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Date: Mon, 13 Jan 2014 08:52:27 +0100
From: Jan Kara <jack@...e.cz>
To: Miklos Szeredi <miklos@...redi.hu>
Cc: viro@...IV.linux.org.uk, torvalds@...ux-foundation.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
hch@...radead.org, akpm@...ux-foundation.org, dhowells@...hat.com,
zab@...hat.com, jack@...e.cz, luto@...capital.net, mszeredi@...e.cz
Subject: Re: [PATCH 07/11] vfs: add cross-rename
On Wed 08-01-14 23:10:11, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@...e.cz>
>
> If flags contain RENAME_EXCHANGE then exchange source and destination files.
> There's no restriction on the type of the files; e.g. a directory can be
> exchanged with a symlink.
>
> Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
> ---
> fs/dcache.c | 46 +++++++++++++++++----
> fs/namei.c | 107 +++++++++++++++++++++++++++++++++---------------
> include/linux/dcache.h | 1 +
> include/uapi/linux/fs.h | 1 +
> security/security.c | 16 ++++++++
> 5 files changed, 131 insertions(+), 40 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index 3fbc95c72e31..97c6dbb47eca 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -4020,6 +4020,8 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
> const unsigned char *old_name;
> struct inode *source = old_dentry->d_inode;
> struct inode *target = new_dentry->d_inode;
> + bool new_is_dir = false;
> + unsigned max_links = new_dir->i_sb->s_max_links;
>
> if (source == target)
> return 0;
> @@ -4028,10 +4030,16 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
> if (error)
> return error;
>
> - if (!target)
> + if (!target) {
> error = may_create(new_dir, new_dentry);
> - else
> - error = may_delete(new_dir, new_dentry, is_dir);
> + } else {
> + new_is_dir = d_is_dir(new_dentry);
> +
> + if (!(flags & RENAME_EXCHANGE))
> + error = may_delete(new_dir, new_dentry, is_dir);
> + else
> + error = may_delete(new_dir, new_dentry, new_is_dir);
> + }
> if (error)
> return error;
>
> @@ -4042,10 +4050,17 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
> * If we are going to change the parent - check write permissions,
> * we'll need to flip '..'.
> */
> - if (is_dir && new_dir != old_dir) {
> - error = inode_permission(source, MAY_WRITE);
> - if (error)
> - return error;
> + if (new_dir != old_dir) {
> + if (is_dir) {
> + error = inode_permission(source, MAY_WRITE);
> + if (error)
> + return error;
> + }
> + if ((flags & RENAME_EXCHANGE) && new_is_dir) {
> + error = inode_permission(target, MAY_WRITE);
> + if (error)
> + return error;
> + }
> }
>
> error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry,
> @@ -4055,25 +4070,24 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
>
> old_name = fsnotify_oldname_init(old_dentry->d_name.name);
> dget(new_dentry);
> - if (!is_dir)
> - lock_two_nondirectories(source, target);
> - else if (target)
> - mutex_lock(&target->i_mutex);
> + if (!(flags & RENAME_EXCHANGE)) {
> + if (!is_dir)
> + lock_two_nondirectories(source, target);
> + else if (target)
> + mutex_lock(&target->i_mutex);
> + }
>
> error = -EBUSY;
> if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
> goto out;
>
> - if (is_dir) {
> - unsigned max_links = new_dir->i_sb->s_max_links;
> -
> + if (max_links && new_dir != old_dir) {
> error = -EMLINK;
> - if (max_links && !target && new_dir != old_dir &&
> - new_dir->i_nlink >= max_links)
> + if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links)
> + goto out;
> + if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir &&
> + old_dir->i_nlink > max_links)
This should be >=, shouldn't it?
> goto out;
> -
> - if (target)
> - shrink_dcache_parent(new_dentry);
> } else {
> error = try_break_deleg(source, delegated_inode);
> if (error)
> @@ -4084,27 +4098,40 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
> goto out;
> }
> }
> + if (is_dir && !(flags & RENAME_EXCHANGE) && target)
> + shrink_dcache_parent(new_dentry);
> error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry,
> flags);
> if (error)
> goto out;
>
> - if (target) {
> + if (!(flags & RENAME_EXCHANGE) && target) {
> if (is_dir)
> target->i_flags |= S_DEAD;
> dont_mount(new_dentry);
> }
> - if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
> - d_move(old_dentry, new_dentry);
> + if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) {
> + if (!(flags & RENAME_EXCHANGE))
> + d_move(old_dentry, new_dentry);
> + else
> + d_exchange(old_dentry, new_dentry);
> + }
> out:
> - if (!is_dir)
> - unlock_two_nondirectories(source, target);
> - else if (target)
> - mutex_unlock(&target->i_mutex);
> + if (!(flags & RENAME_EXCHANGE)) {
> + if (!is_dir)
> + unlock_two_nondirectories(source, target);
> + else if (target)
> + mutex_unlock(&target->i_mutex);
> + }
> dput(new_dentry);
> - if (!error)
> + if (!error) {
> fsnotify_move(old_dir, new_dir, old_name, is_dir,
> - target, old_dentry);
> + !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
> + if (flags & RENAME_EXCHANGE) {
> + fsnotify_move(new_dir, old_dir, old_dentry->d_name.name,
> + new_is_dir, NULL, new_dentry);
> + }
> + }
> fsnotify_oldname_free(old_name);
>
> return error;
> @@ -4124,9 +4151,12 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
> bool should_retry = false;
> int error;
>
> - if (flags & ~RENAME_NOREPLACE)
> + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
> return -EOPNOTSUPP;
>
> + if ((flags & RENAME_NOREPLACE) && (flags & RENAME_EXCHANGE))
> + return -EINVAL;
> +
> retry:
> from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags);
> if (IS_ERR(from)) {
> @@ -4161,7 +4191,8 @@ retry:
>
> oldnd.flags &= ~LOOKUP_PARENT;
> newnd.flags &= ~LOOKUP_PARENT;
> - newnd.flags |= LOOKUP_RENAME_TARGET;
> + if (!(flags & RENAME_EXCHANGE))
> + newnd.flags |= LOOKUP_RENAME_TARGET;
>
> retry_deleg:
> trap = lock_rename(new_dir, old_dir);
> @@ -4181,12 +4212,23 @@ retry_deleg:
> error = -EEXIST;
> if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry))
> goto exit5;
> + if (flags & RENAME_EXCHANGE) {
> + error = -ENOENT;
> + if (!new_dentry->d_inode)
> + goto exit5;
Should this be d_is_positive()?
Honza
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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