xen/grant-table: log the lack of grants

log a message when we enter this situation:
1) we already allocated the max number of available grants from hypervisor
and
2) we still need more (but the request fails because of 1)).

Sometimes the lack of grants causes IO hangs in xen_blkfront devices.
Adding this log would help debuging.

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Wengang Wang 2017-07-18 09:40:35 +02:00 коммит произвёл Juergen Gross
Родитель 0e4d394fe5
Коммит 29d11cfd86
1 изменённых файлов: 8 добавлений и 1 удалений

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@ -42,6 +42,7 @@
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/workqueue.h>
#include <linux/ratelimit.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
@ -1072,8 +1073,14 @@ static int gnttab_expand(unsigned int req_entries)
cur = nr_grant_frames;
extra = ((req_entries + (grefs_per_grant_frame-1)) /
grefs_per_grant_frame);
if (cur + extra > gnttab_max_grant_frames())
if (cur + extra > gnttab_max_grant_frames()) {
pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
" cur=%u extra=%u limit=%u"
" gnttab_free_count=%u req_entries=%u\n",
cur, extra, gnttab_max_grant_frames(),
gnttab_free_count, req_entries);
return -ENOSPC;
}
rc = gnttab_map(cur, cur + extra - 1);
if (rc == 0)