NFS: Store the file system "fsid" value in the NFS super block.

This should enable us to detect if we are crossing a mountpoint in the
case where the server is exporting "nohide" mounts.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index fda2b4966179..1a809f6f8989 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -236,6 +236,7 @@ nfs_get_root(struct super_block *sb, struct nfs_fh *rootfh, struct nfs_fsinfo *f
                 return ERR_PTR(error);
         }
 
+        server->fsid = fsinfo->fattr->fsid;
         return nfs_fhget(sb, rootfh, fsinfo->fattr);
 }
 
@@ -1493,6 +1494,7 @@ out:
  */
 static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 {
+        struct nfs_server *server;
         struct nfs_inode *nfsi = NFS_I(inode);
         loff_t cur_isize, new_isize;
         unsigned int    invalid = 0;
@@ -1511,6 +1513,12 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
         if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                 goto out_changed;
 
+        server = NFS_SERVER(inode);
+        /* Update the fsid if and only if this is the root directory */
+        if (inode == inode->i_sb->s_root->d_inode
+                        && !nfs_fsid_equal(&server->fsid, &fattr->fsid))
+                server->fsid = fattr->fsid;
+
         /*
          * Update the read time so we don't revalidate too often.
          */