md/r5cache: handle alloc_page failure
RMW of r5c write back cache uses an extra page to store old data for
prexor. handle_stripe_dirtying() allocates this page by calling
alloc_page(). However, alloc_page() may fail.
To handle alloc_page() failures, this patch adds an extra page to
disk_info. When alloc_page fails, handle_stripe() trys to use these
pages. When these pages are used by other stripe (R5C_EXTRA_PAGE_IN_USE),
the stripe is added to delayed_list.
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 5f817bd..5d3d238 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -2326,15 +2326,40 @@ int r5c_try_caching_write(struct r5conf *conf,
*/
void r5c_release_extra_page(struct stripe_head *sh)
{
+ struct r5conf *conf = sh->raid_conf;
int i;
+ bool using_disk_info_extra_page;
+
+ using_disk_info_extra_page =
+ sh->dev[0].orig_page == conf->disks[0].extra_page;
for (i = sh->disks; i--; )
if (sh->dev[i].page != sh->dev[i].orig_page) {
struct page *p = sh->dev[i].orig_page;
sh->dev[i].orig_page = sh->dev[i].page;
- put_page(p);
+ if (!using_disk_info_extra_page)
+ put_page(p);
}
+
+ if (using_disk_info_extra_page) {
+ clear_bit(R5C_EXTRA_PAGE_IN_USE, &conf->cache_state);
+ md_wakeup_thread(conf->mddev->thread);
+ }
+}
+
+void r5c_use_extra_page(struct stripe_head *sh)
+{
+ struct r5conf *conf = sh->raid_conf;
+ int i;
+ struct r5dev *dev;
+
+ for (i = sh->disks; i--; ) {
+ dev = &sh->dev[i];
+ if (dev->orig_page != dev->page)
+ put_page(dev->orig_page);
+ dev->orig_page = conf->disks[i].extra_page;
+ }
}
/*