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Tue, 23 Jun 2020 07:11:06 +0000 (UTC) Subject: Re: btrfs dev sta not updating To: waxhead@dirtcellar.net, Russell Coker , linux-btrfs@vger.kernel.org References: <4857863.FCrPRfMyHP@liv> <08121825-9c05-87c4-4015-f6f508193fa8@suse.com> <39073b9b-360c-81d1-3c3a-22631b6c2b27@dirtcellar.net> From: Nikolay Borisov Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= xsFNBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABzSJOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuZGU+wsF4BBMBAgAiBQJYijkSAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAAKCRBxvoJG5T8oV/B6D/9a8EcRPdHg8uLEPywuJR8URwXzkofT5bZE IfGF0Z+Lt2ADe+nLOXrwKsamhweUFAvwEUxxnndovRLPOpWerTOAl47lxad08080jXnGfYFS Dc+ew7C3SFI4tFFHln8Y22Q9075saZ2yQS1ywJy+TFPADIprAZXnPbbbNbGtJLoq0LTiESnD w/SUC6sfikYwGRS94Dc9qO4nWyEvBK3Ql8NkoY0Sjky3B0vL572Gq0ytILDDGYuZVo4alUs8 LeXS5ukoZIw1QYXVstDJQnYjFxYgoQ5uGVi4t7FsFM/6ykYDzbIPNOx49Rbh9W4uKsLVhTzG BDTzdvX4ARl9La2kCQIjjWRg+XGuBM5rxT/NaTS78PXjhqWNYlGc5OhO0l8e5DIS2tXwYMDY LuHYNkkpMFksBslldvNttSNei7xr5VwjVqW4vASk2Aak5AleXZS+xIq2FADPS/XSgIaepyTV tkfnyreep1pk09cjfXY4A7qpEFwazCRZg9LLvYVc2M2eFQHDMtXsH59nOMstXx2OtNMcx5p8 0a5FHXE/HoXz3p9bD0uIUq6p04VYOHsMasHqHPbsMAq9V2OCytJQPWwe46bBjYZCOwG0+x58 fBFreP/NiJNeTQPOa6FoxLOLXMuVtpbcXIqKQDoEte9aMpoj9L24f60G4q+pL/54ql2VRscK d87BTQRYigc+ARAAyJSq9EFk28++SLfg791xOh28tLI6Yr8wwEOvM3wKeTfTZd+caVb9gBBy wxYhIopKlK1zq2YP7ZjTP1aPJGoWvcQZ8fVFdK/1nW+Z8/NTjaOx1mfrrtTGtFxVBdSCgqBB jHTnlDYV1R5plJqK+ggEP1a0mr/rpQ9dFGvgf/5jkVpRnH6BY0aYFPprRL8ZCcdv2DeeicOO YMobD5g7g/poQzHLLeT0+y1qiLIFefNABLN06Lf0GBZC5l8hCM3Rpb4ObyQ4B9PmL/KTn2FV Xq/c0scGMdXD2QeWLePC+yLMhf1fZby1vVJ59pXGq+o7XXfYA7xX0JsTUNxVPx/MgK8aLjYW hX+TRA4bCr4uYt/S3ThDRywSX6Hr1lyp4FJBwgyb8iv42it8KvoeOsHqVbuCIGRCXqGGiaeX Wa0M/oxN1vJjMSIEVzBAPi16tztL/wQtFHJtZAdCnuzFAz8ue6GzvsyBj97pzkBVacwp3/Mw qbiu7sDz7yB0d7J2tFBJYNpVt/Lce6nQhrvon0VqiWeMHxgtQ4k92Eja9u80JDaKnHDdjdwq FUikZirB28UiLPQV6PvCckgIiukmz/5ctAfKpyYRGfez+JbAGl6iCvHYt/wAZ7Oqe/3Cirs5 KhaXBcMmJR1qo8QH8eYZ+qhFE3bSPH446+5oEw8A9v5oonKV7zMAEQEAAcLBXwQYAQIACQUC WIoHPgIbDAAKCRBxvoJG5T8oV1pyD/4zdXdOL0lhkSIjJWGqz7Idvo0wjVHSSQCbOwZDWNTN JBTP0BUxHpPu/Z8gRNNP9/k6i63T4eL1xjy4umTwJaej1X15H8Hsh+zakADyWHadbjcUXCkg OJK4NsfqhMuaIYIHbToi9K5pAKnV953xTrK6oYVyd/Rmkmb+wgsbYQJ0Ur1Ficwhp6qU1CaJ mJwFjaWaVgUERoxcejL4ruds66LM9Z1Qqgoer62ZneID6ovmzpCWbi2sfbz98+kW46aA/w8r 7sulgs1KXWhBSv5aWqKU8C4twKjlV2XsztUUsyrjHFj91j31pnHRklBgXHTD/pSRsN0UvM26 lPs0g3ryVlG5wiZ9+JbI3sKMfbdfdOeLxtL25ujs443rw1s/PVghphoeadVAKMPINeRCgoJH zZV/2Z/myWPRWWl/79amy/9MfxffZqO9rfugRBORY0ywPHLDdo9Kmzoxoxp9w3uTrTLZaT9M KIuxEcV8wcVjr+Wr9zRl06waOCkgrQbTPp631hToxo+4rA1jiQF2M80HAet65ytBVR2pFGZF zGYYLqiG+mpUZ+FPjxk9kpkRYz61mTLSY7tuFljExfJWMGfgSg1OxfLV631jV1TcdUnx+h3l Sqs2vMhAVt14zT8mpIuu2VNxcontxgVr1kzYA/tQg32fVRbGr449j1gw57BV9i0vww== Message-ID: <07cfc485-6f2b-ab79-e9dd-21dd2a9ed2b2@suse.com> Date: Tue, 23 Jun 2020 10:11:05 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <39073b9b-360c-81d1-3c3a-22631b6c2b27@dirtcellar.