[PATCH] md: improve the interface to sync_request

1/ change the return value (which is number-of-sectors synced)
 from 'int' to 'sector_t'.
 The number of sectors is usually easily small enough to fit
 in an int, but if resync needs to abort, it may want to return
 the total number of remaining sectors, which could be large.
 Also errors cannot be returned as negative numbers now, so use
 0 instead
2/ Add a 'skipped' return parameter to allow the array to report
 that it skipped the sectors.  This allows md to take this into account
 in the speed calculations.
 Currently there is no important skipping, but the bitmap-based-resync
 that is coming will use this.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 7 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index bfc9f52f0ecf..8476515bfdc7 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1321,7 +1321,7 @@ static int init_resync(conf_t *conf)
  *
  */
 
-static int sync_request(mddev_t *mddev, sector_t sector_nr, int go_faster)
+static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
 {
         conf_t *conf = mddev_to_conf(mddev);
         r10bio_t *r10_bio;
@@ -1335,7 +1335,7 @@ static int sync_request(mddev_t *mddev, sector_t sector_nr, int go_faster)
 
         if (!conf->r10buf_pool)
                 if (init_resync(conf))
-                        return -ENOMEM;
+                        return 0;
 
  skipped:
         max_sector = mddev->size << 1;
@@ -1343,15 +1343,15 @@ static int sync_request(mddev_t *mddev, sector_t sector_nr, int go_faster)
                 max_sector = mddev->resync_max_sectors;
         if (sector_nr >= max_sector) {
                 close_sync(conf);
+                *skipped = 1;
                 return sectors_skipped;
         }
         if (chunks_skipped >= conf->raid_disks) {
                 /* if there has been nothing to do on any drive,
                  * then there is nothing to do at all..
                  */
-                sector_t sec = max_sector - sector_nr;
-                md_done_sync(mddev, sec, 1);
-                return sec + sectors_skipped;
+                *skipped = 1;
+                return (max_sector - sector_nr) + sectors_skipped;
         }
 
         /* make sure whole request will fit in a chunk - if chunks
@@ -1565,17 +1565,22 @@ static int sync_request(mddev_t *mddev, sector_t sector_nr, int go_faster)
                 }
         }
 
+        if (sectors_skipped)
+                /* pretend they weren't skipped, it makes
+                 * no important difference in this case
+                 */
+                md_done_sync(mddev, sectors_skipped, 1);
+
         return sectors_skipped + nr_sectors;
  giveup:
         /* There is nowhere to write, so all non-sync
          * drives must be failed, so try the next chunk...
          */
         {
-        int sec = max_sector - sector_nr;
+        sector_t sec = max_sector - sector_nr;
         sectors_skipped += sec;
         chunks_skipped ++;
         sector_nr = max_sector;
-        md_done_sync(mddev, sec, 1);
         goto skipped;
         }
 }