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([2601:647:4000:d7:1981:d78f:7563:fc3d]) by smtp.gmail.com with ESMTPSA id c80sm3146801pfb.82.2020.05.08.20.08.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 08 May 2020 20:08:24 -0700 (PDT) Subject: Re: [PATCH V10 05/11] blk-mq: support rq filter callback when iterating rqs To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, John Garry , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner References: <20200505020930.1146281-1-ming.lei@redhat.com> <20200505020930.1146281-6-ming.lei@redhat.com> <8d7a14f8-b36c-4f5c-a4af-d5904d3e9ea1@acm.org> <51888b96-1e3b-9810-fb64-47a965b83711@acm.org> <20200509020522.GA1392681@T590> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: Date: Fri, 8 May 2020 20:08:23 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200509020522.GA1392681@T590> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2020-05-08 19:05, Ming Lei wrote: > Fine, then we can save one callback, how about the following way? > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index 586c9d6e904a..5e9c743d887b 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -257,6 +257,7 @@ struct bt_tags_iter_data { > busy_tag_iter_fn *fn; > void *data; > bool reserved; > + bool iterate_all; > }; > > static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) > @@ -274,8 +275,10 @@ static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) > * test and set the bit before assining ->rqs[]. > */ > rq = tags->rqs[bitnr]; > - if (rq && blk_mq_request_started(rq)) > - return iter_data->fn(rq, iter_data->data, reserved); > + if (rq) { > + if (iter_data->iterate_all || blk_mq_request_started(rq)) > + return iter_data->fn(rq, iter_data->data, reserved); > + } How about combining the two if-statements above in the following single if-statement: if (rq && (iter_data->iterate_all || blk_mq_request_started(rq))) ... > @@ -321,8 +326,30 @@ static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, > busy_tag_iter_fn *fn, void *priv) > { > if (tags->nr_reserved_tags) > - bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true); > - bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false); > + bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true, > + false); > + bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false, false); > +} How about inserting comments like /*reserved=*/ and /*iterate_all=*/ in the bt_tags_for_each() call in front of "false" to make these calls easier to read? > +/** > + * blk_mq_all_tag_iter - iterate over all requests in a tag map > + * @tags: Tag map to iterate over. > + * @fn: Pointer to the function that will be called for each > + * request. @fn will be called as follows: @fn(rq, @priv, > + * reserved) where rq is a pointer to a request. 'reserved' > + * indicates whether or not @rq is a reserved request. Return > + * true to continue iterating tags, false to stop. > + * @priv: Will be passed as second argument to @fn. > + * > + * It is the caller's responsility to check rq's state in @fn. ^^^^^^^^^^^^ responsibility? > + */ > +void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, > + void *priv) > +{ > + if (tags->nr_reserved_tags) > + bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true, > + true); > + bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false, true); > } Same comment here: how about inserting /*reserved=*/ and /*iterate_all=*/ comments in the bt_tags_for_each() call? Otherwise this proposal looks good to me. Thanks, Bart.