Btrfs: add a log of past tree roots

This takes some of the free space in the btrfs super block
to record information about most of the roots in the last four
commits.

It also adds a -o recovery to use the root history log when
we're not able to read the tree of tree roots, the extent
tree root, the device tree root or the csum root.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f7e9de724ef2..57080dffdfc6 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -164,7 +164,7 @@ enum {
 	Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
 	Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
 	Opt_enospc_debug, Opt_subvolrootid, Opt_defrag,
-	Opt_inode_cache, Opt_no_space_cache, Opt_err,
+	Opt_inode_cache, Opt_no_space_cache, Opt_recovery, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -198,6 +198,7 @@ static match_table_t tokens = {
 	{Opt_defrag, "autodefrag"},
 	{Opt_inode_cache, "inode_cache"},
 	{Opt_no_space_cache, "no_space_cache"},
+	{Opt_recovery, "recovery"},
 	{Opt_err, NULL},
 };
 
@@ -392,6 +393,10 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
 			printk(KERN_INFO "btrfs: enabling auto defrag");
 			btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
 			break;
+		case Opt_recovery:
+			printk(KERN_INFO "btrfs: enabling auto recovery");
+			btrfs_set_opt(info->mount_opt, RECOVERY);
+			break;
 		case Opt_err:
 			printk(KERN_INFO "btrfs: unrecognized mount option "
 			       "'%s'\n", p);