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Date: Thu, 18 Jun 2009 15:05:59 -0400
From: Valerie Aurora <vaurora@...hat.com>
To: hooanon05@...oo.co.jp
Cc: Arnd Bergmann <arnd@...db.de>, Jan Blunck <jblunck@...e.de>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
viro@...iv.linux.org.uk, bharata@...ibm.com, dwmw2@...radead.org,
mszeredi@...e.cz
Subject: Re: [PATCH 15/32] union-mount: Documentation
On Mon, May 25, 2009 at 05:43:10PM +0900, hooanon05@...oo.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 <jblunck@...e.de>
---
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)
--
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