From: Jens Axboe <axboe@fb.com>
To: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Hannes Reinecke <hare@suse.de>,
Bart Van Assche <bvanassche@acm.org>,
Christoph Hellwig <hch@lst.de>, Jan Kara <jack@suse.cz>,
"Linux Block Layer Mailinglist" <linux-block@vger.kernel.org>,
Linux FSDEVEL Mailinglist <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 1/2] block: bio: ensure newly added bio flags don't override BVEC_POOL_IDX
Date: Thu, 21 Mar 2019 14:15:14 +0000 [thread overview]
Message-ID: <78cf685f-2bb4-c494-4677-afa513b47339@fb.com> (raw)
In-Reply-To: <20190321123045.32396-2-jthumshirn@suse.de>
On 3/21/19 6:30 AM, Johannes Thumshirn wrote:
> With the introduction of BIO_ALLOCED we've used up all available bits in
> bio::bi_flags.
>
> Make sure no-one adds a new one and thus overrides the BVEC_POOL_IDX
Two minor things:
> diff --git a/block/bio.c b/block/bio.c
> index 4db1008309ed..8c689aed46a0 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -2126,12 +2126,20 @@ static void __init biovec_init_slabs(void)
> }
> }
>
> +static inline void bio_flag_buildtime_check(void)
> +{
> + BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
> +}
> +
> static int __init init_bio(void)
> {
> bio_slab_max = 2;
> bio_slab_nr = 0;
> bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab),
> GFP_KERNEL);
> +
> + bio_flag_buildtime_check();
> +
Just add the BUILD_BUG_ON() here, don't put it in a function.
> +enum {
> + BIO_SEG_VALID = 1, /* bi_phys_segments valid */
> + BIO_CLONED = 2, /* doesn't own data */
> + BIO_BOUNCED = 3, /* bio is a bounce bio */
> + BIO_USER_MAPPED = 4, /* contains user pages */
> + BIO_NULL_MAPPED = 5, /* contains invalid user pages */
> + BIO_QUIET = 6, /* Make BIO Quiet */
> + BIO_CHAIN = 7, /* chained bio, ->bi_remaining in effect */
> + BIO_REFFED = 8, /* bio has elevated ->bi_cnt */
> + BIO_THROTTLED = 9, /* This bio has already been subjected to
> + * throttling rules. Don't do it again. */
> + BIO_TRACE_COMPLETION = 10, /* bio_endio() should trace the final completion
> + * of this bio. */
> + BIO_QUEUE_ENTERED = 11, /* can use blk_queue_enter_live() */
> + BIO_TRACKED = 12, /* set if bio goes through the rq_qos path */
> + BIO_FLAG_LAST
> +};
Let's order this after the BIO_NO_PAGE_REF patch, so we can avoid
having to explicitly initialize the values.
You also haven't solved the issue of now having an extra bit, 2/2 uses
the last bit which the other patch already took...
--
Jens Axboe
next prev parent reply other threads:[~2019-03-21 14:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 12:30 [PATCH 0/2] add flag for tracking bio allocation Johannes Thumshirn
2019-03-21 12:30 ` [PATCH 1/2] block: bio: ensure newly added bio flags don't override BVEC_POOL_IDX Johannes Thumshirn
2019-03-21 13:18 ` Hannes Reinecke
2019-03-21 13:22 ` Johannes Thumshirn
2019-03-21 14:15 ` Jens Axboe [this message]
2019-03-21 14:21 ` Jens Axboe
2019-03-21 14:23 ` Johannes Thumshirn
2019-03-21 14:25 ` Jens Axboe
2019-03-21 15:54 ` Hannes Reinecke
2019-03-22 10:24 ` Johannes Thumshirn
2019-03-21 12:30 ` [PATCH 2/2] bio: introduce BIO_ALLOCED flag and check it in bio_free Johannes Thumshirn
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=78cf685f-2bb4-c494-4677-afa513b47339@fb.com \
--to=axboe@fb.com \
--cc=bvanassche@acm.org \
--cc=hare@suse.de \
--cc=hch@lst.de \
--cc=jack@suse.cz \
--cc=jthumshirn@suse.de \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).