Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

librbd: fix state machine race conditions during shut down #7761

Merged
merged 2 commits into from Feb 24, 2016
Merged

librbd: fix state machine race conditions during shut down #7761

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
514519a
librbd: avoid close race-condition within ImageState
Feb 23, 2016
e67099d
librbd: deterministically unblock writes on snap set
Feb 23, 2016
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
99 changes: 55 additions & 44 deletions src/librbd/ImageState.cc
View file
Open in desktop
Expand Up @@ -5,6 +5,7 @@
#include "common/dout.h"
#include "common/errno.h"
#include "common/Cond.h"
#include "common/WorkQueue.h"
#include "librbd/ImageCtx.h"
#include "librbd/Utils.h"
#include "librbd/image/CloseRequest.h"
Expand All @@ -18,6 +19,7 @@

namespace librbd {

using util::create_async_context_callback;
using util::create_context_callback;

template <typename I>
Expand All @@ -44,12 +46,13 @@ void ImageState<I>::open(Context *on_finish) {
CephContext *cct = m_image_ctx->cct;
ldout(cct, 20) << __func__ << dendl;

Mutex::Locker locker(m_lock);
m_lock.Lock();
assert(m_state == STATE_UNINITIALIZED);

Action action(ACTION_TYPE_OPEN);
action.refresh_seq = m_refresh_seq;
execute_action(action, on_finish);

execute_action_unlock(action, on_finish);
}

template <typename I>
Expand All @@ -67,12 +70,12 @@ void ImageState<I>::close(Context *on_finish) {
CephContext *cct = m_image_ctx->cct;
ldout(cct, 20) << __func__ << dendl;

Mutex::Locker locker(m_lock);
m_lock.Lock();
assert(!is_closed());

Action action(ACTION_TYPE_CLOSE);
action.refresh_seq = m_refresh_seq;
execute_action(action, on_finish);
execute_action_unlock(action, on_finish);
}

template <typename I>
Expand Down Expand Up @@ -112,22 +115,22 @@ void ImageState<I>::refresh(Context *on_finish) {

Action action(ACTION_TYPE_REFRESH);
action.refresh_seq = m_refresh_seq;
execute_action(action, on_finish);
m_lock.Unlock();
execute_action_unlock(action, on_finish);
}

template <typename I>
int ImageState<I>::refresh_if_required() {
C_SaferCond ctx;
{
Mutex::Locker locker(m_lock);
m_lock.Lock();
if (m_last_refresh == m_refresh_seq || is_closed()) {
m_lock.Unlock();
return 0;
}

Action action(ACTION_TYPE_REFRESH);
action.refresh_seq = m_refresh_seq;
execute_action(action, &ctx);
execute_action_unlock(action, &ctx);
}

return ctx.wait();
Expand All @@ -138,10 +141,11 @@ void ImageState<I>::snap_set(const std::string &snap_name, Context *on_finish) {
CephContext *cct = m_image_ctx->cct;
ldout(cct, 20) << __func__ << ": snap_name=" << snap_name << dendl;

Mutex::Locker locker(m_lock);
Action action(ACTION_TYPE_SET_SNAP);
action.snap_name = snap_name;
execute_action(action, on_finish);

m_lock.Lock();
execute_action_unlock(action, on_finish);
}

template <typename I>
Expand Down Expand Up @@ -192,72 +196,80 @@ void ImageState<I>::append_context(const Action &action, Context *context) {
}

template <typename I>
void ImageState<I>::execute_next_action() {
void ImageState<I>::execute_next_action_unlock() {
assert(m_lock.is_locked());
assert(!m_actions_contexts.empty());
switch (m_actions_contexts.front().first.action_type) {
case ACTION_TYPE_OPEN:
send_open();
send_open_unlock();
return;
case ACTION_TYPE_CLOSE:
send_close();
send_close_unlock();
return;
case ACTION_TYPE_REFRESH:
send_refresh();
send_refresh_unlock();
return;
case ACTION_TYPE_SET_SNAP:
send_set_snap();
send_set_snap_unlock();
return;
}
assert(false);
}

template <typename I>
void ImageState<I>::execute_action(const Action &action, Context *on_finish) {
void ImageState<I>::execute_action_unlock(const Action &action,
Context *on_finish) {
assert(m_lock.is_locked());

append_context(action, on_finish);
if (!is_transition_state()) {
execute_next_action();
execute_next_action_unlock();
} else {
m_lock.Unlock();
}
}

template <typename I>
void ImageState<I>::complete_action(State next_state, int r) {
void ImageState<I>::complete_action_unlock(State next_state, int r) {
assert(m_lock.is_locked());
assert(!m_actions_contexts.empty());

ActionContexts action_contexts(std::move(m_actions_contexts.front()));
m_actions_contexts.pop_front();

m_state = next_state;
m_lock.Unlock();

for (auto ctx : action_contexts.second) {
ctx->complete(r);
}
m_lock.Lock();

m_state = next_state;
if (!is_transition_state() && !m_actions_contexts.empty()) {
execute_next_action();
if (next_state != STATE_CLOSED) {
m_lock.Lock();
if (!is_transition_state() && !m_actions_contexts.empty()) {
execute_next_action_unlock();
} else {
m_lock.Unlock();
}
}
}

template <typename I>
void ImageState<I>::send_open() {
void ImageState<I>::send_open_unlock() {
assert(m_lock.is_locked());
CephContext *cct = m_image_ctx->cct;
ldout(cct, 10) << this << " " << __func__ << dendl;

m_state = STATE_OPENING;

