On 04/13/2017 05:06 PM, Jes Sorensen wrote:
On 04/13/2017 04:37 PM, Shaohua Li wrote:
On Thu, Apr 13, 2017 at 01:50:06PM -0400, Jes Sorensen wrote:
Hi Neil,
Looking at trying to phase out the ioctl usage, I am trying to
introduce a
helper for the 'is the array valid' situation.
Now looking at places like Incremental.c (around like 557 in my current
tree):
/* 7b/ if yes, */
/* - if number of OK devices match expected, or -R and there */
/* are enough, */
/* + add any bitmap file */
/* + start the array (auto-readonly). */
if (md_get_array_info(mdfd, &ainf) == 0) {
if (c->export) {
printf("MD_STARTED=already\n");
} else if (c->verbose >= 0)
pr_err("%s attached to %s which is already active.\n",
devname, chosen_name);
rv = 0;
goto out_unlock;
}
I am wondering if there are any side effects/assumptions about
GET_ARRAY_INFO that I am not considering? Basically I am making the
assumption that if /sys/block/md<X>/md exists, the array is valid.
what does 'valid' really mean? md<x>/md exists after a md device is
allocated,
the md device might not have any under layer disks bound yet.
The code in Incremental.c already deals with sysfs higher up in the
code, so
I guess the question is if the above test is even relevant anymore?
Alternative, do we need export a new state in sysfs 'running'?
I'd assume 'running' means the md device has a personality attached. See
array_state_show(), !running == 'clear' or 'inactive'.
Good point, I guess what I am trying to figure out is what is assumed
when ioctl(GET_ARRAY_INFO) returns 0 and how do we map it to sysfs?
Looking some more at this, it may be simpler than I thought. How about
this approach (only compile tested):
int md_array_active(int fd)
{
struct mdinfo *sra;
struct mdu_array_info_s array;
int ret;
sra = sysfs_read(fd, NULL, GET_VERSION | GET_DISKS);
if (sra) {
if (!sra->array.raid_disks &&
!(sra->array.major_version == -1 &&
sra->array.minor_version == -2))
ret = -ENODEV;
else
ret = 0;
free(sra);
} else {
ret = ioctl(fd, GET_ARRAY_INFO, &array);
}
return !ret;
}
Note 'major = -1 && minor = -2' is sysfs_read's way of saying 'external'.
This pretty much mimics what the kernel does in the ioctl handler for
GET_ARRAY_INFO:
case GET_ARRAY_INFO:
if (!mddev->raid_disks && !mddev->external)
err = -ENODEV;
else
err = get_array_info(mddev, argp);
goto out;
What do you think?
Cheers,
Jes
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