On Wed, May 11 2016, Shaohua Li wrote: > On Wed, May 11, 2016 at 08:39:53AM +1000, NeilBrown wrote: >> On Wed, May 11 2016, Jes Sorensen wrote: >> >> > Mike Lovell <mike.lovell@xxxxxxxxxxxxx> writes: >> >> we have a number of systems that have a large number of software >> >> arrays running. its in the couple hundred range. we have been using a >> >> custom built kernel based on 3.4 but are wanting to update to a >> >> mainline kernel and have been experimenting with 4.4. the systems are >> >> running recent centos 6 releases but we have been downgrading the >> >> mdadm version from 3.3.2 in 6.7 to a custom build 3.2.6. we installed >> >> the downgraded version due to a problem with array numbering. i >> >> emailed the list a while ago explaining the issue and submitting a >> >> patch to fix [1]. i never heard anything back and since we had a >> >> simple fix i didn't follow up on it. >> > >> > [snip] >> > >> >> what do you all think? >> >> >> >> thanks >> >> mike >> >> >> >> [1] http://marc.info/?l=linux-raid&m=142387809409798&w=2 >> > >> > Staying consistent in using dev_t rather than casting back and forth to >> > int seems a reasonable fix to apply to mdadm. It obviously won't change >> > the issues with the newer kernels, but I don't see any reason why we >> > shouldn't apply that fix to mdadm. >> > >> > Neil any thoughts on this? >> >> I agree that changing "int" to "dev_t" is a good idea. >> >> We should really fix the more general problem too. >> >> On any kernel with /sys/module/md_mod/parameters/new_array >> find_free_devnm avoid trying anything above 511. (1<<9)-1. >> >> If that fails to find a free number, then it should probably try a name >> like "md_NN" and act as though ci->name is set. >> >> Also, when a "name" given for the md array that is longer than 28 bytes >> we need to fall back to choose an array name ourselves even if ci->name >> is set. Start with md_512 and work upwards. >> Rather than probing we should read /sys/block looking for "md_*" and >> maybe choose 1 more than the largest number found. > > I'm wondering why udev open the device with major/minor without checking if the > device exists. A simple 'stat' check is neat. A big part of the role of udev is to create the device nodes in /dev. NeilBrown
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