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b=JmuE1pQSllbP81NR+PncxxpNsC9Y91+gnqNSG0oyMapw+ayr9VZjmkpgXLWwZx+oF HXwpZWjhMCwIFSOWgC8ouCxlknA9nfMDUCcVD7PMaleI4OmQROXa1sUf5/9HwwiScT YrwCmG+Hvecaqu6UW82NdmbCase9lMxGpHYUHGQu0ALrjlIPJJP/uIzmpzC9JNFwgl Joeiu10r5QaXaXTTeA+b9OqkJxd8fUYzTCLVOTyCZiVrjIBekb6Dv8yYXW2snAQ0Yk pIPalN81Ne6VDFgJ0X4I9MnJqCZmRxC7rURnq4P6bMcKHTYdf3IxvAKZvsP8CI8ylM Aibnmm8+6rs+Q== Received: from [172.24.10.107] (172.24.10.107) by prgmbx01.amust.local (172.24.128.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.20; Mon, 2 Jan 2023 10:44:21 +0100 Message-ID: Date: Mon, 2 Jan 2023 10:44:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v2 17/21] block, blksnap: snapshot image block device Content-Language: en-US To: Hillf Danton CC: "axboe@kernel.dk" , "corbet@lwn.net" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" References: <20221209142331.26395-1-sergei.shtepa@veeam.com> <20230101071813.3329-1-hdanton@sina.com> From: Sergei Shtepa In-Reply-To: <20230101071813.3329-1-hdanton@sina.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [172.24.10.107] X-ClientProxiedBy: colmbx02.amust.local (172.18.0.172) To prgmbx01.amust.local (172.24.128.102) X-EsetResult: clean, is OK X-EsetId: 37303A2924031555657167 X-Veeam-MMEX: True X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 985C2C0002 X-Rspam-User: X-Stat-Signature: gyn1mem7jw3yetdkywk4xmo5fy68pfcf X-HE-Tag: 1672652667-129097 X-HE-Meta: U2FsdGVkX1/TzWrH/gtwTLnH2vUKWZY6enAyd9T+mFjOhn5AZCTEWBRKRcGf9/iky4nf41arQ1kLdGK0kzsvo67W9xTqlL8WFH0BPhB4YUYmX2pyX0c4Rv9+INiFuB8FMYRjWBKi/NVMP9kDZXKJxDzAhwhz4OKYxsy6T2ovTuyvCBaupMTY49jtNUe0vOMRsFPETTvT/KAYK54kh6B+2Dxm5gOvg11KY44eFNOepE35ngf+ewkR05zlHtPlZ+k3nynzNZ/w8STNE35ZkUvOnfnsKAkTFKZA8ZCMFrNCuR6f15oavlmPmcQOEKRKTRVllpS+PX4edwJWegOpxfAbJdB53a+91YE04Hhq5H5mv2TMwxsZK14/x+b8Fu32zQqd37YipiJUZM2B49+aeByGOiHsbRsYKsdTV27IbHHS//jLCQjGOG8n+HEq1U8z8XL6uZ3abhInKSGa5tC+sMxIOz3ai9uEwhr1AgMBADfmbZpIRSpt97Tut4LGQi8Ni52MLvqRunB7QWmvP1Klsc4wAOqiQmhJeZ+gukBp6N47ev18hUg2oyung/SEZ8OmJFOy9aIkbFVBvE0Su09MuFK/CVYsERzkT8vJmWKjhQpLl/xm07E1fU57QYRJvmDiy5D05ZGph+U514FjzVQXmCRRrAgXq4rATVsfWqU+UU9VAyoyAUkUbJLXYpH39BzocEUbGMkdrNMbVfnfnGG/8Y4vvfthGOSp7HYEkaAjol9KQxD42Mh2Kl4IPeJWJSR0x/Xt5GZzg/fT5gyq/3Q8DUoia1lwGdbk5/VJEZuj5jMwcctV6TdU7sDnmoRgr3Fx3P/Fk0ytGpE67Ev5cJfbzHGkFC2SAHFQ1BZQ3s7N0tAraZ8KccWXHvpyoGZKvXEvLnxy4MLxC2FkWnCGX8Af1yReBrftQ07d8ZkM4xJEBBycrXOQo3EimfYkWg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/1/23 08:18, Hillf Danton wrote: > Subject: > Re: [PATCH v2 17/21] block, blksnap: snapshot image block device > From: > Hillf Danton > Date: > 1/1/23, 08:18 > > To: > Sergei Shtepa > CC: > "axboe@kernel.dk" , "corbet@lwn.net" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" > > > This is the first time you've received an email from this sender > hdanton@sina.com, please exercise caution when clicking on links or opening > attachments. > > > On 9 Dec 2022 15:23:27 +0100 Sergei Shtepa > > Provides the operation of block devices of snapshot images. Read and > > write operations are redirected to the regions of difference blocks for > > block device (struct diff_area). > > > > Signed-off-by: Sergei Shtepa > > --- > > Thanks for your patchset. Thanks for the review. > > > +static int snapimage_kthread_worker_fn(void *param) > > +{ > > + struct snapimage *snapimage = param; > > + struct bio *bio; > > + int ret = 0; > > + > > + while (!kthread_should_stop()) { > > + bio = get_bio_from_queue(snapimage); > > + if (!bio) { > > + schedule_timeout_interruptible(HZ / 100); > > + continue; > > + } > > Given the wake_up_process() below, s$HZ / 100$HZ * 1000$ to avoid > unnecessary wakeups [1]. > > And because of no signal handling added, use schedule_timeout_idle() instead. Yes, this function will be rewritten to eliminate unnecessary wake-ups. The code that Christoph proposed in the letter at Dec 15 should work well. > > [1] > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20210419085027.761150-2-elver%40google.com%2F&data=05%7C01%7Csergei.shtepa%40veeam.com%7C765d591d47ad4d93857208daebc92508%7Cba07baab431b49edadd7cbc3542f5140%7C1%7C1%7C638081546440884849%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=rbINOq7m31DFhjHLnQKFHQuoWB64ZhmnWbAVLuNwv7w%3D&reserved=0 > > > + > > + snapimage_process_bio(snapimage, bio); > > + } > > + > > + while ((bio = get_bio_from_queue(snapimage))) > > + snapimage_process_bio(snapimage, bio); > > + > > + return ret; > > +} > > + > > +static void snapimage_submit_bio(struct bio *bio) > > +{ > > + struct snapimage *snapimage = bio->bi_bdev->bd_disk->private_data; > > + gfp_t gfp = GFP_NOIO; > > + > > + if (bio->bi_opf & REQ_NOWAIT) > > + gfp |= GFP_NOWAIT; > > + if (snapimage->is_ready) { > > + spin_lock(&snapimage->queue_lock); > > + bio_list_add(&snapimage->queue, bio); > > + spin_unlock(&snapimage->queue_lock); > > + > > + wake_up_process(snapimage->worker); > > + } else > > + bio_io_error(bio); > > +} >