Implement resizing an object, using truncate and/or fallocate to adjust the object. Signed-off-by: David Howells <dhowells@xxxxxxxxxx> cc: linux-cachefs@xxxxxxxxxx Link: https://lore.kernel.org/r/163819646631.215744.13819016478175576761.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1 --- fs/cachefiles/interface.c | 78 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index ad9d311413ff..51c968cd00a6 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -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, };
