From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valerie Aurora Subject: Re: [PATCH 15/32] union-mount: Documentation Date: Thu, 18 Jun 2009 15:05:59 -0400 Message-ID: <20090618190558.GB22206@shell> References: <1242662968-11684-1-git-send-email-jblunck@suse.de> <1242662968-11684-16-git-send-email-jblunck@suse.de> <8417.1243232743@jrobl> <200905250903.08165.arnd@arndb.de> <7294.1243240990@jrobl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Arnd Bergmann , Jan Blunck , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, bharata@in.ibm.com, dwmw2@infradead.org, mszeredi@suse.cz To: hooanon05@yahoo.co.jp Return-path: Received: from mx1.redhat.com ([66.187.233.31]:33176 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753830AbZFRTGh (ORCPT ); Thu, 18 Jun 2009 15:06:37 -0400 Content-Disposition: inline In-Reply-To: <7294.1243240990@jrobl> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, May 25, 2009 at 05:43:10PM +0900, hooanon05@yahoo.co.jp wrote: > > Arnd Bergmann: > > Right, but that is consistent with how the kernel would treat a > > rename from one mount point to another, and tools like 'mv' > > can handle this in user space. > > Yes, that is the description in the union mount document. > While it says to rename a regular file is implemented, the code differs > actually. > ---------------------------------------- > +Rename across different levels of the union is implemented as a copy-up > +operation for regular files. Rename of directories simply returns EXDEV, the > +same as if we tried to rename across different mounts. Most applications have > ::: > ---------------------------------------- Ah, we did implement that in an earlier version. I don't know if we dropped the patch by accident or on purpose, but the original version is below. We will either put this feature back or fix the documentation. Thanks! -VAL Subject: union-mount: copyup on rename Add copyup renaming of regular files on union mounts. Directories are still lazyly copied with the help of user-space. Signed-off-by: Jan Blunck --- fs/namei.c | 131 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 124 insertions(+), 7 deletions(-) Index: b/fs/namei.c =================================================================== --- a/fs/namei.c +++ b/fs/namei.c @@ -1532,6 +1532,8 @@ static int do_path_lookup(int dfd, const nd->path = fs->pwd; path_get(&fs->pwd); read_unlock(&fs->lock); + /* Force a union_relookup() */ + nd->um_flags = LAST_LOWLEVEL; } else { struct dentry *dentry; @@ -3684,6 +3686,97 @@ int vfs_rename(struct inode *old_dir, st return error; } +int vfs_rename_union(struct nameidata *oldnd, struct path *old, + struct nameidata *newnd, struct path *new) +{ + struct inode *old_dir = oldnd->path.dentry->d_inode; + struct inode *new_dir = newnd->path.dentry->d_inode; + struct qstr old_name; + char *name; + struct dentry *dentry; + int error; + + if (old->dentry->d_inode == new->dentry->d_inode) + return 0; + + error = may_whiteout(old->dentry, 0); + if (error) + return error; + if (!old_dir->i_op || !old_dir->i_op->whiteout) + return -EPERM; + + if (!new->dentry->d_inode) + error = may_create(new_dir, new->dentry, NULL); + else + error = may_delete(new_dir, new->dentry, 0); + if (error) + return error; + + DQUOT_INIT(old_dir); + DQUOT_INIT(new_dir); + + error = security_inode_rename(old_dir, old->dentry, + new_dir, new->dentry); + if (error) + return error; + + error = -EBUSY; + if (d_mountpoint(old->dentry) || d_mountpoint(new->dentry)) + return error; + + error = -ENOMEM; + name = kmalloc(old->dentry->d_name.len, GFP_KERNEL); + if (!name) + return error; + strncpy(name, old->dentry->d_name.name, old->dentry->d_name.len); + name[old->dentry->d_name.len] = 0; + old_name.len = old->dentry->d_name.len; + old_name.hash = old->dentry->d_name.hash; + old_name.name = name; + + /* possibly delete the existing new file */ + if ((newnd->path.dentry == new->dentry->d_parent) && new->dentry->d_inode) { + /* FIXME: inode may be truncated while we hold a lock */ + error = vfs_unlink(new_dir, new->dentry); + if (error) + goto freename; + + dentry = __lookup_hash(&new->dentry->d_name, + newnd->path.dentry, newnd); + if (IS_ERR(dentry)) + goto freename; + + dput(new->dentry); + new->dentry = dentry; + } + + /* copyup to the new file */ + error = __union_copyup(old, newnd, new); + if (error) + goto freename; + + /* whiteout the old file */ + dentry = __lookup_hash(&old_name, oldnd->path.dentry, oldnd); + error = PTR_ERR(dentry); + if (IS_ERR(dentry)) + goto freename; + error = vfs_whiteout(old_dir, dentry); + dput(dentry); + + /* FIXME: This is acutally unlink() && create() ... */ +/* + if (!error) { + const char *new_name = old_dentry->d_name.name; + fsnotify_move(old_dir, new_dir, old_name.name, new_name, 0, + new_dentry->d_inode, old_dentry->d_inode); + } +*/ +freename: + kfree(old_name.name); + return error; +} + + static int do_rename(int olddfd, const char *oldname, int newdfd, const char *newname) { @@ -3701,10 +3794,7 @@ static int do_rename(int olddfd, const c if (error) goto exit1; - error = -EXDEV; - if (oldnd.path.mnt != newnd.path.mnt) - goto exit2; - +lock: old_dir = oldnd.path.dentry; error = -EBUSY; if (oldnd.last_type != LAST_NORM) @@ -3742,12 +3832,39 @@ static int do_rename(int olddfd, const c error = -ENOTEMPTY; if (new.dentry == trap) goto exit5; - /* renaming on unions is done by the user-space */ + /* renaming of directories on unions is done by the user-space */ + error = -EXDEV; + if (is_unionized(oldnd.path.dentry, oldnd.path.mnt) && + S_ISDIR(old.dentry->d_inode->i_mode)) + goto exit5; + /* renameing of other files on unions is done by copyup */ + if ((is_unionized(oldnd.path.dentry, oldnd.path.mnt) && + (oldnd.um_flags & LAST_LOWLEVEL)) || + (is_unionized(newnd.path.dentry, newnd.path.mnt) && + (newnd.um_flags & LAST_LOWLEVEL))) { + path_put_conditional(&new, &newnd); + path_put_conditional(&old, &oldnd); + unlock_rename(new_dir, old_dir); + error = union_relookup_topmost(&oldnd, + oldnd.flags & ~LOOKUP_PARENT); + if (error) + goto exit2; + error = union_relookup_topmost(&newnd, + newnd.flags & ~LOOKUP_PARENT); + if (error) + goto exit2; + goto lock; + } + error = -EXDEV; - if (is_unionized(oldnd.path.dentry, oldnd.path.mnt)) + if (oldnd.path.mnt != newnd.path.mnt) goto exit5; - if (is_unionized(newnd.path.dentry, newnd.path.mnt)) + + if (is_unionized(oldnd.path.dentry, oldnd.path.mnt) && + (old.dentry->d_parent != oldnd.path.dentry)) { + error = vfs_rename_union(&oldnd, &old, &newnd, &new); goto exit5; + } error = mnt_want_write(oldnd.path.mnt); if (error)