drbd: Replaced md_io_mutex by an atomic: md_io_in_use

The new function drbd_md_get_buffer() aborts waiting for the buffer
in case the disk failes in the meantime.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 12 insertions, 7 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 16969c2b96cd..1b59ab3ab9c7 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3043,8 +3043,8 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
         atomic_set(&mdev->rs_sect_in, 0);
         atomic_set(&mdev->rs_sect_ev, 0);
         atomic_set(&mdev->ap_in_flight, 0);
+        atomic_set(&mdev->md_io_in_use, 0);
 
-        mutex_init(&mdev->md_io_mutex);
         mutex_init(&mdev->data.mutex);
         mutex_init(&mdev->meta.mutex);
         sema_init(&mdev->data.work.s, 0);
@@ -3722,8 +3722,10 @@ void drbd_md_sync(struct drbd_conf *mdev)
         if (!get_ldev_if_state(mdev, D_FAILED))
                 return;
 
-        mutex_lock(&mdev->md_io_mutex);
-        buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
+        buffer = drbd_md_get_buffer(mdev);
+        if (!buffer)
+                goto out;
+
         memset(buffer, 0, 512);
 
         buffer->la_size = cpu_to_be64(drbd_get_capacity(mdev->this_bdev));
@@ -3754,7 +3756,8 @@ void drbd_md_sync(struct drbd_conf *mdev)
          * since we updated it on metadata. */
         mdev->ldev->md.la_size_sect = drbd_get_capacity(mdev->this_bdev);
 
-        mutex_unlock(&mdev->md_io_mutex);
+        drbd_md_put_buffer(mdev);
+out:
         put_ldev(mdev);
 }
 
@@ -3774,8 +3777,9 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
         if (!get_ldev_if_state(mdev, D_ATTACHING))
                 return ERR_IO_MD_DISK;
 
-        mutex_lock(&mdev->md_io_mutex);
-        buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
+        buffer = drbd_md_get_buffer(mdev);
+        if (!buffer)
+                goto out;
 
         if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
                 /* NOTE: can't do normal error processing here as this is
@@ -3836,7 +3840,8 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
                 mdev->sync_conf.al_extents = 127;
 
  err:
-        mutex_unlock(&mdev->md_io_mutex);
+        drbd_md_put_buffer(mdev);
+ out:
         put_ldev(mdev);
 
         return rv;