Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932308Ab0FOSmy (ORCPT ); Tue, 15 Jun 2010 14:42:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50408 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932274Ab0FOSmm (ORCPT ); Tue, 15 Jun 2010 14:42:42 -0400 From: Valerie Aurora To: Alexander Viro Cc: Miklos Szeredi , Jan Blunck , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Valerie Aurora Subject: [PATCH 30/38] union-mount: Implement union-aware rename() Date: Tue, 15 Jun 2010 11:40:00 -0700 Message-Id: <1276627208-17242-31-git-send-email-vaurora@redhat.com> In-Reply-To: <1276627208-17242-1-git-send-email-vaurora@redhat.com> References: <1276627208-17242-1-git-send-email-vaurora@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4828 Lines: 142 On rename() of a file on union mount, copyup and whiteout the source file. Both are done under the rename mutex. I believe this is actually atomic. XXX - May not need to do file copyup under the lock. XXX - Convert newly empty unioned dirs to not-unioned --- fs/namei.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 files changed, 70 insertions(+), 6 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index d2f2618..6096413 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3155,6 +3155,7 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, { struct dentry *old_dir, *new_dir; struct path old, new; + struct path to_whiteout = {NULL, NULL}; struct dentry *trap; struct nameidata oldnd, newnd; char *from; @@ -3170,13 +3171,9 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, goto exit1; error = -EXDEV; + /* Union mounts will pass below test - dirs always on topmost */ if (oldnd.path.mnt != newnd.path.mnt) goto exit2; - /* Rename on union mounts not implemented yet */ - /* XXX much harsher check than necessary - can do some renames */ - if (IS_DIR_UNIONED(oldnd.path.dentry) || - IS_DIR_UNIONED(newnd.path.dentry)) - goto exit2; old_dir = oldnd.path.dentry; error = -EBUSY; if (oldnd.last_type != LAST_NORM) @@ -3199,7 +3196,7 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, error = -ENOENT; if (!old.dentry->d_inode) goto exit4; - /* unless the source is a directory trailing slashes give -ENOTDIR */ + /* unless the source is a directory, trailing slashes give -ENOTDIR */ if (!S_ISDIR(old.dentry->d_inode->i_mode)) { error = -ENOTDIR; if (oldnd.last.name[oldnd.last.len]) @@ -3211,6 +3208,11 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, error = -EINVAL; if (old.dentry == trap) goto exit4; + error = -EXDEV; + /* Can't rename a directory from a lower layer */ + if (IS_DIR_UNIONED(oldnd.path.dentry) && + IS_DIR_UNIONED(old.dentry)) + goto exit4; error = lookup_hash(&newnd, &newnd.last, &new); if (error) goto exit4; @@ -3218,6 +3220,48 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, error = -ENOTEMPTY; if (new.dentry == trap) goto exit5; + error = -EXDEV; + /* Can't rename over directories on the lower layer */ + if (IS_DIR_UNIONED(newnd.path.dentry) && + IS_DIR_UNIONED(new.dentry)) + goto exit5; + + /* If source is on lower layer, copy up */ + if (IS_DIR_UNIONED(oldnd.path.dentry) && + (old.mnt != oldnd.path.mnt)) { + /* Save the lower path to avoid a second lookup for whiteout */ + to_whiteout.mnt = mntget(old.mnt); + to_whiteout.dentry = dget(old.dentry); + error = __union_copyup(&oldnd, &old); + if (error) + goto exit5; + } + + /* If target is on lower layer, get negative dentry for topmost */ + if (IS_DIR_UNIONED(newnd.path.dentry) && + (new.mnt != newnd.path.mnt)) { + struct dentry *dentry; + /* + * At this point, source and target are both files, + * the source is on the topmost layer, and the target + * is on a lower layer. We want the target dentry to + * disappear from the namespace, and give vfs_rename a + * negative dentry from the topmost layer. + */ + /* We already did lookup once, no need to check perm */ + dentry = __lookup_hash(&newnd.last, newnd.path.dentry, &newnd); + if (IS_ERR(dentry)) { + error = PTR_ERR(dentry); + goto exit5; + } + /* We no longer need the lower target dentry. It + * definitely should be removed from the hash table */ + /* XXX what about failure case? */ + d_delete(new.dentry); + mntput(new.mnt); + new.mnt = mntget(newnd.path.mnt); + new.dentry = dentry; + } error = mnt_want_write(oldnd.path.mnt); if (error) @@ -3228,6 +3272,26 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, goto exit6; error = vfs_rename(old_dir->d_inode, old.dentry, new_dir->d_inode, new.dentry); + if (error) + goto exit6; + /* Now whiteout the source */ + if (IS_DIR_UNIONED(oldnd.path.dentry)) { + if (!to_whiteout.dentry) { + struct dentry *dentry; + /* We could have exposed a lower level entry */ + dentry = __lookup_hash(&oldnd.last, oldnd.path.dentry, &oldnd); + if (IS_ERR(dentry)) { + error = PTR_ERR(dentry); + goto exit6; + } + to_whiteout.dentry = dentry; + to_whiteout.mnt = mntget(oldnd.path.mnt); + } + + if (to_whiteout.dentry->d_inode) + error = do_whiteout(&oldnd, &to_whiteout, 0); + path_put(&to_whiteout); + } exit6: mnt_drop_write(oldnd.path.mnt); exit5: -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/