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, 13 insertions, 2 deletions

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 7e9e4c79aec7..99f012a0f207 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -219,6 +219,7 @@ int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
         struct super_block *sb;
         struct ocfs2_super *osb;
         int status = -EINVAL;
+        int use_plocks = 1;
 
         mlog_entry("(0x%p, size:%llu)\n", inode,
                    (unsigned long long)le64_to_cpu(fe->i_size));
@@ -226,6 +227,10 @@ int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
         sb = inode->i_sb;
         osb = OCFS2_SB(sb);
 
+        if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
+            ocfs2_mount_local(osb) || !ocfs2_stack_supports_plocks())
+                use_plocks = 0;
+
         /* this means that read_inode cannot create a superblock inode
          * today.  change if needed. */
         if (!OCFS2_IS_VALID_DINODE(fe) ||
@@ -295,13 +300,19 @@ int ocfs2_populate_inode(struct inode *inode, struct ocfs2_dinode *fe,
 
         switch (inode->i_mode & S_IFMT) {
             case S_IFREG:
-                    inode->i_fop = &ocfs2_fops;
+                    if (use_plocks)
+                            inode->i_fop = &ocfs2_fops;
+                    else
+                            inode->i_fop = &ocfs2_fops_no_plocks;
                     inode->i_op = &ocfs2_file_iops;
                     i_size_write(inode, le64_to_cpu(fe->i_size));
                     break;
             case S_IFDIR:
                     inode->i_op = &ocfs2_dir_iops;
-                    inode->i_fop = &ocfs2_dops;
+                    if (use_plocks)
+                            inode->i_fop = &ocfs2_dops;
+                    else
+                            inode->i_fop = &ocfs2_dops_no_plocks;
                     i_size_write(inode, le64_to_cpu(fe->i_size));
                     break;
             case S_IFLNK: