Unverified Commit 23cdd0ee authored by Chuck Lever's avatar Chuck Lever Committed by Christian Brauner
Browse files

libfs: Fix simple_offset_rename_exchange() 



User space expects the replacement (old) directory entry to have
the same directory offset after the rename.

Suggested-by: default avatarChristian Brauner <brauner@kernel.org>
Fixes: a2e45955 ("shmem: stable directory offsets")
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-2-cel@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 4cece764

fs/libfs.c

+19 −6
Original line number Diff line number Diff line
@@ -295,6 +295,18 @@ int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry) 
	return 0;

}



static int simple_offset_replace(struct offset_ctx *octx, struct dentry *dentry,

				 long offset)

{

	int ret;



	ret = mtree_store(&octx->mt, offset, dentry, GFP_KERNEL);

	if (ret)

		return ret;

	offset_set(dentry, offset);

	return 0;

}



/**

 * simple_offset_remove - Remove an entry to a directory's offset map

 * @octx: directory offset ctx to be updated
@@ -352,6 +364,9 @@ int simple_offset_empty(struct dentry *dentry) 
 * @new_dir: destination parent

 * @new_dentry: destination dentry

 *

 * This API preserves the directory offset values. Caller provides

 * appropriate serialization.

 *

 * Returns zero on success. Otherwise a negative errno is returned and the

 * rename is rolled back.

 */
@@ -369,11 +384,11 @@ int simple_offset_rename_exchange(struct inode *old_dir, 
	simple_offset_remove(old_ctx, old_dentry);

	simple_offset_remove(new_ctx, new_dentry);



	ret = simple_offset_add(new_ctx, old_dentry);

	ret = simple_offset_replace(new_ctx, old_dentry, new_index);

	if (ret)

		goto out_restore;



	ret = simple_offset_add(old_ctx, new_dentry);

	ret = simple_offset_replace(old_ctx, new_dentry, old_index);

	if (ret) {

		simple_offset_remove(new_ctx, old_dentry);

		goto out_restore;
@@ -388,10 +403,8 @@ int simple_offset_rename_exchange(struct inode *old_dir, 
	return 0;



out_restore:

	offset_set(old_dentry, old_index);

	mtree_store(&old_ctx->mt, old_index, old_dentry, GFP_KERNEL);

	offset_set(new_dentry, new_index);

	mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL);

	(void)simple_offset_replace(old_ctx, old_dentry, old_index);

	(void)simple_offset_replace(new_ctx, new_dentry, new_index);

	return ret;

}