From 9dc8d9bfe4415efb61a5e9390706b8a3bffef329 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 20 Dec 2012 21:52:36 +0000 Subject: CacheFiles: Implement invalidation Implement invalidation for CacheFiles. This is in two parts: (1) Provide an invalidation method (which just truncates the backing file). (2) Abort attempts to copy anything read from the backing file whilst invalidation is in progress. Question: CacheFiles uses truncation in a couple of places. It has been using notify_change() rather than sys_truncate() or something similar. This means it bypasses a bunch of checks and suchlike that it possibly should be making (security, file locking, lease breaking, vfsmount write). Should it be using vfs_truncate() as added by a preceding patch or should it use notify_write() and assume that anyone poking around in the cache files on disk gets everything they deserve? Signed-off-by: David Howells --- fs/cachefiles/interface.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++ fs/cachefiles/rdwr.c | 5 ++++- 2 files changed, 53 insertions(+), 1 deletion(-) (limited to 'fs/cachefiles') diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c index 9bff0f878cfd..7a9d574b961c 100644 --- a/fs/cachefiles/interface.c +++ b/fs/cachefiles/interface.c @@ -440,6 +440,54 @@ truncate_failed: return ret; } +/* + * Invalidate an object + */ +static void cachefiles_invalidate_object(struct fscache_operation *op) +{ + struct cachefiles_object *object; + struct cachefiles_cache *cache; + const struct cred *saved_cred; + struct path path; + uint64_t ni_size; + int ret; + + object = container_of(op->object, struct cachefiles_object, fscache); + cache = container_of(object->fscache.cache, + struct cachefiles_cache, cache); + + op->object->cookie->def->get_attr(op->object->cookie->netfs_data, + &ni_size); + + _enter("{OBJ%x},[%llu]", + op->object->debug_id, (unsigned long long)ni_size); + + if (object->backer) { + ASSERT(S_ISREG(object->backer->d_inode->i_mode)); + + fscache_set_store_limit(&object->fscache, ni_size); + + path.dentry = object->backer; + path.mnt = cache->mnt; + + cachefiles_begin_secure(cache, &saved_cred); + ret = vfs_truncate(&path, 0); + if (ret == 0) + ret = vfs_truncate(&path, ni_size); + cachefiles_end_secure(cache, saved_cred); + + if (ret != 0) { + fscache_set_store_limit(&object->fscache, 0); + if (ret == -EIO) + cachefiles_io_error_obj(object, + "Invalidate failed"); + } + } + + fscache_op_complete(op); + _leave(""); +} + /* * dissociate a cache from all the pages it was backing */ @@ -455,6 +503,7 @@ const struct fscache_cache_ops cachefiles_cache_ops = { .lookup_complete = cachefiles_lookup_complete, .grab_object = cachefiles_grab_object, .update_object = cachefiles_update_object, + .invalidate_object = cachefiles_invalidate_object, .drop_object = cachefiles_drop_object, .put_object = cachefiles_put_object, .sync_cache = cachefiles_sync_cache, diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c index 93a0815e0498..2c994885520a 100644 --- a/fs/cachefiles/rdwr.c +++ b/fs/cachefiles/rdwr.c @@ -174,7 +174,10 @@ static void cachefiles_read_copier(struct fscache_operation *_op) _debug("- copy {%lu}", monitor->back_page->index); recheck: - if (PageUptodate(monitor->back_page)) { + if (test_bit(FSCACHE_COOKIE_INVALIDATING, + &object->fscache.cookie->flags)) { + error = -ESTALE; + } else if (PageUptodate(monitor->back_page)) { copy_highpage(monitor->netfs_page, monitor->back_page); fscache_mark_page_cached(monitor->op, monitor->netfs_page); -- cgit v1.2.3