File 0118-Btrfs-progs-try-other-mirrors-on-read-failure.patch of Package btrfsprogs

From ff0e1b17030a9b1e027c8b77f67ab44136e172ac Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Mon, 7 Nov 2011 16:41:01 -0500
Subject: [PATCH 19/35] Btrfs-progs: try other mirrors on read failure

If we hit a bad disk and the read doesn't work, try other mirrors in case we
have other disks with good copies.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 restore.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/restore.c b/restore.c
index f062a2b..4dabae2 100644
--- a/restore.c
+++ b/restore.c
@@ -244,9 +244,16 @@ again:
 
 	done = pread(dev_fd, inbuf+count, length, dev_bytenr);
 	if (done < length) {
-		ret = -1;
-		fprintf(stderr, "Short read %d\n", errno);
-		goto out;
+		num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
+					      bytenr, length);
+		mirror_num++;
+		if (mirror_num >= num_copies) {
+			ret = -1;
+			fprintf(stderr, "Exhausted mirrors trying to read\n");
+			goto out;
+		}
+		fprintf(stderr, "Trying another mirror\n");
+		goto again;
 	}
 
 	count += length;
-- 
1.7.6.233.gd79bc