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md.c
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1 /*-------------------------------------------------------------------------
2  *
3  * md.c
4  * This code manages relations that reside on magnetic disk.
5  *
6  * Or at least, that was what the Berkeley folk had in mind when they named
7  * this file. In reality, what this code provides is an interface from
8  * the smgr API to Unix-like filesystem APIs, so it will work with any type
9  * of device for which the operating system provides filesystem support.
10  * It doesn't matter whether the bits are on spinning rust or some other
11  * storage technology.
12  *
13  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
14  * Portions Copyright (c) 1994, Regents of the University of California
15  *
16  *
17  * IDENTIFICATION
18  * src/backend/storage/smgr/md.c
19  *
20  *-------------------------------------------------------------------------
21  */
22 #include "postgres.h"
23 
24 #include <unistd.h>
25 #include <fcntl.h>
26 #include <sys/file.h>
27 
28 #include "access/xlogutils.h"
29 #include "commands/tablespace.h"
30 #include "common/file_utils.h"
31 #include "miscadmin.h"
32 #include "pg_trace.h"
33 #include "pgstat.h"
34 #include "storage/bufmgr.h"
35 #include "storage/fd.h"
36 #include "storage/md.h"
37 #include "storage/relfilelocator.h"
38 #include "storage/smgr.h"
39 #include "storage/sync.h"
40 #include "utils/memutils.h"
41 
42 /*
43  * The magnetic disk storage manager keeps track of open file
44  * descriptors in its own descriptor pool. This is done to make it
45  * easier to support relations that are larger than the operating
46  * system's file size limit (often 2GBytes). In order to do that,
47  * we break relations up into "segment" files that are each shorter than
48  * the OS file size limit. The segment size is set by the RELSEG_SIZE
49  * configuration constant in pg_config.h.
50  *
51  * On disk, a relation must consist of consecutively numbered segment
52  * files in the pattern
53  * -- Zero or more full segments of exactly RELSEG_SIZE blocks each
54  * -- Exactly one partial segment of size 0 <= size < RELSEG_SIZE blocks
55  * -- Optionally, any number of inactive segments of size 0 blocks.
56  * The full and partial segments are collectively the "active" segments.
57  * Inactive segments are those that once contained data but are currently
58  * not needed because of an mdtruncate() operation. The reason for leaving
59  * them present at size zero, rather than unlinking them, is that other
60  * backends and/or the checkpointer might be holding open file references to
61  * such segments. If the relation expands again after mdtruncate(), such
62  * that a deactivated segment becomes active again, it is important that
63  * such file references still be valid --- else data might get written
64  * out to an unlinked old copy of a segment file that will eventually
65  * disappear.
66  *
67  * File descriptors are stored in the per-fork md_seg_fds arrays inside
68  * SMgrRelation. The length of these arrays is stored in md_num_open_segs.
69  * Note that a fork's md_num_open_segs having a specific value does not
70  * necessarily mean the relation doesn't have additional segments; we may
71  * just not have opened the next segment yet. (We could not have "all
72  * segments are in the array" as an invariant anyway, since another backend
73  * could extend the relation while we aren't looking.) We do not have
74  * entries for inactive segments, however; as soon as we find a partial
75  * segment, we assume that any subsequent segments are inactive.
76  *
77  * The entire MdfdVec array is palloc'd in the MdCxt memory context.
78  */
79 
80 typedef struct _MdfdVec
81 {
82  File mdfd_vfd; /* fd number in fd.c's pool */
83  BlockNumber mdfd_segno; /* segment number, from 0 */
85 
86 static MemoryContext MdCxt; /* context for all MdfdVec objects */
87 
88 
89 /* Populate a file tag describing an md.c segment file. */
90 #define INIT_MD_FILETAG(a,xx_rlocator,xx_forknum,xx_segno) \
91 ( \
92  memset(&(a), 0, sizeof(FileTag)), \
93  (a).handler = SYNC_HANDLER_MD, \
94  (a).rlocator = (xx_rlocator), \
95  (a).forknum = (xx_forknum), \
96  (a).segno = (xx_segno) \
97 )
98 
99 
100 /*** behavior for mdopen & _mdfd_getseg ***/
101 /* ereport if segment not present */
102 #define EXTENSION_FAIL (1 << 0)
103 /* return NULL if segment not present */
104 #define EXTENSION_RETURN_NULL (1 << 1)
105 /* create new segments as needed */
106 #define EXTENSION_CREATE (1 << 2)
107 /* create new segments if needed during recovery */
108 #define EXTENSION_CREATE_RECOVERY (1 << 3)
109 /*
110  * Allow opening segments which are preceded by segments smaller than
111  * RELSEG_SIZE, e.g. inactive segments (see above). Note that this breaks
112  * mdnblocks() and related functionality henceforth - which currently is ok,
113  * because this is only required in the checkpointer which never uses
114  * mdnblocks().
115  */
116 #define EXTENSION_DONT_CHECK_SIZE (1 << 4)
117 /* don't try to open a segment, if not already open */
118 #define EXTENSION_DONT_OPEN (1 << 5)
119 
120 
121 /* local routines */
122 static void mdunlinkfork(RelFileLocatorBackend rlocator, ForkNumber forknum,
123  bool isRedo);
124 static MdfdVec *mdopenfork(SMgrRelation reln, ForkNumber forknum, int behavior);
125 static void register_dirty_segment(SMgrRelation reln, ForkNumber forknum,
126  MdfdVec *seg);
127 static void register_unlink_segment(RelFileLocatorBackend rlocator, ForkNumber forknum,
128  BlockNumber segno);
129 static void register_forget_request(RelFileLocatorBackend rlocator, ForkNumber forknum,
130  BlockNumber segno);
131 static void _fdvec_resize(SMgrRelation reln,
132  ForkNumber forknum,
133  int nseg);
134 static char *_mdfd_segpath(SMgrRelation reln, ForkNumber forknum,
135  BlockNumber segno);
136 static MdfdVec *_mdfd_openseg(SMgrRelation reln, ForkNumber forknum,
137  BlockNumber segno, int oflags);
138 static MdfdVec *_mdfd_getseg(SMgrRelation reln, ForkNumber forknum,
139  BlockNumber blkno, bool skipFsync, int behavior);
140 static BlockNumber _mdnblocks(SMgrRelation reln, ForkNumber forknum,
141  MdfdVec *seg);
142 
143 static inline int
145 {
146  int flags = O_RDWR | PG_BINARY;
147 
149  flags |= PG_O_DIRECT;
150 
151  return flags;
152 }
153 
154 /*
155  * mdinit() -- Initialize private state for magnetic disk storage manager.
156  */
157 void
158 mdinit(void)
159 {
161  "MdSmgr",
163 }
164 
165 /*
166  * mdexists() -- Does the physical file exist?
167  *
168  * Note: this will return true for lingering files, with pending deletions
169  */
170 bool
172 {
173  /*
174  * Close it first, to ensure that we notice if the fork has been unlinked
175  * since we opened it. As an optimization, we can skip that in recovery,
176  * which already closes relations when dropping them.
177  */
178  if (!InRecovery)
179  mdclose(reln, forknum);
180 
181  return (mdopenfork(reln, forknum, EXTENSION_RETURN_NULL) != NULL);
182 }
183 
184 /*
185  * mdcreate() -- Create a new relation on magnetic disk.
186  *
187  * If isRedo is true, it's okay for the relation to exist already.
188  */
189 void
190 mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)
191 {
192  MdfdVec *mdfd;
193  char *path;
194  File fd;
195 
196  if (isRedo && reln->md_num_open_segs[forknum] > 0)
197  return; /* created and opened already... */
198 
199  Assert(reln->md_num_open_segs[forknum] == 0);
200 
201  /*
202  * We may be using the target table space for the first time in this
203  * database, so create a per-database subdirectory if needed.
204  *
205  * XXX this is a fairly ugly violation of module layering, but this seems
206  * to be the best place to put the check. Maybe TablespaceCreateDbspace
207  * should be here and not in commands/tablespace.c? But that would imply
208  * importing a lot of stuff that smgr.c oughtn't know, either.
209  */
212  isRedo);
213 
214  path = relpath(reln->smgr_rlocator, forknum);
215 
216  fd = PathNameOpenFile(path, _mdfd_open_flags() | O_CREAT | O_EXCL);
217 
218  if (fd < 0)
219  {
220  int save_errno = errno;
221 
222  if (isRedo)
224  if (fd < 0)
225  {
226  /* be sure to report the error reported by create, not open */
227  errno = save_errno;
228  ereport(ERROR,
230  errmsg("could not create file \"%s\": %m", path)));
231  }
232  }
233 
234  pfree(path);
235 
236  _fdvec_resize(reln, forknum, 1);
237  mdfd = &reln->md_seg_fds[forknum][0];
238  mdfd->mdfd_vfd = fd;
239  mdfd->mdfd_segno = 0;
240 
241  if (!SmgrIsTemp(reln))
242  register_dirty_segment(reln, forknum, mdfd);
243 }
244 
245 /*
246  * mdunlink() -- Unlink a relation.
247  *
248  * Note that we're passed a RelFileLocatorBackend --- by the time this is called,
249  * there won't be an SMgrRelation hashtable entry anymore.
