From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:53662 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754148AbdARO31 (ORCPT ); Wed, 18 Jan 2017 09:29:27 -0500 Subject: [PATCH 2/2] fscache: Clear outstanding writes when disabling a cookie From: David Howells To: viro@ZenIV.linux.org.uk Cc: Jeff Layton , Steve Dickson , Jianhong Yin , linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org Date: Wed, 18 Jan 2017 14:29:25 +0000 Message-ID: <148474976519.30883.9154306651716215349.stgit@warthog.procyon.org.uk> In-Reply-To: <148474975781.30883.1102772060203480956.stgit@warthog.procyon.org.uk> References: <148474975781.30883.1102772060203480956.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: fscache_disable_cookie() needs to clear the outstanding writes on the cookie it's disabling because they cannot be completed after. Without this, fscache_nfs_open_file() gets stuck because it disables the cookie when the file is opened for writing but can't uncache the pages till afterwards - otherwise there's a race between the open routine and anyone who already has it open R/O and is still reading from it. Looking in /proc/pid/stack of the offending process shows: [] __fscache_wait_on_page_write+0x82/0x9b [fscache] [] __fscache_uncache_all_inode_pages+0x91/0xe1 [fscache] [] nfs_fscache_open_file+0x59/0x9e [nfs] [] nfs4_file_open+0x17f/0x1b8 [nfsv4] [] do_dentry_open+0x16d/0x2b7 [] vfs_open+0x5c/0x65 [] path_openat+0x785/0x8fb [] do_filp_open+0x48/0x9e [] do_sys_open+0x13b/0x1cb [] SyS_open+0x19/0x1b [] do_syscall_64+0x80/0x17a [] return_from_SYSCALL_64+0x0/0x7a [] 0xffffffffffffffff Reported-by: Jianhong Yin Signed-off-by: David Howells Acked-by: Jeff Layton Acked-by: Steve Dickson --- fs/fscache/cookie.c | 5 +++++ fs/fscache/object.c | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c index 4304072161aa..40d61077bead 100644 --- a/fs/fscache/cookie.c +++ b/fs/fscache/cookie.c @@ -542,6 +542,7 @@ void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate) hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) { if (invalidate) set_bit(FSCACHE_OBJECT_RETIRED, &object->flags); + clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL); } } else { @@ -560,6 +561,10 @@ void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate) wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t, TASK_UNINTERRUPTIBLE); + /* Make sure any pending writes are cancelled. */ + if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) + fscache_invalidate_writes(cookie); + /* Reset the cookie state if it wasn't relinquished */ if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) { atomic_inc(&cookie->n_active); diff --git a/fs/fscache/object.c b/fs/fscache/object.c index 9e792e30f4db..be02a086ed9b 100644 --- a/fs/fscache/object.c +++ b/fs/fscache/object.c @@ -645,6 +645,12 @@ static const struct fscache_state *fscache_kill_object(struct fscache_object *ob fscache_mark_object_dead(object); object->oob_event_mask = 0; + if (test_bit(FSCACHE_OBJECT_RETIRED, &object->flags)) { + /* Reject any new read/write ops and abort any that are pending. */ + clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); + fscache_cancel_all_ops(object); + } + if (list_empty(&object->dependents) && object->n_ops == 0 && object->n_children == 0)