ocfs2: Use -errno instead of dlm_status for ocfs2_dlm_lock/unlock() API.

Change the ocfs2_dlm_lock/unlock() functions to return -errno values.
This is the first step towards elminiating dlm_status in
fs/ocfs2/dlmglue.c.  The change also passes -errno values to
->unlock_ast().

[ Fix a return code in dlmglue.c and change the error translation table into
  an array of ints. --Mark ]

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 135 insertions, 7 deletions

diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index 9953804..0aec2fc 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -18,6 +18,7 @@
  * General Public License for more details.
  */
 
+#include "cluster/masklog.h"
 #include "stackglue.h"
 
 static struct ocfs2_locking_protocol *lproto;
@@ -77,7 +78,126 @@ static int flags_to_o2dlm(u32 flags)
 }
 #undef map_flag
 
-enum dlm_status ocfs2_dlm_lock(struct dlm_ctxt *dlm,
+/*
+ * Map an o2dlm status to standard errno values.
+ *
+ * o2dlm only uses a handful of these, and returns even fewer to the
+ * caller. Still, we try to assign sane values to each error.
+ *
+ * The following value pairs have special meanings to dlmglue, thus
+ * the right hand side needs to stay unique - never duplicate the
+ * mapping elsewhere in the table!
+ *
+ * DLM_NORMAL:		0
+ * DLM_NOTQUEUED:	-EAGAIN
+ * DLM_CANCELGRANT:	-DLM_ECANCEL
+ * DLM_CANCEL:		-DLM_EUNLOCK
+ */
+/* Keep in sync with dlmapi.h */
+static int status_map[] = {
+	[DLM_NORMAL]			= 0,		/* Success */
+	[DLM_GRANTED]			= -EINVAL,
+	[DLM_DENIED]			= -EACCES,
+	[DLM_DENIED_NOLOCKS]		= -EACCES,
+	[DLM_WORKING]			= -EBUSY,
+	[DLM_BLOCKED]			= -EINVAL,
+	[DLM_BLOCKED_ORPHAN]		= -EINVAL,
+	[DLM_DENIED_GRACE_PERIOD]	= -EACCES,
+	[DLM_SYSERR]			= -ENOMEM,	/* It is what it is */
+	[DLM_NOSUPPORT]			= -EPROTO,
+	[DLM_CANCELGRANT]		= -DLM_ECANCEL, /* Cancel after grant */
+	[DLM_IVLOCKID]			= -EINVAL,
+	[DLM_SYNC]			= -EINVAL,
+	[DLM_BADTYPE]			= -EINVAL,
+	[DLM_BADRESOURCE]		= -EINVAL,
+	[DLM_MAXHANDLES]		= -ENOMEM,
+	[DLM_NOCLINFO]			= -EINVAL,
+	[DLM_NOLOCKMGR]			= -EINVAL,
+	[DLM_NOPURGED]			= -EINVAL,
+	[DLM_BADARGS]			= -EINVAL,
+	[DLM_VOID]			= -EINVAL,
+	[DLM_NOTQUEUED]			= -EAGAIN,	/* Trylock failed */
+	[DLM_IVBUFLEN]			= -EINVAL,
+	[DLM_CVTUNGRANT]		= -EPERM,
+	[DLM_BADPARAM]			= -EINVAL,
+	[DLM_VALNOTVALID]		= -EINVAL,
+	[DLM_REJECTED]			= -EPERM,
+	[DLM_ABORT]			= -EINVAL,
+	[DLM_CANCEL]			= -DLM_EUNLOCK,	/* Successful cancel */
+	[DLM_IVRESHANDLE]		= -EINVAL,
+	[DLM_DEADLOCK]			= -EDEADLK,
+	[DLM_DENIED_NOASTS]		= -EINVAL,
+	[DLM_FORWARD]			= -EINVAL,
+	[DLM_TIMEOUT]			= -ETIMEDOUT,
+	[DLM_IVGROUPID]			= -EINVAL,
+	[DLM_VERS_CONFLICT]		= -EOPNOTSUPP,
+	[DLM_BAD_DEVICE_PATH]		= -ENOENT,
+	[DLM_NO_DEVICE_PERMISSION]	= -EPERM,
+	[DLM_NO_CONTROL_DEVICE]		= -ENOENT,
+	[DLM_RECOVERING]		= -ENOTCONN,
+	[DLM_MIGRATING]			= -ERESTART,
+	[DLM_MAXSTATS]			= -EINVAL,
+};
+static int dlm_status_to_errno(enum dlm_status status)
+{
+	BUG_ON(status > (sizeof(status_map) / sizeof(status_map[0])));
+
+	return status_map[status];
+}
+
+static void o2dlm_lock_ast_wrapper(void *astarg)
+{
+	BUG_ON(lproto == NULL);
+
+	lproto->lp_lock_ast(astarg);
+}
+
+static void o2dlm_blocking_ast_wrapper(void *astarg, int level)
+{
+	BUG_ON(lproto == NULL);
+
+	lproto->lp_blocking_ast(astarg, level);
+}
+
+static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
+{
+	int error;
+
+	BUG_ON(lproto == NULL);
+
+	/*
+	 * XXX: CANCEL values are sketchy.
+	 *
+	 * Currently we have preserved the o2dlm paradigm.  You can get
+	 * unlock_ast() whether the cancel succeded or not.
+	 *
+	 * First, we're going to pass DLM_EUNLOCK just like fs/dlm does for
+	 * successful unlocks.  That is a clean behavior.
+	 *
+	 * In o2dlm, you can get both the lock_ast() for the lock being
+	 * granted and the unlock_ast() for the CANCEL failing.  A
+	 * successful cancel sends DLM_NORMAL here.  If the
+	 * lock grant happened before the cancel arrived, you get
+	 * DLM_CANCELGRANT.  For now, we'll use DLM_ECANCEL to signify
+	 * CANCELGRANT - the CANCEL was supposed to happen but didn't.  We
+	 * can then use DLM_EUNLOCK to signify a successful CANCEL -
+	 * effectively, the CANCEL caused the lock to roll back.
+	 *
+	 * In the future, we will likely move the o2dlm to send only one
+	 * ast - either unlock_ast() for a successful CANCEL or lock_ast()
+	 * when the grant succeeds.  At that point, we'll send DLM_ECANCEL
+	 * for all cancel results (CANCELGRANT will no longer exist).
+	 */
+	error = dlm_status_to_errno(status);
+
+	/* Successful unlock is DLM_EUNLOCK */
+	if (!error)
+		error = -DLM_EUNLOCK;
+
+	lproto->lp_unlock_ast(astarg, error);
+}
+
+int ocfs2_dlm_lock(struct dlm_ctxt *dlm,
 		   int mode,
 		   struct dlm_lockstatus *lksb,
 		   u32 flags,
@@ -85,27 +205,35 @@ enum dlm_status ocfs2_dlm_lock(struct dlm_ctxt *dlm,
 		   unsigned int namelen,
 		   void *astarg)
 {
+	enum dlm_status status;
 	int o2dlm_mode = mode_to_o2dlm(mode);
 	int o2dlm_flags = flags_to_o2dlm(flags);
+	int ret;
 
