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[72.132.29.68]) by smtp.gmail.com with ESMTPSA id b203sm19739492pfb.11.2021.01.26.09.22.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Jan 2021 09:22:57 -0800 (PST) Subject: Re: [PATCH] bdev: Do not return EBUSY if bdev discard races with write To: Jan Kara Cc: Maxim Levitsky , linux-fsdevel@vger.kernel.org, "Darrick J. Wong" References: <20210107154034.1490-1-jack@suse.cz> <20210126100215.GA10966@quack2.suse.cz> From: Jens Axboe Message-ID: <29be3d51-43b4-b4eb-66e0-669c517ed830@kernel.dk> Date: Tue, 26 Jan 2021 10:22:56 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210126100215.GA10966@quack2.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 1/26/21 3:02 AM, Jan Kara wrote: > On Thu 07-01-21 16:40:34, Jan Kara wrote: >> blkdev_fallocate() tries to detect whether a discard raced with an >> overlapping write by calling invalidate_inode_pages2_range(). However >> this check can give both false negatives (when writing using direct IO >> or when writeback already writes out the written pagecache range) and >> false positives (when write is not actually overlapping but ends in the >> same page when blocksize < pagesize). This actually causes issues for >> qemu which is getting confused by EBUSY errors. >> >> Fix the problem by removing this conflicting write detection since it is >> inherently racy and thus of little use anyway. >> >> Reported-by: Maxim Levitsky >> CC: "Darrick J. Wong" >> Link: https://lore.kernel.org/qemu-devel/20201111153913.41840-1-mlevitsk@redhat.com >> Signed-off-by: Jan Kara > > Jens, can you please pick up this patch? Thanks! Picked it up for 5.12, hope that works. It looks simple enough but not really meeting criteria for 5.11 at this point. -- Jens Axboe