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authorLars Ellenberg <lars.ellenberg@linbit.com>2010-09-14 20:26:27 +0200
committerPhilipp Reisner <philipp.reisner@linbit.com>2010-10-14 18:38:50 +0200
commite9e6f3ec535d7b7c9e2ca64ad691e743e7d3c2f0 (patch)
treecbc17d81b9d937b4fc515548f30f5ed00be193ee /drivers/block
parent22cc37a943832c948808884604ec6f5ff2594c1d (diff)
drbd: fix for possible deadlock on IO error during resync
Scenario: Something (say, flush-147:0) is in drbd_al_begin_io, holding a local_cnt, waiting for the resync to make progress. Disk fails, worker in after_state_ch does drbd_rs_cancel_all, then waits for local_cnt to drop to zero. flush-147:0 is woken by drbd_rs_cancel_all, needs to write an AL transaction, and queues that on the worker. Deadlock. Fix: do not wait in the worker, have put_ldev() trigger the state change D_FAILED -> D_DISKLESS when necessary. put_ldev() cannot do the state change directly, as it may or may not already hold various spinlocks. We queue a short work instead. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/drbd/drbd_int.h8
-rw-r--r--drivers/block/drbd/drbd_main.c68
2 files changed, 54 insertions, 22 deletions
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 8ab6fed39539..c07c370c4c82 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -852,6 +852,7 @@ enum {
BITMAP_IO, /* suspend application io;
once no more io in flight, start bitmap io */
BITMAP_IO_QUEUED, /* Started bitmap IO */
+ GO_DISKLESS, /* Disk failed, local_cnt reached zero, we are going diskless */
RESYNC_AFTER_NEG, /* Resync after online grow after the attach&negotiate finished. */
NET_CONGESTED, /* The data socket is congested */
@@ -976,6 +977,7 @@ struct drbd_conf {
unsigned int ko_count;
struct drbd_work resync_work,
unplug_work,
+ go_diskless,
md_sync_work;
struct timer_list resync_timer;
struct timer_list md_sync_timer;
@@ -1278,6 +1280,7 @@ extern void drbd_queue_bitmap_io(struct drbd_conf *mdev,
extern int drbd_bmio_set_n_write(struct drbd_conf *mdev);
extern int drbd_bmio_clear_n_write(struct drbd_conf *mdev);
extern int drbd_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *), char *why);
+extern void drbd_go_diskless(struct drbd_conf *mdev);
/* Meta data layout
@@ -2123,8 +2126,11 @@ static inline void put_ldev(struct drbd_conf *mdev)
int i = atomic_dec_return(&mdev->local_cnt);
__release(local);
D_ASSERT(i >= 0);
- if (i == 0)
+ if (i == 0) {
+ if (mdev->state.disk == D_FAILED)
+ drbd_go_diskless(mdev);
wake_up(&mdev->misc_wait);
+ }
}
#ifndef __CHECKER__
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 63f45d730f3f..f89b97466d07 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -77,6 +77,7 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused);
static void md_sync_timer_fn(unsigned long data);
static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused);
MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
"Lars Ellenberg <lars@linbit.com>");
@@ -1363,42 +1364,46 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
os.disk > D_INCONSISTENT && ns.disk == D_INCONSISTENT)
drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, NULL, "set_n_write from invalidate");
+ /* first half of local IO error */
if (os.disk > D_FAILED && ns.disk == D_FAILED) {
- enum drbd_io_error_p eh;