250  *
251  * forknum can be a fork number to delete a specific fork, or InvalidForkNumber
252  * to delete all forks.
253  *
254  * For regular relations, we don't unlink the first segment file of the rel,
255  * but just truncate it to zero length, and record a request to unlink it after
256  * the next checkpoint. Additional segments can be unlinked immediately,
257  * however. Leaving the empty file in place prevents that relfilenumber
258  * from being reused. The scenario this protects us from is:
259  * 1. We delete a relation (and commit, and actually remove its file).
260  * 2. We create a new relation, which by chance gets the same relfilenumber as
261  * the just-deleted one (OIDs must've wrapped around for that to happen).
262  * 3. We crash before another checkpoint occurs.
263  * During replay, we would delete the file and then recreate it, which is fine
264  * if the contents of the file were repopulated by subsequent WAL entries.
265  * But if we didn't WAL-log insertions, but instead relied on fsyncing the
266  * file after populating it (as we do at wal_level=minimal), the contents of
267  * the file would be lost forever. By leaving the empty file until after the
268  * next checkpoint, we prevent reassignment of the relfilenumber until it's
269  * safe, because relfilenumber assignment skips over any existing file.
270  *
271  * Additional segments, if any, are truncated and then unlinked. The reason
272  * for truncating is that other backends may still hold open FDs for these at
273  * the smgr level, so that the kernel can't remove the file yet. We want to
274  * reclaim the disk space right away despite that.
275  *
276  * We do not need to go through this dance for temp relations, though, because
277  * we never make WAL entries for temp rels, and so a temp rel poses no threat
278  * to the health of a regular rel that has taken over its relfilenumber.
279  * The fact that temp rels and regular rels have different file naming
280  * patterns provides additional safety. Other backends shouldn't have open
281  * FDs for them, either.
282  *
283  * We also don't do it while performing a binary upgrade. There is no reuse
284  * hazard in that case, since after a crash or even a simple ERROR, the
285  * upgrade fails and the whole cluster must be recreated from scratch.
286  * Furthermore, it is important to remove the files from disk immediately,
287  * because we may be about to reuse the same relfilenumber.
288  *
289  * All the above applies only to the relation's main fork; other forks can
290  * just be removed immediately, since they are not needed to prevent the
291  * relfilenumber from being recycled. Also, we do not carefully
292  * track whether other forks have been created or not, but just attempt to
293  * unlink them unconditionally; so we should never complain about ENOENT.
294  *
295  * If isRedo is true, it's unsurprising for the relation to be already gone.
296  * Also, we should remove the file immediately instead of queuing a request
297  * for later, since during redo there's no possibility of creating a
298  * conflicting relation.
299  *
300  * Note: we currently just never warn about ENOENT at all. We could warn in
301  * the main-fork, non-isRedo case, but it doesn't seem worth the trouble.
302  *
303  * Note: any failure should be reported as WARNING not ERROR, because
304  * we are usually not in a transaction anymore when this is called.
305  */
306 void
307 mdunlink(RelFileLocatorBackend rlocator, ForkNumber forknum, bool isRedo)
308 {
309  /* Now do the per-fork work */
310  if (forknum == InvalidForkNumber)
311  {
312  for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
313  mdunlinkfork(rlocator, forknum, isRedo);
314  }
315  else
316  mdunlinkfork(rlocator, forknum, isRedo);
317 }
318 
319 /*
320  * Truncate a file to release disk space.
321  */
322 static int
323 do_truncate(const char *path)
324 {
325  int save_errno;
326  int ret;
327 
328  ret = pg_truncate(path, 0);
329 
330  /* Log a warning here to avoid repetition in callers. */
331  if (ret < 0 && errno != ENOENT)
332  {
333  save_errno = errno;
336  errmsg("could not truncate file \"%s\": %m", path)));
337  errno = save_errno;
338  }
339 
340  return ret;
341 }
342 
343 static void
344 mdunlinkfork(RelFileLocatorBackend rlocator, ForkNumber forknum, bool isRedo)
345 {
346  char *path;
347  int ret;
348  int save_errno;
349 
350  path = relpath(rlocator, forknum);
351 
352  /*
353  * Truncate and then unlink the first segment, or just register a request
354  * to unlink it later, as described in the comments for mdunlink().
355  */
356  if (isRedo || IsBinaryUpgrade || forknum != MAIN_FORKNUM ||
357  RelFileLocatorBackendIsTemp(rlocator))
358  {
359  if (!RelFileLocatorBackendIsTemp(rlocator))
360  {
361  /* Prevent other backends' fds from holding on to the disk space */
362  ret = do_truncate(path);
363 
364  /* Forget any pending sync requests for the first segment */
365  save_errno = errno;
366  register_forget_request(rlocator, forknum, 0 /* first seg */ );
367  errno = save_errno;
368  }
369  else
370  ret = 0;
371 
372  /* Next unlink the file, unless it was already found to be missing */
373  if (ret >= 0 || errno != ENOENT)
374  {
375  ret = unlink(path);
376  if (ret < 0 && errno != ENOENT)
377  {
378  save_errno = errno;
381  errmsg("could not remove file \"%s\": %m", path)));
382  errno = save_errno;
383  }
384  }
385  }
386  else
387  {
388  /* Prevent other backends' fds from holding on to the disk space */
389  ret = do_truncate(path);
390 
391  /* Register request to unlink first segment later */
392  save_errno = errno;
393  register_unlink_segment(rlocator, forknum, 0 /* first seg */ );
394  errno = save_errno;
395  }
396 
397  /*
398  * Delete any additional segments.
399  *
400  * Note that because we loop until getting ENOENT, we will correctly
401  * remove all inactive segments as well as active ones. Ideally we'd
402  * continue the loop until getting exactly that errno, but that risks an
403  * infinite loop if the problem is directory-wide (for instance, if we
404  * suddenly can't read the data directory itself). We compromise by
405  * continuing after a non-ENOENT truncate error, but stopping after any
406  * unlink error. If there is indeed a directory-wide problem, additional
407  * unlink attempts wouldn't work anyway.
408  */
409  if (ret >= 0 || errno != ENOENT)
410  {
411  char *segpath = (char *) palloc(strlen(path) + 12);
412  BlockNumber segno;
413 
414  for (segno = 1;; segno++)
415  {
416  sprintf(segpath, "%s.%u", path, segno);
417 
418  if (!RelFileLocatorBackendIsTemp(rlocator))
419  {
420  /*
421  * Prevent other backends' fds from holding on to the disk
422  * space. We're done if we see ENOENT, though.
423  */
424  if (do_truncate(segpath) < 0 && errno == ENOENT)
425  break;
426 
427  /*
428  * Forget any pending sync requests for this segment before we
429  * try to unlink.
430  */
431  register_forget_request(rlocator, forknum, segno);
432  }
433 
434  if (unlink(segpath) < 0)
435  {
436  /* ENOENT is expected after the last segment... */
437  if (errno != ENOENT)
440  errmsg("could not remove file \"%s\": %m", segpath)));
441  break;
442  }
443  }
444  pfree(segpath);
445  }
446 
447  pfree(path);
448 }
449 
450 /*
451  * mdextend() -- Add a block to the specified relation.
452  *
453  * The semantics are nearly the same as mdwrite(): write at the
454  * specified position. However, this is to be used for the case of
455  * extending a relation (i.e., blocknum is at or beyond the current
456  * EOF). Note that we assume writing a block beyond current EOF
457  * causes intervening file space to become filled with zeroes.
458  */
459 void
460 mdextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
461  const void *buffer, bool skipFsync)
462 {
463  off_t seekpos;
464  int nbytes;
465  MdfdVec *v;
466 
467  /* If this build supports direct I/O, the buffer must be I/O aligned. */
468  if (PG_O_DIRECT != 0 && PG_IO_ALIGN_SIZE <= BLCKSZ)
469  Assert((uintptr_t) buffer == TYPEALIGN(PG_IO_ALIGN_SIZE, buffer));
470 
471  /* This assert is too expensive to have on normally ... */
472 #ifdef CHECK_WRITE_VS_EXTEND
473  Assert(blocknum >= mdnblocks(reln, forknum));
474 #endif
475 
476  /*
477  * If a relation manages to grow to 2^32-1 blocks, refuse to extend it any
478  * more --- we mustn't create a block whose number actually is
479  * InvalidBlockNumber. (Note that this failure should be unreachable
480  * because of upstream checks in bufmgr.c.)
481  */
482  if (blocknum == InvalidBlockNumber)
483  ereport(ERROR,
484  (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
485  errmsg("cannot extend file \"%s\" beyond %u blocks",
486  relpath(reln->smgr_rlocator, forknum),
488 
489  v = _mdfd_getseg(reln, forknum, blocknum, skipFsync, EXTENSION_CREATE);
490 
491  seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
492 
493  Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
494 
495  if ((nbytes = FileWrite(v->mdfd_vfd, buffer, BLCKSZ, seekpos, WAIT_EVENT_DATA_FILE_EXTEND)) != BLCKSZ)
496  {
497  if (nbytes < 0)
498  ereport(ERROR,
500  errmsg("could not extend file \"%s\": %m",
501  FilePathName(v->mdfd_vfd)),
502  errhint("Check free disk space.")));
503  /* short write: complain appropriately */
504  ereport(ERROR,
505  (errcode(ERRCODE_DISK_FULL),
506  errmsg("could not extend file \"%s\": wrote only %d of %d bytes at block %u",
508  nbytes, BLCKSZ, blocknum),
509  errhint("Check free disk space.")));
510  }
511 
512  if (!skipFsync && !SmgrIsTemp(reln))
513  register_dirty_segment(reln, forknum, v);
514 
515  Assert(_mdnblocks(reln, forknum, v) <= ((BlockNumber) RELSEG_SIZE));
516 }
517 
518 /*
519  * mdzeroextend() -- Add new zeroed out blocks to the specified relation.