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 23.06.20 г. 9:17 ч., waxhead wrote: > > > Nikolay Borisov wrote: >> >> >> On 23.06.20 г. 5:09 ч., Russell Coker wrote: >>> [395198.926320] BTRFS warning (device sdc1): csum failed root 5 ino >>> 276 off >>> 19267584 csum 0x8941f998 expected csum 0xccd545e0 mirror 1 >>> [395199.147439] BTRFS warning (device sdc1): csum failed root 5 ino >>> 276 off >>> 20611072 csum 0x8941f998 expected csum 0xdaf657cb mirror 1 >>> [395199.183680] BTRFS warning (device sdc1): csum failed root 5 ino >>> 276 off >>> 24190976 csum 0x8941f998 expected csum 0xcddce0b1 mirror 1 >>> [395199.185172] BTRFS warning (device sdc1): csum failed root 5 ino >>> 276 off >>> 19267584 csum 0x8941f998 expected csum 0xccd545e0 mirror 1 >>> [395199.330841] BTRFS warning (device sdc1): csum failed root 5 ino >>> 277 off 0 >>> csum 0x8941f998 expected csum 0xa54d865c mirror 1 >>> >>> I have a USB stick that's corrupted, I get the above kernel messages >>> when I >>> try to copy files from it.  But according to btrfs dev sta it has had >>> 0 read >>> and 0 corruption errors. >>> >>> root@xev:/mnt/tmp# btrfs dev sta . >>> [/dev/sdc1].write_io_errs    0 >>> [/dev/sdc1].read_io_errs     0 >>> [/dev/sdc1].flush_io_errs    0 >>> [/dev/sdc1].corruption_errs  0 >>> [/dev/sdc1].generation_errs  0 >>> root@xev:/mnt/tmp# uname -a >>> Linux xev 5.6.0-2-amd64 #1 SMP Debian 5.6.14-1 (2020-05-23) x86_64 >>> GNU/Linux >>> >> >> The read/write io err counters are updated when even repair bio have >> failed. So in your case you had some checksum errors, but btrfs managed >> to repair them by reading from a different mirror. In this case those >> aren't really counted as io errs since in the end you did get the >> correct data. >> > I don't think this is what most people expect. > A simple way to solve this could be to put the non-fatal errors in > parentheses if this can be done easily. > > For example: > [/dev/sdc1].write_io_errs    0 (5) > > IMHO this would be more readable and more useful. Frankly just by looking at this example output, without having read any accompanying documentation it would be hard to deduce what's the difference between the numbers. Furthermore, those error numbers are persisted on disk, so if we want to add new persistent error numbers the disk format would have to be changed. On the other hand we *could* make even transient errors be counted as persistent ones e.g. in read_io_errs. But this leads to a different can of worms - if a user sees read_io_errs should they be worried because potentially some data is stale or not (give we won't be distinguishing between unrepairable vs transient ones). Weighing pros and cons of adding "transient" errors I'd say the effort would be better invested if instead we clearly document how errors are counted, admittedly that's a department we are severely lacking in!