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/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 5602450..aa95566 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -61,7 +61,6 @@
static void ext4_finish_bio(struct bio *bio)
{
int i;
- int error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
struct bio_vec *bvec;
bio_for_each_segment_all(bvec, bio, i) {
@@ -88,7 +87,7 @@
}
#endif
- if (error) {
+ if (bio->bi_error) {
SetPageError(page);
set_bit(AS_EIO, &page->mapping->flags);
}
@@ -107,7 +106,7 @@
continue;
}
clear_buffer_async_write(bh);
- if (error)
+ if (bio->bi_error)
buffer_io_error(bh);
} while ((bh = bh->b_this_page) != head);
bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
@@ -310,27 +309,25 @@
}
/* BIO completion function for page writeback */
-static void ext4_end_bio(struct bio *bio, int error)
+static void ext4_end_bio(struct bio *bio)
{
ext4_io_end_t *io_end = bio->bi_private;
sector_t bi_sector = bio->bi_iter.bi_sector;
BUG_ON(!io_end);
bio->bi_end_io = NULL;
- if (test_bit(BIO_UPTODATE, &bio->bi_flags))
- error = 0;
- if (error) {
+ if (bio->bi_error) {
struct inode *inode = io_end->inode;
ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
"(offset %llu size %ld starting block %llu)",
- error, inode->i_ino,
+ bio->bi_error, inode->i_ino,
(unsigned long long) io_end->offset,
(long) io_end->size,
(unsigned long long)
bi_sector >> (inode->i_blkbits - 9));
- mapping_set_error(inode->i_mapping, error);
+ mapping_set_error(inode->i_mapping, bio->bi_error);
}
if (io_end->flag & EXT4_IO_END_UNWRITTEN) {