md: add explicit method to signal the end of a reshape.

Currently raid5 (the only module that supports restriping)
notices that the reshape has finished be sync_request being
given a large value, and handles any cleanup them.

This patch changes it so md_check_recovery calls into an
explicit finish_reshape method as well.

The clean-up from sync_request can do things that need to be
done promptly, typically things local to the raid5_conf_t
structure.

The "finish_reshape" method is called under the mddev_lock
so it can do things involving reconfiguring the device.

This allows us to get rid of md_set_array_sectors_locked, which
would have caused a deadlock if you tried to stop and array
while a reshape was happening.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 30 insertions, 20 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 5694eb8941b6..a0f22dd33234 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3850,6 +3850,7 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski
         if (sector_nr >= max_sector) {
                 /* just being told to finish up .. nothing much to do */
                 unplug_slaves(mddev);
+
                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
                         end_reshape(conf);
                         return 0;
@@ -4836,43 +4837,49 @@ static int raid5_start_reshape(mddev_t *mddev)
 
 static void end_reshape(raid5_conf_t *conf)
 {
-        struct block_device *bdev;
 
         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
-                mddev_t *mddev = conf->mddev;
-
-                md_set_array_sectors_lock(mddev, raid5_size(mddev, 0,
-                                                       conf->raid_disks));
-                set_capacity(mddev->gendisk, mddev->array_sectors);
-                mddev->changed = 1;
-                conf->previous_raid_disks = conf->raid_disks;
 
-                bdev = bdget_disk(conf->mddev->gendisk, 0);
-                if (bdev) {
-                        mutex_lock(&bdev->bd_inode->i_mutex);
-                        i_size_write(bdev->bd_inode,
-                                     (loff_t)conf->mddev->array_sectors << 9);
-                        mutex_unlock(&bdev->bd_inode->i_mutex);
-                        bdput(bdev);
-                }
                 spin_lock_irq(&conf->device_lock);
+                conf->previous_raid_disks = conf->raid_disks;
                 conf->expand_progress = MaxSector;
                 spin_unlock_irq(&conf->device_lock);
-                conf->mddev->reshape_position = MaxSector;
 
                 /* read-ahead size must cover two whole stripes, which is
                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
                  */
                 {
-                        int data_disks = conf->previous_raid_disks - conf->max_degraded;
-                        int stripe = data_disks *
-                                (conf->mddev->chunk_size / PAGE_SIZE);
+                        int data_disks = conf->raid_disks - conf->max_degraded;
+                        int stripe = data_disks * (conf->chunk_size
+                                                   / PAGE_SIZE);
                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
                 }
         }
 }
 
+static void raid5_finish_reshape(mddev_t *mddev)
+{
+        struct block_device *bdev;
+
+        if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+
+                md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
+                set_capacity(mddev->gendisk, mddev->array_sectors);
+                mddev->changed = 1;
+                mddev->reshape_position = MaxSector;
+
+                bdev = bdget_disk(mddev->gendisk, 0);
+                if (bdev) {
+                        mutex_lock(&bdev->bd_inode->i_mutex);
+                        i_size_write(bdev->bd_inode,
+                                     (loff_t)mddev->array_sectors << 9);
+                        mutex_unlock(&bdev->bd_inode->i_mutex);
+                        bdput(bdev);
+                }
+        }
+}
+
 static void raid5_quiesce(mddev_t *mddev, int state)
 {
         raid5_conf_t *conf = mddev_to_conf(mddev);
@@ -5098,6 +5105,7 @@ static struct mdk_personality raid6_personality =
 #ifdef CONFIG_MD_RAID5_RESHAPE
         .check_reshape  = raid5_check_reshape,
         .start_reshape  = raid5_start_reshape,
+        .finish_reshape = raid5_finish_reshape,
 #endif
         .quiesce        = raid5_quiesce,
         .takeover       = raid6_takeover,
@@ -5121,6 +5129,7 @@ static struct mdk_personality raid5_personality =
 #ifdef CONFIG_MD_RAID5_RESHAPE
         .check_reshape  = raid5_check_reshape,
         .start_reshape  = raid5_start_reshape,
+        .finish_reshape = raid5_finish_reshape,
 #endif
         .quiesce        = raid5_quiesce,
         .takeover       = raid5_takeover,
@@ -5146,6 +5155,7 @@ static struct mdk_personality raid4_personality =
 #ifdef CONFIG_MD_RAID5_RESHAPE
         .check_reshape  = raid5_check_reshape,
         .start_reshape  = raid5_start_reshape,
+        .finish_reshape = raid5_finish_reshape,
 #endif
         .quiesce        = raid5_quiesce,
 };