diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/utils/cache/relmapper.c | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/src/backend/utils/cache/relmapper.c b/src/backend/utils/cache/relmapper.c index 79e09181b6b..e7345e1410f 100644 --- a/src/backend/utils/cache/relmapper.c +++ b/src/backend/utils/cache/relmapper.c @@ -788,16 +788,6 @@ read_relmap_file(RelMapFile *map, char *dbpath, bool lock_held, int elevel) Assert(elevel >= ERROR); - /* Open the target file. */ - snprintf(mapfilename, sizeof(mapfilename), "%s/%s", dbpath, - RELMAPPER_FILENAME); - fd = OpenTransientFile(mapfilename, O_RDONLY | PG_BINARY); - if (fd < 0) - ereport(elevel, - (errcode_for_file_access(), - errmsg("could not open file \"%s\": %m", - mapfilename))); - /* * Grab the lock to prevent the file from being updated while we read it, * unless the caller is already holding the lock. If the file is updated @@ -808,6 +798,24 @@ read_relmap_file(RelMapFile *map, char *dbpath, bool lock_held, int elevel) if (!lock_held) LWLockAcquire(RelationMappingLock, LW_SHARED); + /* + * Open the target file. + * + * Because Windows isn't happy about the idea of renaming over a file + * that someone has open, we only open this file after acquiring the lock, + * and for the same reason, we close it before releasing the lock. That + * way, by the time write_relmap_file() acquires an exclusive lock, no + * one else will have it open. + */ + snprintf(mapfilename, sizeof(mapfilename), "%s/%s", dbpath, + RELMAPPER_FILENAME); + fd = OpenTransientFile(mapfilename, O_RDONLY | PG_BINARY); + if (fd < 0) + ereport(elevel, + (errcode_for_file_access(), + errmsg("could not open file \"%s\": %m", + mapfilename))); + /* Now read the data. */ pgstat_report_wait_start(WAIT_EVENT_RELATION_MAP_READ); r = read(fd, map, sizeof(RelMapFile)); @@ -825,15 +833,15 @@ read_relmap_file(RelMapFile *map, char *dbpath, bool lock_held, int elevel) } pgstat_report_wait_end(); - if (!lock_held) - LWLockRelease(RelationMappingLock); - if (CloseTransientFile(fd) != 0) ereport(elevel, (errcode_for_file_access(), errmsg("could not close file \"%s\": %m", mapfilename))); + if (!lock_held) + LWLockRelease(RelationMappingLock); + /* check for correct magic number, etc */ if (map->magic != RELMAPPER_FILEMAGIC || map->num_mappings < 0 || |