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Groups > linux.kernel > #1377111
| From | Stanislav Brabec <sbrabec@suse.cz> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: loop subsystem corrupted after mounting multiple btrfs sub-volumes |
| Date | 2016-04-12 20:40 +0200 |
| Message-ID | <rnbod-3xO-1@gated-at.bofh.it> (permalink) |
| References | (3 earlier) <r6tAR-640-7@gated-at.bofh.it> <r6uQi-6PP-15@gated-at.bofh.it> <r6w5I-7UQ-31@gated-at.bofh.it> <r6wS6-8v1-35@gated-at.bofh.it> <r6xl8-fl-7@gated-at.bofh.it> |
| Organization | SUSE Linux, s. r. o. |
On Feb 26, 2016 at 21:30 Al Viro wrote: > Sigh... sys_mount() (mount_bdev(), actually) has no way to tell if two > loop devices refer to the same underlying object. As far as it's > concerned, you are asking to mount a completely unrelated block device. > Which just happens to see the data (living in separate pagecache, even) > modified behind its back (with some delay) after it gets written to another > device. Filesystem drivers generally don't like when something is screwing > the underlying data, to put it mildly... > I wrote a loop device reuse patch for mount -oloop. [PATCH 0/3] btrfs-safe implementation of -oloop http://marc.info/?l=util-linux-ng&m=146048532307963&w=2 [PATCH 1/3] libmount: Re-organize is_mounted_same_loopfile() http://marc.info/?l=util-linux-ng&m=146048535907971&w=2 [PATCH 2/3] libmount: reuse existing loop device http://marc.info/?l=util-linux-ng&m=146048537807980&w=2 [PATCH 3/3] mount: Handle EROFS before calling mount() syscall http://marc.info/?l=util-linux-ng&m=146048542007990&w=2 However it works for me, there are still some controversial issues described in [PATCH 0/3]. These patches will hide corruption of kernel loop control structures mentioned earlier in this thread and in most cases prevent data corruption. -- Best Regards / S pozdravem, Stanislav Brabec software developer --------------------------------------------------------------------- SUSE LINUX, s. r. o. e-mail: sbrabec@suse.com Lihovarská 1060/12 tel: +49 911 7405384547 190 00 Praha 9 fax: +420 284 084 001 Czech Republic http://www.suse.cz/ PGP: 830B 40D5 9E05 35D8 5E27 6FA3 717C 209F A04F CD76
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Re: loop subsystem corrupted after mounting multiple btrfs sub-volumes Stanislav Brabec <sbrabec@suse.cz> - 2016-04-12 20:40 +0200
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