Patch "NFS: Don't revalidate the directory permissions on a lookup failure" has been added to the 5.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    NFS: Don't revalidate the directory permissions on a lookup failure

to the 5.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfs-don-t-revalidate-the-directory-permissions-on-a-.patch
and it can be found in the queue-5.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9d9f6ad45143661b3a7fe02f77a914aebc3b01c0
Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date:   Mon Mar 8 14:42:51 2021 -0500

    NFS: Don't revalidate the directory permissions on a lookup failure
    
    [ Upstream commit 82e7ca1334ab16e2e04fafded1cab9dfcdc11b40 ]
    
    There should be no reason to expect the directory permissions to change
    just because the directory contents changed or a negative lookup timed
    out. So let's avoid doing a full call to nfs_mark_for_revalidate() in
    that case.
    Furthermore, if this is a negative dentry, and we haven't actually done
    a new lookup, then we have no reason yet to believe the directory has
    changed at all. So let's remove the gratuitous directory inode
    invalidation altogether when called from
    nfs_lookup_revalidate_negative().
    
    Reported-by: Geert Jansen <gerardu@xxxxxxxxxx>
    Fixes: 5ceb9d7fdaaf ("NFS: Refactor nfs_lookup_revalidate()")
    Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
    Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ef827ae193d2..7bcc6fcf1096 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1401,6 +1401,15 @@ int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
 	goto out;
 }
 
+static void nfs_mark_dir_for_revalidate(struct inode *inode)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	spin_lock(&inode->i_lock);
+	nfsi->cache_validity |= NFS_INO_REVAL_PAGECACHE;
+	spin_unlock(&inode->i_lock);
+}
+
 /*
  * We judge how long we want to trust negative
  * dentries by looking at the parent inode mtime.
@@ -1435,7 +1444,6 @@ nfs_lookup_revalidate_done(struct inode *dir, struct dentry *dentry,
 			__func__, dentry);
 		return 1;
 	case 0:
-		nfs_mark_for_revalidate(dir);
 		if (inode && S_ISDIR(inode->i_mode)) {
 			/* Purge readdir caches. */
 			nfs_zap_caches(inode);
@@ -1525,6 +1533,13 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry,
 	nfs_free_fattr(fattr);
 	nfs_free_fhandle(fhandle);
 	nfs4_label_free(label);
+
+	/*
+	 * If the lookup failed despite the dentry change attribute being
+	 * a match, then we should revalidate the directory cache.
+	 */
+	if (!ret && nfs_verify_change_attribute(dir, dentry->d_time))
+		nfs_mark_dir_for_revalidate(dir);
 	return nfs_lookup_revalidate_done(dir, dentry, inode, ret);
 }
 
@@ -1567,7 +1582,7 @@ nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
 		error = nfs_lookup_verify_inode(inode, flags);
 		if (error) {
 			if (error == -ESTALE)
-				nfs_zap_caches(dir);
+				nfs_mark_dir_for_revalidate(dir);
 			goto out_bad;
 		}
 		nfs_advise_use_readdirplus(dir);
@@ -2064,7 +2079,6 @@ nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle,
 	dput(parent);
 	return d;
 out_error:
-	nfs_mark_for_revalidate(dir);
 	d = ERR_PTR(error);
 	goto out;
 }