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Commit f5a73672 authored by Neil Brown's avatar Neil Brown Committed by Trond Myklebust
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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: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarTrond 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;

}