[LU-8855] 32 bit compat stat() syscalls expect device majors and minors to be less than 256

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.10.0
• Severity: 3
• Assignee: John Hammond
• Reporter: John Hammond

Description

A customer reported having problems accessing a file on Lustre with a 32-bit binary running on a 64-bit kernel:

31583 access("infile_how", F_OK)        = 0
31583 open("infile_how", O_RDWR)        = 3
31583 fstat(3, 0xfff4d52c)              = -1 EOVERFLOW (Value too large for defined data type)
31583 stat("infile_how", 0xfff4d51c)    = -1 EOVERFLOW (Value too large for defined data type)

That fstat() doesn't return EOVERFLOW on the local file system:

31823 access("infile_how", F_OK <unfinished ...>
31824 fstat(0,  <unfinished ...>
31823 <... access resumed> )            = 0
31824 <... fstat resumed> {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
31823 open("infile_how", O_RDWR <unfinished ...>
31824 fstat(1,  <unfinished ...>
31823 <... open resumed> )              = 3
31824 <... fstat resumed> {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
31823 fstat(3,  <unfinished ...>
31824 fstat(2,  <unfinished ...>
31823 <... fstat resumed> {st_mode=S_IFIFO, st_size=876682292077977496, ...}) = 0
31824 <... fstat resumed> {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
31823 stat("infile_how", {st_mode=S_IFIFO, st_size=876682292077977496, ...}) = 0

The values packed into stat->dev and stat->rdev by ll_getattr() are failing the old_valid_dev() checks in cp_compat_stat() from compat_sys_newfstat() and compat_sys_newstat().