Fix transient mdsync() errors of truncated relations due to 72a98a6395.

[postgresql] / src / backend / storage / smgr / md.c

diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 2981b414b53fab50e5290c86db57871c5c6b109d..f7c4311dec82b7c1503cffcb822f215ac27a5e21 100644 (file)
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -163,23 +163,29 @@ static CycleCtr mdsync_cycle_ctr = 0;
 static CycleCtr mdckpt_cycle_ctr = 0;
 
 
-typedef enum                                   /* behavior for mdopen & _mdfd_getseg */
-{
-       /* ereport if segment not present, create in recovery */
-       EXTENSION_FAIL,
-       /* return NULL if not present, create in recovery */
-       EXTENSION_RETURN_NULL,
-       /* return NULL if not present */
-       EXTENSION_REALLY_RETURN_NULL,
-       /* create new segments as needed */
-       EXTENSION_CREATE
-} ExtensionBehavior;
+/*** behavior for mdopen & _mdfd_getseg ***/
+/* ereport if segment not present */
+#define EXTENSION_FAIL                         (1 << 0)
+/* return NULL if segment not present */
+#define EXTENSION_RETURN_NULL          (1 << 1)
+/* create new segments as needed */
+#define EXTENSION_CREATE                       (1 << 2)
+/* create new segments if needed during recovery */
+#define EXTENSION_CREATE_RECOVERY      (1 << 3)
+/*
+ * Allow opening segments which are preceded by segments smaller than
+ * RELSEG_SIZE, e.g. inactive segments (see above). Note that this is breaks
+ * mdnblocks() and related functionality henceforth - which currently is ok,
+ * because this is only required in the checkpointer which never uses
+ * mdnblocks().
+ */
+#define EXTENSION_DONT_CHECK_SIZE      (1 << 4)
+
 
 /* local routines */
 static void mdunlinkfork(RelFileNodeBackend rnode, ForkNumber forkNum,
                         bool isRedo);
-static MdfdVec *mdopen(SMgrRelation reln, ForkNumber forknum,
-          ExtensionBehavior behavior);
+static MdfdVec *mdopen(SMgrRelation reln, ForkNumber forknum, int behavior);
 static void register_dirty_segment(SMgrRelation reln, ForkNumber forknum,
                                           MdfdVec *seg);
 static void register_unlink(RelFileNodeBackend rnode);
@@ -189,7 +195,7 @@ static char *_mdfd_segpath(SMgrRelation reln, ForkNumber forknum,
 static MdfdVec *_mdfd_openseg(SMgrRelation reln, ForkNumber forkno,
                          BlockNumber segno, int oflags);
 static MdfdVec *_mdfd_getseg(SMgrRelation reln, ForkNumber forkno,
-                        BlockNumber blkno, bool skipFsync, ExtensionBehavior behavior);
+                        BlockNumber blkno, bool skipFsync, int behavior);
 static BlockNumber _mdnblocks(SMgrRelation reln, ForkNumber forknum,
                   MdfdVec *seg);
 
@@ -570,7 +576,7 @@ mdextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
  * invent one out of whole cloth.
  */
 static MdfdVec *
-mdopen(SMgrRelation reln, ForkNumber forknum, ExtensionBehavior behavior)
+mdopen(SMgrRelation reln, ForkNumber forknum, int behavior)
 {
        MdfdVec    *mdfd;
        char       *path;
@@ -596,8 +602,7 @@ mdopen(SMgrRelation reln, ForkNumber forknum, ExtensionBehavior behavior)
                        fd = PathNameOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, 0600);
                if (fd < 0)
                {
-                       if ((behavior == EXTENSION_RETURN_NULL ||
-                                behavior == EXTENSION_REALLY_RETURN_NULL) &&
+                       if ((behavior & EXTENSION_RETURN_NULL) &&
                                FILE_POSSIBLY_DELETED(errno))
                        {
                                pfree(path);
@@ -690,8 +695,8 @@ mdwriteback(SMgrRelation reln, ForkNumber forknum,
                int                     segnum_start,
                                        segnum_end;
 
-               v = _mdfd_getseg(reln, forknum, blocknum, false,
-                                                EXTENSION_REALLY_RETURN_NULL);
+               v = _mdfd_getseg(reln, forknum, blocknum, true /* not used */ ,
+                                                EXTENSION_RETURN_NULL);
 
                /*
                 * We might be flushing buffers of already removed relations, that's
@@ -737,7 +742,8 @@ mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
                                                                                reln->smgr_rnode.node.relNode,
                                                                                reln->smgr_rnode.backend);
 
