AFS: implement file locking

Implement file locking for AFS.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/afs/Makefile

@@ -8,6 +8,7 @@ kafs-objs := \
 	cmservice.o \
 	dir.o \
 	file.o \
+	flock.o \
 	fsclient.o \
 	inode.o \
 	main.o \

fs/afs/afs.h

@@ -37,6 +37,13 @@ typedef enum {
 	AFS_FTYPE_SYMLINK	= 3,
 } afs_file_type_t;
 
+typedef enum {
+	AFS_LOCK_READ		= 0,	/* read lock request */
+	AFS_LOCK_WRITE		= 1,	/* write lock request */
+} afs_lock_type_t;
+
+#define AFS_LOCKWAIT		(5 * 60) /* time until a lock times out (seconds) */
+
 /*
  * AFS file identifier
  */
@@ -120,6 +127,7 @@ struct afs_file_status {
 	struct afs_fid		parent;		/* parent dir ID for non-dirs only */
 	time_t			mtime_client;	/* last time client changed data */
 	time_t			mtime_server;	/* last time server changed data */
+	s32			lock_count;	/* file lock count (0=UNLK -1=WRLCK +ve=#RDLCK */
 };
 
 /*

fs/afs/afs_fs.h

@@ -31,6 +31,9 @@ enum AFS_FS_Operations {
 	FSGETVOLUMEINFO		= 148,	/* AFS Get information about a volume */
 	FSGETVOLUMESTATUS	= 149,	/* AFS Get volume status information */
 	FSGETROOTVOLUME		= 151,	/* AFS Get root volume name */
+	FSSETLOCK		= 156,	/* AFS Request a file lock */
+	FSEXTENDLOCK		= 157,	/* AFS Extend a file lock */
+	FSRELEASELOCK		= 158,	/* AFS Release a file lock */
 	FSLOOKUP		= 161,	/* AFS lookup file in directory */
 	FSFETCHDATA64		= 65537, /* AFS Fetch file data */
 	FSSTOREDATA64		= 65538, /* AFS Store file data */

fs/afs/callback.c

@@ -125,6 +125,9 @@ static void afs_break_callback(struct afs_server *server,
 		spin_unlock(&server->cb_lock);
 
 		queue_work(afs_callback_update_worker, &vnode->cb_broken_work);
+		if (list_empty(&vnode->granted_locks) &&
+		    !list_empty(&vnode->pending_locks))
+			afs_lock_may_be_available(vnode);
 		spin_unlock(&vnode->lock);
 	}
 }

fs/afs/dir.c

@@ -44,6 +44,7 @@ const struct file_operations afs_dir_file_operations = {
 	.open		= afs_dir_open,
 	.release	= afs_release,
 	.readdir	= afs_readdir,
+	.lock		= afs_lock,
 };
 
 const struct inode_operations afs_dir_inode_operations = {

fs/afs/file.c

@@ -34,6 +34,8 @@ const struct file_operations afs_file_operations = {
 	.mmap		= generic_file_readonly_mmap,
 	.splice_read	= generic_file_splice_read,
 	.fsync		= afs_fsync,
+	.lock		= afs_lock,
+	.flock		= afs_flock,
 };
 
 const struct inode_operations afs_file_inode_operations = {