btrfs: Switch to generic xattr handlers

The btrfs_{set,remove}xattr inode operations check for a read-only root
(btrfs_root_readonly) before calling into generic_{set,remove}xattr.  If
this check is moved into __btrfs_setxattr, we can get rid of
btrfs_{set,remove}xattr.

This patch applies to mainline, I would like to keep it together with
the other xattr cleanups if possible, though.  Could you please review?

Thanks,
Andreas

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 03224b0..3bfb252 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -237,6 +237,9 @@
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	int ret;
 
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
 	if (trans)
 		return do_setxattr(trans, inode, name, value, size, flags);
 
@@ -432,25 +435,6 @@
 	NULL,
 };
 
-int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
-		   size_t size, int flags)
-{
-	struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
-
-	if (btrfs_root_readonly(root))
-		return -EROFS;
-	return generic_setxattr(dentry, name, value, size, flags);
-}
-
-int btrfs_removexattr(struct dentry *dentry, const char *name)
-{
-	struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
-
-	if (btrfs_root_readonly(root))
-		return -EROFS;
-	return generic_removexattr(dentry, name);
-}
-
 static int btrfs_initxattrs(struct inode *inode,
 			    const struct xattr *xattr_array, void *fs_info)
 {