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/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 411c7b2..341202e 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1189,7 +1189,7 @@
* another kernel subsystem, and we just pass it through.
*/
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
- err = -EIO;
+ bio->bi_error = -EIO;
goto out;
}
@@ -1211,6 +1211,7 @@
"io error in %s sector %lld, len %d,\n",
(rw == READ) ? "READ" : "WRITE",
(unsigned long long) iter.bi_sector, len);
+ bio->bi_error = err;
break;
}
}
@@ -1218,7 +1219,7 @@
nd_iostat_end(bio, start);
out:
- bio_endio(bio, err);
+ bio_endio(bio);
}
static int btt_rw_page(struct block_device *bdev, sector_t sector,