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, 13 insertions, 1 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 22d604601957..0fc2bd34039d 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -171,7 +171,8 @@ static int ocfs2_dir_release(struct inode *inode, struct file *file)
         return 0;
 }
 
-static int ocfs2_sync_file(struct file *file, int datasync)
+static int ocfs2_sync_file(struct file *file, loff_t start, loff_t end,
+                           int datasync)
 {
         int err = 0;
         journal_t *journal;
@@ -184,6 +185,16 @@ static int ocfs2_sync_file(struct file *file, int datasync)
                               file->f_path.dentry->d_name.name,
                               (unsigned long long)datasync);
 
+        err = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (err)
+                return err;
+
+        /*
+         * Probably don't need the i_mutex at all in here, just putting it here
+         * to be consistent with how fsync used to be called, someone more
+         * familiar with the fs could possibly remove it.
+         */
+        mutex_lock(&inode->i_mutex);
         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) {
                 /*
                  * We still have to flush drive's caches to get data to the
@@ -200,6 +211,7 @@ static int ocfs2_sync_file(struct file *file, int datasync)
 bail:
         if (err)
                 mlog_errno(err);
+        mutex_unlock(&inode->i_mutex);
 
         return (err < 0) ? -EIO : 0;
 }