SMB_OFF_T start;
SMB_OFF_T size;
int lock_type;
- size_t ref_count;
};
/*
}
/****************************************************************************
- Add an entry into the POSIX locking tdb.
+ Add an entry into the POSIX locking tdb. Returns the number of records that
+ match the given start and size, or -1 on error.
****************************************************************************/
-static BOOL add_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, int lock_type)
+static int add_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, int lock_type)
{
TDB_DATA kbuf = locking_key_fsp(fsp);
TDB_DATA dbuf;
+ struct posix_lock pl;
struct posix_lock *entries;
- size_t count, i, ref_count;
+ size_t i, count;
+ int num_records = 0;
/*
- * Windows is very strange. It allows a write lock to be downgraded to
- * a read lock, but reference counts the locks. This means if you get
- * the following sequence :
+ * Windows is very strange. It allows read locks to be overlayed on
+ * a write lock, but leaves the write lock in force until the first
+ * unlock. It also reference counts the locks. This means the following sequence :
*
+ * process1 process2
+ * ------------------------------------------------------------------------
* WRITE LOCK : start = 0, len = 10
+ * READ LOCK: start =0, len = 10 - FAIL
* READ LOCK : start = 0, len = 10
- *
- * then another process will be able to get a read lock, but the unlock
- * sequence must be done twice to remove the read lock.
- *
- * Under POSIX, the same sequence would not be reference counted, but
+ * READ LOCK: start =0, len = 10 - FAIL
+ * UNLOCK : start = 0, len = 10
+ * READ LOCK: start =0, len = 10 - OK
+ *
+ * Under POSIX, the same sequence in steps 1 and 2 would not be reference counted, but
* would leave a single read lock over the 0-10 region. In order to
- * re-create Windows semantics mapped to POSIX locks, we reference
- * count the POSIX lock request, so that when multiple locks over a
- * region is requested of the Samba POSIX lock code (this can only
- * be an overlay of a read onto a write lock due to the checks already
- * being done in brlock.c) then we map the lock onto POSIX, but just
- * increment the reference count in the tdb. Unlocks decrement the
- * reference count and only do the POSIX unlock call when the refcount
- * reaches zero.
+ * re-create Windows semantics mapped to POSIX locks, we create multiple TDB
+ * entries, one for each overlayed lock request. We are guarenteed by the brlock
+ * semantics that if a write lock is added, then it will be first in the array.
*/
dbuf.dptr = NULL;
dbuf = tdb_fetch(posix_lock_tdb, kbuf);
- /*
- * Look for an existing entry matching this region.
+ /*
+ * New record.
*/
-
- entries = (struct posix_lock *)dbuf.dptr;
- count = (size_t)(dbuf.dsize / sizeof(struct posix_lock));
-
- for (i = 0; i < count; i++) {
- struct posix_lock *entry = &entries[i];
- /*
- * Just increment the ref_count on a matching entry.
- * Note we don't take lock type into account here.
- */
+ pl.fd = fsp->fd;
+ pl.start = start;
+ pl.size = size;
+ pl.lock_type = lock_type;
- if ((entry->fd == fsp->fd) &&
- (entry->start == start) &&
- (entry->size == size)) {
- /* Overwrite the lock type also. */
- entry->lock_type = lock_type;
- ref_count = ++entry->ref_count;
- break;
- }
+ dbuf.dptr = Realloc(dbuf.dptr, dbuf.dsize + sizeof(pl));
+ if (!dbuf.dptr) {
+ DEBUG(0,("add_posix_lock_entry: Realloc fail !\n"));
+ goto fail;
}
- if (i == count) {
- struct posix_lock pl;
+ memcpy(dbuf.dptr + dbuf.dsize, &pl, sizeof(pl));
+ dbuf.dsize += sizeof(pl);
- /*
- * New record needed.
- */
+ count = (size_t)(dbuf.dsize / sizeof(pl));
+ entries = (struct posix_lock *)dbuf.dptr;
- pl.fd = fsp->fd;
- pl.start = start;
- pl.size = size;
- pl.lock_type = lock_type;
- ref_count = pl.ref_count = 1;
+ for (i = 0; i < count; i++) {
+ struct posix_lock *entry = &entries[i];
- dbuf.dptr = Realloc(dbuf.dptr, dbuf.dsize + sizeof(pl));
- if (!dbuf.dptr) {
- DEBUG(0,("add_posix_lock_entry: Realloc fail !\n"));
- goto fail;
- }
+ if (fsp->fd == entry->fd &&
+ start == entry->start &&
+ size == entry->size)
+ num_records++;
- memcpy(dbuf.dptr + dbuf.dsize, &pl, sizeof(pl));
- dbuf.dsize += sizeof(pl);
}
if (tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE) == -1) {
free(dbuf.dptr);
- DEBUG(10,("add_posix_lock: File %s: type = %s: start=%.0f size=%.0f, ref_count = %u :dev=%.0f inode=%.0f\n",
- fsp->fsp_name, posix_lock_type_name(lock_type), (double)start, (double)size, (unsigned int)ref_count,
+ DEBUG(10,("add_posix_lock: File %s: type = %s: start=%.0f size=%.0f: num_records = %d : dev=%.0f inode=%.0f\n",
+ fsp->fsp_name, posix_lock_type_name(lock_type), (double)start, (double)size, num_records,
(double)fsp->dev, (double)fsp->inode ));
- return True;
+ return num_records;
fail:
if (dbuf.dptr)
free(dbuf.dptr);
- return False;
+ return -1;
}
/****************************************************************************
- Delete an entry from the POSIX locking tdb.
