Hello and Good day My name is Daniel, I was experimenting with pNFS block layout, and found 2 bugs in blkmap utility. The source is here: https://git.linux-nfs.org/?p=steved/nfs-utils.git; I am not related to linux development community, so I am sending the email directly, hopefully it reaches the right people Bug1: Some block devices attach not directly under /dev/ but under sub dir like /dev/nvmesh/ Example: /dev/nvmesh/disk00 under /proc/partitions: this disk appears as nvmesh/disk00, but under /sys/block it appears as nvmesh!disk00. See Kernel function kobject_set_name_vargs(). blkmapd does not call it and fails to detect block devices under subdir of /dev/ (because string matching of / and ! fails). Result: pNFS cannot detect and do IO to disks which with 'lsblk' appear under subdir. Bug2: Due to support for old kernels blockmapd incorrectly detects the minor version of a block device. It uses only 8 smallest bits for the minor version. This actually caused data corruption. I have two block devices (major:minor) of 252:257 and 252:1, The pNFS signature is found by blkmapd on disk 252:257 but pnfs IO actually goes to disk 252:1 This is disastrous as some block device drivers deliberately reserve lower bits for partitions of disks, Which causes this issue to be critical. one vendor actually used 8 lowest bits to support 256 partitions, which means that his virtual disks are attached as (major:minor): 252:0 252:256 252:512 ... And pNFS IO always goes to only to the first disk Thanks I am not familiar with the procedure of opening a bug report to the kernel community, and I am very sorry if my direct Email is rude etiquette. I had the best intentions. Daniel Herman-Shmulyan
