When we get the fs information, we forgot to acquire the mutex of device list,
it might cause the problem we might access a device that was removed. Fix
it by acquiring the device list mutex.
Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
---
fs/btrfs/super.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 089991d..6b98358 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1703,7 +1703,11 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
int ret;
- /* holding chunk_muext to avoid allocating new chunks */
+ /*
+ * holding chunk_muext to avoid allocating new chunks, holding
+ * device_list_mutex to avoid the device being removed
+ */
+ mutex_lock(&fs_info->fs_devices->device_list_mutex);
mutex_lock(&fs_info->chunk_mutex);
rcu_read_lock();
list_for_each_entry_rcu(found, head, list) {
@@ -1744,11 +1748,13 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
if (ret) {
mutex_unlock(&fs_info->chunk_mutex);
+ mutex_unlock(&fs_info->fs_devices->device_list_mutex);
return ret;
}
buf->f_bavail += div_u64(total_free_data, factor);
buf->f_bavail = buf->f_bavail >> bits;
mutex_unlock(&fs_info->chunk_mutex);
+ mutex_unlock(&fs_info->fs_devices->device_list_mutex);
buf->f_type = BTRFS_SUPER_MAGIC;
buf->f_bsize = dentry->d_sb->s_blocksize;
--
1.9.3
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