Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * reinit.c
4 : * Reinitialization of unlogged relations
5 : *
6 : * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : * IDENTIFICATION
10 : * src/backend/storage/file/reinit.c
11 : *
12 : *-------------------------------------------------------------------------
13 : */
14 :
15 : #include "postgres.h"
16 :
17 : #include <unistd.h>
18 :
19 : #include "common/relpath.h"
20 : #include "storage/copydir.h"
21 : #include "storage/fd.h"
22 : #include "storage/reinit.h"
23 : #include "utils/hsearch.h"
24 : #include "utils/memutils.h"
25 :
26 : static void ResetUnloggedRelationsInTablespaceDir(const char *tsdirname,
27 : int op);
28 : static void ResetUnloggedRelationsInDbspaceDir(const char *dbspacedirname,
29 : int op);
30 :
31 : typedef struct
32 : {
33 : char oid[OIDCHARS + 1];
34 : } unlogged_relation_entry;
35 :
36 : /*
37 : * Reset unlogged relations from before the last restart.
38 : *
39 : * If op includes UNLOGGED_RELATION_CLEANUP, we remove all forks of any
40 : * relation with an "init" fork, except for the "init" fork itself.
41 : *
42 : * If op includes UNLOGGED_RELATION_INIT, we copy the "init" fork to the main
43 : * fork.
44 : */
45 : void
46 358 : ResetUnloggedRelations(int op)
47 : {
48 : char temp_path[MAXPGPATH + 10 + sizeof(TABLESPACE_VERSION_DIRECTORY)];
49 : DIR *spc_dir;
50 : struct dirent *spc_de;
51 : MemoryContext tmpctx,
52 : oldctx;
53 :
54 : /* Log it. */
55 358 : elog(DEBUG1, "resetting unlogged relations: cleanup %d init %d",
56 : (op & UNLOGGED_RELATION_CLEANUP) != 0,
57 : (op & UNLOGGED_RELATION_INIT) != 0);
58 :
59 : /*
60 : * Just to be sure we don't leak any memory, let's create a temporary
61 : * memory context for this operation.
62 : */
63 358 : tmpctx = AllocSetContextCreate(CurrentMemoryContext,
64 : "ResetUnloggedRelations",
65 : ALLOCSET_DEFAULT_SIZES);
66 358 : oldctx = MemoryContextSwitchTo(tmpctx);
67 :
68 : /*
69 : * First process unlogged files in pg_default ($PGDATA/base)
70 : */
71 358 : ResetUnloggedRelationsInTablespaceDir("base", op);
72 :
73 : /*
74 : * Cycle through directories for all non-default tablespaces.
75 : */
76 358 : spc_dir = AllocateDir("pg_tblspc");
77 :
78 1206 : while ((spc_de = ReadDir(spc_dir, "pg_tblspc")) != NULL)
79 : {
80 848 : if (strcmp(spc_de->d_name, ".") == 0 ||
81 490 : strcmp(spc_de->d_name, "..") == 0)
82 716 : continue;
83 :
84 132 : snprintf(temp_path, sizeof(temp_path), "pg_tblspc/%s/%s",
85 132 : spc_de->d_name, TABLESPACE_VERSION_DIRECTORY);
86 132 : ResetUnloggedRelationsInTablespaceDir(temp_path, op);
87 : }
88 :
89 358 : FreeDir(spc_dir);
90 :
91 : /*
92 : * Restore memory context.
93 : */
94 358 : MemoryContextSwitchTo(oldctx);
95 358 : MemoryContextDelete(tmpctx);
96 358 : }
97 :
98 : /*
99 : * Process one tablespace directory for ResetUnloggedRelations
100 : */
101 : static void
102 490 : ResetUnloggedRelationsInTablespaceDir(const char *tsdirname, int op)
103 : {
104 : DIR *ts_dir;
105 : struct dirent *de;
106 : char dbspace_path[MAXPGPATH * 2];
107 :
108 490 : ts_dir = AllocateDir(tsdirname);
109 :
110 : /*
111 : * If we get ENOENT on a tablespace directory, log it and return. This
112 : * can happen if a previous DROP TABLESPACE crashed between removing the
113 : * tablespace directory and removing the symlink in pg_tblspc. We don't
114 : * really want to prevent database startup in that scenario, so let it
115 : * pass instead. Any other type of error will be reported by ReadDir
116 : * (causing a startup failure).