520  *
521  * Similar to mdextend(), except the relation can be extended by multiple
522  * blocks at once and the added blocks will be filled with zeroes.
523  */
524 void
526  BlockNumber blocknum, int nblocks, bool skipFsync)
527 {
528  MdfdVec *v;
529  BlockNumber curblocknum = blocknum;
530  int remblocks = nblocks;
531 
532  Assert(nblocks > 0);
533 
534  /* This assert is too expensive to have on normally ... */
535 #ifdef CHECK_WRITE_VS_EXTEND
536  Assert(blocknum >= mdnblocks(reln, forknum));
537 #endif
538 
539  /*
540  * If a relation manages to grow to 2^32-1 blocks, refuse to extend it any
541  * more --- we mustn't create a block whose number actually is
542  * InvalidBlockNumber or larger.
543  */
544  if ((uint64) blocknum + nblocks >= (uint64) InvalidBlockNumber)
545  ereport(ERROR,
546  (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
547  errmsg("cannot extend file \"%s\" beyond %u blocks",
548  relpath(reln->smgr_rlocator, forknum),
550 
551  while (remblocks > 0)
552  {
553  BlockNumber segstartblock = curblocknum % ((BlockNumber) RELSEG_SIZE);
554  off_t seekpos = (off_t) BLCKSZ * segstartblock;
555  int numblocks;
556 
557  if (segstartblock + remblocks > RELSEG_SIZE)
558  numblocks = RELSEG_SIZE - segstartblock;
559  else
560  numblocks = remblocks;
561 
562  v = _mdfd_getseg(reln, forknum, curblocknum, skipFsync, EXTENSION_CREATE);
563 
564  Assert(segstartblock < RELSEG_SIZE);
565  Assert(segstartblock + numblocks <= RELSEG_SIZE);
566 
567  /*
568  * If available and useful, use posix_fallocate() (via
569  * FileFallocate()) to extend the relation. That's often more
570  * efficient than using write(), as it commonly won't cause the kernel
571  * to allocate page cache space for the extended pages.
572  *
573  * However, we don't use FileFallocate() for small extensions, as it
574  * defeats delayed allocation on some filesystems. Not clear where
575  * that decision should be made though? For now just use a cutoff of
576  * 8, anything between 4 and 8 worked OK in some local testing.
577  */
578  if (numblocks > 8)
579  {
580  int ret;
581 
582  ret = FileFallocate(v->mdfd_vfd,
583  seekpos, (off_t) BLCKSZ * numblocks,
584  WAIT_EVENT_DATA_FILE_EXTEND);
585  if (ret != 0)
586  {
587  ereport(ERROR,
589  errmsg("could not extend file \"%s\" with FileFallocate(): %m",
590  FilePathName(v->mdfd_vfd)),
591  errhint("Check free disk space."));
592  }
593  }
594  else
595  {
596  int ret;
597 
598  /*
599  * Even if we don't want to use fallocate, we can still extend a
600  * bit more efficiently than writing each 8kB block individually.
601  * pg_pwrite_zeros() (via FileZero()) uses pg_pwritev_with_retry()
602  * to avoid multiple writes or needing a zeroed buffer for the
603  * whole length of the extension.
604  */
605  ret = FileZero(v->mdfd_vfd,
606  seekpos, (off_t) BLCKSZ * numblocks,
607  WAIT_EVENT_DATA_FILE_EXTEND);
608  if (ret < 0)
609  ereport(ERROR,
611  errmsg("could not extend file \"%s\": %m",
612  FilePathName(v->mdfd_vfd)),
613  errhint("Check free disk space."));
614  }
615 
616  if (!skipFsync && !SmgrIsTemp(reln))
617  register_dirty_segment(reln, forknum, v);
618 
619  Assert(_mdnblocks(reln, forknum, v) <= ((BlockNumber) RELSEG_SIZE));
620 
621  remblocks -= numblocks;
622  curblocknum += numblocks;
623  }
624 }
625 
626 /*
627  * mdopenfork() -- Open one fork of the specified relation.
628  *
629  * Note we only open the first segment, when there are multiple segments.
630  *
631  * If first segment is not present, either ereport or return NULL according
632  * to "behavior". We treat EXTENSION_CREATE the same as EXTENSION_FAIL;
633  * EXTENSION_CREATE means it's OK to extend an existing relation, not to
634  * invent one out of whole cloth.
635  */
636 static MdfdVec *
637 mdopenfork(SMgrRelation reln, ForkNumber forknum, int behavior)
638 {
639  MdfdVec *mdfd;
640  char *path;
641  File fd;
642 
643  /* No work if already open */
644  if (reln->md_num_open_segs[forknum] > 0)
645  return &reln->md_seg_fds[forknum][0];
646 
647  path = relpath(reln->smgr_rlocator, forknum);
648 
650 
651  if (fd < 0)
652  {
653  if ((behavior & EXTENSION_RETURN_NULL) &&
654  FILE_POSSIBLY_DELETED(errno))
655  {
656  pfree(path);
657  return NULL;
658  }
659  ereport(ERROR,
661  errmsg("could not open file \"%s\": %m", path)));
662  }
663 
664  pfree(path);
665 
666  _fdvec_resize(reln, forknum, 1);
667  mdfd = &reln->md_seg_fds[forknum][0];
668  mdfd->mdfd_vfd = fd;
669  mdfd->mdfd_segno = 0;
670 
671  Assert(_mdnblocks(reln, forknum, mdfd) <= ((BlockNumber) RELSEG_SIZE));
672 
673  return mdfd;
674 }
675 
676 /*
677  * mdopen() -- Initialize newly-opened relation.
678  */
679 void
681 {
682  /* mark it not open */
683  for (int forknum = 0; forknum <= MAX_FORKNUM; forknum++)
684  reln->md_num_open_segs[forknum] = 0;
685 }
686 
687 /*
688  * mdclose() -- Close the specified relation, if it isn't closed already.
689  */
690 void
692 {
693  int nopensegs = reln->md_num_open_segs[forknum];
694 
695  /* No work if already closed */
696  if (nopensegs == 0)
697  return;
698 
699  /* close segments starting from the end */
700  while (nopensegs > 0)
701  {
702  MdfdVec *v = &reln->md_seg_fds[forknum][nopensegs - 1];
703 
704  FileClose(v->mdfd_vfd);
705  _fdvec_resize(reln, forknum, nopensegs - 1);
706  nopensegs--;
707  }
708 }
709 
710 /*
711  * mdprefetch() -- Initiate asynchronous read of the specified blocks of a relation
712  */
713 bool
715  int nblocks)
716 {
717 #ifdef USE_PREFETCH
718 
720 
721  if ((uint64) blocknum + nblocks > (uint64) MaxBlockNumber + 1)
722  return false;
723 
724  while (nblocks > 0)
725  {
726  off_t seekpos;
727  MdfdVec *v;
728  int nblocks_this_segment;
729 
730  v = _mdfd_getseg(reln, forknum, blocknum, false,
732  if (v == NULL)
733  return false;
734 
735  seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
736 
737  Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
738 
739  nblocks_this_segment =
740  Min(nblocks,
741  RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE)));
742 
743  (void) FilePrefetch(v->mdfd_vfd, seekpos, BLCKSZ * nblocks_this_segment,
744  WAIT_EVENT_DATA_FILE_PREFETCH);
745 
746  blocknum += nblocks_this_segment;
747  nblocks -= nblocks_this_segment;
748  }
749 #endif /* USE_PREFETCH */
750 
751  return true;
752 }
753 
754 /*
755  * Convert an array of buffer address into an array of iovec objects, and
756  * return the number that were required. 'iov' must have enough space for up
757  * to 'nblocks' elements, but the number used may be less depending on
758  * merging. In the case of a run of fully contiguous buffers, a single iovec
759  * will be populated that can be handled as a plain non-vectored I/O.
