[PATCH 1/2] btrfs: Check cancel and pause in interval of scrub operation

[Zhaolei]

From: Zhao Lei <zhao...@cn.fujitsu.com>

Old code checking cancel and pause request inside scrub stripe
operation, like:
  loop() {
    if (parity) {
      scrub_parity_stripe();
      continue;
    }

    check_cancel_and_pause()

    scrub_normal_stripe();
  }

Reason is when introduce raid56 stripe scrub, new code is inserted
simplely to front of loop.

Better to:
  loop() {
    check_cancel_and_pause()

    if (parity)
      scrub_parity_stripe();
    else
      scrub_normal_stripe();
  }

This patch adjusted code place to realize above sequence.

Signed-off-by: Zhao Lei <zhao...@cn.fujitsu.com>
---
 fs/btrfs/scrub.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 94db0fa..f8551b9 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3104,22 +3104,6 @@ static noinline_for_stack int scrub_stripe(struct 
scrub_ctx *sctx,
         */
        ret = 0;
        while (physical < physical_end) {
-               /* for raid56, we skip parity stripe */
-               if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
-                       ret = get_raid56_logic_offset(physical, num,
-                                       map, &logical, &stripe_logical);
-                       logical += base;
-                       if (ret) {
-                               stripe_logical += base;
-                               stripe_end = stripe_logical + increment - 1;
-                               ret = scrub_raid56_parity(sctx, map, scrub_dev,
-                                               ppath, stripe_logical,
-                                               stripe_end);
-                               if (ret)
-                                       goto out;
-                               goto skip;
-                       }
-               }
                /*
                 * canceled?
                 */
@@ -3144,6 +3128,24 @@ static noinline_for_stack int scrub_stripe(struct 
scrub_ctx *sctx,
                        scrub_blocked_if_needed(fs_info);
                }
 
+               /* for raid56, we skip parity stripe */
+               if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
+                       ret = get_raid56_logic_offset(physical, num, map,
+                                                     &logical,
+                                                     &stripe_logical);
+                       logical += base;
+                       if (ret) {
+                               stripe_logical += base;
+                               stripe_end = stripe_logical + increment - 1;
+                               ret = scrub_raid56_parity(sctx, map, scrub_dev,
+                                                         ppath, stripe_logical,
+                                                         stripe_end);
+                               if (ret)
+                                       goto out;
+                               goto skip;
+                       }
+               }
+
                if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
                        key.type = BTRFS_METADATA_ITEM_KEY;
                else
-- 
1.8.5.1

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