117 : */
118 490 : if (ts_dir == NULL && errno == ENOENT)
119 : {
120 0 : ereport(LOG,
121 : (errcode_for_file_access(),
122 : errmsg("could not open directory \"%s\": %m",
123 : tsdirname)));
124 0 : return;
125 : }
126 :
127 2726 : while ((de = ReadDir(ts_dir, tsdirname)) != NULL)
128 : {
129 : /*
130 : * We're only interested in the per-database directories, which have
131 : * numeric names. Note that this code will also (properly) ignore "."
132 : * and "..".
133 : */
134 2236 : if (strspn(de->d_name, "0123456789") != strlen(de->d_name))
135 1040 : continue;
136 :
137 1196 : snprintf(dbspace_path, sizeof(dbspace_path), "%s/%s",
138 1196 : tsdirname, de->d_name);
139 1196 : ResetUnloggedRelationsInDbspaceDir(dbspace_path, op);
140 : }
141 :
142 490 : FreeDir(ts_dir);
143 : }
144 :
145 : /*
146 : * Process one per-dbspace directory for ResetUnloggedRelations
147 : */
148 : static void
149 1196 : ResetUnloggedRelationsInDbspaceDir(const char *dbspacedirname, int op)
150 : {
151 : DIR *dbspace_dir;
152 : struct dirent *de;
153 : char rm_path[MAXPGPATH * 2];
154 :
155 : /* Caller must specify at least one operation. */
156 : Assert((op & (UNLOGGED_RELATION_CLEANUP | UNLOGGED_RELATION_INIT)) != 0);
157 :
158 : /*
159 : * Cleanup is a two-pass operation. First, we go through and identify all
160 : * the files with init forks. Then, we go through again and nuke
161 : * everything with the same OID except the init fork.
162 : */
163 1196 : if ((op & UNLOGGED_RELATION_CLEANUP) != 0)
164 : {
165 : HTAB *hash;
166 : HASHCTL ctl;
167 :
168 : /*
169 : * It's possible that someone could create a ton of unlogged relations
170 : * in the same database & tablespace, so we'd better use a hash table
171 : * rather than an array or linked list to keep track of which files
172 : * need to be reset. Otherwise, this cleanup operation would be
173 : * O(n^2).
174 : */
175 648 : memset(&ctl, 0, sizeof(ctl));
176 648 : ctl.keysize = sizeof(unlogged_relation_entry);
177 648 : ctl.entrysize = sizeof(unlogged_relation_entry);
178 648 : hash = hash_create("unlogged hash", 32, &ctl, HASH_ELEM);
179 :
180 : /* Scan the directory. */
181 648 : dbspace_dir = AllocateDir(dbspacedirname);
182 179240 : while ((de = ReadDir(dbspace_dir, dbspacedirname)) != NULL)
183 : {
184 : ForkNumber forkNum;
185 : int oidchars;
186 : unlogged_relation_entry ent;
187 :
188 : /* Skip anything that doesn't look like a relation data file. */
189 178592 : if (!parse_filename_for_nontemp_relation(de->d_name, &oidchars,
190 : &forkNum))
191 178588 : continue;
192 :
193 : /* Also skip it unless this is the init fork. */
194 176084 : if (forkNum != INIT_FORKNUM)
195 176080 : continue;
196 :
197 : /*
198 : * Put the OID portion of the name into the hash table, if it
199 : * isn't already.
200 : */
201 4 : memset(ent.oid, 0, sizeof(ent.oid));
202 4 : memcpy(ent.oid, de->d_name, oidchars);
203 4 : hash_search(hash, &ent, HASH_ENTER, NULL);
204 : }
205 :
206 : /* Done with the first pass. */
207 648 : FreeDir(dbspace_dir);
208 :
209 : /*
210 : * If we didn't find any init forks, there's no point in continuing;
211 : * we can bail out now.
