgwriter.h"
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/md.h"
#include "storage/relfilenode.h"
#include "storage/smgr.h"
#include "storage/sync.h"
#include "utils/hsearch.h"
#include "utils/memutils.h"

Include dependency graph for md.c:

Go to the source code of this file.

Data Structures
struct	_MdfdVec

Macros
#define	INIT_MD_FILETAG(a, xx_rnode, xx_forknum, xx_segno)
#define	EXTENSION_FAIL   (1 << 0)
#define	EXTENSION_RETURN_NULL   (1 << 1)
#define	EXTENSION_CREATE   (1 << 2)
#define	EXTENSION_CREATE_RECOVERY   (1 << 3)
#define	EXTENSION_DONT_CHECK_SIZE   (1 << 4)

Typedefs
typedef struct _MdfdVec	MdfdVec

Functions
static void	mdunlinkfork (RelFileNodeBackend rnode, ForkNumber forkNum, bool isRedo)
static MdfdVec *	mdopenfork (SMgrRelation reln, ForkNumber forknum, int behavior)
static void	register_dirty_segment (SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
static void	register_unlink_segment (RelFileNodeBackend rnode, ForkNumber forknum, BlockNumber segno)
static void	register_forget_request (RelFileNodeBackend rnode, ForkNumber forknum, BlockNumber segno)
static void	_fdvec_resize (SMgrRelation reln, ForkNumber forknum, int nseg)
static char *	_mdfd_segpath (SMgrRelation reln, ForkNumber forknum, BlockNumber segno)
static MdfdVec *	_mdfd_openseg (SMgrRelation reln, ForkNumber forkno, BlockNumber segno, int oflags)
static MdfdVec *	_mdfd_getseg (SMgrRelation reln, ForkNumber forkno, BlockNumber blkno, bool skipFsync, int behavior)
static BlockNumber	_mdnblocks (SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
void	mdinit (void)
bool	mdexists (SMgrRelation reln, ForkNumber forkNum)
void	mdcreate (SMgrRelation reln, ForkNumber forkNum, bool isRedo)
void	mdunlink (RelFileNodeBackend rnode, ForkNumber forkNum, bool isRedo)
void	mdextend (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer, bool skipFsync)
void	mdopen (SMgrRelation reln)
void	mdclose (SMgrRelation reln, ForkNumber forknum)
void	mdprefetch (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum)
void	mdwriteback (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, BlockNumber nblocks)
void	mdread (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer)
void	mdwrite (SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, char *buffer, bool skipFsync)
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 (RelFileNode *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)

Variables
static MemoryContext	MdCxt

Macro Definition Documentation

EXTENSION_CREATE

#define EXTENSION_CREATE   (1 << 2)

Definition at line 108 of file md.c.

Referenced by _mdfd_getseg(), and mdextend().

EXTENSION_CREATE_RECOVERY

#define EXTENSION_CREATE_RECOVERY   (1 << 3)

Definition at line 110 of file md.c.

Referenced by _mdfd_getseg(), mdread(), and mdwrite().

EXTENSION_DONT_CHECK_SIZE

#define EXTENSION_DONT_CHECK_SIZE   (1 << 4)

Definition at line 118 of file md.c.

Referenced by _mdfd_getseg(), and mdsyncfiletag().

EXTENSION_FAIL

#define EXTENSION_FAIL   (1 << 0)

Definition at line 104 of file md.c.

Referenced by _mdfd_getseg(), mdnblocks(), mdprefetch(), mdread(), and mdwrite().

EXTENSION_RETURN_NULL

#define EXTENSION_RETURN_NULL   (1 << 1)

Definition at line 106 of file md.c.

Referenced by _mdfd_getseg(), mdexists(), mdopenfork(), mdsyncfiletag(), and mdwriteback().

INIT_MD_FILETAG

#define INIT_MD_FILETAG	(		a,
			xx_rnode,
			xx_forknum,
			xx_segno
	)

Value:

( \
    memset(&(a), 0, sizeof(FileTag)), \
    (a).handler = SYNC_HANDLER_MD, \
    (a).rnode = (xx_rnode), \
    (a).forknum = (xx_forknum), \
    (a).segno = (xx_segno) \
)

Definition at line 92 of file md.c.

