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authorShaohua Li <shli@fb.com>2015-09-02 22:49:47 +0200
committerNeilBrown <neilb@suse.com>2015-11-01 03:48:26 +0100
commit0fd22b45b2d2e1de162d6a47327d449e0ed45ad2 (patch)
tree19405695d4fee2c0d07ede5af8d95e54952c459b /drivers/md/raid5-cache.c
parentraid5-cache: switching to state machine for log disk cache flush (diff)
downloadlinux-0fd22b45b2d2e1de162d6a47327d449e0ed45ad2.tar.xz
linux-0fd22b45b2d2e1de162d6a47327d449e0ed45ad2.zip
raid5-cache: fix a user-after-free bug
r5l_compress_stripe_end_list() can free an io_unit. This breaks the assumption only reclaimer can free io_unit. We can add a reference count based io_unit free, but since only reclaim can wait io_unit becoming to STRIPE_END state, we use a simple global wait queue here. Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: NeilBrown <neilb@suse.com>
Diffstat (limited to 'drivers/md/raid5-cache.c')
-rw-r--r--drivers/md/raid5-cache.c18
1 files changed, 7 insertions, 11 deletions
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 41542ebd813b..496f8e2578cc 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -79,6 +79,7 @@ struct r5l_log {
* dones't wait for specific io_unit
* switching to IO_UNIT_STRIPE_END
* state) */
+ wait_queue_head_t iounit_wait;
struct list_head no_space_stripes; /* pending stripes, log has no space */
spinlock_t no_space_stripes_lock;
@@ -109,7 +110,6 @@ struct r5l_io_unit {
struct list_head stripe_list; /* stripes added to the io_unit */
int state;
- wait_queue_head_t wait_state;
};
/* r5l_io_unit state */
@@ -162,7 +162,6 @@ static struct r5l_io_unit *r5l_alloc_io_unit(struct r5l_log *log)
INIT_LIST_HEAD(&io->log_sibling);
INIT_LIST_HEAD(&io->stripe_list);
io->state = IO_UNIT_RUNNING;
- init_waitqueue_head(&io->wait_state);
return io;
}
@@ -243,8 +242,8 @@ static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
r5l_wake_reclaim(log, 0);
r5l_compress_stripe_end_list(log);
+ wake_up(&log->iounit_wait);
}
- wake_up(&io->wait_state);
}
static void r5l_set_io_unit_state(struct r5l_io_unit *io,
@@ -622,10 +621,11 @@ void r5l_flush_stripe_to_raid(struct r5l_log *log)
submit_bio(WRITE_FLUSH, &log->flush_bio);
}
-static void r5l_kick_io_unit(struct r5l_log *log, struct r5l_io_unit *io)
+static void r5l_kick_io_unit(struct r5l_log *log)
{
md_wakeup_thread(log->rdev->mddev->thread);
- wait_event(io->wait_state, io->state >= IO_UNIT_STRIPE_END);
+ wait_event_lock_irq(log->iounit_wait, !list_empty(&log->stripe_end_ios),
+ log->io_list_lock);
}
static void r5l_write_super(struct r5l_log *log, sector_t cp);
@@ -670,12 +670,7 @@ static void r5l_do_reclaim(struct r5l_log *log)
else if (!list_empty(&log->running_ios))
target_list = &log->running_ios;
- io = list_first_entry(target_list,
- struct r5l_io_unit, log_sibling);
- spin_unlock_irq(&log->io_list_lock);
- /* nobody else can delete the io, we are safe */
- r5l_kick_io_unit(log, io);
- spin_lock_irq(&log->io_list_lock);
+ r5l_kick_io_unit(log);
}
spin_unlock_irq(&log->io_list_lock);
@@ -1079,6 +1074,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
log->rdev->mddev, "reclaim");
if (!log->reclaim_thread)
goto reclaim_thread;
+ init_waitqueue_head(&log->iounit_wait);
INIT_LIST_HEAD(&log->no_space_stripes);
spin_lock_init(&log->no_space_stripes_lock);