Btrfs: get write access when removing a device
Steps to reproduce: # mkfs.btrfs -d single -m single <disk0> <disk1> # mount -o ro <disk0> <mnt0> # mount -o ro <disk0> <mnt1> # mount -o remount,rw <mnt0> # umount <mnt0> # btrfs device delete <disk1> <mnt1> We can remove a device from a R/O filesystem. The reason is that we just check the R/O flag of the super block object. It is not enough, because the kernel may set the R/O flag only for the mount point. We need invoke mnt_want_write_file() to do a full check. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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@ -2270,20 +2270,23 @@ out:
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return ret;
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return ret;
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}
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}
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static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
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static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
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{
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{
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struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
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struct btrfs_ioctl_vol_args *vol_args;
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struct btrfs_ioctl_vol_args *vol_args;
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int ret;
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int ret;
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if (!capable(CAP_SYS_ADMIN))
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return -EPERM;
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if (root->fs_info->sb->s_flags & MS_RDONLY)
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ret = mnt_want_write_file(file);
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return -EROFS;
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if (ret)
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return ret;
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if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
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if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
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1)) {
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1)) {
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pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
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pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
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mnt_drop_write_file(file);
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return -EINPROGRESS;
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return -EINPROGRESS;
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}
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}
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@ -2300,6 +2303,7 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
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kfree(vol_args);
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kfree(vol_args);
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out:
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out:
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mutex_unlock(&root->fs_info->volume_mutex);
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mutex_unlock(&root->fs_info->volume_mutex);
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mnt_drop_write_file(file);
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atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
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atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
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return ret;
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return ret;
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}
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}
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@ -3842,7 +3846,7 @@ long btrfs_ioctl(struct file *file, unsigned int
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case BTRFS_IOC_ADD_DEV:
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case BTRFS_IOC_ADD_DEV:
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return btrfs_ioctl_add_dev(root, argp);
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return btrfs_ioctl_add_dev(root, argp);
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case BTRFS_IOC_RM_DEV:
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case BTRFS_IOC_RM_DEV:
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return btrfs_ioctl_rm_dev(root, argp);
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return btrfs_ioctl_rm_dev(file, argp);
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case BTRFS_IOC_FS_INFO:
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case BTRFS_IOC_FS_INFO:
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return btrfs_ioctl_fs_info(root, argp);
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return btrfs_ioctl_fs_info(root, argp);
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case BTRFS_IOC_DEV_INFO:
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case BTRFS_IOC_DEV_INFO:
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