bio_alloc_bioset() allocates bvecs from bvec_slabs which can only
allocate maximum 256 bvec (eg, 1M for 4k pages). We can't bump
BLK_DEF_MAX_SECTORS to exceed this value otherwise bio_alloc_bioset will
fail.
In the future, we can extend the size either bvec_slabs array is
expanded or the upcoming multipage bvec is added if pages are
contiguous. This one is suitable for stable.
Fixes: d2be537c3ba (block: bump BLK_DEF_MAX_SECTORS to 2560)
Reported-by: Sebastian Roesner <sroesner-kernel...@roesner-online.de>
Cc: sta...@vger.kernel.org (4.2+)
Cc: Ming Lei <ming....@canonical.com>
Reviewed-by: Jeff Moyer <jmo...@redhat.com>
Signed-off-by: Shaohua Li <s...@fb.com>
---
include/linux/blkdev.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7e5d7e0..da64325 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1153,7 +1153,11 @@ extern int blk_verify_command(unsigned char *cmd,
fmode_t has_write_perm);
enum blk_default_limits {
BLK_MAX_SEGMENTS = 128,
BLK_SAFE_MAX_SECTORS = 255,
- BLK_DEF_MAX_SECTORS = 2560,
+ /*
+ * if you change this, please also change bvec_alloc and BIO_MAX_PAGES.
+ * Otherwise bio_alloc_bioset will break.
+ */
+ BLK_DEF_MAX_SECTORS = BIO_MAX_SECTORS,
BLK_MAX_SEGMENT_SIZE = 65536,
BLK_SEG_BOUNDARY_MASK = 0xFFFFFFFFUL,
};
--
2.8.0.rc2