212 : */
213 648 : if (hash_get_num_entries(hash) == 0)
214 : {
215 644 : hash_destroy(hash);
216 644 : return;
217 : }
218 :
219 : /*
220 : * Now, make a second pass and remove anything that matches.
221 : */
222 4 : dbspace_dir = AllocateDir(dbspacedirname);
223 602 : while ((de = ReadDir(dbspace_dir, dbspacedirname)) != NULL)
224 : {
225 : ForkNumber forkNum;
226 : int oidchars;
227 : bool found;
228 : unlogged_relation_entry ent;
229 :
230 : /* Skip anything that doesn't look like a relation data file. */
231 598 : if (!parse_filename_for_nontemp_relation(de->d_name, &oidchars,
232 : &forkNum))
233 16 : continue;
234 :
235 : /* We never remove the init fork. */
236 586 : if (forkNum == INIT_FORKNUM)
237 4 : continue;
238 :
239 : /*
240 : * See whether the OID portion of the name shows up in the hash
241 : * table.
242 : */
243 582 : memset(ent.oid, 0, sizeof(ent.oid));
244 582 : memcpy(ent.oid, de->d_name, oidchars);
245 582 : hash_search(hash, &ent, HASH_FIND, &found);
246 :
247 : /* If so, nuke it! */
248 582 : if (found)
249 : {
250 8 : snprintf(rm_path, sizeof(rm_path), "%s/%s",
251 8 : dbspacedirname, de->d_name);
252 8 : if (unlink(rm_path) < 0)
253 0 : ereport(ERROR,
254 : (errcode_for_file_access(),
255 : errmsg("could not remove file \"%s\": %m",
256 : rm_path)));
257 : else
258 8 : elog(DEBUG2, "unlinked file \"%s\"", rm_path);
259 : }
260 : }
261 :
262 : /* Cleanup is complete. */
263 4 : FreeDir(dbspace_dir);
264 4 : hash_destroy(hash);
265 : }
266 :
267 : /*
268 : * Initialization happens after cleanup is complete: we copy each init
269 : * fork file to the corresponding main fork file. Note that if we are
270 : * asked to do both cleanup and init, we may never get here: if the
271 : * cleanup code determines that there are no init forks in this dbspace,
272 : * it will return before we get to this point.
273 : */
274 552 : if ((op & UNLOGGED_RELATION_INIT) != 0)
275 : {
276 : /* Scan the directory. */
277 548 : dbspace_dir = AllocateDir(dbspacedirname);
278 150072 : while ((de = ReadDir(dbspace_dir, dbspacedirname)) != NULL)
279 : {
280 : ForkNumber forkNum;
281 : int oidchars;
282 : char oidbuf[OIDCHARS + 1];
283 : char srcpath[MAXPGPATH * 2];
284 : char dstpath[MAXPGPATH];
285 :
286 : /* Skip anything that doesn't look like a relation data file. */
287 149524 : if (!parse_filename_for_nontemp_relation(de->d_name, &oidchars,
288 : &forkNum))
289 149520 : continue;
290 :
291 : /* Also skip it unless this is the init fork. */
292 147392 : if (forkNum != INIT_FORKNUM)
293 147388 : continue;
294 :
295 : /* Construct source pathname. */
296 4 : snprintf(srcpath, sizeof(srcpath), "%s/%s",
297 4 : dbspacedirname, de->d_name);
298 :
299 : /* Construct destination pathname. */
300 4 : memcpy(oidbuf, de->d_name, oidchars);
301 4 : oidbuf[oidchars] = '\0';
302 4 : snprintf(dstpath, sizeof(dstpath), "%s/%s%s",
303 8 : dbspacedirname, oidbuf, de->d_name + oidchars + 1 +
304 4 : strlen(forkNames[INIT_FORKNUM]));
305 :
306 : /* OK, we're ready to perform the actual copy. */
307 4 : elog(DEBUG2, "copying %s to %s", srcpath, dstpath);
308 4 : copy_file(srcpath, dstpath);
309 : }
310 :
311 548 : FreeDir(dbspace_dir);
312 :
313 : /*
314 : * copy_file() above has already called pg_flush_data() on the files
315 : * it created. Now we need to fsync those files, because a checkpoint
316 : * won't do it for us while we're in recovery. We do this in a
317 : * separate pass to allow the kernel to perform all the flushes
318 : * (especially the metadata ones) at once.