 	BUG_ON(lproto == NULL);
 
-	return dlmlock(dlm, o2dlm_mode, lksb, o2dlm_flags, name, namelen,
-		       lproto->lp_lock_ast, astarg,
-		       lproto->lp_blocking_ast);
+	status = dlmlock(dlm, o2dlm_mode, lksb, o2dlm_flags, name, namelen,
+		       o2dlm_lock_ast_wrapper, astarg,
+		       o2dlm_blocking_ast_wrapper);
+	ret = dlm_status_to_errno(status);
+	return ret;
 }
 
-enum dlm_status ocfs2_dlm_unlock(struct dlm_ctxt *dlm,
+int ocfs2_dlm_unlock(struct dlm_ctxt *dlm,
 		     struct dlm_lockstatus *lksb,
 		     u32 flags,
 		     void *astarg)
 {
+	enum dlm_status status;
 	int o2dlm_flags = flags_to_o2dlm(flags);
+	int ret;
 
 	BUG_ON(lproto == NULL);
 
-	return dlmunlock(dlm, lksb, o2dlm_flags,
-			 lproto->lp_unlock_ast, astarg);
+	status = dlmunlock(dlm, lksb, o2dlm_flags,
+			 o2dlm_unlock_ast_wrapper, astarg);
+	ret = dlm_status_to_errno(status);
+	return ret;
 }