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authorStefan Behrens <sbehrens@giantdisaster.de>2012-11-06 11:43:11 +0100
committerJosef Bacik <jbacik@fusionio.com>2012-12-12 17:15:41 -0500
commitff023aac31198e88507d626825379b28ea481d4d (patch)
tree7798bcbc762fdd3c91b013b6bb8264e3087a215d /fs/btrfs/dev-replace.h
parent618919236ba54361e93106f4951d233a7ade63cd (diff)
Btrfs: add code to scrub to copy read data to another disk
The device replace procedure makes use of the scrub code. The scrub code is the most efficient code to read the allocated data of a disk, i.e. it reads sequentially in order to avoid disk head movements, it skips unallocated blocks, it uses read ahead mechanisms, and it contains all the code to detect and repair defects. This commit adds code to scrub to allow the scrub code to copy read data to another disk. One goal is to be able to perform as fast as possible. Therefore the write requests are collected until huge bios are built, and the write process is decoupled from the read process with some kind of flow control, of course, in order to limit the allocated memory. The best performance on spinning disks could by reached when the head movements are avoided as much as possible. Therefore a single worker is used to interface the read process with the write process. The regular scrub operation works as fast as before, it is not negatively influenced and actually it is more or less unchanged. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Diffstat (limited to 'fs/btrfs/dev-replace.h')
-rw-r--r--fs/btrfs/dev-replace.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/fs/btrfs/dev-replace.h b/fs/btrfs/dev-replace.h
new file mode 100644
index 000000000000..1fb5c89037ee
--- /dev/null
+++ b/fs/btrfs/dev-replace.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) STRATO AG 2012. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#if !defined(__BTRFS_DEV_REPLACE__)
+#define __BTRFS_DEV_REPLACE__
+
+static inline void btrfs_dev_replace_stats_inc(atomic64_t *stat_value)
+{
+ atomic64_inc(stat_value);
+}
+#endif