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fs: add mnt_allow_writers() and simplify mount_setattr_prepare()

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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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2022-02-03 14:14:08 +01:00
parent 538f4f022a
commit a26f788b6e
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 22 additions and 6 deletions
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28
fs/namespace.c
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@ -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)) {
*err = mnt_hold_writers(m);
if (*err)
goto out;
}
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: