Hi,
At first, I am not sure whether this is an issue.
mmap a file in a DAX mountpoint, open another file
in a non-DAX mountpoint with O_DIRECT, write the
mapped area to the other file.
This write Success on pmem ramdisk(memmap=2G!20G like)
This write Fail(Bad address) on nvdimm pmem devices.
This write Fail(Bad address) on brd based ramdisk.
If we skip the O_DIRECT flag, all tests pass.
If we write from DAX to DAX, all tests pass.
If we write from non-DAX to DAX, all tests pass.
Kernel version: Linus tree commit 44b4b46.
I have checked back to v4.6 testing on nvdimm devices,
all the same results. I do remember that this test
passed on nvdimms back to May 2016 and i have some
notes for that. However things changed a lot, test
scripts, kernel code, even the nvdimm and machine
firmweare.
Thanks,
Xiong
sh-4.2# cat tbad.sh
#!/bin/bash
[ -z "$1" ] && exit 1
DEV="$1"
MNT=/tbdmnt
cc t_mmap_dio.c
mkdir -p $MNT
wipefs -af $DEV
mkfs.xfs -fq $DEV && \
mount -o dax $DEV $MNT && \
xfs_io -f -c "w -W 0 268435456" $MNT/ts > /dev/null && \
xfs_io -f -c "w -W 0 268435456" ./td > /dev/null
if ./a.out $MNT/ts ./td 16777216 "$DEV" ; then
echo PASS
else
echo FAIL
fi
umount $MNT
sh-4.2# cat t_mmap_dio.c
/*
* This programme was originally written by
* Jeff Moyer <[email protected]>
*/
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <libaio.h>
#include <errno.h>
#include <sys/time.h>
void usage(char *prog)
{
fprintf(stderr,
"usage: %s <src file> <dest file> <size> <msg>\n",
prog);
exit(1);
}
void err_exit(char *op, unsigned long len, char *s)
{
fprintf(stderr, "%s(%s) len %lu %s\n",
op, strerror(errno), len, s);
exit(1);
}
int main(int argc, char **argv)
{
int fd, fd2, ret;
char *map;
unsigned long len;
if (argc < 4)
usage(basename(argv[0]));
len = strtoul(argv[3], NULL, 10);
if (errno == ERANGE)
err_exit("strtoul", 0, argv[4]);
/* Open source file and mmap*/
fd = open(argv[1], O_RDWR, 0644);
if (fd < 0)
err_exit("open s", len, argv[4]);
map = (char *)mmap(NULL, len,
PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (map == MAP_FAILED)
err_exit("mmap", len, argv[4]);
/* Open dest file with O_DIRECT */
fd2 = open(argv[2], O_RDWR|O_DIRECT, 0644);
if (fd2 < 0)
err_exit("open d", len, argv[4]);
/* First, test storing to dest file from source mapping */
ret = write(fd2, map, len);
if (ret != len)
err_exit("write", len, argv[4]);
ret = (int)lseek(fd2, 0, SEEK_SET);
if (ret == -1)
err_exit("lseek", len, argv[4]);
/* Next, test reading from dest file into source mapping */
ret = read(fd2, map, len);
if (ret != len)
err_exit("read", len, argv[4]);
ret = msync(map, len, MS_SYNC);
if (ret < 0)
err_exit("msync", len, argv[4]);
ret = munmap(map, len);
if (ret < 0)
err_exit("munmap", len, argv[4]);
ret = close(fd);
if (ret < 0)
err_exit("clsoe fd", len, argv[4]);
ret = close(fd2);
if (ret < 0)
err_exit("close fd2", len, argv[4]);
exit(0);
}
sh-4.2# ndctl list -N
[
{
"dev":"namespace3.0",
"mode":"raw",
"size":8589934592,
"blockdev":"pmem3"
},
{
"dev":"namespace2.0",
"mode":"raw",
"size":8589934592,
"blockdev":"pmem2"
},
{
"dev":"namespace1.0",
"mode":"memory",
"size":2147483648,
"blockdev":"pmem1"
},
{
"dev":"namespace0.0",
"mode":"memory",
"size":2147483648,
"blockdev":"pmem0"
}
]
sh-4.2# modinfo brd
filename:
/lib/modules/4.10.0-rc4-master-44b4b46+/kernel/drivers/block/brd.ko
alias: rd
alias: block-major-1-*
license: GPL
srcversion: 25AABF2EF57F6A37AFFEBA6
depends:
intree: Y
vermagic: 4.10.0-rc4-master-44b4b46+ SMP mod_unload modversions
parm: rd_nr:Maximum number of brd devices (int)
parm: rd_size:Size of each RAM disk in kbytes. (ulong)
parm: max_part:Num Minors to reserve between devices (int)
sh-4.2# uname -r
4.10.0-rc4-master-44b4b46+
sh-4.2# bash tbad.sh /dev/pmem0
/dev/pmem0: 4 bytes were erased at offset 0x00000000 (xfs): 58 46 53 42
PASS
sh-4.2# bash tbad.sh /dev/pmem2
/dev/pmem2: 4 bytes were erased at offset 0x00000000 (xfs): 58 46 53 42
write(Bad address) len 16777216 /dev/pmem2
FAIL
sh-4.2# bash tbad.sh /dev/ram0
/dev/ram0: 4 bytes were erased at offset 0x00000000 (xfs): 58 46 53 42
write(Bad address) len 16777216 /dev/ram0
FAIL
sh-4.2# df .
Filesystem 1K-blocks Used Available Use%
Mounted on
/dev/mapper/rhxxxxxxxxxxxxxxxxx-01-root 52399104 43658792 8740312 84% /
sh-4.2#
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