Btrfs: fix possible empty list access when flushing the delalloc inodes
We didn't have a lock to protect the access to the delalloc inodes list, that is
we might access a empty delalloc inodes list if someone start flushing delalloc
inodes because the delalloc inodes were moved into a other list temporarily.
Fix it by wrapping the access with a lock.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index fbaf1ac..0ec8766 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8450,6 +8450,7 @@
INIT_LIST_HEAD(&works);
INIT_LIST_HEAD(&splice);
+ mutex_lock(&root->delalloc_mutex);
spin_lock(&root->delalloc_lock);
list_splice_init(&root->delalloc_inodes, &splice);
while (!list_empty(&splice)) {
@@ -8495,6 +8496,7 @@
list_splice_tail(&splice, &root->delalloc_inodes);
spin_unlock(&root->delalloc_lock);
}
+ mutex_unlock(&root->delalloc_mutex);
return ret;
}
@@ -8536,6 +8538,7 @@
INIT_LIST_HEAD(&splice);
+ mutex_lock(&fs_info->delalloc_root_mutex);
spin_lock(&fs_info->delalloc_root_lock);
list_splice_init(&fs_info->delalloc_roots, &splice);
while (!list_empty(&splice) && nr) {
@@ -8575,6 +8578,7 @@
list_splice_tail(&splice, &fs_info->delalloc_roots);
spin_unlock(&fs_info->delalloc_root_lock);
}
+ mutex_unlock(&fs_info->delalloc_root_mutex);
return ret;
}