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Btrfs: fix unprotected device list access when getting the fs information

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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@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Miao Xie 2014-09-03 21:35:40 +08:00 committed by Chris Mason
parent fe48a5c00f
commit 15484377f5
1 changed files with 7 additions and 1 deletions
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8
fs/btrfs/super.c
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@ -1696,7 +1696,11 @@ 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) {
@ -1737,11 +1741,13 @@ 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;