760  */
761 static int
762 buffers_to_iovec(struct iovec *iov, void **buffers, int nblocks)
763 {
764  struct iovec *iovp;
765  int iovcnt;
766 
767  Assert(nblocks >= 1);
768 
769  /* If this build supports direct I/O, buffers must be I/O aligned. */
770  for (int i = 0; i < nblocks; ++i)
771  {
772  if (PG_O_DIRECT != 0 && PG_IO_ALIGN_SIZE <= BLCKSZ)
773  Assert((uintptr_t) buffers[i] ==
774  TYPEALIGN(PG_IO_ALIGN_SIZE, buffers[i]));
775  }
776 
777  /* Start the first iovec off with the first buffer. */
778  iovp = &iov[0];
779  iovp->iov_base = buffers[0];
780  iovp->iov_len = BLCKSZ;
781  iovcnt = 1;
782 
783  /* Try to merge the rest. */
784  for (int i = 1; i < nblocks; ++i)
785  {
786  void *buffer = buffers[i];
787 
788  if (((char *) iovp->iov_base + iovp->iov_len) == buffer)
789  {
790  /* Contiguous with the last iovec. */
791  iovp->iov_len += BLCKSZ;
792  }
793  else
794  {
795  /* Need a new iovec. */
796  iovp++;
797  iovp->iov_base = buffer;
798  iovp->iov_len = BLCKSZ;
799  iovcnt++;
800  }
801  }
802 
803  return iovcnt;
804 }
805 
806 /*
807  * mdreadv() -- Read the specified blocks from a relation.
808  */
809 void
810 mdreadv(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
811  void **buffers, BlockNumber nblocks)
812 {
813  while (nblocks > 0)
814  {
815  struct iovec iov[PG_IOV_MAX];
816  int iovcnt;
817  off_t seekpos;
818  int nbytes;
819  MdfdVec *v;
820  BlockNumber nblocks_this_segment;
821  size_t transferred_this_segment;
822  size_t size_this_segment;
823 
824  v = _mdfd_getseg(reln, forknum, blocknum, false,
826 
827  seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
828 
829  Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
830 
831  nblocks_this_segment =
832  Min(nblocks,
833  RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE)));
834  nblocks_this_segment = Min(nblocks_this_segment, lengthof(iov));
835 
836  iovcnt = buffers_to_iovec(iov, buffers, nblocks_this_segment);
837  size_this_segment = nblocks_this_segment * BLCKSZ;
838  transferred_this_segment = 0;
839 
840  /*
841  * Inner loop to continue after a short read. We'll keep going until
842  * we hit EOF rather than assuming that a short read means we hit the
843  * end.
844  */
845  for (;;)
846  {
847  TRACE_POSTGRESQL_SMGR_MD_READ_START(forknum, blocknum,
851  reln->smgr_rlocator.backend);
852  nbytes = FileReadV(v->mdfd_vfd, iov, iovcnt, seekpos,
853  WAIT_EVENT_DATA_FILE_READ);
854  TRACE_POSTGRESQL_SMGR_MD_READ_DONE(forknum, blocknum,
858  reln->smgr_rlocator.backend,
859  nbytes,
860  size_this_segment - transferred_this_segment);
861 
862 #ifdef SIMULATE_SHORT_READ
863  nbytes = Min(nbytes, 4096);
864 #endif
865 
866  if (nbytes < 0)
867  ereport(ERROR,
869  errmsg("could not read blocks %u..%u in file \"%s\": %m",
870  blocknum,
871  blocknum + nblocks_this_segment - 1,
872  FilePathName(v->mdfd_vfd))));
873 
874  if (nbytes == 0)
875  {
876  /*
877  * We are at or past EOF, or we read a partial block at EOF.
878  * Normally this is an error; upper levels should never try to
879  * read a nonexistent block. However, if zero_damaged_pages
880  * is ON or we are InRecovery, we should instead return zeroes
881  * without complaining. This allows, for example, the case of
882  * trying to update a block that was later truncated away.
883  */
885  {
886  for (BlockNumber i = transferred_this_segment / BLCKSZ;
887  i < nblocks_this_segment;
888  ++i)
889  memset(buffers[i], 0, BLCKSZ);
890  break;
891  }
892  else
893  ereport(ERROR,
895  errmsg("could not read blocks %u..%u in file \"%s\": read only %zu of %zu bytes",
896  blocknum,
897  blocknum + nblocks_this_segment - 1,
899  transferred_this_segment,
900  size_this_segment)));
901  }
902 
903  /* One loop should usually be enough. */
904  transferred_this_segment += nbytes;
905  Assert(transferred_this_segment <= size_this_segment);
906  if (transferred_this_segment == size_this_segment)
907  break;
908 
909  /* Adjust position and vectors after a short read. */
910  seekpos += nbytes;
911  iovcnt = compute_remaining_iovec(iov, iov, iovcnt, nbytes);
912  }
913 
914  nblocks -= nblocks_this_segment;
915  buffers += nblocks_this_segment;
916  blocknum += nblocks_this_segment;
917  }
918 }
919 
920 /*
921  * mdwritev() -- Write the supplied blocks at the appropriate location.
922  *
923  * This is to be used only for updating already-existing blocks of a
924  * relation (ie, those before the current EOF). To extend a relation,
925  * use mdextend().
926  */
927 void
928 mdwritev(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
929  const void **buffers, BlockNumber nblocks, bool skipFsync)
930 {
931  /* This assert is too expensive to have on normally ... */
932 #ifdef CHECK_WRITE_VS_EXTEND
933  Assert((uint64) blocknum + (uint64) nblocks <= (uint64) mdnblocks(reln, forknum));
934 #endif
935 
936  while (nblocks > 0)
937  {
938  struct iovec iov[PG_IOV_MAX];
939  int iovcnt;
940  off_t seekpos;
941  int nbytes;
942  MdfdVec *v;
943  BlockNumber nblocks_this_segment;
944  size_t transferred_this_segment;
945  size_t size_this_segment;
946 
947  v = _mdfd_getseg(reln, forknum, blocknum, skipFsync,
949 
950  seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
951 
952  Assert(seekpos < (off_t) BLCKSZ * RELSEG_SIZE);
953 
954  nblocks_this_segment =
955  Min(nblocks,
956  RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE)));
957  nblocks_this_segment = Min(nblocks_this_segment, lengthof(iov));
958 
959  iovcnt = buffers_to_iovec(iov, (void **) buffers, nblocks_this_segment);
960  size_this_segment = nblocks_this_segment * BLCKSZ;
961  transferred_this_segment = 0;
962 
963  /*
964  * Inner loop to continue after a short write. If the reason is that
965  * we're out of disk space, a future attempt should get an ENOSPC
966  * error from the kernel.
967  */
968  for (;;)
969  {
970  TRACE_POSTGRESQL_SMGR_MD_WRITE_START(forknum, blocknum,
974  reln->smgr_rlocator.backend);
975  nbytes = FileWriteV(v->mdfd_vfd, iov, iovcnt, seekpos,
976  WAIT_EVENT_DATA_FILE_WRITE);
977  TRACE_POSTGRESQL_SMGR_MD_WRITE_DONE(forknum, blocknum,
981  reln->smgr_rlocator.backend,
982  nbytes,
983  size_this_segment - transferred_this_segment);
984 
985 #ifdef SIMULATE_SHORT_WRITE
986  nbytes = Min(nbytes, 4096);
987 #endif
988 
989  if (nbytes < 0)
990  {
991  bool enospc = errno == ENOSPC;
992 
993  ereport(ERROR,
995  errmsg("could not write blocks %u..%u in file \"%s\": %m",
996  blocknum,
997  blocknum + nblocks_this_segment - 1,
998  FilePathName(v->mdfd_vfd)),
999  enospc ? errhint("Check free disk space.") : 0));
1000  }
1001 
1002  /* One loop should usually be enough. */
1003  transferred_this_segment += nbytes;
1004  Assert(transferred_this_segment <= size_this_segment);
1005  if (transferred_this_segment == size_this_segment)
1006  break;
1007 
1008  /* Adjust position and iovecs after a short write. */
1009  seekpos += nbytes;
1010  iovcnt = compute_remaining_iovec(iov, iov, iovcnt, nbytes);
1011  }
1012 
1013  if (!skipFsync && !SmgrIsTemp(reln))
1014  register_dirty_segment(reln, forknum, v);
1015 
1016  nblocks -= nblocks_this_segment;
1017  buffers += nblocks_this_segment;
1018  blocknum += nblocks_this_segment;
1019  }
1020 }
1021 
1022 
1023 /*
1024  * mdwriteback() -- Tell the kernel to write pages back to storage.
1025  *
1026  * This accepts a range of blocks because flushing several pages at once is
1027  * considerably more efficient than doing so individually.
1028  */
1029 void
1031  BlockNumber blocknum, BlockNumber nblocks)
1032 {
1034 
1035  /*
1036  * Issue flush requests in as few requests as possible; have to split at
1037  * segment boundaries though, since those are actually separate files.
1038  */
1039  while (nblocks > 0)
1040  {
1041  BlockNumber nflush = nblocks;
1042  off_t seekpos;
1043  MdfdVec *v;
1044  int segnum_start,
1045  segnum_end;
1046 
1047  v = _mdfd_getseg(reln, forknum, blocknum, true /* not used */ ,
1049 
1050  /*
1051  * We might be flushing buffers of already removed relations, that's
1052  * ok, just ignore that case. If the segment file wasn't open already
1053  * (ie from a recent mdwrite()), then we don't want to re-open it, to
1054  * avoid a race with PROCSIGNAL_BARRIER_SMGRRELEASE that might leave
1055  * us with a descriptor to a file that is about to be unlinked.
