fuse: nfs export special lookups

Implement the get_parent export operation by sending a LOOKUP request with
".." as the name.

Implement looking up an inode by node ID after it has been evicted from
the cache.  This is done by seding a LOOKUP request with "." as the name
(for all file types, not just directories).

The filesystem can set the FUSE_EXPORT_SUPPORT flag in the INIT reply, to
indicate that it supports these special lookups.

Thanks to John Muir for the original implementation of this feature.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: David Teigland <teigland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 5d3146da64e6..3a876076bdd1 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -363,6 +363,9 @@ struct fuse_conn {
         /** Do not send separate SETATTR request before open(O_TRUNC)  */
         unsigned atomic_o_trunc : 1;
 
+        /** Filesystem supports NFS exporting.  Only set in INIT */
+        unsigned export_support : 1;
+
         /*
          * The following bitfields are only for optimization purposes
          * and hence races in setting them will not cause malfunction
@@ -473,6 +476,9 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
                         int generation, struct fuse_attr *attr,
                         u64 attr_valid, u64 attr_version);
 
+int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
+                     struct fuse_entry_out *outarg, struct inode **inode);
+
 /**
  * Send FORGET command
  */