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, 8 insertions, 3 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 2c1705b6acd7..28b8c3f3cda3 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -55,7 +55,7 @@ static ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
 static ssize_t nfs_file_write(struct kiocb *, const struct iovec *iov,
                                 unsigned long nr_segs, loff_t pos);
 static int  nfs_file_flush(struct file *, fl_owner_t id);
-static int  nfs_file_fsync(struct file *, int datasync);
+static int  nfs_file_fsync(struct file *, loff_t, loff_t, int datasync);
 static int nfs_check_flags(int flags);
 static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl);
 static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl);
@@ -308,7 +308,7 @@ nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
  * fall back to doing a synchronous write.
  */
 static int
-nfs_file_fsync(struct file *file, int datasync)
+nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
         struct dentry *dentry = file->f_path.dentry;
         struct nfs_open_context *ctx = nfs_file_open_context(file);
@@ -316,11 +316,15 @@ nfs_file_fsync(struct file *file, int datasync)
         int have_error, status;
         int ret = 0;
 
-
         dprintk("NFS: fsync file(%s/%s) datasync %d\n",
                         dentry->d_parent->d_name.name, dentry->d_name.name,
                         datasync);
 
+        ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (ret)
+                return ret;
+        mutex_lock(&inode->i_mutex);
+
         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
         have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
         status = nfs_commit_inode(inode, FLUSH_SYNC);
@@ -332,6 +336,7 @@ nfs_file_fsync(struct file *file, int datasync)
         if (!ret && !datasync)
                 /* application has asked for meta-data sync */
                 ret = pnfs_layoutcommit_inode(inode, true);
+        mutex_unlock(&inode->i_mutex);
         return ret;
 }