On 04/04/2018 02:34 AM, David Sterba wrote:
Replace a WARN_ON with a proper check and message in case something goes really wrong and resumed balance cannot set up its exclusive status.
The check is a user friendly assertion, I don't expect to ever happen under normal circumstances. Also document that the paused balance starts here and owns the exclusive op status.
Signed-off-by: David Sterba <dste...@suse.com> --- fs/btrfs/volumes.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index eb78c1d0ce2b..843982a2cbdb 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3982,6 +3982,20 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info) struct btrfs_key key; int ret;+ /*+ * This should never happen, as the paused balance state is recovered + * during mount without any chance of other exclusive ops to collide. + * Let it fail early and do not continue mount. + * + * Otherwise, this gives the exclusive op status to balance and keeps + * in paused state until user intervention (cancel or umount). + */ + if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) { + btrfs_err(fs_info, + "cannot set exclusive op status to resume balance"); + return -EINVAL; + }
We need the test_and_set_bit(BTRFS_FS_EXCL_OP) only if we confirm that there is a pending balance. Its better to test and set at the same place as WARN_ON before. Thanks, Anand
path = btrfs_alloc_path(); if (!path) return -ENOMEM; @@ -4018,8 +4032,6 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info) btrfs_balance_sys(leaf, item, &disk_bargs); btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);- WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));- mutex_lock(&fs_info->volume_mutex); mutex_lock(&fs_info->balance_mutex);
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