Btrfs: make btrfs_map_block() return entire free extent for each device of RAID0...

btrfs_map_block() will only return a single stripe length, but we want the
full extent be mapped to each disk when we are trimming the extent,
so we add length to btrfs_bio_stripe and fill it if we are mapping for REQ_DISCARD.

Signed-off-by: Li Dongyang <lidongyang@novell.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8ba3c9e..c440c89 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2956,7 +2956,10 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
        struct extent_map_tree *em_tree = &map_tree->map_tree;
        u64 offset;
        u64 stripe_offset;
+       u64 stripe_end_offset;
        u64 stripe_nr;
+       u64 stripe_nr_orig;
+       u64 stripe_nr_end;
        int stripes_allocated = 8;
        int stripes_required = 1;
        int stripe_index;
@@ -2965,7 +2968,7 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
        int max_errors = 0;
        struct btrfs_multi_bio *multi = NULL;
 
-       if (multi_ret && !(rw & REQ_WRITE))
+       if (multi_ret && !(rw & (REQ_WRITE | REQ_DISCARD)))
                stripes_allocated = 1;
 again:
        if (multi_ret) {
@@ -3011,7 +3014,15 @@ again:
                        max_errors = 1;
                }
        }
-       if (multi_ret && (rw & REQ_WRITE) &&
+       if (rw & REQ_DISCARD) {
+               if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
+                                BTRFS_BLOCK_GROUP_RAID1 |
+                                BTRFS_BLOCK_GROUP_DUP |
+                                BTRFS_BLOCK_GROUP_RAID10)) {
+                       stripes_required = map->num_stripes;
+               }
+       }
+       if (multi_ret && (rw & (REQ_WRITE | REQ_DISCARD)) &&
            stripes_allocated < stripes_required) {
                stripes_allocated = map->num_stripes;
                free_extent_map(em);
@@ -3031,12 +3042,15 @@ again:
        /* stripe_offset is the offset of this block in its stripe*/
        stripe_offset = offset - stripe_offset;
 
-       if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
-                        BTRFS_BLOCK_GROUP_RAID10 |
-                        BTRFS_BLOCK_GROUP_DUP)) {
+       if (rw & REQ_DISCARD)
+               *length = min_t(u64, em->len - offset, *length);
+       else if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
+                             BTRFS_BLOCK_GROUP_RAID1 |
+                             BTRFS_BLOCK_GROUP_RAID10 |
+                             BTRFS_BLOCK_GROUP_DUP)) {
                /* we limit the length of each bio to what fits in a stripe */
                *length = min_t(u64, em->len - offset,
-                             map->stripe_len - stripe_offset);
+                               map->stripe_len - stripe_offset);
        } else {
                *length = em->len - offset;
        }
@@ -3046,8 +3060,19 @@ again:
 
        num_stripes = 1;
        stripe_index = 0;
-       if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
-               if (unplug_page || (rw & REQ_WRITE))
+       stripe_nr_orig = stripe_nr;
+       stripe_nr_end = (offset + *length + map->stripe_len - 1) &
+                       (~(map->stripe_len - 1));
+       do_div(stripe_nr_end, map->stripe_len);
+       stripe_end_offset = stripe_nr_end * map->stripe_len -
+                           (offset + *length);
+       if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
+               if (rw & REQ_DISCARD)
+                       num_stripes = min_t(u64, map->num_stripes,
+                                           stripe_nr_end - stripe_nr_orig);
+               stripe_index = do_div(stripe_nr, map->num_stripes);
+       } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
+               if (unplug_page || (rw & (REQ_WRITE | REQ_DISCARD)))
                        num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
@@ -3058,7 +3083,7 @@ again:
                }
 
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
-               if (rw & REQ_WRITE)
+               if (rw & (REQ_WRITE | REQ_DISCARD))
                        num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
@@ -3071,6 +3096,10 @@ again:
 
                if (unplug_page || (rw & REQ_WRITE))
                        num_stripes = map->sub_stripes;
+               else if (rw & REQ_DISCARD)
+                       num_stripes = min_t(u64, map->sub_stripes *
+                                           (stripe_nr_end - stripe_nr_orig),
+                                           map->num_stripes);
                else if (mirror_num)
                        stripe_index += mirror_num - 1;
                else {
@@ -3088,24 +3117,101 @@ again:
        }
        BUG_ON(stripe_index >= map->num_stripes);
 
