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* [PATCH] iomap: Break build if io_inline_bio is not last in iomap_ioend
@ 2021-06-29  6:41 Nikolay Borisov
  2021-06-29  6:52 ` Christoph Hellwig
  0 siblings, 1 reply; 2+ messages in thread
From: Nikolay Borisov @ 2021-06-29  6:41 UTC (permalink / raw)
  To: hch; +Cc: djwong, linux-fsdevel, Nikolay Borisov

Comments are good but unfortunately they can't effectively enforce
certain invariants, to that effect let's break the build in case
io_inline_bio is, for whatever reason, not the last member of
iomap_ioend.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/iomap/buffered-io.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 9023717c5188..f0421e139697 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1225,6 +1225,10 @@ iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc,
 	bio->bi_write_hint = inode->i_write_hint;
 	wbc_init_bio(wbc, bio);
 
+
+	BUILD_BUG_ON(offsetof(struct iomap_ioend, io_inline_bio) + sizeof(struct bio)
+		     != sizeof(struct iomap_ioend));
+
 	ioend = container_of(bio, struct iomap_ioend, io_inline_bio);
 	INIT_LIST_HEAD(&ioend->io_list);
 	ioend->io_type = wpc->iomap.type;
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] iomap: Break build if io_inline_bio is not last in iomap_ioend
  2021-06-29  6:41 [PATCH] iomap: Break build if io_inline_bio is not last in iomap_ioend Nikolay Borisov
@ 2021-06-29  6:52 ` Christoph Hellwig
  0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2021-06-29  6:52 UTC (permalink / raw)
  To: Nikolay Borisov; +Cc: hch, djwong, linux-fsdevel

On Tue, Jun 29, 2021 at 09:41:49AM +0300, Nikolay Borisov wrote:
> +	BUILD_BUG_ON(offsetof(struct iomap_ioend, io_inline_bio) + sizeof(struct bio)
> +		     != sizeof(struct iomap_ioend));

Please fix the overly long line and the incorrect operator placement.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2021-06-29  6:41 [PATCH] iomap: Break build if io_inline_bio is not last in iomap_ioend Nikolay Borisov
2021-06-29  6:52 ` Christoph Hellwig

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