Zone Append bios only need a valid block device in struct bio, but
not the device in the btrfs_bio. Use the information from
btrfs_zoned_get_device to set up bi_bdev and fix zoned writes on
multi-device file system with non-homogeneous capabilities and remove
the pointless btrfs_bio.device assignment.
Add big fat comments explaining what is going on here.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/btrfs/extent_io.c | 43 ++++++++++++++++++++++++++++---------------
1 file changed, 28 insertions(+), 15 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 7ca4e9b80f023..e789676373ab0 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3330,24 +3330,37 @@ static int alloc_new_bio(struct btrfs_inode *inode,
ret = calc_bio_boundaries(bio_ctrl, inode, file_offset);
if (ret < 0)
goto error;
- if (wbc) {
- struct block_device *bdev;
- bdev = fs_info->fs_devices->latest_dev->bdev;
- bio_set_dev(bio, bdev);
- wbc_init_bio(wbc, bio);
- }
- if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
- struct btrfs_device *device;
+ if (wbc) {
+ /*
+ * For Zone append we need the correct block_device that we are
+ * going to write to set in the bio to be able to respect the
+ * hardware limitation. Look it up here:
+ */
+ if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+ struct btrfs_device *dev;
+
+ dev = btrfs_zoned_get_device(fs_info, disk_bytenr,
+ fs_info->sectorsize);
+ if (IS_ERR(dev)) {
+ ret = PTR_ERR(dev);
+ goto error;
+ }
- device = btrfs_zoned_get_device(fs_info, disk_bytenr,
- fs_info->sectorsize);
- if (IS_ERR(device)) {
- ret = PTR_ERR(device);
- goto error;
+ bio_set_dev(bio, dev->bdev);
+ } else {
+ /*
+ * Otherwise pick the last added device to support
+ * cgroup writeback. For multi-device file systems this
+ * means blk-cgroup policies have to always be set on the
+ * last added/replaced device. This is a bit odd but has
+ * been like that for a long time.
+ */
+ bio_set_dev(bio, fs_info->fs_devices->latest_dev->bdev);
}
-
- btrfs_bio(bio)->device = device;
+ wbc_init_bio(wbc, bio);
+ } else {
+ ASSERT(bio_op(bio) != REQ_OP_ZONE_APPEND);
}
return 0;
error:
--
2.30.2