+ Delete an entry from the POSIX locking tdb. Returns a copy of the entry being
+ deleted and the number of remaining matching records, or -1 on error.
****************************************************************************/
-static BOOL delete_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size)
+static int delete_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, struct posix_lock *pl)
{
TDB_DATA kbuf = locking_key_fsp(fsp);
TDB_DATA dbuf;
struct posix_lock *locks;
size_t i, count;
+ int num_records = 0;
dbuf.dptr = NULL;
-
+
dbuf = tdb_fetch(posix_lock_tdb, kbuf);
if (!dbuf.dptr) {
locks = (struct posix_lock *)dbuf.dptr;
count = (size_t)(dbuf.dsize / sizeof(*locks));
+ /*
+ * Count the number of entries that match this
+ * unlock request.
+ */
+
+ for (i = 0; i < count; i++) {
+ struct posix_lock *entry = &locks[i];
+
+ if (entry->fd == fsp->fd &&
+ entry->start == start &&
+ entry->size == size) {
+ num_records++;
+ }
+ }
+
for (i=0; i<count; i++) {
- struct posix_lock *pl = &locks[i];
+ struct posix_lock *entry = &locks[i];
- if (pl->fd == fsp->fd &&
- pl->start == start &&
- pl->size == size) {
+ if (entry->fd == fsp->fd &&
+ entry->start == start &&
+ entry->size == size) {
- pl->ref_count--;
+ num_records--; /* We're deleting one. */
- DEBUG(10,("delete_posix_lock_entry: type = %s: start=%.0f size=%.0f, ref_count = %u\n",
+ DEBUG(10,("delete_posix_lock_entry: type = %s: start=%.0f size=%.0f, num_records = %d\n",
posix_lock_type_name(pl->lock_type), (double)pl->start, (double)pl->size,
- (unsigned int)pl->ref_count ));
-
- if (pl->ref_count == 0) {
- /* Found it - delete it. */
- if (count == 1) {
- tdb_delete(posix_lock_tdb, kbuf);
- } else {
- if (i < count-1) {
- memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i));
- }
- dbuf.dsize -= sizeof(*locks);
- tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE);
- }
+ (unsigned int)num_records ));
+
+ /* Make a copy if requested. */
+ if (pl)
+ *pl = *entry;
+
+ /* Found it - delete it. */
+ if (count == 1) {
+ tdb_delete(posix_lock_tdb, kbuf);
} else {
- /* Just re-store the new ref count. */
+ if (i < count-1) {
+ memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i));
+ }
+ dbuf.dsize -= sizeof(*locks);
tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE);
}
free(dbuf.dptr);
- return True;
+ return num_records;
}
}
fail:
if (dbuf.dptr)
free(dbuf.dptr);
- return False;
+ return -1;
}
/****************************************************************************
/****************************************************************************
Pathetically try and map a 64 bit lock offset into 31 bits. I hate Windows :-).
****************************************************************************/
+
static uint32 map_lock_offset(uint32 high, uint32 low)
{
unsigned int i;
SMB_OFF_T count;
BOOL ret = True;
int posix_lock_type = map_posix_lock_type(fsp,lock_type);
+ int ref_count;
DEBUG(5,("set_posix_lock: File %s, offset = %.0f, count = %.0f, type = %s\n",
fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) ));
* file descriptors will not be held separately by the kernel (POSIX
* braindamage), but will be merged into one continuous lock
* range. We cope with this case in the release_posix_lock code
- * below. JRA.
+ * below. We need to add the posix lock entry into the tdb before
+ * doing the real posix lock call to deal with the locking overlay
+ * case described above in add_posix_lock_entry().
*/
- ret = posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type);
+ ref_count = add_posix_lock_entry(fsp,offset,count,posix_lock_type);
+
+ if (ref_count == 1) {
+ /*
+ * First lock entry created. Do a real POSIX lock.
+ */
+ ret = posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type);
- if (ret)
- add_posix_lock_entry(fsp,offset,count,posix_lock_type);
+ /*
+ * Oops, POSIX lock failed, delete the tdb entry.
+ */
+ if (!ret)
+ delete_posix_lock_entry(fsp,offset,count,NULL);
+ }
return ret;
}
TALLOC_CTX *ul_ctx = NULL;
struct unlock_list *ulist = NULL;
struct unlock_list *ul = NULL;
+ struct posix_lock deleted_lock;
+ int num_entries;
DEBUG(5,("release_posix_lock: File %s, offset = %.0f, count = %.0f\n",
fsp->fsp_name, (double)u_offset, (double)u_count ));
* if it may have been split into multiple smaller POSIX unlock ranges.
*/
- delete_posix_lock_entry(fsp, offset, count);
+ num_entries = delete_posix_lock_entry(fsp, offset, count, &deleted_lock);
+
+ if (num_entries == -1) {
+ smb_panic("release_posix_lock: unable find entry to delete !\n");
+ }
+
+ /*
+ * If num_entries is > 0, and the lock_type we just deleted from the tdb was
+ * a POSIX write lock, then rather than doing an unlock we need to downgrade
+ * the POSIX lock to a read lock.
+ */
+
+ if (num_entries > 0 && deleted_lock.lock_type == F_WRLCK) {
+ return posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_RDLCK);
+ }
+
+ /*
+ * Only do the POSIX unlock when the num_entries is now zero.
+ */
+
+ if (num_entries > 0) {
+ DEBUG(10, ("release_posix_lock: num_entries = %d\n", num_entries ));
+ return True;
+ }
if ((ul_ctx = talloc_init()) == NULL) {
DEBUG(0,("release_posix_lock: unable to init talloc context.\n"));
git.samba.org / samba.git / commitdiff