+ enum drbd_io_error_p eh = EP_PASS_ON;
+
+ if (drbd_send_state(mdev))
+ dev_warn(DEV, "Notified peer that my disk is broken.\n");
+ else
+ dev_err(DEV, "Sending state for drbd_io_error() failed\n");
+
+ drbd_rs_cancel_all(mdev);
- eh = EP_PASS_ON;
if (get_ldev_if_state(mdev, D_FAILED)) {
eh = mdev->ldev->dc.on_io_error;
put_ldev(mdev);
}
+ if (eh == EP_CALL_HELPER)
+ drbd_khelper(mdev, "local-io-error");
+ }
- drbd_rs_cancel_all(mdev);
- /* since get_ldev() only works as long as disk>=D_INCONSISTENT,
- and it is D_DISKLESS here, local_cnt can only go down, it can
- not increase... It will reach zero */
- wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
+
+ /* second half of local IO error handling,
+ * after local_cnt references have reached zero: */
+ if (os.disk == D_FAILED && ns.disk == D_DISKLESS) {
mdev->rs_total = 0;
mdev->rs_failed = 0;
atomic_set(&mdev->rs_pending_cnt, 0);
-
- spin_lock_irq(&mdev->req_lock);
- _drbd_set_state(_NS(mdev, disk, D_DISKLESS), CS_HARD, NULL);
- spin_unlock_irq(&mdev->req_lock);
-
- if (eh == EP_CALL_HELPER)
- drbd_khelper(mdev, "local-io-error");
}
if (os.disk > D_DISKLESS && ns.disk == D_DISKLESS) {
+ int c = atomic_read(&mdev->local_cnt);
- if (os.disk == D_FAILED) /* && ns.disk == D_DISKLESS*/ {
- if (drbd_send_state(mdev))
- dev_warn(DEV, "Notified peer that my disk is broken.\n");
- else
- dev_err(DEV, "Sending state in drbd_io_error() failed\n");
- }
+ if (drbd_send_state(mdev))
+ dev_warn(DEV, "Notified peer that I detached my disk.\n");
+ else
+ dev_err(DEV, "Sending state for detach failed\n");
- wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
+ if (c != 0) {
+ dev_err(DEV, "Logic bug, local_cnt=%d, but should be 0\n", c);
+ wait_event(mdev->misc_wait, !atomic_read(&mdev->local_cnt));
+ }
lc_destroy(mdev->resync);
mdev->resync = NULL;
lc_destroy(mdev->act_log);
@@ -2803,11 +2808,13 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
INIT_LIST_HEAD(&mdev->meta.work.q);
INIT_LIST_HEAD(&mdev->resync_work.list);
INIT_LIST_HEAD(&mdev->unplug_work.list);
+ INIT_LIST_HEAD(&mdev->go_diskless.list);
INIT_LIST_HEAD(&mdev->md_sync_work.list);
INIT_LIST_HEAD(&mdev->bm_io_work.w.list);
mdev->resync_work.cb = w_resync_inactive;
mdev->unplug_work.cb = w_send_write_hint;
+ mdev->go_diskless.cb = w_go_diskless;
mdev->md_sync_work.cb = w_md_sync;
mdev->bm_io_work.w.cb = w_bitmap_io;
init_timer(&mdev->resync_timer);
@@ -2885,6 +2892,7 @@ void drbd_mdev_cleanup(struct drbd_conf *mdev)
D_ASSERT(list_empty(&mdev->meta.work.q));
D_ASSERT(list_empty(&mdev->resync_work.list));
D_ASSERT(list_empty(&mdev->unplug_work.list));
+ D_ASSERT(list_empty(&mdev->go_diskless.list));
}
@@ -3712,6 +3720,24 @@ static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
return 1;
}
+static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+{
+ D_ASSERT(mdev->state.disk == D_FAILED);
+ D_ASSERT(atomic_read(&mdev->local_cnt) == 0);
+
+ drbd_force_state(mdev, NS(disk, D_DISKLESS));
+
+ clear_bit(GO_DISKLESS, &mdev->flags);
+ return 1;
+}
+
+void drbd_go_diskless(struct drbd_conf *mdev)
+{
+ D_ASSERT(mdev->state.disk == D_FAILED);
+ if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
+ drbd_queue_work_front(&mdev->data.work, &mdev->go_diskless);
+}
+
/**
* drbd_queue_bitmap_io() - Queues an IO operation on the whole bitmap
* @mdev: DRBD device.