fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio (20d9600c) · Commits · 戴 / test

When using devices that support max_segments > BIO_MAX_PAGES (256), direct IO tries to allocate a bio with more pages than allowed, which leads to an oops in dio_bio_alloc(). Clamp the request to the supported maximum, and change dio_bio_alloc() to reflect that bio_alloc() will always return a bio when called with __GFP_WAIT and a valid number of vectors. [akpm@linux-foundation.org: remove redundant BUG_ON()] Signed-off-by:

David Dillow <dillowda@ornl.gov> Reviewed-by:

Jeff Moyer <jmoyer@redhat.com> Cc: <stable@kernel.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/direct-io.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -325,12 +325,16 @@ void dio_end_io(struct bio *bio, int error)
		}
		EXPORT_SYMBOL_GPL(dio_end_io);

		static int
		static void
		dio_bio_alloc(struct dio dio, struct block_device bdev,
		sector_t first_sector, int nr_vecs)
		{
		struct bio *bio;

		/*
		* bio_alloc() is guaranteed to return a bio when called with
		* __GFP_WAIT and we request a valid number of vectors.
		*/
		bio = bio_alloc(GFP_KERNEL, nr_vecs);

		bio->bi_bdev = bdev;
		@@ -342,7 +346,6 @@ dio_bio_alloc(struct dio dio, struct block_device bdev,

		dio->bio = bio;
		dio->logical_offset_in_bio = dio->cur_page_fs_offset;
		return 0;
		}

		/*
		@@ -583,8 +586,9 @@ static int dio_new_bio(struct dio *dio, sector_t start_sector)
		goto out;
		sector = start_sector << (dio->blkbits - 9);
		nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev));
		nr_pages = min(nr_pages, BIO_MAX_PAGES);
		BUG_ON(nr_pages <= 0);
		ret = dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages);
		dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages);
		dio->boundary = 0;
		out:
		return ret;

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