Unverified Commit a26f788b authored by Christian Brauner's avatar Christian Brauner
Browse files

fs: add mnt_allow_writers() and simplify mount_setattr_prepare() 

Add a tiny helper that lets us simplify the control-flow and can be used
in the next patch to avoid adding another condition open-coded into
mount_setattr_prepare(). Instead we can add it into the new helper.

Link: https://lore.kernel.org/r/20220203131411.3093040-5-brauner@kernel.org


Cc: Seth Forshee <seth.forshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 538f4f02

fs/namespace.c

+22 −6
Original line number Diff line number Diff line
@@ -3998,6 +3998,22 @@ static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) 
	return 0;

}



/**

 * mnt_allow_writers() - check whether the attribute change allows writers

 * @kattr: the new mount attributes

 * @mnt: the mount to which @kattr will be applied

 *

 * Check whether thew new mount attributes in @kattr allow concurrent writers.

 *

 * Return: true if writers need to be held, false if not

 */

static inline bool mnt_allow_writers(const struct mount_kattr *kattr,

				     const struct mount *mnt)

{

	return !(kattr->attr_set & MNT_READONLY) ||

	       (mnt->mnt.mnt_flags & MNT_READONLY);

}



static struct mount *mount_setattr_prepare(struct mount_kattr *kattr,

					   struct mount *mnt, int *err)

{
@@ -4028,12 +4044,12 @@ static struct mount *mount_setattr_prepare(struct mount_kattr *kattr, 


		last = m;



		if ((kattr->attr_set & MNT_READONLY) &&

		    !(m->mnt.mnt_flags & MNT_READONLY)) {

		if (mnt_allow_writers(kattr, m))

			continue;



		*err = mnt_hold_writers(m);

		if (*err)

			goto out;

		}

	} while (kattr->recurse && (m = next_mnt(m, mnt)));



out: