With the introduction of BIO_NO_PAGE_REF we've used up all available bits
in bio::bi_flags.
Convert the defines of the flags to an enum and add a BUILD_BUG_ON() call
to make sure no-one adds a new one and thus overrides the BVEC_POOL_IDX
causing crashes.
Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
This used to be part of my bio patchset but as it's a) not clear why we
end up calling bio_put() on the on-stack bio and b) the needed prep patch
for the fix introduces a regression, I've decided to sent this patch out
as it's valid on it's own.
I dropped Hannes' and Christoph's R-b though, as the context changed.
---
block/bio.c | 3 +++
include/linux/blk_types.h | 29 ++++++++++++++++-------------
2 files changed, 19 insertions(+), 13 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index 8d516d508ae3..c2592c5d70b9 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -2218,6 +2218,9 @@ static int __init init_bio(void)
bio_slab_nr = 0;
bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab),
GFP_KERNEL);
+
+ BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
+
if (!bio_slabs)
panic("bio: can't allocate bios\n");
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 791fee35df88..be418275763c 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -215,21 +215,24 @@ struct bio {
/*
* bio flags
*/
-#define BIO_NO_PAGE_REF 0 /* don't put release vec pages */
-#define BIO_SEG_VALID 1 /* bi_phys_segments valid */
-#define BIO_CLONED 2 /* doesn't own data */
-#define BIO_BOUNCED 3 /* bio is a bounce bio */
-#define BIO_USER_MAPPED 4 /* contains user pages */
-#define BIO_NULL_MAPPED 5 /* contains invalid user pages */
-#define BIO_QUIET 6 /* Make BIO Quiet */
-#define BIO_CHAIN 7 /* chained bio, ->bi_remaining in effect */
-#define BIO_REFFED 8 /* bio has elevated ->bi_cnt */
-#define BIO_THROTTLED 9 /* This bio has already been subjected to
+enum {
+ BIO_NO_PAGE_REF, /* don't put release vec pages */
+ BIO_SEG_VALID, /* bi_phys_segments valid */
+ BIO_CLONED, /* doesn't own data */
+ BIO_BOUNCED, /* bio is a bounce bio */
+ BIO_USER_MAPPED, /* contains user pages */
+ BIO_NULL_MAPPED, /* contains invalid user pages */
+ BIO_QUIET, /* Make BIO Quiet */
+ BIO_CHAIN, /* chained bio, ->bi_remaining in effect */
+ BIO_REFFED, /* bio has elevated ->bi_cnt */
+ BIO_THROTTLED, /* This bio has already been subjected to
* throttling rules. Don't do it again. */
-#define BIO_TRACE_COMPLETION 10 /* bio_endio() should trace the final completion
+ BIO_TRACE_COMPLETION, /* bio_endio() should trace the final completion
* of this bio. */
-#define BIO_QUEUE_ENTERED 11 /* can use blk_queue_enter_live() */
-#define BIO_TRACKED 12 /* set if bio goes through the rq_qos path */
+ BIO_QUEUE_ENTERED, /* can use blk_queue_enter_live() */
+ BIO_TRACKED, /* set if bio goes through the rq_qos path */
+ BIO_FLAG_LAST
+};
/* See BVEC_POOL_OFFSET below before adding new flags */
--
2.16.4
