Btrfs: get write access for qgroup operations

We need get write access for qgroup operations, or we will modify the R/O fs.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 48 insertions, 25 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 12b18c01b911..657d83ca9dea 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3558,8 +3558,9 @@ out:
         return ret;
 }
 
-static long btrfs_ioctl_quota_ctl(struct btrfs_root *root, void __user *arg)
+static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
 {
+        struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
         struct btrfs_ioctl_quota_ctl_args *sa;
         struct btrfs_trans_handle *trans = NULL;
         int ret;
@@ -3568,12 +3569,15 @@ static long btrfs_ioctl_quota_ctl(struct btrfs_root *root, void __user *arg)
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        if (root->fs_info->sb->s_flags & MS_RDONLY)
-                return -EROFS;
+        ret = mnt_want_write_file(file);
+        if (ret)
+                return ret;
 
         sa = memdup_user(arg, sizeof(*sa));
-        if (IS_ERR(sa))
-                return PTR_ERR(sa);
+        if (IS_ERR(sa)) {
+                ret = PTR_ERR(sa);
+                goto drop_write;
+        }
 
         if (sa->cmd != BTRFS_QUOTA_CTL_RESCAN) {
                 trans = btrfs_start_transaction(root, 2);
@@ -3606,14 +3610,16 @@ static long btrfs_ioctl_quota_ctl(struct btrfs_root *root, void __user *arg)
                 if (err && !ret)
                         ret = err;
         }
-
 out:
         kfree(sa);
+drop_write:
+        mnt_drop_write_file(file);
         return ret;
 }
 
-static long btrfs_ioctl_qgroup_assign(struct btrfs_root *root, void __user *arg)
+static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
 {
+        struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
         struct btrfs_ioctl_qgroup_assign_args *sa;
         struct btrfs_trans_handle *trans;
         int ret;
@@ -3622,12 +3628,15 @@ static long btrfs_ioctl_qgroup_assign(struct btrfs_root *root, void __user *arg)
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        if (root->fs_info->sb->s_flags & MS_RDONLY)
-                return -EROFS;
+        ret = mnt_want_write_file(file);
+        if (ret)
+                return ret;
 
         sa = memdup_user(arg, sizeof(*sa));
-        if (IS_ERR(sa))
-                return PTR_ERR(sa);
+        if (IS_ERR(sa)) {
+                ret = PTR_ERR(sa);
+                goto drop_write;
+        }
 
         trans = btrfs_join_transaction(root);
         if (IS_ERR(trans)) {
@@ -3650,11 +3659,14 @@ static long btrfs_ioctl_qgroup_assign(struct btrfs_root *root, void __user *arg)
 
 out:
         kfree(sa);
+drop_write:
+        mnt_drop_write_file(file);
         return ret;
 }
 
-static long btrfs_ioctl_qgroup_create(struct btrfs_root *root, void __user *arg)
+static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
 {
+        struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
         struct btrfs_ioctl_qgroup_create_args *sa;
         struct btrfs_trans_handle *trans;
         int ret;
@@ -3663,12 +3675,15 @@ static long btrfs_ioctl_qgroup_create(struct btrfs_root *root, void __user *arg)
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        if (root->fs_info->sb->s_flags & MS_RDONLY)
-                return -EROFS;
+        ret = mnt_want_write_file(file);
+        if (ret)
+                return ret;
 
         sa = memdup_user(arg, sizeof(*sa));
-        if (IS_ERR(sa))
-                return PTR_ERR(sa);
+        if (IS_ERR(sa)) {
+                ret = PTR_ERR(sa);
+                goto drop_write;
+        }
 
         trans = btrfs_join_transaction(root);
         if (IS_ERR(trans)) {
@@ -3690,11 +3705,14 @@ static long btrfs_ioctl_qgroup_create(struct btrfs_root *root, void __user *arg)
 
 out:
         kfree(sa);
+drop_write:
+        mnt_drop_write_file(file);
         return ret;
 }
 
-static long btrfs_ioctl_qgroup_limit(struct btrfs_root *root, void __user *arg)
+static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
 {
+        struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
         struct btrfs_ioctl_qgroup_limit_args *sa;
         struct btrfs_trans_handle *trans;
         int ret;
@@ -3704,12 +3722,15 @@ static long btrfs_ioctl_qgroup_limit(struct btrfs_root *root, void __user *arg)
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        if (root->fs_info->sb->s_flags & MS_RDONLY)
-                return -EROFS;
+        ret = mnt_want_write_file(file);
+        if (ret)
+                return ret;
 
         sa = memdup_user(arg, sizeof(*sa));
-        if (IS_ERR(sa))
-                return PTR_ERR(sa);
+        if (IS_ERR(sa)) {
+                ret = PTR_ERR(sa);
+                goto drop_write;
+        }
 
         trans = btrfs_join_transaction(root);
         if (IS_ERR(trans)) {
@@ -3732,6 +3753,8 @@ static long btrfs_ioctl_qgroup_limit(struct btrfs_root *root, void __user *arg)
 
 out:
         kfree(sa);
+drop_write:
+        mnt_drop_write_file(file);
         return ret;
 }
 
@@ -3907,13 +3930,13 @@ long btrfs_ioctl(struct file *file, unsigned int
         case BTRFS_IOC_GET_DEV_STATS:
                 return btrfs_ioctl_get_dev_stats(root, argp);
         case BTRFS_IOC_QUOTA_CTL:
-                return btrfs_ioctl_quota_ctl(root, argp);
+                return btrfs_ioctl_quota_ctl(file, argp);
         case BTRFS_IOC_QGROUP_ASSIGN:
-                return btrfs_ioctl_qgroup_assign(root, argp);
+                return btrfs_ioctl_qgroup_assign(file, argp);
         case BTRFS_IOC_QGROUP_CREATE:
-                return btrfs_ioctl_qgroup_create(root, argp);
+                return btrfs_ioctl_qgroup_create(file, argp);
         case BTRFS_IOC_QGROUP_LIMIT:
-                return btrfs_ioctl_qgroup_limit(root, argp);
+                return btrfs_ioctl_qgroup_limit(file, argp);
         case BTRFS_IOC_DEV_REPLACE:
                 return btrfs_ioctl_dev_replace(root, argp);
         }