The first arg of submit_bio is used for block dump

[Finix1979]

Because some kernel version of submit_bio use the first argument for block dump function. We could use the result of bio_data_dir instead of 0.

Signed-off-by: Finix Yan [email protected]

Motivation and Context

When enable block dump by "echo 1 > /proc/sys/vm/block_dump"
I got "[47410.364655] z_wr_int(17446): READ block 1348575456 on nvme0n1p1 (8 sectors)"
But from iostat it shows this block device only has WRITE operation.

I notice that submit_bio of kernel 3.10 use the first argument "rw" for statistic.

void submit_bio(int rw, struct bio *bio)
{
.......
if (unlikely(block_dump)) {
char b[BDEVNAME_SIZE];
printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
current->comm, task_pid_nr(current),
(rw & WRITE) ? "WRITE" : "READ",
(unsigned long long)bio->bi_sector,
bdevname(bio->bi_bdev, b),
count);
}
}

The output of block dump always reports READ instead of WRITE because rw is passed 0.

Description

How Has This Been Tested?

Types of changes

• [x ] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[behlendorf]

Indeed, thanks for catching and fixing this.