1056  */
1057  if (!v)
1058  return;
1059 
1060  /* compute offset inside the current segment */
1061  segnum_start = blocknum / RELSEG_SIZE;
1062 
1063  /* compute number of desired writes within the current segment */
1064  segnum_end = (blocknum + nblocks - 1) / RELSEG_SIZE;
1065  if (segnum_start != segnum_end)
1066  nflush = RELSEG_SIZE - (blocknum % ((BlockNumber) RELSEG_SIZE));
1067 
1068  Assert(nflush >= 1);
1069  Assert(nflush <= nblocks);
1070 
1071  seekpos = (off_t) BLCKSZ * (blocknum % ((BlockNumber) RELSEG_SIZE));
1072 
1073  FileWriteback(v->mdfd_vfd, seekpos, (off_t) BLCKSZ * nflush, WAIT_EVENT_DATA_FILE_FLUSH);
1074 
1075  nblocks -= nflush;
1076  blocknum += nflush;
1077  }
1078 }
1079 
1080 /*
1081  * mdnblocks() -- Get the number of blocks stored in a relation.
1082  *
1083  * Important side effect: all active segments of the relation are opened
1084  * and added to the md_seg_fds array. If this routine has not been
1085  * called, then only segments up to the last one actually touched
1086  * are present in the array.
1087  */
1090 {
1091  MdfdVec *v;
1092  BlockNumber nblocks;
1093  BlockNumber segno;
1094 
1095  mdopenfork(reln, forknum, EXTENSION_FAIL);
1096 
1097  /* mdopen has opened the first segment */
1098  Assert(reln->md_num_open_segs[forknum] > 0);
1099 
1100  /*
1101  * Start from the last open segments, to avoid redundant seeks. We have
1102  * previously verified that these segments are exactly RELSEG_SIZE long,
1103  * and it's useless to recheck that each time.
1104  *
1105  * NOTE: this assumption could only be wrong if another backend has
1106  * truncated the relation. We rely on higher code levels to handle that
1107  * scenario by closing and re-opening the md fd, which is handled via
1108  * relcache flush. (Since the checkpointer doesn't participate in
1109  * relcache flush, it could have segment entries for inactive segments;
1110  * that's OK because the checkpointer never needs to compute relation
1111  * size.)
1112  */
1113  segno = reln->md_num_open_segs[forknum] - 1;
1114  v = &reln->md_seg_fds[forknum][segno];
1115 
1116  for (;;)
1117  {
1118  nblocks = _mdnblocks(reln, forknum, v);
1119  if (nblocks > ((BlockNumber) RELSEG_SIZE))
1120  elog(FATAL, "segment too big");
1121  if (nblocks < ((BlockNumber) RELSEG_SIZE))
1122  return (segno * ((BlockNumber) RELSEG_SIZE)) + nblocks;
1123 
1124  /*
1125  * If segment is exactly RELSEG_SIZE, advance to next one.
1126  */
1127  segno++;
1128 
1129  /*
1130  * We used to pass O_CREAT here, but that has the disadvantage that it
1131  * might create a segment which has vanished through some operating
1132  * system misadventure. In such a case, creating the segment here
1133  * undermines _mdfd_getseg's attempts to notice and report an error
1134  * upon access to a missing segment.
1135  */
1136  v = _mdfd_openseg(reln, forknum, segno, 0);
1137  if (v == NULL)
1138  return segno * ((BlockNumber) RELSEG_SIZE);
1139  }
1140 }
1141 
1142 /*
1143  * mdtruncate() -- Truncate relation to specified number of blocks.
1144  */
1145 void
1147 {
1148  BlockNumber curnblk;
1149  BlockNumber priorblocks;
1150  int curopensegs;
1151 
1152  /*
1153  * NOTE: mdnblocks makes sure we have opened all active segments, so that
1154  * truncation loop will get them all!
1155  */
1156  curnblk = mdnblocks(reln, forknum);
1157  if (nblocks > curnblk)
1158  {
1159  /* Bogus request ... but no complaint if InRecovery */
1160  if (InRecovery)
1161  return;
1162  ereport(ERROR,
1163  (errmsg("could not truncate file \"%s\" to %u blocks: it's only %u blocks now",
1164  relpath(reln->smgr_rlocator, forknum),
1165  nblocks, curnblk)));
1166  }
1167  if (nblocks == curnblk)
1168  return; /* no work */
1169 
1170  /*
1171  * Truncate segments, starting at the last one. Starting at the end makes
1172  * managing the memory for the fd array easier, should there be errors.
1173  */
1174  curopensegs = reln->md_num_open_segs[forknum];
1175  while (curopensegs > 0)
1176  {
1177  MdfdVec *v;
1178 
1179  priorblocks = (curopensegs - 1) * RELSEG_SIZE;
1180 
1181  v = &reln->md_seg_fds[forknum][curopensegs - 1];
1182 
1183  if (priorblocks > nblocks)
1184  {
1185  /*
1186  * This segment is no longer active. We truncate the file, but do
1187  * not delete it, for reasons explained in the header comments.
1188  */
1189  if (FileTruncate(v->mdfd_vfd, 0, WAIT_EVENT_DATA_FILE_TRUNCATE) < 0)
1190  ereport(ERROR,
1192  errmsg("could not truncate file \"%s\": %m",
1193  FilePathName(v->mdfd_vfd))));
1194 
1195  if (!SmgrIsTemp(reln))
1196  register_dirty_segment(reln, forknum, v);
1197 
1198  /* we never drop the 1st segment */
1199  Assert(v != &reln->md_seg_fds[forknum][0]);
1200 
1201  FileClose(v->mdfd_vfd);
1202  _fdvec_resize(reln, forknum, curopensegs - 1);
1203  }
1204  else if (priorblocks + ((BlockNumber) RELSEG_SIZE) > nblocks)
1205  {
1206  /*
1207  * This is the last segment we want to keep. Truncate the file to
1208  * the right length. NOTE: if nblocks is exactly a multiple K of
1209  * RELSEG_SIZE, we will truncate the K+1st segment to 0 length but
1210  * keep it. This adheres to the invariant given in the header
1211  * comments.
1212  */
1213  BlockNumber lastsegblocks = nblocks - priorblocks;
1214 
1215  if (FileTruncate(v->mdfd_vfd, (off_t) lastsegblocks * BLCKSZ, WAIT_EVENT_DATA_FILE_TRUNCATE) < 0)
1216  ereport(ERROR,
1218  errmsg("could not truncate file \"%s\" to %u blocks: %m",
1219  FilePathName(v->mdfd_vfd),
1220  nblocks)));
1221  if (!SmgrIsTemp(reln))
1222  register_dirty_segment(reln, forknum, v);
1223  }
1224  else
1225  {
1226  /*
1227  * We still need this segment, so nothing to do for this and any
1228  * earlier segment.
1229  */
1230  break;
1231  }
1232  curopensegs--;
1233  }
1234 }
1235 
1236 /*
1237  * mdregistersync() -- Mark whole relation as needing fsync
1238  */
1239 void
1241 {
1242  int segno;
1243  int min_inactive_seg;
1244 
1245  /*
1246  * NOTE: mdnblocks makes sure we have opened all active segments, so that
1247  * the loop below will get them all!
1248  */
1249  mdnblocks(reln, forknum);
1250 
1251  min_inactive_seg = segno = reln->md_num_open_segs[forknum];
1252 
1253  /*
1254  * Temporarily open inactive segments, then close them after sync. There
1255  * may be some inactive segments left opened after error, but that is
1256  * harmless. We don't bother to clean them up and take a risk of further
1257  * trouble. The next mdclose() will soon close them.
1258  */
1259  while (_mdfd_openseg(reln, forknum, segno, 0) != NULL)
1260  segno++;
1261 
1262  while (segno > 0)
1263  {
1264  MdfdVec *v = &reln->md_seg_fds[forknum][segno - 1];
1265 
1266  register_dirty_segment(reln, forknum, v);
1267 
1268  /* Close inactive segments immediately */
1269  if (segno > min_inactive_seg)
1270  {
1271  FileClose(v->mdfd_vfd);
1272  _fdvec_resize(reln, forknum, segno - 1);
1273  }
1274 
1275  segno--;
1276  }
1277 }
1278 
1279 /*
1280  * mdimmedsync() -- Immediately sync a relation to stable storage.
1281  *
1282  * Note that only writes already issued are synced; this routine knows
1283  * nothing of dirty buffers that may exist inside the buffer manager. We
1284  * sync active and inactive segments; smgrDoPendingSyncs() relies on this.
1285  * Consider a relation skipping WAL. Suppose a checkpoint syncs blocks of
1286  * some segment, then mdtruncate() renders that segment inactive. If we
1287  * crash before the next checkpoint syncs the newly-inactive segment, that
1288  * segment may survive recovery, reintroducing unwanted data into the table.
1289  */
1290 void
1292 {
1293  int segno;
1294  int min_inactive_seg;
1295 
1296  /*
1297  * NOTE: mdnblocks makes sure we have opened all active segments, so that
1298  * the loop below will get them all!
1299  */
1300  mdnblocks(reln, forknum);
1301 
1302  min_inactive_seg = segno = reln->md_num_open_segs[forknum];
1303 
1304  /*
1305  * Temporarily open inactive segments, then close them after sync. There
1306  * may be some inactive segments left opened after fsync() error, but that
1307  * is harmless. We don't bother to clean them up and take a risk of
1308  * further trouble. The next mdclose() will soon close them.
