btrfs: Fix data checksum error cause by replace with io-load.
xfstests btrfs/070 sometimes failed.
In my test machine, its fail rate is about 30%.
In another vm(vmware), its fail rate is about 50%.
Reason:
btrfs/070 do replace and defrag with fsstress simultaneously,
after above operation, checksum error is found by scrub.
Actually, it have no relationship with defrag operation, only
replace with fsstress can trigger this bug.
New data writen to target device have possibility rewrited by
old data from source device by replace code in debug, to avoid
above problem, we can set target block group to readonly in
replace period, so new data requested by other operation will
not write to same place with replace code.
Before patch(4.1-rc3):
30% failed in 100 xfstests.
After patch:
0% failed in 300 xfstests.
It also happened in btrfs/071 as it's another scrub with IO load tests.
Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 281de3f..7555ddc 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3407,7 +3407,7 @@
u64 chunk_tree;
u64 chunk_objectid;
u64 chunk_offset;
- int ret;
+ int ret = 0;
int slot;
struct extent_buffer *l;
struct btrfs_key key;
@@ -3435,8 +3435,14 @@
if (path->slots[0] >=
btrfs_header_nritems(path->nodes[0])) {
ret = btrfs_next_leaf(root, path);
- if (ret)
+ if (ret < 0)
break;
+ if (ret > 0) {
+ ret = 0;
+ break;
+ }
+ } else {
+ ret = 0;
}
}
@@ -3478,6 +3484,22 @@
if (!cache)
goto skip;
+ /*
+ * we need call btrfs_inc_block_group_ro() with scrubs_paused,
+ * to avoid deadlock caused by:
+ * btrfs_inc_block_group_ro()
+ * -> btrfs_wait_for_commit()
+ * -> btrfs_commit_transaction()
+ * -> btrfs_scrub_pause()
+ */
+ scrub_pause_on(fs_info);
+ ret = btrfs_inc_block_group_ro(root, cache);
+ scrub_pause_off(fs_info);
+ if (ret) {
+ btrfs_put_block_group(cache);
+ break;
+ }
+
dev_replace->cursor_right = found_key.offset + length;
dev_replace->cursor_left = found_key.offset;
dev_replace->item_needs_writeback = 1;
@@ -3517,6 +3539,8 @@
scrub_pause_off(fs_info);
+ btrfs_dec_block_group_ro(root, cache);
+
btrfs_put_block_group(cache);
if (ret)
break;
@@ -3539,11 +3563,7 @@
btrfs_free_path(path);
- /*
- * ret can still be 1 from search_slot or next_leaf,
- * that's not an error
- */
- return ret < 0 ? ret : 0;
+ return ret;
}
static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index fbe7c10..b7fb0b2 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2785,7 +2785,9 @@
return -ENOSPC;
/* step one, relocate all the extents inside this chunk */
+ btrfs_scrub_pause(root);
ret = btrfs_relocate_block_group(extent_root, chunk_offset);
+ btrfs_scrub_continue(root);
if (ret)
return ret;