On Wed, Apr 30, 2025 at 08:35:34AM +0000, Hans Holmberg wrote:
> Allow read-only mounts on rtdevs and logdevs that are marked as
> read-only and make sure those mounts can't be remounted read-write.
>
> Use the sb_open_mode helper to make sure that we don't try to open
> devices with write access enabled for read-only mounts.
>
> Signed-off-by: Hans Holmberg <hans.holmberg@xxxxxxx>
This looks good, thanks Hans!
Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> ---
>
> Changes since v1:
> - Switched to using the sb_open_mode helper that does exactly
> what we want.
>
> fs/xfs/xfs_super.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index b2dd0c0bf509..5e456a6073ca 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -380,10 +380,11 @@ xfs_blkdev_get(
> struct file **bdev_filep)
> {
> int error = 0;
> + blk_mode_t mode;
>
> - *bdev_filep = bdev_file_open_by_path(name,
> - BLK_OPEN_READ | BLK_OPEN_WRITE | BLK_OPEN_RESTRICT_WRITES,
> - mp->m_super, &fs_holder_ops);
> + mode = sb_open_mode(mp->m_super->s_flags);
> + *bdev_filep = bdev_file_open_by_path(name, mode,
> + mp->m_super, &fs_holder_ops);
> if (IS_ERR(*bdev_filep)) {
> error = PTR_ERR(*bdev_filep);
> *bdev_filep = NULL;
> @@ -1969,6 +1970,20 @@ xfs_remount_rw(
> struct xfs_sb *sbp = &mp->m_sb;
> int error;
>
> + if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp &&
> + bdev_read_only(mp->m_logdev_targp->bt_bdev)) {
> + xfs_warn(mp,
> + "ro->rw transition prohibited by read-only logdev");
> + return -EACCES;
> + }
> +
> + if (mp->m_rtdev_targp &&
> + bdev_read_only(mp->m_rtdev_targp->bt_bdev)) {
> + xfs_warn(mp,
> + "ro->rw transition prohibited by read-only rtdev");
> + return -EACCES;
> + }
> +
> if (xfs_has_norecovery(mp)) {
> xfs_warn(mp,
> "ro->rw transition prohibited on norecovery mount");
> --
> 2.34.1
>
