Re: [PATCH] xfs: test that zone_gc_low_space writes start gc for rw fses

On 26/03/2026 07:11, Christoph Hellwig wrote:
> On Wed, Mar 25, 2026 at 01:50:13PM +0100, Hans Holmberg wrote:
>> Test that writes to the systfs attribute zone_gc_low_space triggers
> 
> s/systfs/sysfs/
> 
>> +get_scratch_mountstat() {
>> +	awk -v mount="$SCRATCH_MNT" -v stat="$1" \
>> +		'$0~"mounted on "mount" with fstype xfs"{f=1} f&&index($0,stat){print $NF;exit}' \
>> +		/proc/self/mountstats
>> +}
>> +
>> +get_user_available_rt_blocks() {
>> +	get_scratch_mountstat "user available RT blocks:"
>> +}
>> +
>> +gc_required() {
>> +	get_scratch_mountstat "RT GC required:"
>> +}
> 
> Should these go to common/xfs ?

That would be useful I think.
And make them not specific to scratch?

_xfs_get_mountstats <MOUNTPOINT>
_xfs_get_rt_gc_required <MOUNTPOINT>
_xfs_get_user_available_rt_blocks <MOUNTPOINT>

> 
>> +
>> +# figure out if the rt section is internal or not
>> +if [ -z "$SCRATCH_RTDEV" ]; then
>> +	zdev=$SCRATCH_DEV
>> +else
>> +	zdev=$SCRATCH_RTDEV
>> +fi
> 
> Same for this asa new helper?

Yes, something like:

_xfs_get_scratch_rtdev

> 
>> +[ "$rt_available_post" -gt "$rt_available_pre" ] && _fail "gc should not run while read only"
> 
> Split up either using \ or a real if statement to avoid the overly long
> line.
> 
>> +[ "$rt_available_pre" -ge "$rt_available_post" ] && _fail "gc did not free up space"
> 
> Same here.
> 
> Otherwise this looks good.
> 
>