From: Miklos Szeredi Date: Mon, 21 May 2012 15:30:20 +0000 (+0200) Subject: nfs: don't open in ->d_revalidate X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=0ef97dcfce4179a2eba046b855ee2f91d6f1b414;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git 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 --- 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); diff --git a/fs/nfs/file.c b/fs/nfs/file.c index 56311ca5f9f8..a6708e6b438d 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -879,12 +879,81 @@ const struct file_operations nfs_file_operations = { static int nfs4_file_open(struct inode *inode, struct file *filp) { + struct nfs_open_context *ctx; + struct dentry *dentry = filp->f_path.dentry; + struct dentry *parent = NULL; + struct inode *dir; + unsigned openflags = filp->f_flags; + struct iattr attr; + int err; + + BUG_ON(inode != dentry->d_inode); /* - * NFSv4 opens are handled in d_lookup and d_revalidate. If we get to - * this point, then something is very wrong + * If no cached dentry exists or if it's negative, NFSv4 handled the + * opens in ->lookup() or ->create(). + * + * We only get this far for a cached positive dentry. We skipped + * revalidation, so handle it here by dropping the dentry and returning + * -EOPENSTALE. The VFS will retry the lookup/create/open. */ - dprintk("NFS: %s called! inode=%p filp=%p\n", __func__, inode, filp); - return -ENOTDIR; + + dprintk("NFS: open file(%s/%s)\n", + dentry->d_parent->d_name.name, + dentry->d_name.name); + + if ((openflags & O_ACCMODE) == 3) + openflags--; + + /* We can't create new files here */ + openflags &= ~(O_CREAT|O_EXCL); + + parent = dget_parent(dentry); + dir = parent->d_inode; + + ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode); + err = 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); + } + + inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + switch (err) { + 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)); + nfs_file_set_open_context(filp, ctx); + err = 0; + +out_put_ctx: + put_nfs_open_context(ctx); +out: + dput(parent); + return err; + +out_drop: + d_drop(dentry); + err = -EOPENSTALE; + goto out_put_ctx; } const struct file_operations nfs4_file_operations = {