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| author | Rusty Russell <rusty@rustcorp.com.au> | 2009-07-30 11:52:08 +0930 |
|---|---|---|
| committer | Stefan Metzmacher <metze@samba.org> | 2009-07-31 14:40:28 +0200 |
| commit | 3b2f074bda8734a0b30a3e31117c0217d890809c (patch) | |
| tree | d31c49e0b44eacdeeca18eb9a18e26e05e2f7b60 | |
| parent | fa91bc67199f0d45a0e570b43aeafd816a5491bf (diff) | |
| download | samba-3b2f074bda8734a0b30a3e31117c0217d890809c.tar.gz samba-3b2f074bda8734a0b30a3e31117c0217d890809c.tar.bz2 samba-3b2f074bda8734a0b30a3e31117c0217d890809c.zip | |
tdb: Reimplementation of Metze's "lib/tdb: if we know pwrite and pread are thread/fork safe tdb_reopen_all() should be a noop".
This version just wraps the reopen code, so we still re-grab the lock and do
the normal sanity checks.
The reason we do this at all is to avoid global fd limits, see:
http://forums.fedoraforum.org/showthread.php?t=210393
Note also that this whole reopen concept is fundamentally racy: if the parent
goes away before the child calls tdb_reopen_all, the database can be left
without an active lock and another TDB_CLEAR_IF_FIRST opener will clear it.
A fork_with_tdbs() wrapper could use a pipe to solve this, but it's hardly
elegant (what if there are other independent things which have similar needs?).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
| -rw-r--r-- | lib/tdb/common/open.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c index b19e4cea29..49b8e85f12 100644 --- a/lib/tdb/common/open.c +++ b/lib/tdb/common/open.c @@ -425,6 +425,9 @@ int tdb_reopen(struct tdb_context *tdb) goto fail; } +/* If we have real pread & pwrite, we can skip reopen. */ +#if !defined(LIBREPLACE_PREAD_NOT_REPLACED) || \ + !defined(LIBREPLACE_PWRITE_NOT_REPLACED) if (tdb_munmap(tdb) != 0) { TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: munmap failed (%s)\n", strerror(errno))); goto fail; @@ -436,11 +439,6 @@ int tdb_reopen(struct tdb_context *tdb) TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: open failed (%s)\n", strerror(errno))); goto fail; } - if ((tdb->flags & TDB_CLEAR_IF_FIRST) && - (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n")); - goto fail; - } if (fstat(tdb->fd, &st) != 0) { TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: fstat failed (%s)\n", strerror(errno))); goto fail; @@ -450,6 +448,13 @@ int tdb_reopen(struct tdb_context *tdb) goto fail; } tdb_mmap(tdb); +#endif /* fake pread or pwrite */ + + if ((tdb->flags & TDB_CLEAR_IF_FIRST) && + (tdb->methods->tdb_brlock(tdb, ACTIVE_LOCK, F_RDLCK, F_SETLKW, 0, 1) == -1)) { + TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n")); + goto fail; + } return 0; |