1309  */
1310  while (_mdfd_openseg(reln, forknum, segno, 0) != NULL)
1311  segno++;
1312 
1313  while (segno > 0)
1314  {
1315  MdfdVec *v = &reln->md_seg_fds[forknum][segno - 1];
1316 
1317  /*
1318  * fsyncs done through mdimmedsync() should be tracked in a separate
1319  * IOContext than those done through mdsyncfiletag() to differentiate
1320  * between unavoidable client backend fsyncs (e.g. those done during
1321  * index build) and those which ideally would have been done by the
1322  * checkpointer. Since other IO operations bypassing the buffer
1323  * manager could also be tracked in such an IOContext, wait until
1324  * these are also tracked to track immediate fsyncs.
1325  */
1326  if (FileSync(v->mdfd_vfd, WAIT_EVENT_DATA_FILE_IMMEDIATE_SYNC) < 0)
1329  errmsg("could not fsync file \"%s\": %m",
1330  FilePathName(v->mdfd_vfd))));
1331 
1332  /* Close inactive segments immediately */
1333  if (segno > min_inactive_seg)
1334  {
1335  FileClose(v->mdfd_vfd);
1336  _fdvec_resize(reln, forknum, segno - 1);
1337  }
1338 
1339  segno--;
1340  }
1341 }
1342 
1343 /*
1344  * register_dirty_segment() -- Mark a relation segment as needing fsync
1345  *
1346  * If there is a local pending-ops table, just make an entry in it for
1347  * ProcessSyncRequests to process later. Otherwise, try to pass off the
1348  * fsync request to the checkpointer process. If that fails, just do the
1349  * fsync locally before returning (we hope this will not happen often
1350  * enough to be a performance problem).
1351  */
1352 static void
1354 {
1355  FileTag tag;
1356 
1357  INIT_MD_FILETAG(tag, reln->smgr_rlocator.locator, forknum, seg->mdfd_segno);
1358 
1359  /* Temp relations should never be fsync'd */
1360  Assert(!SmgrIsTemp(reln));
1361 
1362  if (!RegisterSyncRequest(&tag, SYNC_REQUEST, false /* retryOnError */ ))
1363  {
1364  instr_time io_start;
1365 
1366  ereport(DEBUG1,
1367  (errmsg_internal("could not forward fsync request because request queue is full")));
1368 
1370 
1371  if (FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) < 0)
1374  errmsg("could not fsync file \"%s\": %m",
1375  FilePathName(seg->mdfd_vfd))));
1376 
1377  /*
1378  * We have no way of knowing if the current IOContext is
1379  * IOCONTEXT_NORMAL or IOCONTEXT_[BULKREAD, BULKWRITE, VACUUM] at this
1380  * point, so count the fsync as being in the IOCONTEXT_NORMAL
1381  * IOContext. This is probably okay, because the number of backend
1382  * fsyncs doesn't say anything about the efficacy of the
1383  * BufferAccessStrategy. And counting both fsyncs done in
1384  * IOCONTEXT_NORMAL and IOCONTEXT_[BULKREAD, BULKWRITE, VACUUM] under
1385  * IOCONTEXT_NORMAL is likely clearer when investigating the number of
1386  * backend fsyncs.
1387  */
1389  IOOP_FSYNC, io_start, 1);
1390  }
1391 }
1392 
1393 /*
1394  * register_unlink_segment() -- Schedule a file to be deleted after next checkpoint
1395  */
1396 static void
1398  BlockNumber segno)
1399 {
1400  FileTag tag;
1401 
1402  INIT_MD_FILETAG(tag, rlocator.locator, forknum, segno);
1403 
1404  /* Should never be used with temp relations */
1405  Assert(!RelFileLocatorBackendIsTemp(rlocator));
1406 
1407  RegisterSyncRequest(&tag, SYNC_UNLINK_REQUEST, true /* retryOnError */ );
1408 }
1409 
1410 /*
1411  * register_forget_request() -- forget any fsyncs for a relation fork's segment
1412  */
1413 static void
1415  BlockNumber segno)
1416 {
1417  FileTag tag;
1418 
1419  INIT_MD_FILETAG(tag, rlocator.locator, forknum, segno);
1420 
1421  RegisterSyncRequest(&tag, SYNC_FORGET_REQUEST, true /* retryOnError */ );
1422 }
1423 
1424 /*
1425  * ForgetDatabaseSyncRequests -- forget any fsyncs and unlinks for a DB
1426  */
1427 void
1429 {
1430  FileTag tag;
1431  RelFileLocator rlocator;
1432 
1433  rlocator.dbOid = dbid;
1434  rlocator.spcOid = 0;
1435  rlocator.relNumber = 0;
1436 
1438 
1439  RegisterSyncRequest(&tag, SYNC_FILTER_REQUEST, true /* retryOnError */ );
1440 }
1441 
1442 /*
1443  * DropRelationFiles -- drop files of all given relations
1444  */
1445 void
1446 DropRelationFiles(RelFileLocator *delrels, int ndelrels, bool isRedo)
1447 {
1448  SMgrRelation *srels;
1449  int i;
1450 
1451  srels = palloc(sizeof(SMgrRelation) * ndelrels);
1452  for (i = 0; i < ndelrels; i++)
1453  {
1454  SMgrRelation srel = smgropen(delrels[i], INVALID_PROC_NUMBER);
1455 
1456  if (isRedo)
1457  {
1458  ForkNumber fork;
1459 
1460  for (fork = 0; fork <= MAX_FORKNUM; fork++)
1461  XLogDropRelation(delrels[i], fork);
1462  }
1463  srels[i] = srel;
1464  }
1465 
1466  smgrdounlinkall(srels, ndelrels, isRedo);
1467 
1468  for (i = 0; i < ndelrels; i++)
1469  smgrclose(srels[i]);
1470  pfree(srels);
1471 }
1472 
1473 
1474 /*
1475  * _fdvec_resize() -- Resize the fork's open segments array
1476  */
1477 static void
1479  ForkNumber forknum,
1480  int nseg)
1481 {
1482  if (nseg == 0)
1483  {
1484  if (reln->md_num_open_segs[forknum] > 0)
1485  {
1486  pfree(reln->md_seg_fds[forknum]);
1487  reln->md_seg_fds[forknum] = NULL;
1488  }
1489  }
1490  else if (reln->md_num_open_segs[forknum] == 0)
1491  {
1492  reln->md_seg_fds[forknum] =
1493  MemoryContextAlloc(MdCxt, sizeof(MdfdVec) * nseg);
1494  }
1495  else
1496  {
1497  /*
1498  * It doesn't seem worthwhile complicating the code to amortize
1499  * repalloc() calls. Those are far faster than PathNameOpenFile() or
1500  * FileClose(), and the memory context internally will sometimes avoid
1501  * doing an actual reallocation.
1502  */
1503  reln->md_seg_fds[forknum] =
1504  repalloc(reln->md_seg_fds[forknum],
1505  sizeof(MdfdVec) * nseg);
1506  }
1507 
1508  reln->md_num_open_segs[forknum] = nseg;
1509 }
1510 
1511 /*
1512  * Return the filename for the specified segment of the relation. The
1513  * returned string is palloc'd.
1514  */
1515 static char *
1517 {
1518  char *path,
1519  *fullpath;
1520 
1521  path = relpath(reln->smgr_rlocator, forknum);
1522 
1523  if (segno > 0)
1524  {
1525  fullpath = psprintf("%s.%u", path, segno);
1526  pfree(path);
1527  }
1528  else
1529  fullpath = path;
1530 
1531  return fullpath;
1532 }
1533 
1534 /*
1535  * Open the specified segment of the relation,
1536  * and make a MdfdVec object for it. Returns NULL on failure.
1537  */
1538 static MdfdVec *
1540  int oflags)
1541 {
1542  MdfdVec *v;
1543  File fd;
1544  char *fullpath;
1545 
1546  fullpath = _mdfd_segpath(reln, forknum, segno);
1547 
1548  /* open the file */
1549  fd = PathNameOpenFile(fullpath, _mdfd_open_flags() | oflags);
1550 
1551  pfree(fullpath);
1552 
1553  if (fd < 0)
1554  return NULL;
1555 
1556  /*
1557  * Segments are always opened in order from lowest to highest, so we must
1558  * be adding a new one at the end.
1559  */
1560  Assert(segno == reln->md_num_open_segs[forknum]);
1561 
1562  _fdvec_resize(reln, forknum, segno + 1);
1563 
1564  /* fill the entry */
1565  v = &reln->md_seg_fds[forknum][segno];
1566  v->mdfd_vfd = fd;
1567  v->mdfd_segno = segno;
1568 
1569  Assert(_mdnblocks(reln, forknum, v) <= ((BlockNumber) RELSEG_SIZE));
1570 
1571  /* all done */
1572  return v;
1573 }
1574 
1575 /*
1576  * _mdfd_getseg() -- Find the segment of the relation holding the
1577  * specified block.
1578  *
1579  * If the segment doesn't exist, we ereport, return NULL, or create the
1580  * segment, according to "behavior". Note: skipFsync is only used in the
1581  * EXTENSION_CREATE case.
