Commit 6f9bda23 authored by Anna Schumaker's avatar Anna Schumaker Committed by Trond Myklebust
Browse files

NFS: Fix directory delegation verifier checks 



Doing this check in nfs_check_verifier() resulted in many, many more
lookups on the wire when running Christoph's delegation benchmarking
script. After some experimentation, I found that we can treat directory
delegations exactly the same as having a delegated verifier when we
reach nfs4_lookup_revalidate() for the best performance.

Reported-by: default avatarChristoph Hellwig <hch@lst.de>
Fixes: 156b0948 ("NFS: Request a directory delegation on ACCESS, CREATE, and UNLINK")
Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 5a74af51

fs/nfs/dir.c

+2 −19
Original line number Diff line number Diff line
@@ -1516,14 +1516,6 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry, 
	if (!nfs_dentry_verify_change(dir, dentry))

		return 0;



	/*

	 * If we have a directory delegation then we don't need to revalidate

	 * the directory. The delegation will either get recalled or we will

	 * receive a notification when it changes.

	 */

	if (nfs_have_directory_delegation(dir))

		return 0;



	/* Revalidate nfsi->cache_change_attribute before we declare a match */

	if (nfs_mapping_need_revalidate_inode(dir)) {

		if (rcu_walk)
@@ -2216,13 +2208,6 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry, 
}

EXPORT_SYMBOL_GPL(nfs_atomic_open);



static int

nfs_lookup_revalidate_delegated_parent(struct inode *dir, struct dentry *dentry,

				       struct inode *inode)

{

	return nfs_lookup_revalidate_done(dir, dentry, inode, 1);

}



static int

nfs4_lookup_revalidate(struct inode *dir, const struct qstr *name,

		       struct dentry *dentry, unsigned int flags)
@@ -2247,12 +2232,10 @@ nfs4_lookup_revalidate(struct inode *dir, const struct qstr *name, 
	if (inode == NULL)

		goto full_reval;



	if (nfs_verifier_is_delegated(dentry))

	if (nfs_verifier_is_delegated(dentry) ||

	    nfs_have_directory_delegation(inode))

		return nfs_lookup_revalidate_delegated(dir, dentry, inode);



	if (nfs_have_directory_delegation(dir))

		return nfs_lookup_revalidate_delegated_parent(dir, dentry, inode);



	/* NFS only supports OPEN on regular files */

	if (!S_ISREG(inode->i_mode))

		goto full_reval;