diff options
authorNeilBrown <>2017-07-05 12:22:20 +1000
committerGreg Kroah-Hartman <>2017-07-27 15:08:06 -0700
commit9ebfb4fa3ab7ea99b5d93305b10ee3714501b465 (patch)
parent4dd0aa9ae6d0e948848f87b4c040cea8163a59bf (diff)
NFS: only invalidate dentrys that are clearly invalid.
commit cc89684c9a265828ce061037f1f79f4a68ccd3f7 upstream. Since commit bafc9b754f75 ("vfs: More precise tests in d_invalidate") in v3.18, a return of '0' from ->d_revalidate() will cause the dentry to be invalidated even if it has filesystems mounted on or it or on a descendant. The mounted filesystem is unmounted. This means we need to be careful not to return 0 unless the directory referred to truly is invalid. So -ESTALE or -ENOENT should invalidate the directory. Other errors such a -EPERM or -ERESTARTSYS should be returned from ->d_revalidate() so they are propagated to the caller. A particular problem can be demonstrated by: 1/ mount an NFS filesystem using NFSv3 on /mnt 2/ mount any other filesystem on /mnt/foo 3/ ls /mnt/foo 4/ turn off network, or otherwise make the server unable to respond 5/ ls /mnt/foo & 6/ cat /proc/$!/stack # note that nfs_lookup_revalidate is in the call stack 7/ kill -9 $! # this results in -ERESTARTSYS being returned 8/ observe that /mnt/foo has been unmounted. This patch changes nfs_lookup_revalidate() to only treat -ESTALE from nfs_lookup_verify_inode() and -ESTALE or -ENOENT from ->lookup() as indicating an invalid inode. Other errors are returned. Also nfs_check_inode_attributes() is changed to return -ESTALE rather than -EIO. This is consistent with the error returned in similar circumstances from nfs_update_inode(). As this bug allows any user to unmount a filesystem mounted on an NFS filesystem, this fix is suitable for stable kernels. Fixes: bafc9b754f75 ("vfs: More precise tests in d_invalidate") Signed-off-by: NeilBrown <> Signed-off-by: Anna Schumaker <> Signed-off-by: Greg Kroah-Hartman <>
2 files changed, 10 insertions, 6 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 53e02b8bd9bd..d04ec3814779 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1167,11 +1167,13 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
/* Force a full look up iff the parent directory has changed */
if (!nfs_is_exclusive_create(dir, flags) &&
nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
- if (nfs_lookup_verify_inode(inode, flags)) {
+ error = nfs_lookup_verify_inode(inode, flags);
+ if (error) {
if (flags & LOOKUP_RCU)
return -ECHILD;
- goto out_zap_parent;
+ if (error == -ESTALE)
+ goto out_zap_parent;
+ goto out_error;
goto out_valid;
@@ -1195,8 +1197,10 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error);
- if (error)
+ if (error == -ESTALE || error == -ENOENT)
goto out_bad;
+ if (error)
+ goto out_error;
if (nfs_compare_fh(NFS_FH(inode), fhandle))
goto out_bad;
if ((error = nfs_refresh_inode(inode, fattr)) != 0)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index bf4ec5ecc97e..76ae25661d3f 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1278,9 +1278,9 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat
return 0;
/* Has the inode gone and changed behind our back? */
if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid)
- return -EIO;
+ return -ESTALE;
if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
- return -EIO;
+ return -ESTALE;
if (!nfs_file_has_buffered_writers(nfsi)) {
/* Verify a few of the more important attributes */