This reverts commit 0eae2747ec1dd ("btrfs: move commit out of sysfs
when changing features").
Unlike most btrfs file operations, sysfs don't go through the normal
open/read/write routine which will initiate a sb_start_*write/read.
This is very dangerous on frozen btrfs, if using the pending changes
method, sysfs change can make fs_info->pending_changes to 1, and later
sync_fs() call will cause deadlock.
So revert the patch to deal the deadlock caused by the following workload:
freeze() -> change features -> sync() -> unfreeze()
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
fs/btrfs/sysfs.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 226f726..b2e7bb4 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -111,6 +111,7 @@ static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
{
struct btrfs_fs_info *fs_info;
struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
+ struct btrfs_trans_handle *trans;
u64 features, set, clear;
unsigned long val;
int ret;
@@ -152,6 +153,10 @@ static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
btrfs_info(fs_info, "%s %s feature flag",
val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
+ trans = btrfs_start_transaction(fs_info->fs_root, 0);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
spin_lock(&fs_info->super_lock);
features = get_features(fs_info, fa->feature_set);
if (val)
@@ -161,11 +166,9 @@ static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
set_features(fs_info, fa->feature_set, features);
spin_unlock(&fs_info->super_lock);
- /*
- * We don't want to do full transaction commit from inside sysfs
- */
- btrfs_set_pending(fs_info, COMMIT);
- wake_up_process(fs_info->transaction_kthread);
+ ret = btrfs_commit_transaction(trans, fs_info->fs_root);
+ if (ret)
+ return ret;
return count;
}
--
2.2.2
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