From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759147Ab0GPTvS (ORCPT ); Fri, 16 Jul 2010 15:51:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56647 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754991Ab0GPTvQ (ORCPT ); Fri, 16 Jul 2010 15:51:16 -0400 Date: Fri, 16 Jul 2010 15:50:51 -0400 From: Valerie Aurora To: Ian Kent Cc: Alexander Viro , Miklos Szeredi , Jan Blunck , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, David Woodhouse Subject: Re: [PATCH 06/38] whiteout: Add vfs_whiteout() and whiteout inode operation Message-ID: <20100716195051.GA21201@shell> References: <1276627208-17242-1-git-send-email-vaurora@redhat.com> <1276627208-17242-7-git-send-email-vaurora@redhat.com> <20100713035217.GA3949@zeus.themaw.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100713035217.GA3949@zeus.themaw.net> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 13, 2010 at 11:52:19AM +0800, Ian Kent wrote: > > Couple of comments below. Thank you very much for the review! > On Tue, Jun 15, 2010 at 11:39:36AM -0700, Valerie Aurora wrote: > > From: Jan Blunck > > > > Whiteout a given directory entry. File systems that support whiteouts > > must implement the new ->whiteout() directory inode operation. > > > > XXX - Only whiteout when there is a matching entry in a lower layer. > > > > XXX - MS_WHITEOUT only indicates whiteouts, but we also use it for > > fallthrus. Can we just check root->i_op->whiteout and ->fallthru? Or > > do we need an MS_FALLTHRU? > > > > Signed-off-by: Jan Blunck > > Signed-off-by: David Woodhouse > > Signed-off-by: Valerie Aurora > > --- > > Documentation/filesystems/vfs.txt | 10 +++++- > > fs/dcache.c | 4 ++- > > fs/namei.c | 73 ++++++++++++++++++++++++++++++++++++- > > include/linux/dcache.h | 6 +++ > > include/linux/fs.h | 2 + > > 5 files changed, 92 insertions(+), 3 deletions(-) > > > > diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt > > index 3de2f32..8846b4f 100644 > > --- a/Documentation/filesystems/vfs.txt > > +++ b/Documentation/filesystems/vfs.txt > > @@ -308,7 +308,7 @@ struct inode_operations > > ----------------------- > > > > This describes how the VFS can manipulate an inode in your > > -filesystem. As of kernel 2.6.22, the following members are defined: > > +filesystem. As of kernel 2.6.33, the following members are defined: > > > > struct inode_operations { > > int (*create) (struct inode *,struct dentry *,int, struct nameidata *); > > @@ -319,6 +319,7 @@ struct inode_operations { > > int (*mkdir) (struct inode *,struct dentry *,int); > > int (*rmdir) (struct inode *,struct dentry *); > > int (*mknod) (struct inode *,struct dentry *,int,dev_t); > > + int (*whiteout) (struct inode *, struct dentry *, struct dentry *); > > int (*rename) (struct inode *, struct dentry *, > > struct inode *, struct dentry *); > > int (*readlink) (struct dentry *, char __user *,int); > > @@ -382,6 +383,13 @@ otherwise noted. > > will probably need to call d_instantiate() just as you would > > in the create() method > > > > + whiteout: called by the rmdir(2) and unlink(2) system calls on a > > + layered file system. Only required if you want to support > > + whiteouts. The first dentry passed in is that for the old > > + dentry if it exists, and a negative dentry otherwise. The > > + second is the dentry for the whiteout itself. This method > > + must unlink() or rmdir() the original entry if it exists. > > + > > rename: called by the rename(2) system call to rename the object to > > have the parent and name given by the second inode and dentry. > > > > diff --git a/fs/dcache.c b/fs/dcache.c > > index f1358e5..265015d 100644 > > --- a/fs/dcache.c > > +++ b/fs/dcache.c > > @@ -992,8 +992,10 @@ EXPORT_SYMBOL(d_alloc_name); > > /* the caller must hold dcache_lock */ > > static void __d_instantiate(struct dentry *dentry, struct inode *inode) > > { > > - if (inode) > > + if (inode) { > > + dentry->d_flags &= ~DCACHE_WHITEOUT; > > list_add(&dentry->d_alias, &inode->i_dentry); > > + } > > dentry->d_inode = inode; > > fsnotify_d_instantiate(dentry, inode); > > } > > diff --git a/fs/namei.c b/fs/namei.c > > index f731108..2c723e2 100644 > > --- a/fs/namei.c > > +++ b/fs/namei.c > > @@ -1356,7 +1356,6 @@ static int may_delete(struct inode *dir,struct dentry *victim,int isdir) > > if (!victim->d_inode) > > return -ENOENT; > > > > - BUG_ON(victim->d_parent->d_inode != dir); > > audit_inode_child(victim, dir); > > > > error = inode_permission(dir, MAY_WRITE | MAY_EXEC); > > @@ -2168,6 +2167,78 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) > > return sys_mkdirat(AT_FDCWD, pathname, mode); > > } > > > > +/** > > + * vfs_whiteout: create a whiteout for the given directory entry > > + * @dir: parent inode > > + * @dentry: directory entry to whiteout > > + * > > + * Create a whiteout for the given directory entry. A whiteout > > + * prevents lookup from dropping down to a lower layer of a union > > + * mounted file system. > > + * > > + * There are two important cases: (a) The directory entry to be > > + * whited-out may already exist, in which case it must first be > > + * deleted before we create the whiteout, and (b) no such directory > > + * entry exists and we only have to create the whiteout itself. > > + * > > + * The caller must pass in a dentry for the directory entry to be > > + * whited-out - a positive one if it exists, and a negative if not. > > + * When this function returns, the caller should dput() the old, now > > + * defunct dentry it passed in. The dentry for the whiteout itself is > > + * created inside this function. > > + */ > > +static int vfs_whiteout(struct inode *dir, struct dentry *old_dentry, int isdir) > > +{ > > + int err; > > + struct inode *old_inode = old_dentry->d_inode; > > + struct dentry *parent, *whiteout; > > + > > + BUG_ON(old_dentry->d_parent->d_inode != dir); > > + > > + if (!dir->i_op || !dir->i_op->whiteout) > > + return -EOPNOTSUPP; > > + > > + /* > > + * If the old dentry is positive, then we have to delete this > > + * entry before we create the whiteout. The file system > > + * ->whiteout() op does the actual delete, but we do all the > > + * VFS-level checks and changes here. > > + */ > > + if (old_inode) { > > + mutex_lock(&old_inode->i_mutex); > > + if (d_mountpoint(old_dentry)) { > > + mutex_unlock(&old_inode->i_mutex); > > + return -EBUSY; > > + } > > + if (isdir) { > > + dentry_unhash(old_dentry); > > + err = security_inode_rmdir(dir, old_dentry); > > + } else { > > + err = security_inode_unlink(dir, old_dentry); > > One to many tabs. Thanks, fixed. > > + } > > + } > > + > > + parent = dget_parent(old_dentry); > > + whiteout = d_alloc_name(parent, old_dentry->d_name.name); > > + > > + if (!err) > > + err = dir->i_op->whiteout(dir, old_dentry, whiteout); > > err may be used unitialized. Thanks, fixed. > > + > > + if (old_inode) { > > + mutex_unlock(&old_inode->i_mutex); > > + if (!err) { > > + fsnotify_link_count(old_inode); > > + d_delete(old_dentry); > > + } > > + if (isdir) > > + dput(old_dentry); > > + } > > + > > + dput(whiteout); > > + dput(parent); > > + return err; > > +} > > + > > /* > > * We try to drop the dentry early: we should have > > * a usage count of 2 if we're the only user of this > > diff --git a/include/linux/dcache.h b/include/linux/dcache.h > > index eebb617..630baef 100644 > > --- a/include/linux/dcache.h > > +++ b/include/linux/dcache.h > > @@ -183,6 +183,7 @@ d_iput: no no no yes > > #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched by inotify */ > > > > #define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */ > > +#define DCACHE_WHITEOUT 0x0080 /* This negative dentry is a whiteout */ > > > > #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 /* Parent inode is watched by some fsnotify listener */ > > DCACHE_WHITEOUT == DCACHE_FSNOTIFY_PARENT_WATCHED, is that intended? That's a merge error, thanks! -VAL