btrfs: reada: ignore creating reada_extent for a non-existent device
For a non-existent device, old code bypasses adding it in dev's reada
queue.
And to solve problem of unfinished waitting in raid5/6,
commit 5fbc7c59fd22 ("Btrfs: fix unfinished readahead thread for
raid5/6 degraded mounting")
adding an exception for the first stripe, in short, the first
stripe will always be processed whether the device exists or not.
Actually we have a better way for the above request: just bypass
creation of the reada_extent for non-existent device, it will make
code simple and effective.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 5bcd567..dd5f361f 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -371,6 +371,11 @@
struct reada_zone *zone;
dev = bbio->stripes[nzones].dev;
+
+ /* cannot read ahead on missing device. */
+ if (!dev->bdev)
+ continue;
+
zone = reada_find_zone(fs_info, dev, logical, bbio);
if (!zone)
continue;
@@ -423,15 +428,9 @@
*/
continue;
}
- if (!dev->bdev) {
- /*
- * cannot read ahead on missing device, but for RAID5/6,
- * REQ_GET_READ_MIRRORS return 1. So don't skip missing
- * device for such case.
- */
- if (nzones > 1)
- continue;
- }
+ if (!dev->bdev)
+ continue;
+
if (dev_replace_is_ongoing &&
dev == fs_info->dev_replace.tgtdev) {
/*