[Cluster-devel] [PATCH] gfs2: Make sure FITRIM minlen is rounded up to fs block size

[Andrew Price <anprice@redhat.com>]

On 22/03/2022 19:05, Andrew Price wrote:
> Per fstrim(8) we must round up the minlen argument to the fs block size.
> The current calculation doesn't take into account devices that have a
> discard granularity and requested minlen less than 1 fs block, so the
> value can get shifted away to zero in the translation to fs blocks.
> 
> The zero minlen passed to gfs2_rgrp_send_discards() then allows
> sb_issue_discard() to be called with nr_sects == 0 which returns -EINVAL
> and results in gfs2_rgrp_send_discards() returning -EIO.

Adding test results. xfstests interprets fstrim failures as "FITRIM not 
supported" and doesn't run them, so I got these results:

5.17:

Ran: generic/260 generic/288 generic/537
Not run: generic/260 generic/288 generic/537
Passed all 3 tests

5.17 + patch:

Ran: generic/260 generic/288 generic/537
Passed all 3 tests

(Those 3 tests are in the ones in the 'quick' and 'trim' groups)

Andy

> Make sure minlen is never < 1 fs block by taking the max of the
> requested minlen and the fs block size before comparing to the device's
> discard granularity and shifting to fs blocks.
> 
> Fixes: 076f0faa764ab ("GFS2: Fix FITRIM argument handling")
> Signed-off-by: Andrew Price <anprice@redhat.com>
> ---
>   fs/gfs2/rgrp.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
> index 0fb3c01bc557..a34945cbf32a 100644
> --- a/fs/gfs2/rgrp.c
> +++ b/fs/gfs2/rgrp.c
> @@ -1415,7 +1415,8 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
>   
>   	start = r.start >> bs_shift;
>   	end = start + (r.len >> bs_shift);
> -	minlen = max_t(u64, r.minlen,
> +	minlen = max_t(u64, r.minlen, sdp->sd_sb.sb_bsize);
> +	minlen = max_t(u64, minlen,
>   		       q->limits.discard_granularity) >> bs_shift;
>   
>   	if (end <= start || minlen > sdp->sd_max_rg_data)