From 0ef97dcfce4179a2eba046b855ee2f91d6f1b414 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 21 May 2012 17:30:20 +0200 Subject: 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 CC: Trond Myklebust Signed-off-by: Al Viro --- fs/nfs/dir.c | 56 +++++--------------------------------------------------- 1 file changed, 5 insertions(+), 51 deletions(-) (limited to 'fs/nfs/dir.c') diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 0989a2099688..f430057ff3b3 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1354,10 +1354,10 @@ out: } #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, @@ -1519,13 +1519,11 @@ no_open: 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->flags & LOOKUP_RCU) @@ -1554,57 +1552,13 @@ static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd) /* 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; - 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; + /* Let f_op->open() actually open (and revalidate) the file */ + ret = 1; - 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); -- cgit v1.2.3