Referenced by ForgetDatabaseSyncRequests(), register_dirty_segment(), register_forget_request(), and register_unlink_segment().

Typedef Documentation

MdfdVec

typedef struct _MdfdVec MdfdVec

Function Documentation

_fdvec_resize()

static void _fdvec_resize ( SMgrRelation  reln, ForkNumber  forknum, int  nseg  )

static

Definition at line 1033 of file md.c.

References SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, MemoryContextAlloc(), pfree(), and repalloc().

Referenced by _mdfd_openseg(), mdclose(), mdcreate(), mdopenfork(), and mdtruncate().

{
    if (nseg == 0)
    {
        if (reln->md_num_open_segs[forknum] > 0)
        {
            pfree(reln->md_seg_fds[forknum]);
            reln->md_seg_fds[forknum] = NULL;
        }
    }
    else if (reln->md_num_open_segs[forknum] == 0)
    {
        reln->md_seg_fds[forknum] =
            MemoryContextAlloc(MdCxt, sizeof(MdfdVec) * nseg);
    }
    else
    {
        /*
         * It doesn't seem worthwhile complicating the code by having a more
         * aggressive growth strategy here; the number of segments doesn't
         * grow that fast, and the memory context internally will sometimes
         * avoid doing an actual reallocation.
         */
        reln->md_seg_fds[forknum] =
            repalloc(reln->md_seg_fds[forknum],
                     sizeof(MdfdVec) * nseg);
    }

    reln->md_num_open_segs[forknum] = nseg;
}

_mdfd_getseg()

static MdfdVec * _mdfd_getseg ( SMgrRelation  reln, ForkNumber  forkno, BlockNumber  blkno, bool  skipFsync, int  behavior  )

static

Definition at line 1134 of file md.c.

References _mdfd_openseg(), _mdfd_segpath(), _mdnblocks(), Assert, elog, ereport, errcode_for_file_access(), errmsg(), ERROR, EXTENSION_CREATE, EXTENSION_CREATE_RECOVERY, EXTENSION_DONT_CHECK_SIZE, EXTENSION_FAIL, EXTENSION_RETURN_NULL, FATAL, FILE_POSSIBLY_DELETED, InRecovery, SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, mdextend(), _MdfdVec::mdfd_segno, mdopenfork(), palloc0(), and pfree().

Referenced by mdextend(), mdprefetch(), mdread(), mdsyncfiletag(), mdwrite(), and mdwriteback().

{
    MdfdVec    *v;
    BlockNumber targetseg;
    BlockNumber nextsegno;

    /* some way to handle non-existent segments needs to be specified */
    Assert(behavior &
           (EXTENSION_FAIL | EXTENSION_CREATE | EXTENSION_RETURN_NULL));

    targetseg = blkno / ((BlockNumber) RELSEG_SIZE);

    /* if an existing and opened segment, we're done */
    if (targetseg < reln->md_num_open_segs[forknum])
    {
        v = &reln->md_seg_fds[forknum][targetseg];
        return v;
    }

    /*
     * The target segment is not yet open. Iterate over all the segments
     * between the last opened and the target segment. This way missing
     * segments either raise an error, or get created (according to
     * 'behavior'). Start with either the last opened, or the first segment if
     * none was opened before.
     */
    if (reln->md_num_open_segs[forknum] > 0)
        v = &reln->md_seg_fds[forknum][reln->md_num_open_segs[forknum] - 1];
    else
    {
        v = mdopenfork(reln, forknum, behavior);
        if (!v)
            return NULL;        /* if behavior & EXTENSION_RETURN_NULL */
    }

    for (nextsegno = reln->md_num_open_segs[forknum];
         nextsegno <= targetseg; nextsegno++)
    {
        BlockNumber nblocks = _mdnblocks(reln, forknum, v);
        int         flags = 0;

