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/dcache.c b/fs/dcache.c
index ca02c13..66cba5a 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2483,12 +2483,14 @@
dentry->d_name.name = dentry->d_iname;
} else {
/*
- * Both are internal. Just copy target to dentry
+ * Both are internal.
*/
- memcpy(dentry->d_iname, target->d_name.name,
- target->d_name.len + 1);
- dentry->d_name.len = target->d_name.len;
- return;
+ unsigned int i;
+ BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
+ for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
+ swap(((long *) &dentry->d_iname)[i],
+ ((long *) &target->d_iname)[i]);
+ }
}
}
swap(dentry->d_name.len, target->d_name.len);
@@ -2545,13 +2547,15 @@
* __d_move - move a dentry
* @dentry: entry to move
* @target: new dentry
+ * @exchange: exchange the two dentries
*
* Update the dcache to reflect the move of a file name. Negative
* dcache entries should not be moved in this way. Caller must hold
* rename_lock, the i_mutex of the source and target directories,
* and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
*/
-static void __d_move(struct dentry * dentry, struct dentry * target)
+static void __d_move(struct dentry *dentry, struct dentry *target,
+ bool exchange)
{
if (!dentry->d_inode)
printk(KERN_WARNING "VFS: moving negative dcache entry\n");
@@ -2573,8 +2577,15 @@
__d_drop(dentry);
__d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
- /* Unhash the target: dput() will then get rid of it */
+ /*
+ * Unhash the target (d_delete() is not usable here). If exchanging
+ * the two dentries, then rehash onto the other's hash queue.
+ */
__d_drop(target);
+ if (exchange) {
+ __d_rehash(target,
+ d_hash(dentry->d_parent, dentry->d_name.hash));
+ }
list_del(&dentry->d_u.d_child);
list_del(&target->d_u.d_child);
@@ -2601,6 +2612,8 @@
write_seqcount_end(&dentry->d_seq);
dentry_unlock_parents_for_move(dentry, target);
+ if (exchange)
+ fsnotify_d_move(target);
spin_unlock(&target->d_lock);
fsnotify_d_move(dentry);
spin_unlock(&dentry->d_lock);
@@ -2618,11 +2631,30 @@
void d_move(struct dentry *dentry, struct dentry *target)
{
write_seqlock(&rename_lock);
- __d_move(dentry, target);
+ __d_move(dentry, target, false);
write_sequnlock(&rename_lock);
}
EXPORT_SYMBOL(d_move);
+/*
+ * d_exchange - exchange two dentries
+ * @dentry1: first dentry
+ * @dentry2: second dentry
+ */
+void d_exchange(struct dentry *dentry1, struct dentry *dentry2)
+{
+ write_seqlock(&rename_lock);
+
+ WARN_ON(!dentry1->d_inode);
+ WARN_ON(!dentry2->d_inode);
+ WARN_ON(IS_ROOT(dentry1));
+ WARN_ON(IS_ROOT(dentry2));
+
+ __d_move(dentry1, dentry2, true);
+
+ write_sequnlock(&rename_lock);
+}
+
/**
* d_ancestor - search for an ancestor
* @p1: ancestor dentry
@@ -2670,7 +2702,7 @@
m2 = &alias->d_parent->d_inode->i_mutex;
out_unalias:
if (likely(!d_mountpoint(alias))) {
- __d_move(alias, dentry);
+ __d_move(alias, dentry, false);
ret = alias;
}
out_err: