exportfs: Return the minimum required handle size

The exportfs encode handle function should return the minimum required
handle size. This helps user to find out the handle size by passing 0
handle size in the first step and then redoing to the call again with
the returned handle size value.

Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index ff27d7a477b2..b4ffad859adb 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -21,9 +21,13 @@ static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
         int len = *max_len;
         int type;
 
-        if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
-            (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
+        if (connectable && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
+                *max_len = BTRFS_FID_SIZE_CONNECTABLE;
                 return 255;
+        } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
+                *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
+                return 255;
+        }
 
         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
         type = FILEID_BTRFS_WITHOUT_PARENT;