Hi Neil Just wondering what the status is here - do you need any more from me or is it on your stack? The patch helped but didn't cure. After a clean boot it mounted correctly first try. Then I unmounted, stopped and re-assembled the array. The next mount failed. The subsequent mount succeeded. How do other block devices initialise their partitions on 'discovery'? David David Greaves wrote: > Neil Brown wrote: >> On Tuesday April 24, david@xxxxxxxxxxxx wrote: >>> Neil, isn't it easy to just do this after an assemble? >> Yes, but it should not be needed, and I'd like to understand why it >> is. >> One of the last things do_md_run does is >> mddev->changed = 1; >> >> When you next open /dev/md_d0, md_open is called which calls >> check_disk_change(). >> This will call into md_fops->md_media_changed which will return the >> value of mddev->changed, which will be '1'. >> So check_disk_change will then call md_fops->revalidate_disk which >> will set mddev->changed to 0, and will then set bd_invalidated to 1 >> (as bd_disk->minors > 1 (being 64)). >> >> md_open will then return into do_open (in fs/block_dev.c) and because >> bd_invalidated is true, it will call rescan_partitions and the >> partitions will appear. >> >> Hmmm... there is room for a race there. If some other process opens >> /dev/md_d0 before mdadm gets to close it, it will call >> rescan_partitions before first calling bd_set_size to update the size >> of the bdev. So when we try to read the partition table, it will >> appear to be reading past the EOF, and will not actually read >> anything.. >> >> I guess udev must be opening the block device at exactly the wrong >> time. >> >> I can simulate this by holding /dev/md_d0 open while assembling the >> array. If I do that, the partitions don't get created. >> Yuck. >> >> Maybe I could call bd_set_size in md_open before calling >> check_disk_change.. >> >> Yep, this patch seems to fix it. Could you confirm? > almost... > > teak:~# mdadm --assemble /dev/md_d0 --auto=parts /dev/sd[bcdef]1 > mdadm: /dev/md_d0 has been started with 5 drives. > teak:~# mount /media > teak:~# umount /media > teak:~# mdadm --stop /dev/md_d0 > mdadm: stopped /dev/md_d0 > teak:~# mdadm --assemble /dev/md_d0 --auto=parts /dev/sd[bcdef]1 > mdadm: /dev/md_d0 has been started with 5 drives. > teak:~# mount /media > mount: No such file or directory > teak:~# mount /media > teak:~# > (second mount succeeds second time around) > > > > md: md_d0 stopped. > md: bind<sdc1> > md: bind<sdd1> > md: bind<sdb1> > md: bind<sdf1> > md: bind<sde1> > raid5: device sde1 operational as raid disk 0 > raid5: device sdf1 operational as raid disk 4 > raid5: device sdb1 operational as raid disk 3 > raid5: device sdd1 operational as raid disk 2 > raid5: device sdc1 operational as raid disk 1 > raid5: allocated 5236kB for md_d0 > raid5: raid level 5 set md_d0 active with 5 out of 5 devices, algorithm 2 > RAID5 conf printout: > --- rd:5 wd:5 > disk 0, o:1, dev:sde1 > disk 1, o:1, dev:sdc1 > disk 2, o:1, dev:sdd1 > disk 3, o:1, dev:sdb1 > disk 4, o:1, dev:sdf1 > md_d0: bitmap initialized from disk: read 1/1 pages, set 0 bits, status: 0 > created bitmap (10 pages) for device md_d0 > md_d0: p1 p2 > Filesystem "md_d0p1": Disabling barriers, not supported with external log device > XFS mounting filesystem md_d0p1 > Ending clean XFS mount for filesystem: md_d0p1 > md: md_d0 stopped. > md: unbind<sde1> > md: export_rdev(sde1) > md: unbind<sdf1> > md: export_rdev(sdf1) > md: unbind<sdb1> > md: export_rdev(sdb1) > md: unbind<sdd1> > md: export_rdev(sdd1) > md: unbind<sdc1> > md: export_rdev(sdc1) > md: md_d0 stopped. > md: bind<sdc1> > md: bind<sdd1> > md: bind<sdb1> > md: bind<sdf1> > md: bind<sde1> > raid5: device sde1 operational as raid disk 0 > raid5: device sdf1 operational as raid disk 4 > raid5: device sdb1 operational as raid disk 3 > raid5: device sdd1 operational as raid disk 2 > raid5: device sdc1 operational as raid disk 1 > raid5: allocated 5236kB for md_d0 > raid5: raid level 5 set md_d0 active with 5 out of 5 devices, algorithm 2 > RAID5 conf printout: > --- rd:5 wd:5 > disk 0, o:1, dev:sde1 > disk 1, o:1, dev:sdc1 > disk 2, o:1, dev:sdd1 > disk 3, o:1, dev:sdb1 > disk 4, o:1, dev:sdf1 > md_d0: bitmap initialized from disk: read 1/1 pages, set 0 bits, status: 0 > created bitmap (10 pages) for device md_d0 > md_d0: p1 p2 > XFS: Invalid device [/dev/md_d0p2], error=-2 > Filesystem "md_d0p1": Disabling barriers, not supported with external log device > XFS mounting filesystem md_d0p1 > Ending clean XFS mount for filesystem: md_d0p1 > > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
