btrfs: zoned: use bio_add_zone_append_page

A zoned device has its own hardware restrictions e.g. max_zone_append_size
when using REQ_OP_ZONE_APPEND. To follow these restrictions, use
bio_add_zone_append_page() instead of bio_add_page(). We need target device
to use bio_add_zone_append_page(), so this commit reads the chunk
information to cache the target device to btrfs_io_bio(bio)->device.

Caching only the target device is sufficient here as zoned filesystems
only supports the single profile at the moment. Once more profiles will be
supported btrfs_io_bio can hold an extent_map to be able to check for the
restrictions of all devices the btrfs_bio will be mapped to.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -3109,6 +3109,7 @@ static bool btrfs_bio_add_page(struct bio *bio, struct page *page,
 {
 	const sector_t sector = disk_bytenr >> SECTOR_SHIFT;
 	bool contig;
+	int ret;
 
 	if (prev_bio_flags != bio_flags)
 		return false;
@@ -3123,7 +3124,12 @@ static bool btrfs_bio_add_page(struct bio *bio, struct page *page,
 	if (btrfs_bio_fits_in_stripe(page, size, bio, bio_flags))
 		return false;
 
-	return bio_add_page(bio, page, size, pg_offset) == size;
+	if (bio_op(bio) == REQ_OP_ZONE_APPEND)
+		ret = bio_add_zone_append_page(bio, page, size, pg_offset);
+	else
+		ret = bio_add_page(bio, page, size, pg_offset);
+
+	return ret == size;
 }
 
 /*
@@ -3154,7 +3160,9 @@ static int submit_extent_page(unsigned int opf,
 	int ret = 0;
 	struct bio *bio;
 	size_t io_size = min_t(size_t, size, PAGE_SIZE);
-	struct extent_io_tree *tree = &BTRFS_I(page->mapping->host)->io_tree;
+	struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
+	struct extent_io_tree *tree = &inode->io_tree;
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 
 	ASSERT(bio_ret);
 
@@ -3185,11 +3193,26 @@ static int submit_extent_page(unsigned int opf,
 	if (wbc) {
 		struct block_device *bdev;
 
-		bdev = BTRFS_I(page->mapping->host)->root->fs_info->fs_devices->latest_bdev;
+		bdev = fs_info->fs_devices->latest_bdev;
 		bio_set_dev(bio, bdev);
 		wbc_init_bio(wbc, bio);
 		wbc_account_cgroup_owner(wbc, page, io_size);
 	}
+	if (btrfs_is_zoned(fs_info) && bio_op(bio) == REQ_OP_ZONE_APPEND) {
+		struct extent_map *em;
+		struct map_lookup *map;
+
+		em = btrfs_get_chunk_map(fs_info, disk_bytenr, io_size);
+		if (IS_ERR(em))
+			return PTR_ERR(em);
+
+		map = em->map_lookup;
+		/* We only support single profile for now */
+		ASSERT(map->num_stripes == 1);
+		btrfs_io_bio(bio)->device = map->stripes[0].dev;
+
+		free_extent_map(em);
+	}
 
 	*bio_ret = bio;