Now, btrfs check has a kernel scrub equivalent.
A new option, --scrub is added for "btrfs check".
If --scrub is given, btrfs check will just act like kernel scrub, to
check every copy of extent and do a report on corrupted data and if it's
recoverable.
The advantage compare to kernel scrub is:
1) No race
Unlike kernel scrub, which is done in parallel, offline scrub is done
by a single thread.
Although it may be slower than kernel one, it's safer and no false
alert.
2) Correctness
Kernel has a known bug (fix submitted) which will recovery RAID5/6
data but screw up P/Q, due to the hardness coding in kernel.
While in btrfs-progs, no page, (almost) no memory size limit, we're
can focus on the scrub, and make things easier.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
Documentation/btrfs-check.asciidoc | 7 ++++++
cmds-check.c | 12 +++++++++-
ctree.h | 3 +++
scrub.c | 49 ++++++++++++++++++++++++++++++++++++++
4 files changed, 70 insertions(+), 1 deletion(-)
diff --git a/Documentation/btrfs-check.asciidoc
b/Documentation/btrfs-check.asciidoc
index 633cbbf6..d421afa4 100644
--- a/Documentation/btrfs-check.asciidoc
+++ b/Documentation/btrfs-check.asciidoc
@@ -91,6 +91,13 @@ the entire free space cache. This option with 'v2' provides
an alternative
method of clearing the free space cache that doesn't require mounting the
filesystem.
+--scrub::
+kernel scrub equivalent.
++
+Off-line scrub has better reconstruction check than kernel. Won't cause
+possible silent data corruption for RAID5
++
+NOTE: Repair is not supported yet.
DANGEROUS OPTIONS
-----------------
diff --git a/cmds-check.c b/cmds-check.c
index 1dba2985..3a16a1ff 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -12588,6 +12588,7 @@ int cmd_check(int argc, char **argv)
int clear_space_cache = 0;
int qgroup_report = 0;
int qgroups_repaired = 0;
+ int scrub = 0;
unsigned ctree_flags = OPEN_CTREE_EXCLUSIVE;
while(1) {
@@ -12595,7 +12596,8 @@ int cmd_check(int argc, char **argv)
enum { GETOPT_VAL_REPAIR = 257, GETOPT_VAL_INIT_CSUM,
GETOPT_VAL_INIT_EXTENT, GETOPT_VAL_CHECK_CSUM,
GETOPT_VAL_READONLY, GETOPT_VAL_CHUNK_TREE,
- GETOPT_VAL_MODE, GETOPT_VAL_CLEAR_SPACE_CACHE };
+ GETOPT_VAL_MODE, GETOPT_VAL_CLEAR_SPACE_CACHE,
+ GETOPT_VAL_SCRUB };
static const struct option long_options[] = {
{ "super", required_argument, NULL, 's' },
{ "repair", no_argument, NULL, GETOPT_VAL_REPAIR },
@@ -12617,6 +12619,7 @@ int cmd_check(int argc, char **argv)
GETOPT_VAL_MODE },
{ "clear-space-cache", required_argument, NULL,
GETOPT_VAL_CLEAR_SPACE_CACHE},
+ { "scrub", no_argument, NULL, GETOPT_VAL_SCRUB },
{ NULL, 0, NULL, 0}
};
@@ -12701,6 +12704,9 @@ int cmd_check(int argc, char **argv)
}
ctree_flags |= OPEN_CTREE_WRITES;
break;
+ case GETOPT_VAL_SCRUB:
+ scrub = 1;
+ break;
}
}
@@ -12755,6 +12761,10 @@ int cmd_check(int argc, char **argv)
global_info = info;
root = info->fs_root;
+ if (scrub) {
+ ret = btrfs_scrub(info, repair);
+ goto err_out;
+ }
if (clear_space_cache == 1) {
if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE)) {
error(
diff --git a/ctree.h b/ctree.h
index fe7c077e..8f669ee7 100644
--- a/ctree.h
+++ b/ctree.h
@@ -2803,4 +2803,7 @@ int btrfs_punch_hole(struct btrfs_trans_handle *trans,
/* csum.c */
int btrfs_read_one_data_csum(struct btrfs_fs_info *fs_info, u64 bytenr,
void *csum_ret);
+
+/* scrub.c */
+int btrfs_scrub(struct btrfs_fs_info *fs_info, int repair);
#endif
diff --git a/scrub.c b/scrub.c
index 8f122012..00662da0 100644
--- a/scrub.c
+++ b/scrub.c
@@ -953,3 +953,52 @@ out:
btrfs_free_path(path);
return ret;
}
+
+int btrfs_scrub(struct btrfs_fs_info *fs_info, int repair)
+{
+ struct btrfs_block_group_cache *bg_cache;
+ struct btrfs_scrub_progress scrub_ctx = {0};
+ int ret = 0;
+
+ /*
+ * TODO: To support repair, which should not be quite hard
+ */
+ if (repair) {
+ error("Read-write scrub is not supported yet");
+ return 1;
+ }
+
+ bg_cache = btrfs_lookup_first_block_group(fs_info, 0);
+ if (!bg_cache) {
+ error("no block group is found");
+ return -ENOENT;
+ }
+
+ while (1) {
+ ret = scrub_one_block_group(fs_info, &scrub_ctx, bg_cache);
+ if (ret < 0 && ret != -EIO)
+ break;
+
+ bg_cache = btrfs_lookup_first_block_group(fs_info,
+ bg_cache->key.objectid + bg_cache->key.offset);
+ if (!bg_cache)
+ break;
+ }
+
+ printf("Scrub result:\n");
+ printf("Tree bytes scrubbed: %llu\n", scrub_ctx.tree_bytes_scrubbed);
+ printf("Tree extents scrubbed: %llu\n",
scrub_ctx.tree_extents_scrubbed);
+ printf("Data bytes scrubbed: %llu\n", scrub_ctx.data_bytes_scrubbed);
+ printf("Data extents scrubbed: %llu\n",
scrub_ctx.data_extents_scrubbed);
+ printf("Data bytes without csum: %llu\n", scrub_ctx.csum_discards *
+ fs_info->tree_root->sectorsize);
+ printf("Read error: %llu\n", scrub_ctx.read_errors);
+ printf("Verify error: %llu\n", scrub_ctx.verify_errors);
+ printf("Csum error: %llu\n", scrub_ctx.csum_errors);
+ if (scrub_ctx.csum_errors || scrub_ctx.read_errors ||
+ scrub_ctx.uncorrectable_errors || scrub_ctx.verify_errors)
+ ret = 1;
+ else
+ ret = 0;
+ return ret;
+}
--
2.11.0
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