From ef778e7ae67cd426c30cad43378b908f5eb0bad5 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 20 Dec 2012 21:52:36 +0000 Subject: FS-Cache: Provide proper invalidation Provide a proper invalidation method rather than relying on the netfs retiring the cookie it has and getting a new one. The problem with this is that isn't easy for the netfs to make sure that it has completed/cancelled all its outstanding storage and retrieval operations on the cookie it is retiring. Instead, have the cache provide an invalidation method that will cancel or wait for all currently outstanding operations before invalidating the cache, and will cause new operations to queue up behind that. Whilst invalidation is in progress, some requests will be rejected until the cache can stack a barrier on the operation queue to cause new operations to be deferred behind it. Signed-off-by: David Howells --- fs/fscache/page.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) (limited to 'fs/fscache/page.c') diff --git a/fs/fscache/page.c b/fs/fscache/page.c index b38b13d2a555..7bf9d2557052 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -361,6 +361,11 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, if (hlist_empty(&cookie->backing_objects)) goto nobufs; + if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { + _leave(" = -ENOBUFS [invalidating]"); + return -ENOBUFS; + } + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(page, !=, NULL); @@ -483,6 +488,11 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, if (hlist_empty(&cookie->backing_objects)) goto nobufs; + if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { + _leave(" = -ENOBUFS [invalidating]"); + return -ENOBUFS; + } + ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(*nr_pages, >, 0); ASSERT(!list_empty(pages)); @@ -591,6 +601,11 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX); ASSERTCMP(page, !=, NULL); + if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { + _leave(" = -ENOBUFS [invalidating]"); + return -ENOBUFS; + } + if (fscache_wait_for_deferred_lookup(cookie) < 0) return -ERESTARTSYS; @@ -730,6 +745,37 @@ superseded: _leave(""); } +/* + * Clear the pages pending writing for invalidation + */ +void fscache_invalidate_writes(struct fscache_cookie *cookie) +{ + struct page *page; + void *results[16]; + int n, i; + + _enter(""); + + while (spin_lock(&cookie->stores_lock), + n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0, + ARRAY_SIZE(results), + FSCACHE_COOKIE_PENDING_TAG), + n > 0) { + for (i = n - 1; i >= 0; i--) { + page = results[i]; + radix_tree_delete(&cookie->stores, page->index); + } + + spin_unlock(&cookie->stores_lock); + + for (i = n - 1; i >= 0; i--) + page_cache_release(results[i]); + } + + spin_unlock(&cookie->stores_lock); + _leave(""); +} + /* * request a page be stored in the cache * - returns: @@ -776,6 +822,11 @@ int __fscache_write_page(struct fscache_cookie *cookie, fscache_stat(&fscache_n_stores); + if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) { + _leave(" = -ENOBUFS [invalidating]"); + return -ENOBUFS; + } + op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY); if (!op) goto nomem; -- cgit v1.2.3