From: Anand Jain <anand.jain@oracle.com>
Date: Fri, 10 Aug 2018 13:53:21 +0800
Subject: btrfs: add helper to obtain number of devices with ongoing dev-replace
Git-commit: 1da739678e0b7a764a0f1ef46886f919f19f6446
Patch-mainline: v4.20-rc1
References: bsc#1178897
When the replace is running the fs_devices::num_devices also includes
the replaced device, however in some operations like device delete and
balance it needs the actual num_devices without the repalced devices.
The function btrfs_num_devices() just provides that.
And here is a scenario how balance and repalce items could co-exist:
Consider balance is started and paused, now start the replace followed
by a unmount or system power-cycle. During following mount, the
open_ctree() first restarts the balance so it must check for the device
replace otherwise our num_devices calculation will be wrong.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
fs/btrfs/volumes.c | 34 ++++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1853,6 +1853,24 @@ void btrfs_assign_next_active_device(str
fs_info->fs_devices->latest_bdev = next_device->bdev;
}
+/*
+ * Return btrfs_fs_devices::num_devices excluding the device that's being
+ * currently replaced.
+ */
+static u64 btrfs_num_devices(struct btrfs_fs_info *fs_info)
+{
+ u64 num_devices = fs_info->fs_devices->num_devices;
+
+ btrfs_dev_replace_read_lock(&fs_info->dev_replace);
+ if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
+ ASSERT(num_devices > 1);
+ num_devices--;
+ }
+ btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
+
+ return num_devices;
+}
+
int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
u64 devid)
{
@@ -1864,13 +1882,7 @@ int btrfs_rm_device(struct btrfs_fs_info
mutex_lock(&uuid_mutex);
- num_devices = fs_info->fs_devices->num_devices;
- btrfs_dev_replace_read_lock(&fs_info->dev_replace);
- if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
- WARN_ON(num_devices < 1);
- num_devices--;
- }
- btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
+ num_devices = btrfs_num_devices(fs_info);
ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);
if (ret)
@@ -3857,13 +3869,7 @@ int btrfs_balance(struct btrfs_balance_c
}
}
- num_devices = fs_info->fs_devices->num_devices;
- btrfs_dev_replace_read_lock(&fs_info->dev_replace);
- if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
- BUG_ON(num_devices < 1);
- num_devices--;
- }
- btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
+ num_devices = btrfs_num_devices(fs_info);
allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE | BTRFS_BLOCK_GROUP_DUP;
if (num_devices > 1)
allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);