        Assert(nextsegno == v->mdfd_segno + 1);

        if (nblocks > ((BlockNumber) RELSEG_SIZE))
            elog(FATAL, "segment too big");

        if ((behavior & EXTENSION_CREATE) ||
            (InRecovery && (behavior & EXTENSION_CREATE_RECOVERY)))
        {
            /*
             * Normally we will create new segments only if authorized by the
             * caller (i.e., we are doing mdextend()).  But when doing WAL
             * recovery, create segments anyway; this allows cases such as
             * replaying WAL data that has a write into a high-numbered
             * segment of a relation that was later deleted. We want to go
             * ahead and create the segments so we can finish out the replay.
             *
             * We have to maintain the invariant that segments before the last
             * active segment are of size RELSEG_SIZE; therefore, if
             * extending, pad them out with zeroes if needed.  (This only
             * matters if in recovery, or if the caller is extending the
             * relation discontiguously, but that can happen in hash indexes.)
             */
            if (nblocks < ((BlockNumber) RELSEG_SIZE))
            {
                char       *zerobuf = palloc0(BLCKSZ);

                mdextend(reln, forknum,
                         nextsegno * ((BlockNumber) RELSEG_SIZE) - 1,
                         zerobuf, skipFsync);
                pfree(zerobuf);
            }
            flags = O_CREAT;
        }
        else if (!(behavior & EXTENSION_DONT_CHECK_SIZE) &&
                 nblocks < ((BlockNumber) RELSEG_SIZE))
        {
            /*
             * When not extending (or explicitly including truncated
             * segments), only open the next segment if the current one is
             * exactly RELSEG_SIZE.  If not (this branch), either return NULL
             * or fail.
             */
            if (behavior & EXTENSION_RETURN_NULL)
            {
                /*
                 * Some callers discern between reasons for _mdfd_getseg()
                 * returning NULL based on errno. As there's no failing
                 * syscall involved in this case, explicitly set errno to
                 * ENOENT, as that seems the closest interpretation.
                 */
                errno = ENOENT;
                return NULL;
            }

            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not open file \"%s\" (target block %u): previous segment is only %u blocks",
                            _mdfd_segpath(reln, forknum, nextsegno),
                            blkno, nblocks)));
        }

        v = _mdfd_openseg(reln, forknum, nextsegno, flags);

        if (v == NULL)
        {
            if ((behavior & EXTENSION_RETURN_NULL) &&
                FILE_POSSIBLY_DELETED(errno))
                return NULL;
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not open file \"%s\" (target block %u): %m",
                            _mdfd_segpath(reln, forknum, nextsegno),
                            blkno)));
        }
    }

    return v;
}

_mdfd_openseg()

static MdfdVec * _mdfd_openseg ( SMgrRelation  reln, ForkNumber  forkno, BlockNumber  segno, int  oflags  )

static

Definition at line 1094 of file md.c.

References _fdvec_resize(), _mdfd_segpath(), _mdnblocks(), Assert, fd(), SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_segno, _MdfdVec::mdfd_vfd, PathNameOpenFile(), pfree(), and PG_BINARY.

Referenced by _mdfd_getseg(), and mdnblocks().

{
    MdfdVec    *v;
    int         fd;
    char       *fullpath;

    fullpath = _mdfd_segpath(reln, forknum, segno);

    /* open the file */
    fd = PathNameOpenFile(fullpath, O_RDWR | PG_BINARY | oflags);

    pfree(fullpath);

    if (fd < 0)
        return NULL;

    if (segno <= reln->md_num_open_segs[forknum])
        _fdvec_resize(reln, forknum, segno + 1);

    /* fill the entry */
    v = &reln->md_seg_fds[forknum][segno];
    v->mdfd_vfd = fd;
    v->mdfd_segno = segno;

    Assert(_mdnblocks(reln, forknum, v) <= ((BlockNumber) RELSEG_SIZE));

    /* all done */
    return v;
}

_mdfd_segpath()

static char * _mdfd_segpath ( SMgrRelation  reln, ForkNumber  forknum, BlockNumber  segno  )

static

Definition at line 1071 of file md.c.

References pfree(), psprintf(), relpath, and SMgrRelationData::smgr_rnode.

Referenced by _mdfd_getseg(), _mdfd_openseg(), and mdsyncfiletag().

{
    char       *path,
               *fullpath;

    path = relpath(reln->smgr_rnode, forknum);

    if (segno > 0)
    {
        fullpath = psprintf("%s.%u", path, segno);
        pfree(path);
    }
    else
        fullpath = path;

    return fullpath;
}

_mdnblocks()

static BlockNumber _mdnblocks ( SMgrRelation  reln, ForkNumber  forknum, MdfdVec *  seg  )

static

Definition at line 1259 of file md.c.

