On Thu, Jun 17, 2021 at 06:12:56PM +0800, Wang Yugui wrote: > the major/minor value of statx(kernel samples/vfs/test-statx.c) does not > match /usr/bin/stat. > > major/minor of statx result seems be truncated by something like > old_decode_dev()? I've checked the code first, both stat/statx seem to be doing the same thing. > [root@T640 vfs]# ./test-statx /ssd/ > statx(/ssd/) = 0 > results=1fff > Size: 200 Blocks: 0 IO Block: 4096 directory > Device: 00:31 Inode: 256 Links: 1 So Device is 00:31, printed as two fields in hex. > Access: (0755/drwxr-xr-x) Uid: 0 Gid: 0 > Access: 2021-06-16 19:16:56.644344956+0800 > Modify: 2021-05-06 16:14:33.676248229+0800 > Change: 2021-05-06 16:14:33.676248229+0800 > Birth: 2020-11-18 14:03:35.324915316+0800 > Attributes: 0000000000002000 (........ ........ ........ ........ ........ ..-..... ..?-.... .---.-..) > [root@T640 vfs]# stat /ssd/ > File: ‘/ssd/’ > Size: 200 Blocks: 0 IO Block: 4096 directory > Device: 31h/49d Inode: 256 Links: 1 And here it's also 31, the 'h' suffix means it's hexadecimal and "49d" si the same value in decimal. > Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) > Access: 2021-06-16 19:16:56.644344956 +0800 > Modify: 2021-05-06 16:14:33.676248229 +0800 > Change: 2021-05-06 16:14:33.676248229 +0800 > Birth: - > > vfat output sample: > [root@T640 vfs]# ./test-statx /boot/efi/ > statx(/boot/efi/) = 0 > results=17ff > Size: 4096 Blocks: 8 IO Block: 4096 directory > Device: 08:01 Inode: 1 Links: 3 08:01 > Access: (0700/drwx------) Uid: 0 Gid: 0 > Access: 1970-01-01 08:00:00.000000000+0800 > Modify: 1970-01-01 08:00:00.000000000+0800 > Change: 1970-01-01 08:00:00.000000000+0800 > Attributes: 0000000000002000 (........ ........ ........ ........ ........ ..-..... ..?-.... ........) > [root@T640 vfs]# stat /boot/efi/ > File: ‘/boot/efi/’ > Size: 4096 Blocks: 8 IO Block: 4096 directory > Device: 801h/2049d Inode: 1 Links: 3 801h == 0801h the same value, so it's just a matter of formatting the output and the values are indeed the same. If you change the format in test-statx.c to "%2xh/%2dd" and the value to "(stx->stx_dev_major << 8) + stx->stx_dev_minor", the output is exactly the same.
