ocfs2: POSIX file locks support

This is actually pretty easy since fs/dlm already handles the bulk of the
work. The Ocfs2 userspace cluster stack module already uses fs/dlm as the
underlying lock manager, so I only had to add the right calls.

Cluster-aware POSIX locks ("plocks") can be turned off by the same means at
UNIX locks - mount with 'noflocks', or create a local-only Ocfs2 volume.
Internally, the file system uses two sets of file_operations, depending on
whether cluster aware plocks is required. This turns out to be easier than
implementing local-only versions of ->lock.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index ed38796052d..1015ef16a8b 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2237,6 +2237,10 @@ const struct inode_operations ocfs2_special_file_iops = {
         .permission     = ocfs2_permission,
 };
 
+/*
+ * Other than ->lock, keep ocfs2_fops and ocfs2_dops in sync with
+ * ocfs2_fops_no_plocks and ocfs2_dops_no_plocks!
+ */
 const struct file_operations ocfs2_fops = {
         .llseek         = generic_file_llseek,
         .read           = do_sync_read,
@@ -2251,6 +2255,7 @@ const struct file_operations ocfs2_fops = {
 #ifdef CONFIG_COMPAT
         .compat_ioctl   = ocfs2_compat_ioctl,
 #endif
+        .lock           = ocfs2_lock,
         .flock          = ocfs2_flock,
         .splice_read    = ocfs2_file_splice_read,
         .splice_write   = ocfs2_file_splice_write,
@@ -2267,5 +2272,51 @@ const struct file_operations ocfs2_dops = {
 #ifdef CONFIG_COMPAT
         .compat_ioctl   = ocfs2_compat_ioctl,
 #endif
+        .lock           = ocfs2_lock,
+        .flock          = ocfs2_flock,
+};
+
+/*
+ * POSIX-lockless variants of our file_operations.
+ *
+ * These will be used if the underlying cluster stack does not support
+ * posix file locking, if the user passes the "localflocks" mount
+ * option, or if we have a local-only fs.
+ *
+ * ocfs2_flock is in here because all stacks handle UNIX file locks,
+ * so we still want it in the case of no stack support for
+ * plocks. Internally, it will do the right thing when asked to ignore
+ * the cluster.
+ */
+const struct file_operations ocfs2_fops_no_plocks = {
+        .llseek         = generic_file_llseek,
+        .read           = do_sync_read,
+        .write          = do_sync_write,
+        .mmap           = ocfs2_mmap,
+        .fsync          = ocfs2_sync_file,
+        .release        = ocfs2_file_release,
+        .open           = ocfs2_file_open,
+        .aio_read       = ocfs2_file_aio_read,
+        .aio_write      = ocfs2_file_aio_write,
+        .unlocked_ioctl = ocfs2_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl   = ocfs2_compat_ioctl,
+#endif
+        .flock          = ocfs2_flock,
+        .splice_read    = ocfs2_file_splice_read,
+        .splice_write   = ocfs2_file_splice_write,
+};
+
+const struct file_operations ocfs2_dops_no_plocks = {
+        .llseek         = generic_file_llseek,
+        .read           = generic_read_dir,
+        .readdir        = ocfs2_readdir,
+        .fsync          = ocfs2_sync_file,
+        .release        = ocfs2_dir_release,
+        .open           = ocfs2_dir_open,
+        .unlocked_ioctl = ocfs2_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl   = ocfs2_compat_ioctl,
+#endif
         .flock          = ocfs2_flock,
 };