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authorChristoph Hellwig <hch@lst.de>2015-07-20 15:29:37 +0200
committerJens Axboe <axboe@fb.com>2015-07-29 08:55:15 -0600
commit4246a0b63bd8f56a1469b12eafeb875b1041a451 (patch)
tree3281bb158d658ef7f208ad380c0ecee600a5ab5e /drivers/md/dm-cache-target.c
parent0034af036554c39eefd14d835a8ec3496ac46712 (diff)
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>
Diffstat (limited to 'drivers/md/dm-cache-target.c')
-rw-r--r--drivers/md/dm-cache-target.c24
1 files changed, 13 insertions, 11 deletions
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 1b4e1756b169..04d0dadc48b1 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -919,14 +919,14 @@ static void defer_writethrough_bio(struct cache *cache, struct bio *bio)
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 @@ static void migration_success_post_commit(struct dm_cache_migration *mg)
* 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 issue_copy(struct dm_cache_migration *mg)
}
}
-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 @@ static void overwrite_endio(struct bio *bio, int err)
dm_unhook_bio(&pb->hook_info, bio);
- if (err)
+ if (bio->bi_error)
mg->err = true;
mg->requeue_holder = false;
@@ -1358,7 +1358,7 @@ static void issue_discard(struct dm_cache_migration *mg)
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 @@ static void process_discard_bio(struct cache *cache, struct prealloc *structs,
calc_discard_block_range(cache, bio, &b, &e);
if (b == e) {
- bio_endio(bio, 0);
+ bio_endio(bio);
return;
}
@@ -2213,8 +2213,10 @@ static void requeue_deferred_bios(struct cache *cache)
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 @@ static int cache_map(struct dm_target *ti, struct bio *bio)
* 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;