References ereport, errcode_for_file_access(), errmsg(), ERROR, FilePathName(), FileSize(), and _MdfdVec::mdfd_vfd.

Referenced by _mdfd_getseg(), _mdfd_openseg(), mdextend(), mdnblocks(), and mdopenfork().

{
    off_t       len;

    len = FileSize(seg->mdfd_vfd);
    if (len < 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not seek to end of file \"%s\": %m",
                        FilePathName(seg->mdfd_vfd))));
    /* note that this calculation will ignore any partial block at EOF */
    return (BlockNumber) (len / BLCKSZ);
}

DropRelationFiles()

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

Definition at line 1001 of file md.c.

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

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

{
    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);
}

ForgetDatabaseSyncRequests()

void ForgetDatabaseSyncRequests

(

Oid

dbid

)

Definition at line 983 of file md.c.

References RelFileNode::dbNode, INIT_MD_FILETAG, InvalidBlockNumber, InvalidForkNumber, RegisterSyncRequest(), RelFileNode::relNode, RelFileNode::spcNode, and SYNC_FILTER_REQUEST.

Referenced by dbase_redo(), and dropdb().

{
    FileTag     tag;
    RelFileNode rnode;

    rnode.dbNode = dbid;
    rnode.spcNode = 0;
    rnode.relNode = 0;

    INIT_MD_FILETAG(tag, rnode, InvalidForkNumber, InvalidBlockNumber);

    RegisterSyncRequest(&tag, SYNC_FILTER_REQUEST, true /* retryOnError */ );
}

mdclose()

void mdclose	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 506 of file md.c.

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

Referenced by mdexists().

{
    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];

        /* if not closed already */
        if (v->mdfd_vfd >= 0)
        {
            FileClose(v->mdfd_vfd);
            v->mdfd_vfd = -1;
        }

        nopensegs--;
    }

    /* resize just once, avoids pointless reallocations */
    _fdvec_resize(reln, forknum, 0);
}

mdcreate()

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

Definition at line 178 of file md.c.

References _fdvec_resize(), Assert, RelFileNode::dbNode, ereport, errcode_for_file_access(), errmsg(), ERROR, fd(), SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_segno, _MdfdVec::mdfd_vfd, RelFileNodeBackend::node, PathNameOpenFile(), pfree(), PG_BINARY, relpath, SMgrRelationData::smgr_rnode, RelFileNode::spcNode, and TablespaceCreateDbspace().

{
    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_rnode.node.spcNode,
                            reln->smgr_rnode.node.dbNode,
                            isRedo);

    path = relpath(reln->smgr_rnode, 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;
}

mdexists()

bool mdexists	(	SMgrRelation	reln,
		ForkNumber	forkNum
	)

Definition at line 161 of file md.c.

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

{
    /*
     * Close it first, to ensure that we notice if the fork has been unlinked
     * since we opened it.
     */
    mdclose(reln, forkNum);

    return (mdopenfork(reln, forkNum, EXTENSION_RETURN_NULL) != NULL);
}

mdextend()

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

Definition at line 388 of file md.c.

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_rnode, SmgrIsTemp, and WAIT_EVENT_DATA_FILE_EXTEND.

Referenced by _mdfd_getseg().

{
    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.
     */
    if (blocknum == InvalidBlockNumber)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("cannot extend file \"%s\" beyond %u blocks",
                        relpath(reln->smgr_rnode, 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));
}

mdfiletagmatches()

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

Definition at line 1330 of file md.c.

References RelFileNode::dbNode, and FileTag::rnode.

{
    /*
     * 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->rnode.dbNode == candidate->rnode.dbNode;
}

mdimmedsync()

void mdimmedsync	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 891 of file md.c.

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

{
    int         segno;

    /*
     * NOTE: mdnblocks makes sure we have opened all active segments, so that
     * fsync loop will get them all!
     */
    mdnblocks(reln, forknum);

    segno = reln->md_num_open_segs[forknum];

    while (segno > 0)
    {
        MdfdVec    *v = &reln->md_seg_fds[forknum][segno - 1];

        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))));
        segno--;
    }
}

mdinit()

void mdinit

(

void

)

Definition at line 148 of file md.c.

References ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, and TopMemoryContext.

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

mdnblocks()

BlockNumber mdnblocks	(	SMgrRelation	reln,
		ForkNumber	forknum
	)

Definition at line 739 of file md.c.

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().

{
    MdfdVec    *v = mdopenfork(reln, forknum, EXTENSION_FAIL);
    BlockNumber nblocks;
    BlockNumber segno = 0;

    /* 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);
    }
}

mdopen()

void mdopen

(

SMgrRelation

reln

)

Definition at line 495 of file md.c.

References MAX_FORKNUM, and SMgrRelationData::md_num_open_segs.

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

mdopenfork()

static MdfdVec * mdopenfork ( SMgrRelation  reln, ForkNumber  forknum, int  behavior  )

static

Definition at line 452 of file md.c.

References _fdvec_resize(), _mdnblocks(), Assert, ereport, errcode_for_file_access(), errmsg(), ERROR, EXTENSION_RETURN_NULL, fd(), FILE_POSSIBLY_DELETED, SMgrRelationData::md_num_open_segs, SMgrRelationData::md_seg_fds, _MdfdVec::mdfd_segno, _MdfdVec::mdfd_vfd, PathNameOpenFile(), pfree(), PG_BINARY, relpath, and SMgrRelationData::smgr_rnode.

Referenced by _mdfd_getseg(), mdexists(), and mdnblocks().

{
    MdfdVec    *mdfd;
    char       *path;
    File        fd;

    /* No work if already open */
    if (reln->md_num_open_segs[forknum] > 0)
        return &reln->md_seg_fds[forknum][0];

    path = relpath(reln->smgr_rnode, forknum);

    fd = PathNameOpenFile(path, O_RDWR | PG_BINARY);

    if (fd < 0)
    {
        if ((behavior & EXTENSION_RETURN_NULL) &&
            FILE_POSSIBLY_DELETED(errno))
        {
            pfree(path);
            return NULL;
        }
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open 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;

    Assert(_mdnblocks(reln, forknum, mdfd) <= ((BlockNumber) RELSEG_SIZE));

    return mdfd;
}

mdprefetch()

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

Definition at line 537 of file md.c.

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

{
#ifdef USE_PREFETCH
    off_t       seekpos;
    MdfdVec    *v;

    v = _mdfd_getseg(reln, forknum, blocknum, false, EXTENSION_FAIL);

    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 */
}

mdread()

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

Definition at line 609 of file md.c.

References _mdfd_getseg(), Assert, RelFileNodeBackend::backend, RelFileNode::dbNode, ereport, errcode(), ERRCODE_DATA_CORRUPTED, errcode_for_file_access(), errmsg(), ERROR, EXTENSION_CREATE_RECOVERY, EXTENSION_FAIL, FilePathName(), FileRead(), InRecovery, _MdfdVec::mdfd_vfd, MemSet, RelFileNodeBackend::node, RelFileNode::relNode, SMgrRelationData::smgr_rnode, RelFileNode::spcNode, WAIT_EVENT_DATA_FILE_READ, and zero_damaged_pages.

{
    off_t       seekpos;
    int         nbytes;
    MdfdVec    *v;

    TRACE_POSTGRESQL_SMGR_MD_READ_START(forknum, blocknum,
                                        reln->smgr_rnode.node.spcNode,
                                        reln->smgr_rnode.node.dbNode,
                                        reln->smgr_rnode.node.relNode,
                                        reln->smgr_rnode.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_rnode.node.spcNode,
                                       reln->smgr_rnode.node.dbNode,
                                       reln->smgr_rnode.node.relNode,
                                       reln->smgr_rnode.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)));
    }
}

mdsyncfiletag()

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

Definition at line 1280 of file md.c.

References _mdfd_getseg(), _mdfd_segpath(), EXTENSION_DONT_CHECK_SIZE, EXTENSION_RETURN_NULL, FileSync(), FileTag::forknum, InvalidBackendId, MAXPGPATH, _MdfdVec::mdfd_vfd, pfree(), FileTag::rnode, FileTag::segno, smgropen(), strlcpy(), and WAIT_EVENT_DATA_FILE_SYNC.

{
    SMgrRelation reln = smgropen(ftag->rnode, InvalidBackendId);
    MdfdVec    *v;
    char       *p;

    /* Provide the path for informational messages. */
    p = _mdfd_segpath(reln, ftag->forknum, ftag->segno);
    strlcpy(path, p, MAXPGPATH);
    pfree(p);

    /* Try to open the requested segment. */
    v = _mdfd_getseg(reln,
                     ftag->forknum,
                     ftag->segno * (BlockNumber) RELSEG_SIZE,
                     false,
                     EXTENSION_RETURN_NULL | EXTENSION_DONT_CHECK_SIZE);
    if (v == NULL)
        return -1;

    /* Try to fsync the file. */
    return FileSync(v->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC);
}

mdtruncate()

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

Definition at line 794 of file md.c.

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_rnode, SmgrIsTemp, and WAIT_EVENT_DATA_FILE_TRUNCATE.

{
    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_rnode, 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--;
    }
}

mdunlink()

void mdunlink	(	RelFileNodeBackend	rnode,
		ForkNumber	forkNum,
		bool	isRedo
	)

Definition at line 278 of file md.c.

References InvalidForkNumber, MAX_FORKNUM, and mdunlinkfork().

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

mdunlinkfiletag()

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

Definition at line 1311 of file md.c.

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

{
    char       *p;

    /* Compute the path. */
    p = relpathperm(ftag->rnode, MAIN_FORKNUM);
    strlcpy(path, p, MAXPGPATH);
    pfree(p);

    /* Try to unlink the file. */
    return unlink(path);
}

mdunlinkfork()

static void mdunlinkfork ( RelFileNodeBackend  rnode, ForkNumber  forkNum, bool  isRedo  )

static

Definition at line 291 of file md.c.

References CloseTransientFile(), ereport, errcode_for_file_access(), errmsg(), fd(), ftruncate, MAIN_FORKNUM, OpenTransientFile(), palloc(), pfree(), PG_BINARY, register_forget_request(), register_unlink_segment(), RelFileNodeBackendIsTemp, relpath, sprintf, and WARNING.

Referenced by mdunlink().

{
    char       *path;
    int         ret;

    path = relpath(rnode, forkNum);

    /*
     * Delete or truncate the first segment.
     */
    if (isRedo || forkNum != MAIN_FORKNUM || RelFileNodeBackendIsTemp(rnode))
    {
        /* First, forget any pending sync requests for the first segment */
        if (!RelFileNodeBackendIsTemp(rnode))
            register_forget_request(rnode, forkNum, 0 /* first seg */ );

        /* Next unlink the file */
        ret = unlink(path);
        if (ret < 0 && errno != ENOENT)
            ereport(WARNING,
                    (errcode_for_file_access(),
                     errmsg("could not remove file \"%s\": %m", path)));
    }
    else
    {
        /* truncate(2) would be easier here, but Windows hasn't got it */
        int         fd;

        fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
        if (fd >= 0)
        {
            int         save_errno;

            ret = ftruncate(fd, 0);
            save_errno = errno;
            CloseTransientFile(fd);
            errno = save_errno;
        }
        else
            ret = -1;
        if (ret < 0 && errno != ENOENT)
            ereport(WARNING,
                    (errcode_for_file_access(),
                     errmsg("could not truncate file \"%s\": %m", path)));

        /* Register request to unlink first segment later */
        register_unlink_segment(rnode, forkNum, 0 /* first seg */ );
    }

    /*
     * Delete any additional segments.
     */
    if (ret >= 0)
    {
        char       *segpath = (char *) palloc(strlen(path) + 12);
        BlockNumber segno;

        /*
         * Note that because we loop until getting ENOENT, we will correctly
         * remove all inactive segments as well as active ones.
         */
        for (segno = 1;; segno++)
        {
            /*
             * Forget any pending sync requests for this segment before we try
             * to unlink.
             */
            if (!RelFileNodeBackendIsTemp(rnode))
                register_forget_request(rnode, forkNum, segno);

            sprintf(segpath, "%s.%u", path, segno);
            if (unlink(segpath) < 0)
            {
                /* ENOENT is expected after the last segment... */
                if (errno != ENOENT)
                    ereport(WARNING,
                            (errcode_for_file_access(),
                             errmsg("could not remove file \"%s\": %m", segpath)));
                break;
            }
        }
        pfree(segpath);
    }

    pfree(path);
}

mdwrite()

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

Definition at line 674 of file md.c.

