Commit f5a73672 authored Aug 10, 2010 by Neil Brown Committed by Trond Myklebust Aug 10, 2010

NFS: allow close-to-open cache semantics to apply to root of NFS filesystem





To obey NFS cache semantics, the client must verify the cached
attributes when a file is opened.  In most cases this is done by a call to
d_validate as one of the last steps in path_walk.

However for the root of a filesystem, d_validate is only ever called
on the mounted-on filesystem (except when the path ends '.' or '..').
So NFS has no chance to validate the attributes.

So, in nfs_opendir, we revalidate the attributes if the opened
directory is the mountpoint.  This may cause double-validation for "."
and ".." lookups, but that is better than missing regular /path/name
lookups completely.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

parent 669502ff

fs/nfs/dir.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -140,6 +140,13 @@ nfs_opendir(struct inode inode, struct file filp)

		/* Call generic open code in order to cache credentials */
		res = nfs_open(inode, filp);
		if (filp->f_path.dentry == filp->f_path.mnt->mnt_root) {
		/* This is a mountpoint, so d_revalidate will never
		* have been called, so we need to refresh the
		* inode (for close-open consistency) ourselves.
		*/
		__nfs_revalidate_inode(NFS_SERVER(inode), inode);
		}
		return res;
		}

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