nfs: don't open in ->d_revalidate
NFSv4 can't do reliable opens in d_revalidate, since it cannot know whether a
mount needs to be followed or not. It does check d_mountpoint() on the dentry,
which can result in a weird error if the VFS found that the mount does not in
fact need to be followed, e.g.:
# mount --bind /mnt/nfs /mnt/nfs-clone
# echo something > /mnt/nfs/tmp/bar
# echo x > /tmp/file
# mount --bind /tmp/file /mnt/nfs-clone/tmp/bar
# cat /mnt/nfs/tmp/bar
cat: /mnt/nfs/tmp/bar: Not a directory
Which should, by any sane filesystem, result in "something" being printed.
So instead do the open in f_op->open() and in the unlikely case that the cached
dentry turned out to be invalid, drop the dentry and return EOPENSTALE to let
the VFS retry.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index e8db961..a10bf54 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1325,10 +1325,10 @@
}
#ifdef CONFIG_NFS_V4
-static int nfs_open_revalidate(struct dentry *, struct nameidata *);
+static int nfs4_lookup_revalidate(struct dentry *, struct nameidata *);
const struct dentry_operations nfs4_dentry_operations = {
- .d_revalidate = nfs_open_revalidate,
+ .d_revalidate = nfs4_lookup_revalidate,
.d_delete = nfs_dentry_delete,
.d_iput = nfs_dentry_iput,
.d_automount = nfs_d_automount,
@@ -1490,13 +1490,11 @@
return nfs_lookup(dir, dentry, nd);
}
-static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd)
+static int nfs4_lookup_revalidate(struct dentry *dentry, struct nameidata *nd)
{
struct dentry *parent = NULL;
struct inode *inode;
struct inode *dir;
- struct nfs_open_context *ctx;
- struct iattr attr;
int openflags, ret = 0;
if (nd && (nd->flags & LOOKUP_RCU))
@@ -1525,57 +1523,13 @@
/* We cannot do exclusive creation on a positive dentry */
if ((openflags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
goto no_open_dput;
- /* We can't create new files here */
- openflags &= ~(O_CREAT|O_EXCL);
- ctx = create_nfs_open_context(dentry, openflags);
- ret = PTR_ERR(ctx);
- if (IS_ERR(ctx))
- goto out;
+ /* Let f_op->open() actually open (and revalidate) the file */
+ ret = 1;
- attr.ia_valid = ATTR_OPEN;
- if (openflags & O_TRUNC) {
- attr.ia_valid |= ATTR_SIZE;
- attr.ia_size = 0;
- nfs_wb_all(inode);
- }
-
- /*
- * Note: we're not holding inode->i_mutex and so may be racing with
- * operations that change the directory. We therefore save the
- * change attribute *before* we do the RPC call.
- */
- inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr);
- if (IS_ERR(inode)) {
- ret = PTR_ERR(inode);
- switch (ret) {
- case -EPERM:
- case -EACCES:
- case -EDQUOT:
- case -ENOSPC:
- case -EROFS:
- goto out_put_ctx;
- default:
- goto out_drop;
- }
- }
- iput(inode);
- if (inode != dentry->d_inode)
- goto out_drop;
-
- nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
- ret = nfs_intent_set_file(nd, ctx);
- if (ret >= 0)
- ret = 1;
out:
dput(parent);
return ret;
-out_drop:
- d_drop(dentry);
- ret = 0;
-out_put_ctx:
- put_nfs_open_context(ctx);
- goto out;
no_open_dput:
dput(parent);