fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers

Btrfs needs to be able to control how filemap_write_and_wait_range() is called
in fsync to make it less of a painful operation, so push down taking i_mutex and
the calling of filemap_write_and_wait() down into the ->fsync() handlers.  Some
file systems can drop taking the i_mutex altogether it seems, like ext3 and
ocfs2.  For correctness sake I just pushed everything down in all cases to make
sure that we keep the current behavior the same for everybody, and then each
individual fs maintainer can make up their mind about what to do from there.
Thanks,

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8a45e6d1f6a4..57f578e2560a 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -56,7 +56,7 @@ static int nfs_link(struct dentry *, struct inode *, struct dentry *);
 static int nfs_mknod(struct inode *, struct dentry *, int, dev_t);
 static int nfs_rename(struct inode *, struct dentry *,
                       struct inode *, struct dentry *);
-static int nfs_fsync_dir(struct file *, int);
+static int nfs_fsync_dir(struct file *, loff_t, loff_t, int);
 static loff_t nfs_llseek_dir(struct file *, loff_t, int);
 static void nfs_readdir_clear_array(struct page*);
 
@@ -945,15 +945,19 @@ out:
  * All directory operations under NFS are synchronous, so fsync()
  * is a dummy operation.
  */
-static int nfs_fsync_dir(struct file *filp, int datasync)
+static int nfs_fsync_dir(struct file *filp, loff_t start, loff_t end,
+                         int datasync)
 {
         struct dentry *dentry = filp->f_path.dentry;
+        struct inode *inode = dentry->d_inode;
 
         dfprintk(FILE, "NFS: fsync dir(%s/%s) datasync %d\n",
                         dentry->d_parent->d_name.name, dentry->d_name.name,
                         datasync);
 
+        mutex_lock(&inode->i_mutex);
         nfs_inc_stats(dentry->d_inode, NFSIOS_VFSFSYNC);
+        mutex_unlock(&inode->i_mutex);
         return 0;
 }