-       v = _mdfd_getseg(reln, forknum, blocknum, false, EXTENSION_FAIL);
+       v = _mdfd_getseg(reln, forknum, blocknum, false,
+                                        EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
 
        seekpos = (off_t) BLCKSZ *(blocknum % ((BlockNumber) RELSEG_SIZE));
 
@@ -812,7 +818,8 @@ mdwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
                                                                                 reln->smgr_rnode.node.relNode,
                                                                                 reln->smgr_rnode.backend);
 
-       v = _mdfd_getseg(reln, forknum, blocknum, skipFsync, EXTENSION_FAIL);
+       v = _mdfd_getseg(reln, forknum, blocknum, skipFsync,
+                                        EXTENSION_FAIL | EXTENSION_CREATE_RECOVERY);
 
        seekpos = (off_t) BLCKSZ *(blocknum % ((BlockNumber) RELSEG_SIZE));
 
@@ -1219,7 +1226,9 @@ mdsync(void)
                                        /* Attempt to open and fsync the target segment */
                                        seg = _mdfd_getseg(reln, forknum,
                                                         (BlockNumber) segno * (BlockNumber) RELSEG_SIZE,
-                                                                          false, EXTENSION_RETURN_NULL);
+                                                                          false,
+                                                                          EXTENSION_RETURN_NULL
+                                                                          | EXTENSION_DONT_CHECK_SIZE);
 
                                        INSTR_TIME_SET_CURRENT(sync_start);
 
@@ -1773,14 +1782,18 @@ _mdfd_openseg(SMgrRelation reln, ForkNumber forknum, BlockNumber segno,
  */
 static MdfdVec *
 _mdfd_getseg(SMgrRelation reln, ForkNumber forknum, BlockNumber blkno,
-                        bool skipFsync, ExtensionBehavior behavior)
+                        bool skipFsync, int behavior)
 {
        MdfdVec    *v = mdopen(reln, forknum, behavior);
        BlockNumber targetseg;
        BlockNumber nextsegno;
 
+       /* some way to handle non-existant segments needs to be specified */
+       Assert(behavior &
+                  (EXTENSION_FAIL | EXTENSION_CREATE | EXTENSION_RETURN_NULL));
+
        if (!v)
-               return NULL;                    /* if EXTENSION_(REALLY_)RETURN_NULL */
+               return NULL;                    /* if behavior & EXTENSION_RETURN_NULL */
 
        targetseg = blkno / ((BlockNumber) RELSEG_SIZE);
        for (nextsegno = 1; nextsegno <= targetseg; nextsegno++)
@@ -1795,8 +1808,8 @@ _mdfd_getseg(SMgrRelation reln, ForkNumber forknum, BlockNumber blkno,
                        if (nblocks > ((BlockNumber) RELSEG_SIZE))
                                elog(FATAL, "segment too big");
 
-                       if (behavior == EXTENSION_CREATE ||
-                               (InRecovery && behavior != EXTENSION_REALLY_RETURN_NULL))
+                       if ((behavior & EXTENSION_CREATE) ||
+                               (InRecovery && (behavior & EXTENSION_CREATE_RECOVERY)))
                        {
                                /*
                                 * Normally we will create new segments only if authorized by
@@ -1827,15 +1840,16 @@ _mdfd_getseg(SMgrRelation reln, ForkNumber forknum, BlockNumber blkno,
                                }
                                flags = O_CREAT;
                        }
-                       else if (nblocks < ((BlockNumber) RELSEG_SIZE))
+                       else if (!(behavior & EXTENSION_DONT_CHECK_SIZE) &&
+                                        nblocks < ((BlockNumber) RELSEG_SIZE))
                        {
                                /*
-                                * When not extending, only open the next segment if the
-                                * current one is exactly RELSEG_SIZE.  If not (this branch),
-                                * either return NULL or fail.
+                                * 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 ||
-                                       behavior == EXTENSION_REALLY_RETURN_NULL)
+                               if (behavior & EXTENSION_RETURN_NULL)
                                {
                                        /*
                                         * Some callers discern between reasons for _mdfd_getseg()
@@ -1858,8 +1872,7 @@ _mdfd_getseg(SMgrRelation reln, ForkNumber forknum, BlockNumber blkno,
 
                        if (v->mdfd_chain == NULL)
                        {
-                               if ((behavior == EXTENSION_RETURN_NULL ||
-                                        behavior == EXTENSION_REALLY_RETURN_NULL) &&
+                               if ((behavior & EXTENSION_RETURN_NULL) &&
                                        FILE_POSSIBLY_DELETED(errno))
                                        return NULL;
                                ereport(ERROR,