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 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 | 3 ++-
fs/btrfs/inode.c | 4 ++++
fs/btrfs/transaction.c | 6 +++++-
4 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 84c3b00..ec2dac0 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 f79f385..1c0d8ec 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2241,11 +2241,12 @@ 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/inode.c b/fs/btrfs/inode.c
index a85c23d..a396bb9 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3087,6 +3087,8 @@ void btrfs_run_delayed_iputs(struct btrfs_root *root)
if (empty)
return;
+ down_read(&fs_info->delayed_iput_sem);
+
spin_lock(&fs_info->delayed_iput_lock);
list_splice_init(&fs_info->delayed_iputs, &list);
spin_unlock(&fs_info->delayed_iput_lock);
@@ -3097,6 +3099,8 @@ void btrfs_run_delayed_iputs(struct btrfs_root *root)
iput(delayed->inode);
kfree(delayed);
}
+
+ up_read(&fs_info->delayed_iput_sem);
}
/*
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 7e80f32..175cdef 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2068,8 +2068,12 @@ 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
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