From: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
Steps to reproduce:
while true; do
dd if=/dev/zero of=/btrfs_dir/file count=[fs_size * 75%]
rm /btrfs_dir/file
sync
done
And we'll see dd failed because btrfs return NO_SPACE.
Reason:
Normally, btrfs_commit_transaction() call btrfs_run_delayed_iputs()
in end to free fs space for next write, but sometimes it hadn't
done work on time, because btrfs-cleaner thread get delayed-iputs
from list before, but do iput() after next write.
This is log:
[ 2569.050776] comm=btrfs-cleaner func=btrfs_evict_inode() begin
[ 2569.084280] comm=sync func=btrfs_commit_transaction() call btrfs_run_delayed_iputs()
[ 2569.085418] comm=sync func=btrfs_commit_transaction() done btrfs_run_delayed_iputs()
[ 2569.087554] comm=sync func=btrfs_commit_transaction() end
[ 2569.191081] comm=dd begin
[ 2569.790112] comm=dd func=__btrfs_buffered_write() ret=-28
[ 2569.847479] comm=btrfs-cleaner func=add_pinned_bytes() 0 + 32677888 = 32677888
[ 2569.849530] comm=btrfs-cleaner func=add_pinned_bytes() 32677888 + 23834624 = 56512512
...
[ 2569.903893] comm=btrfs-cleaner func=add_pinned_bytes() 943976448 + 21762048 = 965738496
[ 2569.908270] comm=btrfs-cleaner func=btrfs_evict_inode() end
Fix:
Make btrfs_commit_transaction() wait current running btrfs-cleaner's
delayed-iputs() done in end.
Test:
Use script similar to above(more complex),
before patch:
7 failed in 100 * 20 loop.
after patch:
0 failed in 100 * 20 loop.
Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
---
fs/btrfs/ctree.h | 1 +
fs/btrfs/disk-io.c | 5 ++++-
fs/btrfs/transaction.c | 6 +++++-
3 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f9c89ca..54d4d78 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1513,6 +1513,7 @@ struct btrfs_fs_info {
spinlock_t delayed_iput_lock;
struct list_head delayed_iputs;
+ struct rw_semaphore delayed_iput_sem;
/* this protects tree_mod_seq_list */
spinlock_t tree_mod_seq_lock;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 639f266..df40f60 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1778,7 +1778,9 @@ static int cleaner_kthread(void *arg)
goto sleep;
}
+ down_read(&root->fs_info->delayed_iput_sem);
btrfs_run_delayed_iputs(root);
+ up_read(&root->fs_info->delayed_iput_sem);
btrfs_delete_unused_bgs(root->fs_info);
again = btrfs_clean_one_deleted_snapshot(root);
mutex_unlock(&root->fs_info->cleaner_mutex);
@@ -2241,11 +2243,12 @@ int open_ctree(struct super_block *sb,
spin_lock_init(&fs_info->qgroup_op_lock);
spin_lock_init(&fs_info->buffer_lock);
spin_lock_init(&fs_info->unused_bgs_lock);
- mutex_init(&fs_info->unused_bg_unpin_mutex);
rwlock_init(&fs_info->tree_mod_log_lock);
+ mutex_init(&fs_info->unused_bg_unpin_mutex);
mutex_init(&fs_info->reloc_mutex);
mutex_init(&fs_info->delalloc_root_mutex);
seqlock_init(&fs_info->profiles_lock);
+ init_rwsem(&fs_info->delayed_iput_sem);
init_completion(&fs_info->kobj_unregister);
INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8be4278..d18991f 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2076,8 +2076,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
kmem_cache_free(btrfs_trans_handle_cachep, trans);
- if (current != root->fs_info->transaction_kthread)
+ if (current != root->fs_info->transaction_kthread) {
btrfs_run_delayed_iputs(root);
+ /* make sure that all running delayed iput are done */
+ down_write(&root->fs_info->delayed_iput_sem);
+ up_write(&root->fs_info->delayed_iput_sem);
+ }
return ret;
--
1.8.5.1
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
