usvyatsky_ilya@xxxxxxx <usvyatsky_ilya@xxxxxxx> wrote: > Hi there, > > I am using DM MPIO for quite a while now and in general it works. > Lately I encountered a problem with one of my boxes that is equipped > with USB flash drive and is connected to a disk array. > Namely, the flash drive has an empty bcdDevice entry, which translates > into empty /sys/block/sdXX/device/rev file. > As a result, the 'multipath -ll' command trips over this device and > bails out without listing any array mpathXX devices. > The devices are created in /dev/disk/by-name/ directory, so it's just > the userland tool issue. > > I've built debug version of multipath and found the following: > > 1. The function sysfs_get_rev() (which is generated from macro > declare_sysfs_get_str()) assumes that the rev has to have at least 2 > characters. Since in the case of my device this assumption is false, the > function returns 1. > 2. The caller function is scsi_sysfs_pathinfo() and it returns 1 as > well. > 3. The caller function is sysfs_pathinfo(), which returns 1 as well. > 4. The caller function is pathinfo(), which also returns 1. > 5. The caller function is store_pathinfo(). Here the pathinfo is not > stored and NULL is returned to the caller. > 6. The caller is path_discover() that returns 1. > 7. The caller is path_discovery() that returns non-zero result. > 8. The caller is configure() that bails out on this result. > > I have tried to work around this issue by blacklisting the device, but > unfortunately the only blacklist check that is done prior to call to > store_pathinfo() in the path_discover() is based on the devnode. > This means that effectively I cannot use this workaround since with USB > device I cannot guarantee that it will always be mapped to the same > devnode. > > I'd like to propose a couple of options for a fix for this issue: > > 1. Re-implement sysfs_get_rev() in such a way that rev filed minimal > length is no longer required. > Please see attached a patch that is supposed to take care of this. > 2. Re-implement pathinfo() to check whether vendor and/or product are > blacklisted. > This way non-compliant devices may be blacklisted based on vendor > and/or product name. > > I am not sure, which option is preferable, but I clearly need at least > one of them in the product. > > Your comments are greatly appreciated. > > Please note that my patch is against v. 0.4.7 of the multipath tool. > I realize that upstream may differ significantly, so if option (1) makes > sense I'll revalidate with the latest version and submit the patch if > necessary. The upstream version already removes the minimum size. You should try the multipath-tools git tree version to see if it addresses your issue. http://git.kernel.org/?p=linux/storage/multipath-tools/.git;a=summary -andmike -- Michael Anderson andmike@xxxxxxxxxxxxxxxxxx -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
