vfs: add cross-rename
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@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/namei.c b/fs/namei.c
index 4096d58..c117888 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4031,6 +4031,8 @@
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;
@@ -4039,10 +4041,16 @@
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;
@@ -4056,10 +4064,17 @@
* 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,
@@ -4069,7 +4084,7 @@
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
dget(new_dentry);
- if (!is_dir)
+ if (!is_dir || (flags & RENAME_EXCHANGE))
lock_two_nondirectories(source, target);
else if (target)
mutex_lock(&target->i_mutex);
@@ -4078,25 +4093,25 @@
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 (target)
- shrink_dcache_parent(new_dentry);
- } else {
+ if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir &&
+ old_dir->i_nlink >= max_links)
+ goto out;
+ }
+ if (is_dir && !(flags & RENAME_EXCHANGE) && target)
+ shrink_dcache_parent(new_dentry);
+ if (!is_dir) {
error = try_break_deleg(source, delegated_inode);
if (error)
goto out;
- if (target) {
- error = try_break_deleg(target, delegated_inode);
- if (error)
- goto out;
- }
+ }
+ if (target && !new_is_dir) {
+ error = try_break_deleg(target, delegated_inode);
+ if (error)
+ goto out;
}
if (!flags) {
error = old_dir->i_op->rename(old_dir, old_dentry,
@@ -4108,22 +4123,31 @@
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)
+ if (!is_dir || (flags & RENAME_EXCHANGE))
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;
@@ -4143,7 +4167,10 @@
bool should_retry = false;
int error;
- if (flags & ~RENAME_NOREPLACE)
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+ return -EINVAL;
+
+ if ((flags & RENAME_NOREPLACE) && (flags & RENAME_EXCHANGE))
return -EINVAL;
retry:
@@ -4180,7 +4207,8 @@
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);
@@ -4200,12 +4228,23 @@
error = -EEXIST;
if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry))
goto exit5;
+ if (flags & RENAME_EXCHANGE) {
+ error = -ENOENT;
+ if (d_is_negative(new_dentry))
+ goto exit5;
+
+ if (!d_is_dir(new_dentry)) {
+ error = -ENOTDIR;
+ if (newnd.last.name[newnd.last.len])
+ goto exit5;
+ }
+ }
/* unless the source is a directory trailing slashes give -ENOTDIR */
if (!d_is_dir(old_dentry)) {
error = -ENOTDIR;
if (oldnd.last.name[oldnd.last.len])
goto exit5;
- if (newnd.last.name[newnd.last.len])
+ if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len])
goto exit5;
}
/* source should not be ancestor of target */
@@ -4213,7 +4252,8 @@
if (old_dentry == trap)
goto exit5;
/* target should not be an ancestor of source */
- error = -ENOTEMPTY;
+ if (!(flags & RENAME_EXCHANGE))
+ error = -ENOTEMPTY;
if (new_dentry == trap)
goto exit5;