Steps to reproduce: # mkfs.btrfs <partition> # mount -o ro <partition> <mnt0> # mount -o ro <partition> <mnt1> # mount -o remount,rw <mnt0> # umount <mnt0> # btrfs fi resize 10g <mnt1>
We re-sized 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 <[email protected]> --- fs/btrfs/ioctl.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 7d0214b..c4bcba5 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1293,12 +1293,13 @@ out_ra: return ret; } -static noinline int btrfs_ioctl_resize(struct btrfs_root *root, +static noinline int btrfs_ioctl_resize(struct file *file, void __user *arg) { u64 new_size; u64 old_size; u64 devid = 1; + struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root; struct btrfs_ioctl_vol_args *vol_args; struct btrfs_trans_handle *trans; struct btrfs_device *device = NULL; @@ -1307,12 +1308,13 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root, int ret = 0; int mod = 0; - if (root->fs_info->sb->s_flags & MS_RDONLY) - return -EROFS; - if (!capable(CAP_SYS_ADMIN)) return -EPERM; + ret = mnt_want_write_file(file); + if (ret) + return ret; + mutex_lock(&root->fs_info->volume_mutex); if (root->fs_info->balance_ctl) { printk(KERN_INFO "btrfs: balance in progress\n"); @@ -1415,6 +1417,7 @@ out_free: kfree(vol_args); out: mutex_unlock(&root->fs_info->volume_mutex); + mnt_drop_write_file(file); return ret; } @@ -3759,7 +3762,7 @@ long btrfs_ioctl(struct file *file, unsigned int case BTRFS_IOC_DEFRAG_RANGE: return btrfs_ioctl_defrag(file, argp); case BTRFS_IOC_RESIZE: - return btrfs_ioctl_resize(root, argp); + return btrfs_ioctl_resize(file, argp); case BTRFS_IOC_ADD_DEV: return btrfs_ioctl_add_dev(root, argp); case BTRFS_IOC_RM_DEV: -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
