From fe5124e38d8fbc271a3b5553f54dd6ecd33cf7c7 Mon Sep 17 00:00:00 2001 From: Andrew Tridgell Date: Fri, 24 Aug 2007 02:37:38 +0000 Subject: [PATCH] r24642: prevent recursion with fetch_locked add a note about server_id exists checking (This used to be commit dd951b983c0cde2dd54c5370dc8d6440509b0559) --- source4/ntvfs/common/brlock_tdb.c | 32 +++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/source4/ntvfs/common/brlock_tdb.c b/source4/ntvfs/common/brlock_tdb.c index 25a0a040a58..0bca9d2590a 100644 --- a/source4/ntvfs/common/brlock_tdb.c +++ b/source4/ntvfs/common/brlock_tdb.c @@ -135,9 +135,12 @@ static BOOL brl_tdb_same_context(struct lock_context *ctx1, struct lock_context /* see if lck1 and lck2 overlap + + lck1 is the existing lock. lck2 is the new lock we are + looking at adding */ static BOOL brl_tdb_overlap(struct lock_struct *lck1, - struct lock_struct *lck2) + struct lock_struct *lck2) { /* this extra check is not redundent - it copes with locks that go beyond the end of 64 bit file space */ @@ -151,6 +154,15 @@ static BOOL brl_tdb_overlap(struct lock_struct *lck1, lck2->start >= (lck1->start+lck1->size)) { return False; } + + /* we have a conflict. Now check to see if lck1 really still + * exists, which involves checking if the process still + * exists. We leave this test to last as its the most + * expensive test, especially when we are clustered */ + /* TODO: need to do this via a server_id_exists() call, which + * hasn't been written yet. When clustered this will need to + * call into ctdb */ + return True; } @@ -283,14 +295,6 @@ static NTSTATUS brl_tdb_lock(struct brl_context *brl, NTSTATUS status; struct db_record *rec = NULL; - kbuf.dptr = brlh->key.data; - kbuf.dsize = brlh->key.length; - - rec = brl->db->fetch_locked(brl->db, brl, kbuf); - if (rec == NULL) { - return NT_STATUS_INTERNAL_DB_CORRUPTION; - } - /* if this is a pending lock, then with the chainlock held we try to get the real lock. If we succeed then we don't need to make it pending. This prevents a possible race condition @@ -305,11 +309,19 @@ static NTSTATUS brl_tdb_lock(struct brl_context *brl, brlh->last_lock = lock; if (NT_STATUS_IS_OK(status)) { - talloc_free(rec); return NT_STATUS_OK; } } + kbuf.dptr = brlh->key.data; + kbuf.dsize = brlh->key.length; + + rec = brl->db->fetch_locked(brl->db, brl, kbuf); + if (rec == NULL) { + return NT_STATUS_INTERNAL_DB_CORRUPTION; + } + + dbuf = rec->value; lock.context.smbpid = smbpid; -- 2.34.1