RAID10 can accept as much as half of its disks to be missing, as long as
each sub stripe still has a good mirror.
Thanks to the per-chunk degradable check, we can handle it pretty easily
now.
So Add this special check for RAID10, to allow user to be creative
(or crazy) using btrfs RAID10.
Signed-off-by: Qu Wenruo <w...@suse.com>
---
fs/btrfs/volumes.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f209127a8bc6..65b10d13fc2d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -7088,6 +7088,42 @@ int btrfs_read_sys_array(struct btrfs_fs_info *fs_info)
return -EIO;
}
+static bool check_raid10_rw_degradable(struct btrfs_fs_info *fs_info,
+ struct extent_map *em)
+{
+ struct map_lookup *map = em->map_lookup;
+ int sub_stripes = map->sub_stripes;
+ int num_stripes = map->num_stripes;
+ int tolerance = 1;
+ int i, j;
+
+ ASSERT(sub_stripes == 2);
+ ASSERT(num_stripes % sub_stripes == 0);
+ /*
+ * Check substripes as a group, in each group we need to
+ * have at least one good mirror;
+ */
+ for (i = 0; i < num_stripes / sub_stripes; i ++) {
+ int missing = 0;
+ for (j = 0; j < sub_stripes; j++) {
+ struct btrfs_device *dev = map->stripes[i * 2 + j].dev;
+
+ if (!dev || !dev->bdev ||
+ test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)
||
+ dev->last_flush_error)
+ missing++;
+ }
+ if (missing > tolerance) {
+ btrfs_warn(fs_info,
+"chunk %llu stripes %d,%d missing %d devices, max tolerance is %d for writable
mount",
+ em->start, i, i + sub_stripes - 1, missing,
+ tolerance);
+ return false;
+ }
+ }
+ return true;
+}
+
/*
* Check if all chunks in the fs are OK for read-write degraded mount
*
@@ -7119,6 +7155,14 @@ bool btrfs_check_rw_degradable(struct btrfs_fs_info
*fs_info,
int i;
map = em->map_lookup;
+ if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+ ret = check_raid10_rw_degradable(fs_info, em);
+ if (!ret) {
+ free_extent_map(em);
+ goto out;
+ }
+ goto next;
+ }
max_tolerated =
btrfs_get_num_tolerated_disk_barrier_failures(
map->type);
@@ -7141,6 +7185,7 @@ bool btrfs_check_rw_degradable(struct btrfs_fs_info
*fs_info,
ret = false;
goto out;
}
+next:
next_start = extent_map_end(em);
free_extent_map(em);
--
2.22.0
