Reproduce:
(In integration-4.3 branch)
TEST_DEV=(/dev/vdg /dev/vdh)
TEST_DIR=/mnt/tmp
umount "$TEST_DEV" >/dev/null
mkfs.btrfs -f -d raid1 "${TEST_DEV[@]}"
mount -o nospace_cache "$TEST_DEV" "$TEST_DIR"
btrfs balance start -dusage=0 $TEST_DIR
btrfs filesystem usage $TEST_DIR
dd if=/dev/zero of="$TEST_DIR"/file count=100
btrfs filesystem usage $TEST_DIR
Result:
We can see "no data chunk" in first "btrfs filesystem usage":
# btrfs filesystem usage $TEST_DIR
Overall:
...
Metadata,single: Size:8.00MiB, Used:0.00B
/dev/vdg 8.00MiB
Metadata,RAID1: Size:122.88MiB, Used:112.00KiB
/dev/vdg 122.88MiB
/dev/vdh 122.88MiB
System,single: Size:4.00MiB, Used:0.00B
/dev/vdg 4.00MiB
System,RAID1: Size:8.00MiB, Used:16.00KiB
/dev/vdg 8.00MiB
/dev/vdh 8.00MiB
Unallocated:
/dev/vdg 1.06GiB
/dev/vdh 1.07GiB
And "data chunks changed from raid1 to single" in second
"btrfs filesystem usage":
# btrfs filesystem usage $TEST_DIR
Overall:
...
Data,single: Size:256.00MiB, Used:0.00B
/dev/vdh 256.00MiB
Metadata,single: Size:8.00MiB, Used:0.00B
/dev/vdg 8.00MiB
Metadata,RAID1: Size:122.88MiB, Used:112.00KiB
/dev/vdg 122.88MiB
/dev/vdh 122.88MiB
System,single: Size:4.00MiB, Used:0.00B
/dev/vdg 4.00MiB
System,RAID1: Size:8.00MiB, Used:16.00KiB
/dev/vdg 8.00MiB
/dev/vdh 8.00MiB
Unallocated:
/dev/vdg 1.06GiB
/dev/vdh 841.92MiB
Reason:
btrfs balance delete last data chunk in case of no data in
the filesystem, then we can see "no data chunk" by "fi usage"
command.
And when we do write operation to fs, the only available data
profile is 0x0, result is all new chunks are allocated single type.
Fix:
Allocate a data chunk explicitly to ensure we don't lose the
raid profile for data.
Test:
Test by above script, and confirmed the logic by debug output.
Changelog v1->v2:
1: Update patch description of "Fix" field
2: Use BTRFS_BLOCK_GROUP_DATA for btrfs_force_chunk_alloc instead
of 1
3: Only reserve chunk when doing balance on data chunk.
All suggested-by: Filipe Manana <fdman...@gmail.com>
Reviewed-by: Filipe Manana <fdman...@suse.com>
Signed-off-by: Zhao Lei <zhao...@cn.fujitsu.com>
---
fs/btrfs/volumes.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6fc73586..cd9e5bd 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3277,6 +3277,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
u64 limit_data = bctl->data.limit;
u64 limit_meta = bctl->meta.limit;
u64 limit_sys = bctl->sys.limit;
+ int chunk_reserved = 0;
/* step one make some room on all the devices */
devices = &fs_info->fs_devices->devices;
@@ -3326,6 +3327,8 @@ again:
key.type = BTRFS_CHUNK_ITEM_KEY;
while (1) {
+ u64 chunk_type;
+
if ((!counting && atomic_read(&fs_info->balance_pause_req)) ||
atomic_read(&fs_info->balance_cancel_req)) {
ret = -ECANCELED;
@@ -3371,8 +3374,10 @@ again:
spin_unlock(&fs_info->balance_lock);
}
+ chunk_type = btrfs_chunk_type(leaf, chunk);
ret = should_balance_chunk(chunk_root, leaf, chunk,
found_key.offset);
+
btrfs_release_path(path);
if (!ret) {
mutex_unlock(&fs_info->delete_unused_bgs_mutex);
@@ -3387,6 +3392,25 @@ again:
goto loop;
}
+ if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) && !chunk_reserved) {
+ trans = btrfs_start_transaction(chunk_root, 0);
+ if (IS_ERR(trans)) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
+ ret = PTR_ERR(trans);
+ goto error;
+ }
+
+ ret = btrfs_force_chunk_alloc(trans, chunk_root,
+ BTRFS_BLOCK_GROUP_DATA);
+ if (ret < 0) {
+ mutex_unlock(&fs_info->delete_unused_bgs_mutex);
+ goto error;
+ }
+
+ btrfs_end_transaction(trans, chunk_root);
+ chunk_reserved = 1;
+ }
+
ret = btrfs_relocate_chunk(chunk_root,
found_key.offset);
mutex_unlock(&fs_info->delete_unused_bgs_mutex);
--
1.8.5.1
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