Revert "blk-lib: check for kill signal"

This reverts commit 8a08c5f.

It turns out while this is a perfectly valid and long overdue thing to do
for user initiated discards / zeroing from the ioctl handler, it actually
breaks file system use of the discard helper by interrupting in places
the file system doesn't expect, and by leaving the bio chain in a state
that the file system callers of (at least) __blkdev_issue_discard do
not expect.

Revert the change for now, we'll redo it for the next merge window
after refactoring the code to better split the file system vs ioctl
callers and cleaning up a few other loose ends.

Reported-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240314021623.1908895-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

block/blk-lib.c

@@ -35,26 +35,6 @@ static sector_t bio_discard_limit(struct block_device *bdev, sector_t sector)
 	return round_down(UINT_MAX, discard_granularity) >> SECTOR_SHIFT;
 }
 
-static void await_bio_endio(struct bio *bio)
-{
-	complete(bio->bi_private);
-	bio_put(bio);
-}
-
-/*
- * await_bio_chain - ends @bio and waits for every chained bio to complete
- */
-static void await_bio_chain(struct bio *bio)
-{
-	DECLARE_COMPLETION_ONSTACK_MAP(done,
-			bio->bi_bdev->bd_disk->lockdep_map);
-
-	bio->bi_private = &done;
-	bio->bi_end_io = await_bio_endio;
-	bio_endio(bio);
-	blk_wait_io(&done);
-}
-
 int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop)
 {
@@ -97,10 +77,6 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		 * is disabled.
 		 */
 		cond_resched();
-		if (fatal_signal_pending(current)) {
-			await_bio_chain(bio);
-			return -EINTR;
-		}
 	}
 
 	*biop = bio;
@@ -167,10 +143,6 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
 		nr_sects -= len;
 		sector += len;
 		cond_resched();
-		if (fatal_signal_pending(current)) {
-			await_bio_chain(bio);
-			return -EINTR;
-		}
 	}
 
 	*biop = bio;
@@ -215,10 +187,6 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev,
 				break;
 		}
 		cond_resched();
-		if (fatal_signal_pending(current)) {
-			await_bio_chain(bio);
-			return -EINTR;
-		}
 	}
 
 	*biop = bio;
@@ -309,7 +277,7 @@ int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 		bio_put(bio);
 	}
 	blk_finish_plug(&plug);
-	if (ret && ret != -EINTR && try_write_zeroes) {
+	if (ret && try_write_zeroes) {
 		if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
 			try_write_zeroes = false;
 			goto retry;
@@ -361,12 +329,6 @@ int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector,
 		sector += len;
 		nr_sects -= len;
 		cond_resched();
-		if (fatal_signal_pending(current)) {
-			await_bio_chain(bio);
-			ret = -EINTR;
-			bio = NULL;
-			break;
-		}
 	}
 	if (bio) {
 		ret = submit_bio_wait(bio);