-       for (i = 0; i < num_stripes; i++) {
-               if (unplug_page) {
-                       struct btrfs_device *device;
-                       struct backing_dev_info *bdi;
-
-                       device = map->stripes[stripe_index].dev;
-                       if (device->bdev) {
-                               bdi = blk_get_backing_dev_info(device->bdev);
-                               if (bdi->unplug_io_fn)
-                                       bdi->unplug_io_fn(bdi, unplug_page);
-                       }
-               } else {
+       if (rw & REQ_DISCARD) {
+               for (i = 0; i < num_stripes; i++) {
                        multi->stripes[i].physical =
                                map->stripes[stripe_index].physical +
                                stripe_offset + stripe_nr * map->stripe_len;
                        multi->stripes[i].dev = map->stripes[stripe_index].dev;
+
+                       if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
+                               u64 stripes;
+                               int last_stripe = (stripe_nr_end - 1) %
+                                       map->num_stripes;
+                               int j;
+
+                               for (j = 0; j < map->num_stripes; j++) {
+                                       if ((stripe_nr_end - 1 - j) %
+                                             map->num_stripes == stripe_index)
+                                               break;
+                               }
+                               stripes = stripe_nr_end - 1 - j;
+                               do_div(stripes, map->num_stripes);
+                               multi->stripes[i].length = map->stripe_len *
+                                       (stripes - stripe_nr + 1);
+
+                               if (i == 0) {
+                                       multi->stripes[i].length -=
+                                               stripe_offset;
+                                       stripe_offset = 0;
+                               }
+                               if (stripe_index == last_stripe)
+                                       multi->stripes[i].length -=
+                                               stripe_end_offset;
+                       } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+                               u64 stripes;
+                               int j;
+                               int factor = map->num_stripes /
+                                            map->sub_stripes;
+                               int last_stripe = (stripe_nr_end - 1) % factor;
+                               last_stripe *= map->sub_stripes;
+
+                               for (j = 0; j < factor; j++) {
+                                       if ((stripe_nr_end - 1 - j) % factor ==
+                                           stripe_index / map->sub_stripes)
+                                               break;
+                               }
+                               stripes = stripe_nr_end - 1 - j;
+                               do_div(stripes, factor);
+                               multi->stripes[i].length = map->stripe_len *
+                                       (stripes - stripe_nr + 1);
+
+                               if (i < map->sub_stripes) {
+                                       multi->stripes[i].length -=
+                                               stripe_offset;
+                                       if (i == map->sub_stripes - 1)
+                                               stripe_offset = 0;
+                               }
+                               if (stripe_index >= last_stripe &&
+                                   stripe_index <= (last_stripe +
+                                                    map->sub_stripes - 1)) {
+                                       multi->stripes[i].length -=
+                                               stripe_end_offset;
+                               }
+                       } else
+                               multi->stripes[i].length = *length;
+
+                       stripe_index++;
+                       if (stripe_index == map->num_stripes) {
+                               /* This could only happen for RAID0/10 */
+                               stripe_index = 0;
+                               stripe_nr++;
+                       }
+               }
+       } else {
+               for (i = 0; i < num_stripes; i++) {
+                       if (unplug_page) {
+                               struct btrfs_device *device;
+                               struct backing_dev_info *bdi;
+
+                               device = map->stripes[stripe_index].dev;
+                               if (device->bdev) {
+                                       bdi = blk_get_backing_dev_info(device->
+                                                                      bdev);
+                                       if (bdi->unplug_io_fn)
+                                               bdi->unplug_io_fn(bdi,
+                                                                 unplug_page);
+                               }
+                       } else {
+                               multi->stripes[i].physical =
+                                       map->stripes[stripe_index].physical +
+                                       stripe_offset +
+                                       stripe_nr * map->stripe_len;
+                               multi->stripes[i].dev =
+                                       map->stripes[stripe_index].dev;
+                       }
+                       stripe_index++;
                }
-               stripe_index++;
        }
        if (multi_ret) {
                *multi_ret = multi;

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 7b38d06..cc2eada 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -126,6 +126,7 @@ struct btrfs_fs_devices {
 struct btrfs_bio_stripe {
        struct btrfs_device *dev;
        u64 physical;
+       u64 length; /* only used for discard mappings */
 };
 
 struct btrfs_multi_bio {