References _mdfd_getseg(), Assert, RelFileNodeBackend::backend, RelFileNode::dbNode, ereport, errcode(), errcode_for_file_access(), errhint(), errmsg(), ERROR, EXTENSION_CREATE_RECOVERY, EXTENSION_FAIL, FilePathName(), FileWrite(), _MdfdVec::mdfd_vfd, mdnblocks(), RelFileNodeBackend::node, register_dirty_segment(), RelFileNode::relNode, SMgrRelationData::smgr_rnode, SmgrIsTemp, RelFileNode::spcNode, and WAIT_EVENT_DATA_FILE_WRITE.

{
    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_rnode.node.spcNode,
                                         reln->smgr_rnode.node.dbNode,
                                         reln->smgr_rnode.node.relNode,
                                         reln->smgr_rnode.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_rnode.node.spcNode,
                                        reln->smgr_rnode.node.dbNode,
                                        reln->smgr_rnode.node.relNode,
                                        reln->smgr_rnode.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);
}

mdwriteback()

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

Definition at line 560 of file md.c.

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

{
    /*
     * 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_RETURN_NULL);

        /*
         * We might be flushing buffers of already removed relations, that's
         * ok, just ignore that case.
         */
        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;
    }
}

register_dirty_segment()

static void register_dirty_segment ( SMgrRelation  reln, ForkNumber  forknum, MdfdVec *  seg  )

static

Definition at line 926 of file md.c.

References Assert, data_sync_elevel(), DEBUG1, ereport, errcode_for_file_access(), errmsg(), ERROR, FilePathName(), FileSync(), INIT_MD_FILETAG, _MdfdVec::mdfd_segno, _MdfdVec::mdfd_vfd, RelFileNodeBackend::node, RegisterSyncRequest(), SMgrRelationData::smgr_rnode, SmgrIsTemp, SYNC_REQUEST, and WAIT_EVENT_DATA_FILE_SYNC.

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

{
    FileTag     tag;

    INIT_MD_FILETAG(tag, reln->smgr_rnode.node, forknum, seg->mdfd_segno);

    /* Temp relations should never be fsync'd */
    Assert(!SmgrIsTemp(reln));

    if (!RegisterSyncRequest(&tag, SYNC_REQUEST, false /* retryOnError */ ))
    {
        ereport(DEBUG1,
                (errmsg("could not forward fsync request because request queue is full")));

        if (FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) < 0)
            ereport(data_sync_elevel(ERROR),
                    (errcode_for_file_access(),
                     errmsg("could not fsync file \"%s\": %m",
                            FilePathName(seg->mdfd_vfd))));
    }
}

register_forget_request()

static void register_forget_request ( RelFileNodeBackend  rnode, ForkNumber  forknum, BlockNumber  segno  )

static

Definition at line 969 of file md.c.

References INIT_MD_FILETAG, RelFileNodeBackend::node, RegisterSyncRequest(), and SYNC_FORGET_REQUEST.

Referenced by mdunlinkfork().

{
    FileTag     tag;

    INIT_MD_FILETAG(tag, rnode.node, forknum, segno);

    RegisterSyncRequest(&tag, SYNC_FORGET_REQUEST, true /* retryOnError */ );
}

register_unlink_segment()

static void register_unlink_segment ( RelFileNodeBackend  rnode, ForkNumber  forknum, BlockNumber  segno  )

static

Definition at line 952 of file md.c.

References Assert, INIT_MD_FILETAG, RelFileNodeBackend::node, RegisterSyncRequest(), RelFileNodeBackendIsTemp, and SYNC_UNLINK_REQUEST.

Referenced by mdunlinkfork().

{
    FileTag     tag;

    INIT_MD_FILETAG(tag, rnode.node, forknum, segno);

    /* Should never be used with temp relations */
    Assert(!RelFileNodeBackendIsTemp(rnode));

    RegisterSyncRequest(&tag, SYNC_UNLINK_REQUEST, true /* retryOnError */ );
}

Variable Documentation

MdCxt

MemoryContext MdCxt

static

Definition at line 88 of file md.c.