[PATCH v9 24/41] btrfs: extend btrfs_rmap_block for specifying a device

[Naohiro Aota <naohiro.aota@wdc.com>]

btrfs_rmap_block currently reverse-maps the physical addresses on all
devices to the corresponding logical addresses.

This commit extends the function to match to a specified device. The old
functionality of querying all devices is left intact by specifying NULL as
target device.

We pass block_device instead of btrfs_device to __btrfs_rmap_block. This
function is intended to reverse-map the result of bio, which only have
block_device.

This commit also exports the function for later use.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/block-group.c | 28 ++++++++++++++++++++++------
 fs/btrfs/block-group.h |  3 +++
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 82d556368c85..21e40046dce1 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1644,8 +1644,11 @@ static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
 }
 
 /**
- * btrfs_rmap_block - Map a physical disk address to a list of logical addresses
+ * __btrfs_rmap_block - Map a physical disk address to a list of logical
+ *                      addresses
  * @chunk_start:   logical address of block group
+ * @bdev:	   physical device to resolve. Can be NULL to indicate any
+ *                 device.
  * @physical:	   physical address to map to logical addresses
  * @logical:	   return array of logical addresses which map to @physical
  * @naddrs:	   length of @logical
@@ -1655,9 +1658,9 @@ static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
  * Used primarily to exclude those portions of a block group that contain super
  * block copies.
  */
-EXPORT_FOR_TESTS
-int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
-		     u64 physical, u64 **logical, int *naddrs, int *stripe_len)
+int __btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
+		       struct block_device *bdev, u64 physical, u64 **logical,
+		       int *naddrs, int *stripe_len)
 {
 	struct extent_map *em;
 	struct map_lookup *map;
@@ -1675,6 +1678,7 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
 	map = em->map_lookup;
 	data_stripe_length = em->orig_block_len;
 	io_stripe_size = map->stripe_len;
+	chunk_start = em->start;
 
 	/* For RAID5/6 adjust to a full IO stripe length */
 	if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
@@ -1689,14 +1693,18 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
 	for (i = 0; i < map->num_stripes; i++) {
 		bool already_inserted = false;
 		u64 stripe_nr;
+		u64 offset;
 		int j;
 
 		if (!in_range(physical, map->stripes[i].physical,
 			      data_stripe_length))
 			continue;
 
+		if (bdev && map->stripes[i].dev->bdev != bdev)
+			continue;
+
 		stripe_nr = physical - map->stripes[i].physical;
-		stripe_nr = div64_u64(stripe_nr, map->stripe_len);
+		stripe_nr = div64_u64_rem(stripe_nr, map->stripe_len, &offset);
 
 		if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
 			stripe_nr = stripe_nr * map->num_stripes + i;
@@ -1710,7 +1718,7 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
 		 * instead of map->stripe_len
 		 */
 
-		bytenr = chunk_start + stripe_nr * io_stripe_size;
+		bytenr = chunk_start + stripe_nr * io_stripe_size + offset;
 
 		/* Ensure we don't add duplicate addresses */
 		for (j = 0; j < nr; j++) {
@@ -1732,6 +1740,14 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
 	return ret;
 }
 
+EXPORT_FOR_TESTS
+int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
+		     u64 physical, u64 **logical, int *naddrs, int *stripe_len)
+{
+	return __btrfs_rmap_block(fs_info, chunk_start, NULL, physical, logical,
+				  naddrs, stripe_len);
+}
+
 static int exclude_super_stripes(struct btrfs_block_group *cache)
 {
 	struct btrfs_fs_info *fs_info = cache->fs_info;
diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index 5be47f4bfea7..401e9bcefaec 100644
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -275,6 +275,9 @@ void check_system_chunk(struct btrfs_trans_handle *trans, const u64 type);
 u64 btrfs_get_alloc_profile(struct btrfs_fs_info *fs_info, u64 orig_flags);
 void btrfs_put_block_group_cache(struct btrfs_fs_info *info);
 int btrfs_free_block_groups(struct btrfs_fs_info *info);
+int __btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
+		       struct block_device *bdev, u64 physical, u64 **logical,
+		       int *naddrs, int *stripe_len);
 
 static inline u64 btrfs_data_alloc_profile(struct btrfs_fs_info *fs_info)
 {
-- 
2.27.0