block: add a bi_error field to struct bio
Currently we have two different ways to signal an I/O error on a BIO:
(1) by clearing the BIO_UPTODATE flag
(2) by returning a Linux errno value to the bi_end_io callback
The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario. Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.
So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 1b4e175..04d0dad 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -919,14 +919,14 @@
wake_worker(cache);
}
-static void writethrough_endio(struct bio *bio, int err)
+static void writethrough_endio(struct bio *bio)
{
struct per_bio_data *pb = get_per_bio_data(bio, PB_DATA_SIZE_WT);
dm_unhook_bio(&pb->hook_info, bio);
- if (err) {
- bio_endio(bio, err);
+ if (bio->bi_error) {
+ bio_endio(bio);
return;
}
@@ -1231,7 +1231,7 @@
* The block was promoted via an overwrite, so it's dirty.
*/
set_dirty(cache, mg->new_oblock, mg->cblock);
- bio_endio(mg->new_ocell->holder, 0);
+ bio_endio(mg->new_ocell->holder);
cell_defer(cache, mg->new_ocell, false);
}
free_io_migration(mg);
@@ -1284,7 +1284,7 @@
}
}
-static void overwrite_endio(struct bio *bio, int err)
+static void overwrite_endio(struct bio *bio)
{
struct dm_cache_migration *mg = bio->bi_private;
struct cache *cache = mg->cache;
@@ -1294,7 +1294,7 @@
dm_unhook_bio(&pb->hook_info, bio);
- if (err)
+ if (bio->bi_error)
mg->err = true;
mg->requeue_holder = false;
@@ -1358,7 +1358,7 @@
b = to_dblock(from_dblock(b) + 1);
}
- bio_endio(bio, 0);
+ bio_endio(bio);
cell_defer(mg->cache, mg->new_ocell, false);
free_migration(mg);
}
@@ -1631,7 +1631,7 @@
calc_discard_block_range(cache, bio, &b, &e);
if (b == e) {
- bio_endio(bio, 0);
+ bio_endio(bio);
return;
}
@@ -2213,8 +2213,10 @@
bio_list_merge(&bios, &cache->deferred_bios);
bio_list_init(&cache->deferred_bios);
- while ((bio = bio_list_pop(&bios)))
- bio_endio(bio, DM_ENDIO_REQUEUE);
+ while ((bio = bio_list_pop(&bios))) {
+ bio->bi_error = DM_ENDIO_REQUEUE;
+ bio_endio(bio);
+ }
}
static int more_work(struct cache *cache)
@@ -3119,7 +3121,7 @@
* This is a duplicate writethrough io that is no
* longer needed because the block has been demoted.
*/
- bio_endio(bio, 0);
+ bio_endio(bio);
// FIXME: remap everything as a miss
cell_defer(cache, cell, false);
r = DM_MAPIO_SUBMITTED;