From 00e73adb03ef4453599268779fe354e4e8513e54 Mon Sep 17 00:00:00 2001 From: Jason Dillaman Date: Tue, 11 Aug 2015 09:26:33 -0400 Subject: [PATCH] librbd: prevent race condition between resize requests It was possible that the same resize request could be sent twice if a completed resize op started a newly created resize op while it was also being concurrently started by another thread. Fixes: #12664 Backport: hammer Signed-off-by: Jason Dillaman (cherry picked from commit 6ec431bac1cf9446f3af90209d193dfcf003f2c5) --- src/librbd/AsyncResizeRequest.cc | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/src/librbd/AsyncResizeRequest.cc b/src/librbd/AsyncResizeRequest.cc index 7a4f65b437388..8ddf96726a917 100644 --- a/src/librbd/AsyncResizeRequest.cc +++ b/src/librbd/AsyncResizeRequest.cc @@ -24,21 +24,15 @@ AsyncResizeRequest::AsyncResizeRequest(ImageCtx &image_ctx, Context *on_finish, m_prog_ctx(prog_ctx), m_new_parent_overlap(0), m_xlist_item(this) { - RWLock::WLocker l(m_image_ctx.snap_lock); - m_image_ctx.async_resize_reqs.push_back(&m_xlist_item); - m_original_size = m_image_ctx.size; - compute_parent_overlap(); } AsyncResizeRequest::~AsyncResizeRequest() { AsyncResizeRequest *next_req = NULL; { - RWLock::WLocker l(m_image_ctx.snap_lock); + RWLock::WLocker snap_locker(m_image_ctx.snap_lock); assert(m_xlist_item.remove_myself()); if (!m_image_ctx.async_resize_reqs.empty()) { next_req = m_image_ctx.async_resize_reqs.front(); - next_req->m_original_size = m_image_ctx.size; - next_req->compute_parent_overlap(); } } @@ -125,14 +119,19 @@ bool AsyncResizeRequest::should_complete(int r) { void AsyncResizeRequest::send() { assert(m_image_ctx.owner_lock.is_locked()); - { - RWLock::RLocker l(m_image_ctx.snap_lock); - assert(!m_image_ctx.async_resize_reqs.empty()); - // only allow a single concurrent resize request - if (m_image_ctx.async_resize_reqs.front() != this) { - return; + { + RWLock::WLocker snap_locker(m_image_ctx.snap_lock); + if (!m_xlist_item.is_on_list()) { + m_image_ctx.async_resize_reqs.push_back(&m_xlist_item); + if (m_image_ctx.async_resize_reqs.front() != this) { + return; + } } + + assert(m_image_ctx.async_resize_reqs.front() == this); + m_original_size = m_image_ctx.size; + compute_parent_overlap(); } CephContext *cct = m_image_ctx.cct; -- 2.47.3