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| author | Lars Ellenberg <lars.ellenberg@linbit.com> | 2010-09-03 10:00:09 +0200 |
|---|---|---|
| committer | Philipp Reisner <philipp.reisner@linbit.com> | 2010-10-14 18:38:30 +0200 |
| commit | ee15b038164fcf19b798021762dee3cf5cbc6433 (patch) | |
| tree | 8d2cca781af96296a591a14928ece247fc682ef3 /drivers/block/drbd/drbd_int.h | |
| parent | 63106d3c6c769b6219bd04edde513b12abae3f61 (diff) | |
| download | lwn-ee15b038164fcf19b798021762dee3cf5cbc6433.tar.gz lwn-ee15b038164fcf19b798021762dee3cf5cbc6433.zip | |
drbd: fix race on meta-data update, addendum
addendum to baa33ae4eaa4477b60af7c434c0ddd1d182c1ae7
The race:
drbd_md_sync()
if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
return;
==> RACE with drbd_md_mark_dirty() rearming the timer.
del_timer(&mdev->md_sync_timer);
Fixed by moving the del_timer before the test_and_clear_bit.
Additionally only rearm the timer in drbd_md_mark_dirty, if MD_DIRTY was
not already set, reduce the grace period from five to one second, and
add an ifdef'ed debuging aid to find code paths missing an explicit
drbd_md_sync, if any, as those are the only relevant ones for this race.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Diffstat (limited to 'drivers/block/drbd/drbd_int.h')
| -rw-r--r-- | drivers/block/drbd/drbd_int.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index d5e38de83a19..f9b75fc30569 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -975,6 +975,12 @@ struct drbd_conf { md_sync_work; struct timer_list resync_timer; struct timer_list md_sync_timer; +#ifdef DRBD_DEBUG_MD_SYNC + struct { + unsigned int line; + const char* func; + } last_md_mark_dirty; +#endif /* Used after attach while negotiating new disk state. */ union drbd_state new_state_tmp; @@ -1253,7 +1259,13 @@ extern void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local) extern void drbd_md_set_flag(struct drbd_conf *mdev, int flags) __must_hold(local); extern void drbd_md_clear_flag(struct drbd_conf *mdev, int flags)__must_hold(local); extern int drbd_md_test_flag(struct drbd_backing_dev *, int); +#ifndef DRBD_DEBUG_MD_SYNC extern void drbd_md_mark_dirty(struct drbd_conf *mdev); +#else +#define drbd_md_mark_dirty(m) drbd_md_mark_dirty_(m, __LINE__ , __func__ ) +extern void drbd_md_mark_dirty_(struct drbd_conf *mdev, + unsigned int line, const char *func); +#endif extern void drbd_queue_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *), void (*done)(struct drbd_conf *, int), |