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spf=pass smtp.mailfrom=neilb@suse.de DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 7F59E88E60 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 368B1AC8A; Fri, 7 Apr 2017 01:11:34 +0000 (UTC) From: NeilBrown To: Jens Axboe Date: Fri, 07 Apr 2017 11:10:44 +1000 Message-ID: <149152744444.17489.7959643077115840287.stgit@noble> In-Reply-To: <149152735878.17489.16036848644242802943.stgit@noble> References: <149152735878.17489.16036848644242802943.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Greylist: Sender passed SPF test, Sender IP whitelisted by DNSRBL, ACL 203 matched, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 07 Apr 2017 01:11:35 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 07 Apr 2017 01:11:35 +0000 (UTC) for IP:'195.135.220.15' DOMAIN:'mx2.suse.de' HELO:'mx2.suse.de' FROM:'neilb@suse.de' RCPT:'' X-RedHat-Spam-Score: -1.901 (BAYES_50, DCC_REPUT_00_12, HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, SPF_PASS) 195.135.220.15 mx2.suse.de 195.135.220.15 mx2.suse.de X-Scanned-By: MIMEDefang 2.78 on 10.5.110.25 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-loop: dm-devel@redhat.com Cc: Christoph Hellwig , Mike Snitzer , Ming Lei , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, dm-devel@redhat.com, linux-block@vger.kernel.org, Shaohua Li , Alasdair Kergon Subject: [dm-devel] [PATCH 1/2] block: simple improvements for bio->flags X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 07 Apr 2017 01:11:58 +0000 (UTC) X-Virus-Scanned: ClamAV using ClamSMTP The comment for the 'flags' field of 'bio' mentions "command" which is no longer stored there, and doesn't mention the bvec pool number, which is. BIO_RESET_BITS is set in such a way that it would need to be updated if new bits were added, which is easy to miss. BVEC_POOL_BITS is larger than needed. The BVEC_POOL_IDX() ranges from 0 to 6, so 3 bits are sufficient. This patch make improvements in each of these areas. Signed-off-by: NeilBrown --- include/linux/blk_types.h | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index d703acb55d0f..ff07d891f38f 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -29,7 +29,7 @@ struct bio { * top bits REQ_OP. Use * accessors. */ - unsigned short bi_flags; /* status, command, etc */ + unsigned short bi_flags; /* status, etc and bvec pool number */ unsigned short bi_ioprio; struct bvec_iter bi_iter; @@ -102,12 +102,7 @@ struct bio { #define BIO_REFFED 8 /* bio has elevated ->bi_cnt */ #define BIO_THROTTLED 9 /* This bio has already been subjected to * throttling rules. Don't do it again. */ - -/* - * Flags starting here get preserved by bio_reset() - this includes - * BVEC_POOL_IDX() - */ -#define BIO_RESET_BITS 10 +/* See BVEC_POOL_OFFSET below before adding new flags */ /* * We support 6 different bvec pools, the last one is magic in that it @@ -117,13 +112,22 @@ struct bio { #define BVEC_POOL_MAX (BVEC_POOL_NR - 1) /* - * Top 4 bits of bio flags indicate the pool the bvecs came from. We add + * Top 3 bits of bio flags indicate the pool the bvecs came from. We add * 1 to the actual index so that 0 indicates that there are no bvecs to be * freed. */ -#define BVEC_POOL_BITS (4) +#define BVEC_POOL_BITS (3) #define BVEC_POOL_OFFSET (16 - BVEC_POOL_BITS) #define BVEC_POOL_IDX(bio) ((bio)->bi_flags >> BVEC_POOL_OFFSET) +#if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1) +# error "BVEC_POOL_BITS is too small" +#endif + +/* + * Flags starting here get preserved by bio_reset() - this includes + * only BVEC_POOL_IDX() + */ +#define BIO_RESET_BITS BVEC_POOL_OFFSET /* * Operations and flags common to the bio and request structures.