This is not yet supported and causes crashes. One sad user reported
that it destroyed his filesystem.
One failure is in __btrfs_map_block+0xc1f calling kmalloc(0).
0x5f21f is in __btrfs_map_block (fs/btrfs/volumes.c:4923).
4918 num_stripes = map->num_stripes;
4919 max_errors = nr_parity_stripes(map);
4920
4921 raid_map = kmalloc(sizeof(u64) * num_stripes,
4922 GFP_NOFS);
4923 if (!raid_map) {
4924 ret = -ENOMEM;
4925 goto out;
4926 }
4927
There might be more issues. Until this is really tested, don't allow
users to start the procedure on RAID5/RAID6 filesystems.
Signed-off-by: Stefan Behrens <sbehr...@giantdisaster.de>
---
fs/btrfs/dev-replace.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 7ba7b39..65241f3 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -313,6 +313,11 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
struct btrfs_device *tgt_device = NULL;
struct btrfs_device *src_device = NULL;
+ if (btrfs_fs_incompat(fs_info, RAID56)) {
+ pr_warn("btrfs: dev_replace cannot yet handle RAID5/RAID6\n");
+ return -EINVAL;
+ }
+
switch (args->start.cont_reading_from_srcdev_mode) {
case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
--
1.8.2.2
--
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