1582  */
1583 static MdfdVec *
1585  bool skipFsync, int behavior)
1586 {
1587  MdfdVec *v;
1588  BlockNumber targetseg;
1589  BlockNumber nextsegno;
1590 
1591  /* some way to handle non-existent segments needs to be specified */
1592  Assert(behavior &
1595 
1596  targetseg = blkno / ((BlockNumber) RELSEG_SIZE);
1597 
1598  /* if an existing and opened segment, we're done */
1599  if (targetseg < reln->md_num_open_segs[forknum])
1600  {
1601  v = &reln->md_seg_fds[forknum][targetseg];
1602  return v;
1603  }
1604 
1605  /* The caller only wants the segment if we already had it open. */
1606  if (behavior & EXTENSION_DONT_OPEN)
1607  return NULL;
1608 
1609  /*
1610  * The target segment is not yet open. Iterate over all the segments
1611  * between the last opened and the target segment. This way missing
1612  * segments either raise an error, or get created (according to
1613  * 'behavior'). Start with either the last opened, or the first segment if
1614  * none was opened before.
1615  */
1616  if (reln->md_num_open_segs[forknum] > 0)
1617  v = &reln->md_seg_fds[forknum][reln->md_num_open_segs[forknum] - 1];
1618  else
1619  {
1620  v = mdopenfork(reln, forknum, behavior);
1621  if (!v)
1622  return NULL; /* if behavior & EXTENSION_RETURN_NULL */
1623  }
1624 
1625  for (nextsegno = reln->md_num_open_segs[forknum];
1626  nextsegno <= targetseg; nextsegno++)
1627  {
1628  BlockNumber nblocks = _mdnblocks(reln, forknum, v);
1629  int flags = 0;
1630 
1631  Assert(nextsegno == v->mdfd_segno + 1);
1632 
1633  if (nblocks > ((BlockNumber) RELSEG_SIZE))
1634  elog(FATAL, "segment too big");
1635 
1636  if ((behavior & EXTENSION_CREATE) ||
1637  (InRecovery && (behavior & EXTENSION_CREATE_RECOVERY)))
1638  {
1639  /*
1640  * Normally we will create new segments only if authorized by the
1641  * caller (i.e., we are doing mdextend()). But when doing WAL
1642  * recovery, create segments anyway; this allows cases such as
1643  * replaying WAL data that has a write into a high-numbered
1644  * segment of a relation that was later deleted. We want to go
1645  * ahead and create the segments so we can finish out the replay.
1646  *
1647  * We have to maintain the invariant that segments before the last
1648  * active segment are of size RELSEG_SIZE; therefore, if
1649  * extending, pad them out with zeroes if needed. (This only
1650  * matters if in recovery, or if the caller is extending the
1651  * relation discontiguously, but that can happen in hash indexes.)
1652  */
1653  if (nblocks < ((BlockNumber) RELSEG_SIZE))
1654  {
1655  char *zerobuf = palloc_aligned(BLCKSZ, PG_IO_ALIGN_SIZE,
1656  MCXT_ALLOC_ZERO);
1657 
1658  mdextend(reln, forknum,
1659  nextsegno * ((BlockNumber) RELSEG_SIZE) - 1,
1660  zerobuf, skipFsync);
1661  pfree(zerobuf);
1662  }
1663  flags = O_CREAT;
1664  }
1665  else if (!(behavior & EXTENSION_DONT_CHECK_SIZE) &&
1666  nblocks < ((BlockNumber) RELSEG_SIZE))
1667  {
1668  /*
1669  * When not extending (or explicitly including truncated
1670  * segments), only open the next segment if the current one is
1671  * exactly RELSEG_SIZE. If not (this branch), either return NULL
1672  * or fail.
1673  */
1674  if (behavior & EXTENSION_RETURN_NULL)
1675  {
1676  /*
1677  * Some callers discern between reasons for _mdfd_getseg()
1678  * returning NULL based on errno. As there's no failing
1679  * syscall involved in this case, explicitly set errno to
1680  * ENOENT, as that seems the closest interpretation.
1681  */
1682  errno = ENOENT;
1683  return NULL;
1684  }
1685 
1686  ereport(ERROR,
1688  errmsg("could not open file \"%s\" (target block %u): previous segment is only %u blocks",
1689  _mdfd_segpath(reln, forknum, nextsegno),
1690  blkno, nblocks)));
1691  }
1692 
1693  v = _mdfd_openseg(reln, forknum, nextsegno, flags);
1694 
1695  if (v == NULL)
1696  {
1697  if ((behavior & EXTENSION_RETURN_NULL) &&
1698  FILE_POSSIBLY_DELETED(errno))
1699  return NULL;
1700  ereport(ERROR,
1702  errmsg("could not open file \"%s\" (target block %u): %m",
1703  _mdfd_segpath(reln, forknum, nextsegno),
1704  blkno)));
1705  }
1706  }
1707 
1708  return v;
1709 }
1710 
1711 /*
1712  * Get number of blocks present in a single disk file
1713  */
1714 static BlockNumber
1716 {
1717  off_t len;
1718 
1719  len = FileSize(seg->mdfd_vfd);
1720  if (len < 0)
1721  ereport(ERROR,
1723  errmsg("could not seek to end of file \"%s\": %m",
1724  FilePathName(seg->mdfd_vfd))));
1725  /* note that this calculation will ignore any partial block at EOF */
1726  return (BlockNumber) (len / BLCKSZ);
1727 }
1728 
1729 /*
1730  * Sync a file to disk, given a file tag. Write the path into an output
1731  * buffer so the caller can use it in error messages.
1732  *
1733  * Return 0 on success, -1 on failure, with errno set.
1734  */
1735 int
1736 mdsyncfiletag(const FileTag *ftag, char *path)
1737 {
1739  File file;
1740  instr_time io_start;
1741  bool need_to_close;
1742  int result,
1743  save_errno;
1744 
1745  /* See if we already have the file open, or need to open it. */
1746  if (ftag->segno < reln->md_num_open_segs[ftag->forknum])
1747  {
1748  file = reln->md_seg_fds[ftag->forknum][ftag->segno].mdfd_vfd;
1749  strlcpy(path, FilePathName(file), MAXPGPATH);
1750  need_to_close = false;
1751  }
1752  else
1753  {
1754  char *p;
1755 
1756  p = _mdfd_segpath(reln, ftag->forknum, ftag->segno);
1757  strlcpy(path, p, MAXPGPATH);
1758  pfree(p);
1759 
1760  file = PathNameOpenFile(path, _mdfd_open_flags());
1761  if (file < 0)
1762  return -1;
1763  need_to_close = true;
1764  }
1765 
1767 
1768  /* Sync the file. */
1769  result = FileSync(file, WAIT_EVENT_DATA_FILE_SYNC);
1770  save_errno = errno;
1771 
1772  if (need_to_close)
1773  FileClose(file);
1774 
1776  IOOP_FSYNC, io_start, 1);
1777 
1778  errno = save_errno;
1779  return result;
1780 }
1781 
1782 /*
1783  * Unlink a file, given a file tag. Write the path into an output
1784  * buffer so the caller can use it in error messages.
1785  *
1786  * Return 0 on success, -1 on failure, with errno set.
1787  */
1788 int
1789 mdunlinkfiletag(const FileTag *ftag, char *path)
1790 {
1791  char *p;
1792 
1793  /* Compute the path. */
1794  p = relpathperm(ftag->rlocator, MAIN_FORKNUM);
1795  strlcpy(path, p, MAXPGPATH);
1796  pfree(p);
1797 
1798  /* Try to unlink the file. */
1799  return unlink(path);
1800 }
1801 
1802 /*
1803  * Check if a given candidate request matches a given tag, when processing
1804  * a SYNC_FILTER_REQUEST request. This will be called for all pending
1805  * requests to find out whether to forget them.
1806  */
1807 bool
1808 mdfiletagmatches(const FileTag *ftag, const FileTag *candidate)
1809 {
1810  /*
1811  * For now we only use filter requests as a way to drop all scheduled
1812  * callbacks relating to a given database, when dropping the database.
1813  * We'll return true for all candidates that have the same database OID as
1814  * the ftag from the SYNC_FILTER_REQUEST request, so they're forgotten.
1815  */
1816  return ftag->rlocator.dbOid == candidate->rlocator.dbOid;
1817 }
void TablespaceCreateDbspace(Oid spcOid, Oid dbOid, bool isRedo)
Definition: tablespace.c:112
uint32 BlockNumber
Definition: block.h:31
#define InvalidBlockNumber
Definition: block.h:33
#define MaxBlockNumber
Definition: block.h:35
bool track_io_timing
Definition: bufmgr.c:142
bool zero_damaged_pages
Definition: bufmgr.c:139
#define Min(x, y)
Definition: c.h:1004
#define TYPEALIGN(ALIGNVAL, LEN)
Definition: c.h:804
#define Assert(condition)
Definition: c.h:858
#define PG_BINARY
Definition: c.h:1273
#define lengthof(array)
Definition: c.h:788
int errmsg_internal(const char *fmt,...)
Definition: elog.c:1157
int errcode_for_file_access(void)
Definition: elog.c:880
int errhint(const char *fmt,...)