Context *ctx = create_context_callback<
ImageState<I>, &ImageState<I>::handle_open>(this);
Context *ctx = create_async_context_callback(
*m_image_ctx, create_context_callback<
ImageState<I>, &ImageState<I>::handle_open>(this));
image::OpenRequest<I> *req = image::OpenRequest<I>::create(
m_image_ctx, ctx);

m_lock.Unlock();
req->send();
m_lock.Lock();
}

template <typename I>
Expand All @@ -269,12 +281,12 @@ void ImageState<I>::handle_open(int r) {
lderr(cct) << "failed to open image: " << cpp_strerror(r) << dendl;
}

Mutex::Locker locker(m_lock);
complete_action(r < 0 ? STATE_UNINITIALIZED : STATE_OPEN, r);
m_lock.Lock();
complete_action_unlock(r < 0 ? STATE_UNINITIALIZED : STATE_OPEN, r);
}

template <typename I>
void ImageState<I>::send_close() {
void ImageState<I>::send_close_unlock() {
assert(m_lock.is_locked());
CephContext *cct = m_image_ctx->cct;
ldout(cct, 10) << this << " " << __func__ << dendl;
Expand All @@ -288,7 +300,6 @@ void ImageState<I>::send_close() {

m_lock.Unlock();
req->send();
m_lock.Lock();
}

template <typename I>
Expand All @@ -301,46 +312,46 @@ void ImageState<I>::handle_close(int r) {
<< dendl;
}

Mutex::Locker locker(m_lock);
complete_action(STATE_CLOSED, r);
m_lock.Lock();
complete_action_unlock(STATE_CLOSED, r);
}

template <typename I>
void ImageState<I>::send_refresh() {
void ImageState<I>::send_refresh_unlock() {
assert(m_lock.is_locked());
CephContext *cct = m_image_ctx->cct;
ldout(cct, 10) << this << " " << __func__ << dendl;

m_state = STATE_REFRESHING;

Context *ctx = create_context_callback<
ImageState<I>, &ImageState<I>::handle_refresh>(this);
Context *ctx = create_async_context_callback(
*m_image_ctx, create_context_callback<
ImageState<I>, &ImageState<I>::handle_refresh>(this));
image::RefreshRequest<I> *req = image::RefreshRequest<I>::create(
*m_image_ctx, ctx);

m_lock.Unlock();
req->send();
m_lock.Lock();
}

template <typename I>
void ImageState<I>::handle_refresh(int r) {
CephContext *cct = m_image_ctx->cct;
ldout(cct, 10) << this << " " << __func__ << ": r=" << r << dendl;

Mutex::Locker locker(m_lock);
m_lock.Lock();
assert(!m_actions_contexts.empty());

ActionContexts &action_contexts(m_actions_contexts.front());
assert(action_contexts.first.action_type == ACTION_TYPE_REFRESH);
assert(m_last_refresh <= action_contexts.first.refresh_seq);
m_last_refresh = action_contexts.first.refresh_seq;

complete_action(STATE_OPEN, r);
complete_action_unlock(STATE_OPEN, r);
}

template <typename I>
void ImageState<I>::send_set_snap() {
void ImageState<I>::send_set_snap_unlock() {
assert(m_lock.is_locked());

m_state = STATE_SETTING_SNAP;
Expand All @@ -353,14 +364,14 @@ void ImageState<I>::send_set_snap() {
ldout(cct, 10) << this << " " << __func__ << ": "
<< "snap_name=" << action_contexts.first.snap_name << dendl;

Context *ctx = create_context_callback<
ImageState<I>, &ImageState<I>::handle_set_snap>(this);
Context *ctx = create_async_context_callback(
*m_image_ctx, create_context_callback<
ImageState<I>, &ImageState<I>::handle_set_snap>(this));
image::SetSnapRequest<I> *req = image::SetSnapRequest<I>::create(
*m_image_ctx, action_contexts.first.snap_name, ctx);

m_lock.Unlock();
req->send();
m_lock.Lock();
}

template <typename I>
Expand All @@ -372,8 +383,8 @@ void ImageState<I>::handle_set_snap(int r) {
lderr(cct) << "failed to set snapshot: " << cpp_strerror(r) << dendl;
}

Mutex::Locker locker(m_lock);
complete_action(STATE_OPEN, r);
m_lock.Lock();
complete_action_unlock(STATE_OPEN, r);
}

} // namespace librbd
Expand Down
14 changes: 7 additions & 7 deletions src/librbd/ImageState.h
View file
Open in desktop
Expand Up @@ -96,20 +96,20 @@ class ImageState {
bool is_closed() const;

void append_context(const Action &action, Context *context);
void execute_next_action();
void execute_action(const Action &action, Context *context);
void complete_action(State next_state, int r);
void execute_next_action_unlock();
void execute_action_unlock(const Action &action, Context *context);
void complete_action_unlock(State next_state, int r);

void send_open();
void send_open_unlock();
void handle_open(int r);

void send_close();
void send_close_unlock();
void handle_close(int r);

void send_refresh();
void send_refresh_unlock();
void handle_refresh(int r);

void send_set_snap();
void send_set_snap_unlock();
void handle_set_snap(int r);

};
Expand Down