md/r5cache: fix io_unit handling in r5l_log_endio()

[linux-2.6-block.git] / drivers / md / raid5-cache.c

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index bfa1e907c472e49855f9e0abb4c307cd45514d4d..2dcbafa8e66ca7f5418fce8434fe9674977f0832 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -236,9 +236,10 @@ struct r5l_io_unit {
        bool need_split_bio;
        struct bio *split_bio;
 
-       unsigned int has_flush:1;      /* include flush request */
-       unsigned int has_fua:1;        /* include fua request */
-       unsigned int has_null_flush:1; /* include empty flush request */
+       unsigned int has_flush:1;               /* include flush request */
+       unsigned int has_fua:1;                 /* include fua request */
+       unsigned int has_null_flush:1;          /* include null flush request */
+       unsigned int has_flush_payload:1;       /* include flush payload  */
        /*
         * io isn't sent yet, flush/fua request can only be submitted till it's
         * the first IO in running_ios list
@@ -571,6 +572,8 @@ static void r5l_log_endio(struct bio *bio)
        struct r5l_io_unit *io_deferred;
        struct r5l_log *log = io->log;
        unsigned long flags;
+       bool has_null_flush;
+       bool has_flush_payload;
 
        if (bio->bi_status)
                md_error(log->rdev->mddev, log->rdev);
@@ -580,6 +583,16 @@ static void r5l_log_endio(struct bio *bio)
 
        spin_lock_irqsave(&log->io_list_lock, flags);
        __r5l_set_io_unit_state(io, IO_UNIT_IO_END);
+
+       /*
+        * if the io doesn't not have null_flush or flush payload,
+        * it is not safe to access it after releasing io_list_lock.
+        * Therefore, it is necessary to check the condition with
+        * the lock held.
+        */
+       has_null_flush = io->has_null_flush;
+       has_flush_payload = io->has_flush_payload;
+
        if (log->need_cache_flush && !list_empty(&io->stripe_list))
                r5l_move_to_end_ios(log);
        else
@@ -600,19 +613,23 @@ static void r5l_log_endio(struct bio *bio)
        if (log->need_cache_flush)
                md_wakeup_thread(log->rdev->mddev->thread);
 
-       if (io->has_null_flush) {
+       /* finish flush only io_unit and PAYLOAD_FLUSH only io_unit */
+       if (has_null_flush) {
                struct bio *bi;
 
                WARN_ON(bio_list_empty(&io->flush_barriers));
                while ((bi = bio_list_pop(&io->flush_barriers)) != NULL) {
                        bio_endio(bi);
-                       atomic_dec(&io->pending_stripe);
+                       if (atomic_dec_and_test(&io->pending_stripe)) {
+                               __r5l_stripe_write_finished(io);
+                               return;
+                       }
                }
        }
-
-       /* finish flush only io_unit and PAYLOAD_FLUSH only io_unit */
-       if (atomic_read(&io->pending_stripe) == 0)
-               __r5l_stripe_write_finished(io);
+       /* decrease pending_stripe for flush payload */
+       if (has_flush_payload)
+               if (atomic_dec_and_test(&io->pending_stripe))
+                       __r5l_stripe_write_finished(io);
 }
 
 static void r5l_do_submit_io(struct r5l_log *log, struct r5l_io_unit *io)
@@ -881,6 +898,11 @@ static void r5l_append_flush_payload(struct r5l_log *log, sector_t sect)
        payload->size = cpu_to_le32(sizeof(__le64));
        payload->flush_stripes[0] = cpu_to_le64(sect);
        io->meta_offset += meta_size;
+       /* multiple flush payloads count as one pending_stripe */
+       if (!io->has_flush_payload) {
+               io->has_flush_payload = 1;
+               atomic_inc(&io->pending_stripe);
+       }
        mutex_unlock(&log->io_mutex);
 }
 
@@ -2540,23 +2562,32 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
  */
 int r5c_journal_mode_set(struct mddev *mddev, int mode)
 {
-       struct r5conf *conf = mddev->private;
-       struct r5l_log *log = conf->log;
-
-       if (!log)
-               return -ENODEV;
+       struct r5conf *conf;
+       int err;
 
        if (mode < R5C_JOURNAL_MODE_WRITE_THROUGH ||
            mode > R5C_JOURNAL_MODE_WRITE_BACK)
                return -EINVAL;
 
+       err = mddev_lock(mddev);
+       if (err)
+               return err;
+       conf = mddev->private;
+       if (!conf || !conf->log) {
+               mddev_unlock(mddev);
+               return -ENODEV;
+       }
+
        if (raid5_calc_degraded(conf) > 0 &&
-           mode == R5C_JOURNAL_MODE_WRITE_BACK)
+           mode == R5C_JOURNAL_MODE_WRITE_BACK) {
+               mddev_unlock(mddev);
                return -EINVAL;
+       }
 
        mddev_suspend(mddev);
        conf->log->r5c_journal_mode = mode;
        mddev_resume(mddev);
+       mddev_unlock(mddev);
 
        pr_debug("md/raid:%s: setting r5c cache mode to %d: %s\n",
                 mdname(mddev), mode, r5c_journal_mode_str[mode]);