tdb: cleanup: tdb_lock_list helper to cover tdb_lock and tdb_lock_nonblock

[ccan] / ccan / tdb / lock.c

diff --git a/ccan/tdb/lock.c b/ccan/tdb/lock.c
index a59ba365213e473630617ee69ff1f238585d6782..fd451e58cd314b54167b476e8a74890aa8e23581 100644 (file)
--- a/ccan/tdb/lock.c
+++ b/ccan/tdb/lock.c
@@ -119,6 +119,12 @@ static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
        return fcntl(tdb->fd, F_SETLKW, &fl);
 }
 
+/* list -1 is the alloc list, otherwise a hash chain. */
+static tdb_off_t lock_offset(int list)
+{
+       return FREELIST_TOP + 4*list;
+}
+
 /* a byte range locking function - return 0 on success
    this functions locks/unlocks 1 byte at the specified offset.
 
@@ -146,6 +152,14 @@ int tdb_brlock(struct tdb_context *tdb,
                return -1;
        }
 
+       /* Sanity check */
+       if (tdb->transaction && offset >= lock_offset(-1) && len != 0) {
+               tdb->ecode = TDB_ERR_RDONLY;
+               TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_brlock attempted in transaction at offset %d rw_type=%d flags=%d len=%d\n",
+                        offset, rw_type, flags, (int)len));
+               return -1;
+       }
+
        do {
                ret = fcntl_lock(tdb, rw_type, offset, len,
                                 flags & TDB_LOCK_WAIT);
@@ -234,12 +248,6 @@ int tdb_allrecord_upgrade(struct tdb_context *tdb)
        return -1;
 }
 
-/* list -1 is the alloc list, otherwise a hash chain. */
-static tdb_off_t lock_offset(int list)
-{
-       return FREELIST_TOP + 4*list;
-}
-
 static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
                                           tdb_off_t offset)
 {
@@ -289,7 +297,7 @@ int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
 
        /* Since fcntl locks don't nest, we do a lock for the first one,
           and simply bump the count for future ones */
-       if (tdb->methods->brlock(tdb, ltype, offset, 1, flags)) {
+       if (tdb_brlock(tdb, ltype, offset, 1, flags)) {
                return -1;
        }
 
@@ -301,8 +309,8 @@ int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
        return 0;
 }
 
-/* lock a list in the database. list -1 is the alloc list */
-int tdb_lock(struct tdb_context *tdb, int list, int ltype)
+static int tdb_lock_list(struct tdb_context *tdb, int list, int ltype,
+                        enum tdb_lock_flags waitflag)
 {
        int ret;
 
@@ -316,9 +324,17 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
                tdb->ecode = TDB_ERR_LOCK;
                ret = -1;
        } else {
-               ret = tdb_nest_lock(tdb, lock_offset(list), ltype,
-                                   TDB_LOCK_WAIT);
+               ret = tdb_nest_lock(tdb, lock_offset(list), ltype, waitflag);
        }
+       return ret;
+}
+
+/* lock a list in the database. list -1 is the alloc list */
+int tdb_lock(struct tdb_context *tdb, int list, int ltype)
+{
+       int ret;
+
+       ret = tdb_lock_list(tdb, list, ltype, TDB_LOCK_WAIT);
        if (ret) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
                         "ltype=%d (%s)\n",  list, ltype, strerror(errno)));
@@ -329,18 +345,7 @@ int tdb_lock(struct tdb_context *tdb, int list, int ltype)
 /* lock a list in the database. list -1 is the alloc list. non-blocking lock */
 int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
 {
-       /* a allrecord lock allows us to avoid per chain locks */
-       if (tdb->allrecord_lock.count &&
-           (ltype == tdb->allrecord_lock.ltype || ltype == F_RDLCK)) {
-               return 0;
-       }
-
-       if (tdb->allrecord_lock.count) {
-               tdb->ecode = TDB_ERR_LOCK;
-               return -1;
-       }
-
-       return tdb_nest_lock(tdb, lock_offset(list), ltype, TDB_LOCK_NOWAIT);
+       return tdb_lock_list(tdb, list, ltype, TDB_LOCK_NOWAIT);
 }
 
 
@@ -380,7 +385,7 @@ int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
        if (mark_lock) {
                ret = 0;
        } else {
-               ret = tdb->methods->brunlock(tdb, ltype, offset, 1);
+               ret = tdb_brunlock(tdb, ltype, offset, 1);
        }
 
        /*
@@ -470,7 +475,7 @@ int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
                return -1;
        }
 
-       if (tdb->methods->brlock(tdb, ltype, FREELIST_TOP, 0, flags)) {
+       if (tdb_brlock(tdb, ltype, FREELIST_TOP, 0, flags)) {
                if (flags & TDB_LOCK_WAIT) {
                        TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lockall failed (%s)\n", strerror(errno)));
                }
@@ -514,8 +519,7 @@ int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
                return 0;
        }
 
-       if (!mark_lock &&
-           tdb->methods->brunlock(tdb, ltype, FREELIST_TOP, 0)) {
+       if (!mark_lock && tdb_brunlock(tdb, ltype, FREELIST_TOP, 0)) {
                TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed (%s)\n", strerror(errno)));
                return -1;
        }
@@ -648,7 +652,7 @@ int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
        if (tdb->allrecord_lock.count) {
                return 0;
        }
-       return off ? tdb->methods->brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
+       return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
 }
 
 /*
@@ -662,12 +666,21 @@ int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
        for (i = &tdb->travlocks; i; i = i->next)
                if (i->off == off)
                        return -1;
-       return tdb->methods->brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
+       if (tdb->allrecord_lock.count) {
+               if (tdb->allrecord_lock.ltype == F_WRLCK) {
+                       return 0;
+               }
+               return -1;
+       }
+       return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
 }
 
 int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
 {
-       return tdb->methods->brunlock(tdb, F_WRLCK, off, 1);
+       if (tdb->allrecord_lock.count) {
+               return 0;
+       }
+       return tdb_brunlock(tdb, F_WRLCK, off, 1);
 }
 
 /* fcntl locks don't stack: avoid unlocking someone else's */
@@ -685,7 +698,7 @@ int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
        for (i = &tdb->travlocks; i; i = i->next)
                if (i->off == off)
                        count++;
-       return (count == 1 ? tdb->methods->brunlock(tdb, F_RDLCK, off, 1) : 0);
+       return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0);
 }
 
 bool tdb_have_extra_locks(struct tdb_context *tdb)