Definition: elog.c:1317
int errcode(int sqlerrcode)
Definition: elog.c:857
int errmsg(const char *fmt,...)
Definition: elog.c:1070
#define FATAL
Definition: elog.h:41
#define WARNING
Definition: elog.h:36
#define DEBUG1
Definition: elog.h:30
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:224
#define ereport(elevel,...)
Definition: elog.h:149
void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info)
Definition: fd.c:2110
int io_direct_flags
Definition: fd.c:168
int FileSync(File file, uint32 wait_event_info)
Definition: fd.c:2297
void FileClose(File file)
Definition: fd.c:1978
int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2369
int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2078
int data_sync_elevel(int elevel)
Definition: fd.c:3936
File PathNameOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1575
char * FilePathName(File file)
Definition: fd.c:2461
ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2192
int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2324
off_t FileSize(File file)
Definition: fd.c:2409
ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2136
int FileTruncate(File file, off_t offset, uint32 wait_event_info)
Definition: fd.c:2426
int pg_truncate(const char *path, off_t length)
Definition: fd.c:720
#define IO_DIRECT_DATA
Definition: fd.h:54
#define FILE_POSSIBLY_DELETED(err)
Definition: fd.h:78
int File
Definition: fd.h:51
static ssize_t FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.h:208
#define PG_O_DIRECT
Definition: fd.h:97
#define MCXT_ALLOC_ZERO
Definition: fe_memutils.h:18
int compute_remaining_iovec(struct iovec *destination, const struct iovec *source, int iovcnt, size_t transferred)
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bool IsBinaryUpgrade
Definition: globals.c:118
int i
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void pfree(void *pointer)
Definition: mcxt.c:1520
MemoryContext TopMemoryContext
Definition: mcxt.c:149
void * repalloc(void *pointer, Size size)
Definition: mcxt.c:1540
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:1180
void * palloc_aligned(Size size, Size alignto, int flags)
Definition: mcxt.c:1510
void * palloc(Size size)
Definition: mcxt.c:1316
void mdunlink(RelFileLocatorBackend rlocator, ForkNumber forknum, bool isRedo)
Definition: md.c:307
static void register_forget_request(RelFileLocatorBackend rlocator, ForkNumber forknum, BlockNumber segno)
Definition: md.c:1414
#define EXTENSION_CREATE_RECOVERY
Definition: md.c:108
static BlockNumber _mdnblocks(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
Definition: md.c:1715
static void mdunlinkfork(RelFileLocatorBackend rlocator, ForkNumber forknum, bool isRedo)
Definition: md.c:344
void mdwritev(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, const void **buffers, BlockNumber nblocks, bool skipFsync)
Definition: md.c:928
bool mdfiletagmatches(const FileTag *ftag, const FileTag *candidate)
Definition: md.c:1808
bool mdexists(SMgrRelation reln, ForkNumber forknum)
Definition: md.c:171
void mdreadv(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, void **buffers, BlockNumber nblocks)
Definition: md.c:810
static void register_unlink_segment(RelFileLocatorBackend rlocator, ForkNumber forknum, BlockNumber segno)
Definition: md.c:1397
#define EXTENSION_DONT_OPEN
Definition: md.c:118
BlockNumber mdnblocks(SMgrRelation reln, ForkNumber forknum)
Definition: md.c:1089
int mdunlinkfiletag(const FileTag *ftag, char *path)
Definition: md.c:1789
static MemoryContext MdCxt
Definition: md.c:86
void mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)
Definition: md.c:190
void mdextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, const void *buffer, bool skipFsync)
Definition: md.c:460
static int do_truncate(const char *path)
Definition: md.c:323
void mdinit(void)
Definition: md.c:158
void mdclose(SMgrRelation reln, ForkNumber forknum)
Definition: md.c:691
void mdzeroextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, int nblocks, bool skipFsync)
Definition: md.c:525
static MdfdVec * _mdfd_openseg(SMgrRelation reln, ForkNumber forknum, BlockNumber segno, int oflags)
Definition: md.c:1539
static void register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
Definition: md.c:1353
int mdsyncfiletag(const FileTag *ftag, char *path)
Definition: md.c:1736
void mdwriteback(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, BlockNumber nblocks)
Definition: md.c:1030
static MdfdVec * _mdfd_getseg(SMgrRelation reln, ForkNumber forknum, BlockNumber blkno, bool skipFsync, int behavior)
Definition: md.c:1584
#define EXTENSION_RETURN_NULL
Definition: md.c:104
static char * _mdfd_segpath(SMgrRelation reln, ForkNumber forknum, BlockNumber segno)
Definition: md.c:1516
bool mdprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, int nblocks)
Definition: md.c:714
void mdregistersync(SMgrRelation reln, ForkNumber forknum)
Definition: md.c:1240
void mdopen(SMgrRelation reln)
Definition: md.c:680
#define EXTENSION_CREATE
Definition: md.c:106
static int _mdfd_open_flags(void)
Definition: md.c:144
#define INIT_MD_FILETAG(a, xx_rlocator, xx_forknum, xx_segno)
Definition: md.c:90
#define EXTENSION_DONT_CHECK_SIZE
Definition: md.c:116
#define EXTENSION_FAIL
Definition: md.c:102
static MdfdVec * mdopenfork(SMgrRelation reln, ForkNumber forknum, int behavior)
Definition: md.c:637
void DropRelationFiles(RelFileLocator *delrels, int ndelrels, bool isRedo)
Definition: md.c:1446
static int buffers_to_iovec(struct iovec *iov, void **buffers, int nblocks)
Definition: md.c:762
static void _fdvec_resize(SMgrRelation reln, ForkNumber forknum, int nseg)
Definition: md.c:1478
void ForgetDatabaseSyncRequests(Oid dbid)
Definition: md.c:1428
void mdtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
Definition: md.c:1146
void mdimmedsync(SMgrRelation reln, ForkNumber forknum)
Definition: md.c:1291
struct _MdfdVec MdfdVec
#define AllocSetContextCreate
Definition: memutils.h:129
#define ALLOCSET_DEFAULT_SIZES
Definition: memutils.h:160
#define ERRCODE_DATA_CORRUPTED
Definition: pg_basebackup.c:41
#define MAXPGPATH
#define PG_IO_ALIGN_SIZE
const void size_t len
#define PG_IOV_MAX
Definition: pg_iovec.h:37
@ IOOBJECT_RELATION
Definition: pgstat.h:280
@ IOCONTEXT_NORMAL
Definition: pgstat.h:290
@ IOOP_FSYNC
Definition: pgstat.h:300
instr_time pgstat_prepare_io_time(bool track_io_guc)
Definition: pgstat_io.c:100
void pgstat_count_io_op_time(IOObject io_object, IOContext io_context, IOOp io_op, instr_time start_time, uint32 cnt)
Definition: pgstat_io.c:122
#define sprintf
Definition: port.h:240
size_t strlcpy(char *dst, const char *src, size_t siz)
Definition: strlcpy.c:45
unsigned int Oid
Definition: postgres_ext.h:31
static int fd(const char *x, int i)
Definition: preproc-init.c:105
#define INVALID_PROC_NUMBER
Definition: procnumber.h:26
char * psprintf(const char *fmt,...)
Definition: psprintf.c:46
#define RelFileLocatorBackendIsTemp(rlocator)
ForkNumber
Definition: relpath.h:48
@ MAIN_FORKNUM
Definition: relpath.h:50
@ InvalidForkNumber
Definition: relpath.h:49
#define MAX_FORKNUM
Definition: relpath.h:62
#define relpath(rlocator, forknum)
Definition: relpath.h:94
#define relpathperm(rlocator, forknum)
Definition: relpath.h:90
SMgrRelation smgropen(RelFileLocator rlocator, ProcNumber backend)
Definition: smgr.c:198
void smgrclose(SMgrRelation reln)
Definition: smgr.c:320
void smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo)
Definition: smgr.c:462
#define SmgrIsTemp(smgr)
Definition: smgr.h:73
Definition: sync.h:51
RelFileLocator rlocator
Definition: sync.h:54
int16 forknum
Definition: sync.h:53
uint64 segno
Definition: sync.h:55
RelFileLocator locator
RelFileNumber relNumber
int md_num_open_segs[MAX_FORKNUM+1]
Definition: smgr.h:60
struct _MdfdVec * md_seg_fds[MAX_FORKNUM+1]
Definition: smgr.h:61
RelFileLocatorBackend smgr_rlocator
Definition: smgr.h:37
Definition: md.c:81
File mdfd_vfd
Definition: md.c:82
BlockNumber mdfd_segno
Definition: md.c:83
bool RegisterSyncRequest(const FileTag *ftag, SyncRequestType type, bool retryOnError)
Definition: sync.c:580
@ SYNC_FILTER_REQUEST
Definition: sync.h:28
@ SYNC_FORGET_REQUEST
Definition: sync.h:27
@ SYNC_UNLINK_REQUEST
Definition: sync.h:26
@ SYNC_REQUEST
Definition: sync.h:25
bool InRecovery
Definition: xlogutils.c:50
void XLogDropRelation(RelFileLocator rlocator, ForkNumber forknum)
Definition: xlogutils.c:641