Use the new vfs API get_vfsmount_sb() to get a vfsmount and use it to
do the write protection of the label change transaction.
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
fs/btrfs/sysfs.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index b2e7bb4..cdfa6b9 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -25,6 +25,7 @@
#include <linux/bug.h>
#include <linux/genhd.h>
#include <linux/debugfs.h>
+#include <linux/mount.h>
#include "ctree.h"
#include "disk-io.h"
@@ -374,11 +375,10 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
struct btrfs_fs_info *fs_info = to_fs_info(kobj);
struct btrfs_trans_handle *trans;
struct btrfs_root *root = fs_info->fs_root;
+ struct vfsmount *vfsmount;
int ret;
size_t p_len;
- if (fs_info->sb->s_flags & MS_RDONLY)
- return -EROFS;
/*
* p_len is the len until the first occurrence of either
@@ -389,9 +389,21 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
if (p_len >= BTRFS_LABEL_SIZE)
return -EINVAL;
+ vfsmount = get_vfsmount_sb(fs_info->sb);
+ if (!vfsmount)
+ return -EINVAL;
+
+ ret = mnt_want_write(vfsmount);
+ if (ret) {
+ mntput(vfsmount);
+ return ret;
+ }
+
trans = btrfs_start_transaction(root, 0);
- if (IS_ERR(trans))
- return PTR_ERR(trans);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto out;
+ }
spin_lock(&root->fs_info->super_lock);
memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
@@ -399,9 +411,11 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
spin_unlock(&root->fs_info->super_lock);
ret = btrfs_commit_transaction(trans, root);
+out:
+ mnt_drop_write(vfsmount);
+ mntput(vfsmount);
if (!ret)
return len;
-
return ret;
}
BTRFS_ATTR_RW(label, btrfs_label_show, btrfs_label_store);
--
2.2.2
--
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