Commit 7aff8cf4 authored Jan 14, 2016 by Zhao Lei Committed by David Sterba Feb 18, 2016

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 5fbc7c59 ("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>

parent 4fe7a0e1

fs/btrfs/reada.c

+8 −9

Original line number	Diff line number	Diff line
		@@ -371,6 +371,11 @@ static struct reada_extent reada_find_extent(struct btrfs_root root,
		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 @@ static struct reada_extent reada_find_extent(struct btrfs_root root,
		*/
		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)
		if (!dev->bdev)
		continue;
		}

		if (dev_replace_is_ongoing &&
		dev == fs_info->dev_replace.tgtdev) {
		/*

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