From: NeilBrown <neilb@suse.de>
Date: Mon, 16 Nov 2020 13:47:45 +1100
Subject: [PATCH] NFS: only invalidate dentrys that are clearly invalid.
Patch-mainline: Submitted, 16 Nov 2020 14:00 - linux-nfs
References: bsc#1178669 bsc#1170139
Prior to commit 5ceb9d7fdaaf ("NFS: Refactor nfs_lookup_revalidate()")
and error from nfs_lookup_verify_inode() other than -ESTALE would result
in nfs_lookup_revalidate() returning that error code (-ESTALE is mapped
to zero).
Since that commit, all errors result in zero being returned.
When nfs_lookup_revalidate() returns zero, the dentry is invalidated
and, significantly, if the dentry is a directory that is mounted on,
that mountpoint is lost.
If you:
- mount an NFS filesystem which contains a directory
- mount something (e.g. tmpfs) on that directory
- use iptables (or scissors) to block traffic to the server
- ls -l the-mounted-on-directory
- interrupt the 'ls -l'
you will find that the directory has been unmounted.
This can be fixed by returning the actual error code from
nfs_lookup_verify_inode() rather then zero (except for -ESTALE).
Fixes: 5ceb9d7fdaaf ("NFS: Refactor nfs_lookup_revalidate()")
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: NeilBrown <neilb@suse.com>
---
fs/nfs/dir.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1208,7 +1208,7 @@ nfs_do_lookup_revalidate(struct inode *d
unsigned int flags)
{
struct inode *inode;
- int error;
+ int error = 0;
nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
inode = d_inode(dentry);
@@ -1230,8 +1230,10 @@ nfs_do_lookup_revalidate(struct inode *d
nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
error = nfs_lookup_verify_inode(inode, flags);
if (error) {
- if (error == -ESTALE)
+ if (error == -ESTALE) {
nfs_mark_dir_for_revalidate(dir);
+ error = 0;
+ }
goto out_bad;
}
nfs_advise_use_readdirplus(dir);
@@ -1253,7 +1255,7 @@ out_valid:
out_bad:
if (flags & LOOKUP_RCU)
return -ECHILD;
- return nfs_lookup_revalidate_done(dir, dentry, inode, 0);
+ return nfs_lookup_revalidate_done(dir, dentry, inode, error);
}
static int