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>

2 files changed, 22 insertions, 3 deletions

diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index 4014160903a9..46ce357ca1ab 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -70,7 +70,8 @@ ssize_t v9fs_file_readn(struct file *, char *, char __user *, u32, u64);
 ssize_t v9fs_fid_readn(struct p9_fid *, char *, char __user *, u32, u64);
 void v9fs_blank_wstat(struct p9_wstat *wstat);
 int v9fs_vfs_setattr_dotl(struct dentry *, struct iattr *);
-int v9fs_file_fsync_dotl(struct file *filp, int datasync);
+int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
+                         int datasync);
 ssize_t v9fs_file_write_internal(struct inode *, struct p9_fid *,
                                  const char __user *, size_t, loff_t *, int);
 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index ffed55817f0c..3c173fcc2c5a 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -519,32 +519,50 @@ out:
 }
 
 
-static int v9fs_file_fsync(struct file *filp, int datasync)
+static int v9fs_file_fsync(struct file *filp, loff_t start, loff_t end,
+                           int datasync)
 {
         struct p9_fid *fid;
+        struct inode *inode = filp->f_mapping->host;
         struct p9_wstat wstat;
         int retval;
 
+        retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (retval)
+                return retval;
+
+        mutex_lock(&inode->i_mutex);
         P9_DPRINTK(P9_DEBUG_VFS, "filp %p datasync %x\n", filp, datasync);
 
         fid = filp->private_data;
         v9fs_blank_wstat(&wstat);
 
         retval = p9_client_wstat(fid, &wstat);
+        mutex_unlock(&inode->i_mutex);
+
         return retval;
 }
 
-int v9fs_file_fsync_dotl(struct file *filp, int datasync)
+int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
+                         int datasync)
 {
         struct p9_fid *fid;
+        struct inode *inode = filp->f_mapping->host;
         int retval;
 
+        retval = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (retval)
+                return retval;
+
+        mutex_lock(&inode->i_mutex);
         P9_DPRINTK(P9_DEBUG_VFS, "v9fs_file_fsync_dotl: filp %p datasync %x\n",
                         filp, datasync);
 
         fid = filp->private_data;
 
         retval = p9_client_fsync(fid, datasync);
+        mutex_unlock(&inode->i_mutex);
+
         return retval;
 }