Commit 7623ed67 authored by David Howells's avatar David Howells
Browse files

cachefiles: Implement cookie resize for truncate 



Implement resizing an object, using truncate and/or fallocate to adjust the
object.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819646631.215744.13819016478175576761.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906952877.143852.4140962906331914859.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967162168.1823006.5941985259926902274.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021560394.640689.9972155785508094960.stgit@warthog.procyon.org.uk/ # v4
parent 287fd611

fs/cachefiles/interface.c

+78 −0
Original line number Diff line number Diff line
@@ -220,6 +220,83 @@ static bool cachefiles_lookup_cookie(struct fscache_cookie *cookie) 
	return false;

}



/*

 * Shorten the backing object to discard any dirty data and free up

 * any unused granules.

 */

static bool cachefiles_shorten_object(struct cachefiles_object *object,

				      struct file *file, loff_t new_size)

{

	struct cachefiles_cache *cache = object->volume->cache;

	struct inode *inode = file_inode(file);

	loff_t i_size, dio_size;

	int ret;



	dio_size = round_up(new_size, CACHEFILES_DIO_BLOCK_SIZE);

	i_size = i_size_read(inode);



	trace_cachefiles_trunc(object, inode, i_size, dio_size,

			       cachefiles_trunc_shrink);

	ret = cachefiles_inject_remove_error();

	if (ret == 0)

		ret = vfs_truncate(&file->f_path, dio_size);

	if (ret < 0) {

		trace_cachefiles_io_error(object, file_inode(file), ret,

					  cachefiles_trace_trunc_error);

		cachefiles_io_error_obj(object, "Trunc-to-size failed %d", ret);

		cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);

		return false;

	}



	if (new_size < dio_size) {

		trace_cachefiles_trunc(object, inode, dio_size, new_size,

				       cachefiles_trunc_dio_adjust);

		ret = cachefiles_inject_write_error();

		if (ret == 0)

			ret = vfs_fallocate(file, FALLOC_FL_ZERO_RANGE,

					    new_size, dio_size);

		if (ret < 0) {

			trace_cachefiles_io_error(object, file_inode(file), ret,

						  cachefiles_trace_fallocate_error);

			cachefiles_io_error_obj(object, "Trunc-to-dio-size failed %d", ret);

			cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);

			return false;

		}

	}



	return true;

}



/*

 * Resize the backing object.

 */

static void cachefiles_resize_cookie(struct netfs_cache_resources *cres,

				     loff_t new_size)

{

	struct cachefiles_object *object = cachefiles_cres_object(cres);

	struct cachefiles_cache *cache = object->volume->cache;

	struct fscache_cookie *cookie = object->cookie;

	const struct cred *saved_cred;

	struct file *file = cachefiles_cres_file(cres);

	loff_t old_size = cookie->object_size;



	_enter("%llu->%llu", old_size, new_size);



	if (new_size < old_size) {

		cachefiles_begin_secure(cache, &saved_cred);

		cachefiles_shorten_object(object, file, new_size);

		cachefiles_end_secure(cache, saved_cred);

		object->cookie->object_size = new_size;

		return;

	}



	/* The file is being expanded.  We don't need to do anything

	 * particularly.  cookie->initial_size doesn't change and so the point

	 * at which we have to download before doesn't change.

	 */

	cookie->object_size = new_size;

}



/*

 * Commit changes to the object as we drop it.

 */
@@ -363,5 +440,6 @@ const struct fscache_cache_ops cachefiles_cache_ops = { 
	.withdraw_cookie	= cachefiles_withdraw_cookie,

	.invalidate_cookie	= cachefiles_invalidate_cookie,

	.begin_operation	= cachefiles_begin_operation,

	.resize_cookie		= cachefiles_resize_cookie,

	.prepare_to_write	= cachefiles_prepare_to_write,

};