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

BugLink: https://bugs.launchpad.net/bugs/1919492
[ 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@amazon.com>
Fixes: 5ceb9d7fdaaf ("NFS: Refactor nfs_lookup_revalidate()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ef827ae193d22266b3bbdcea344714e1f7ea69ca..7bcc6fcf10969a69f1780247b3625d24d53b03a5 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1401,6 +1401,15 @@ out_force:
        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 @@ out:
        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 @@ out:
        dput(parent);
        return d;
 out_error:
-       nfs_mark_for_revalidate(dir);
        d = ERR_PTR(error);
        goto out;
 }