fs/affs: make affs exportable

Add standard functions making AFFS work with NFS.

Functions based on ext4 implementation.  Tested on loop device.

Link: http://lkml.kernel.org/r/20170109191208.6085-4-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/fs/affs/namei.c b/fs/affs/namei.c
index 29186d29a3b6..04c3156ff411 100644
--- a/fs/affs/namei.c
+++ b/fs/affs/namei.c
@@ -9,6 +9,7 @@
  */
 
 #include "affs.h"
+#include <linux/exportfs.h>
 
 typedef int (*toupper_t)(int);
 
@@ -465,3 +466,42 @@ done:
         affs_brelse(bh);
         return retval;
 }
+
+static struct inode *affs_nfs_get_inode(struct super_block *sb, u64 ino,
+                                        u32 generation)
+{
+        struct inode *inode;
+
+        if (!affs_validblock(sb, ino))
+                return ERR_PTR(-ESTALE);
+
+        inode = affs_iget(sb, ino);
+        if (IS_ERR(inode))
+                return ERR_CAST(inode);
+
+        if (generation && inode->i_generation != generation) {
+                iput(inode);
+                return ERR_PTR(-ESTALE);
+        }
+
+        return inode;
+}
+
+static struct dentry *affs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+                                        int fh_len, int fh_type)
+{
+        return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+                                    affs_nfs_get_inode);
+}
+
+static struct dentry *affs_fh_to_parent(struct super_block *sb, struct fid *fid,
+                                        int fh_len, int fh_type)
+{
+        return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+                                    affs_nfs_get_inode);
+}
+
+const struct export_operations affs_export_ops = {
+        .fh_to_dentry = affs_fh_to_dentry,
+        .fh_to_parent = affs_fh_to_parent,
+};