319 : */
320 548 : dbspace_dir = AllocateDir(dbspacedirname);
321 150076 : while ((de = ReadDir(dbspace_dir, dbspacedirname)) != NULL)
322 : {
323 : ForkNumber forkNum;
324 : int oidchars;
325 : char oidbuf[OIDCHARS + 1];
326 : char mainpath[MAXPGPATH];
327 :
328 : /* Skip anything that doesn't look like a relation data file. */
329 149528 : if (!parse_filename_for_nontemp_relation(de->d_name, &oidchars,
330 : &forkNum))
331 149524 : continue;
332 :
333 : /* Also skip it unless this is the init fork. */
334 147396 : if (forkNum != INIT_FORKNUM)
335 147392 : continue;
336 :
337 : /* Construct main fork pathname. */
338 4 : memcpy(oidbuf, de->d_name, oidchars);
339 4 : oidbuf[oidchars] = '\0';
340 4 : snprintf(mainpath, sizeof(mainpath), "%s/%s%s",
341 8 : dbspacedirname, oidbuf, de->d_name + oidchars + 1 +
342 4 : strlen(forkNames[INIT_FORKNUM]));
343 :
344 4 : fsync_fname(mainpath, false);
345 : }
346 :
347 548 : FreeDir(dbspace_dir);
348 :
349 : /*
350 : * Lastly, fsync the database directory itself, ensuring the
351 : * filesystem remembers the file creations and deletions we've done.
352 : * We don't bother with this during a call that does only
353 : * UNLOGGED_RELATION_CLEANUP, because if recovery crashes before we
354 : * get to doing UNLOGGED_RELATION_INIT, we'll redo the cleanup step
355 : * too at the next startup attempt.
356 : */
357 548 : fsync_fname(dbspacedirname, true);
358 : }
359 : }
360 :
361 : /*
362 : * Basic parsing of putative relation filenames.
363 : *
364 : * This function returns true if the file appears to be in the correct format
365 : * for a non-temporary relation and false otherwise.
366 : *
367 : * NB: If this function returns true, the caller is entitled to assume that
368 : * *oidchars has been set to the a value no more than OIDCHARS, and thus
369 : * that a buffer of OIDCHARS+1 characters is sufficient to hold the OID
370 : * portion of the filename. This is critical to protect against a possible
371 : * buffer overrun.
372 : */
373 : bool
374 725596 : parse_filename_for_nontemp_relation(const char *name, int *oidchars,
375 : ForkNumber *fork)
376 : {
377 : int pos;
378 :
379 : /* Look for a non-empty string of digits (that isn't too long). */
380 3628608 : for (pos = 0; isdigit((unsigned char) name[pos]); ++pos)
381 : ;
382 725596 : if (pos == 0 || pos > OIDCHARS)
383 8564 : return false;
384 717032 : *oidchars = pos;
385 :
386 : /* Check for a fork name. */
387 717032 : if (name[pos] != '_')
388 537856 : *fork = MAIN_FORKNUM;
389 : else
390 : {
391 : int forkchar;
392 :
393 179176 : forkchar = forkname_chars(&name[pos + 1], fork);
394 179176 : if (forkchar <= 0)
395 0 : return false;
396 179176 : pos += forkchar + 1;
397 : }
398 :
399 : /* Check for a segment number. */
400 717032 : if (name[pos] == '.')
401 : {
402 : int segchar;
403 :
404 0 : for (segchar = 1; isdigit((unsigned char) name[pos + segchar]); ++segchar)
405 : ;
406 0 : if (segchar <= 1)
407 0 : return false;
408 0 : pos += segchar;
409 : }
410 :
411 : /* Now we should be at the end. */
412 717032 : if (name[pos] != '\0')
413 0 : return false;
414 717032 : return true;
415 : }
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