[PATCH 0/2] bcache fixes for Linux v5.18-rc3

[PATCH 0/2] bcache fixes for Linux v5.18-rc3

[Coly Li]

Hi Jens,

There are two regressions introduced in the generic block layer changes
from Linux v5.18-rc1. Both of them may panic the kernel, please take
them for -rc4.

Thanks in advance.

Coly Li
---
Coly Li (2):
  bcache: put bch_bio_map() back to correct location in
    journal_write_unlocked()
  bcache: fix wrong bdev parameter when calling bio_alloc_clone() in
    do_bio_hook()

 drivers/md/bcache/journal.c | 2 +-
 drivers/md/bcache/request.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

-- 
2.34.1

[PATCH 1/2] bcache: put bch_bio_map() back to correct location in journal_write_unlocked()

[Coly Li]

Commit a7c50c940477 ("block: pass a block_device and opf to bio_reset")
moves bch_bio_map() inside journal_write_unlocked() next to the location
where the modified bio_reset() was called.

This change is wrong because calling bch_bio_map() immediately after
bio_reset(), a BUG_ON(!bio->bi_iter.bi_size) inside bch_bio_map() will
be triggered and panic the kernel.

This patch puts bch_bio_map() back to its original correct location in
journal_write_unlocked() and avoid the BUG_ON().

Fixes: a7c50c940477 ("block: pass a block_device and opf to bio_reset")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
---
 drivers/md/bcache/journal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 7c2ca52ca3e4..df5347ea450b 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -771,12 +771,12 @@ static void journal_write_unlocked(struct closure *cl)
 
 		bio_reset(bio, ca->bdev, REQ_OP_WRITE | 
 			  REQ_SYNC | REQ_META | REQ_PREFLUSH | REQ_FUA);
-		bch_bio_map(bio, w->data);
 		bio->bi_iter.bi_sector	= PTR_OFFSET(k, i);
 		bio->bi_iter.bi_size = sectors << 9;
 
 		bio->bi_end_io	= journal_write_endio;
 		bio->bi_private = w;
+		bch_bio_map(bio, w->data);
 
 		trace_bcache_journal_write(bio, w->data->keys);
 		bio_list_add(&list, bio);
-- 
2.34.1

[PATCH 2/2] bcache: fix wrong bdev parameter when calling bio_alloc_clone() in do_bio_hook()

[Coly Li]

Commit abfc426d1b2f ("block: pass a block_device to bio_clone_fast")
calls the modified bio_alloc_clone() in bcache code as:
	bio_init_clone(bio->bi_bdev, bio, orig_bio, GFP_NOIO);

But the first parameter is wrong, where bio->bi_bdev should be
orig_bio->bi_bdev. The wrong bi_bdev panics the kernel when submitting
cache bio.

This patch fixes the wrong bdev parameter usage and avoid the panic.

Fixes: abfc426d1b2f ("block: pass a block_device to bio_clone_fast")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/bcache/request.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index fdd0194f84dd..320fcdfef48e 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -685,7 +685,7 @@ static void do_bio_hook(struct search *s,
 {
 	struct bio *bio = &s->bio.bio;
 
-	bio_init_clone(bio->bi_bdev, bio, orig_bio, GFP_NOIO);
+	bio_init_clone(orig_bio->bi_bdev, bio, orig_bio, GFP_NOIO);
 	/*
 	 * bi_end_io can be set separately somewhere else, e.g. the
 	 * variants in,
-- 
2.34.1

Re: [PATCH 0/2] bcache fixes for Linux v5.18-rc3

[Jens Axboe]

On Wed, 20 Apr 2022 00:04:23 +0800, Coly Li wrote:
> There are two regressions introduced in the generic block layer changes
> from Linux v5.18-rc1. Both of them may panic the kernel, please take
> them for -rc4.
> 
> Thanks in advance.
> 
> Coly Li
> 
> [...]

Applied, thanks!

[1/2] bcache: put bch_bio_map() back to correct location in journal_write_unlocked()
      commit: ff2695e52c9936febf65aa36a1769881da71bec5
[2/2] bcache: fix wrong bdev parameter when calling bio_alloc_clone() in do_bio_hook()
      commit: 9dca4168a37c9cfe182f077f0d2289292e9e3656

Best regards,
-- 
Jens Axboe

Re: [PATCH 0/2] bcache fixes for Linux v5.18-rc3

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>