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fs: add is_idmapped_mnt() helper

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commit bb49e9e730c2906a958eee273a7819f401543d6c upstream.

Multiple places open-code the same check to determine whether a given
mount is idmapped. Introduce a simple helper function that can be used
instead. This allows us to get rid of the fragile open-coding. We will
later change the check that is used to determine whether a given mount
is idmapped. Introducing a helper allows us to do this in a single
place instead of doing it for multiple places.

Link: https://lore.kernel.org/r/20211123114227.3124056-2-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-2-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-2-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christian Brauner
2022-06-28 14:16:09 +02:00
committed by Jaegeuk Kim
parent fe2d3c2473
commit 6a373411de
7 changed files with 20 additions and 6 deletions
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14
include/linux/fs.h
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@@ -2724,6 +2724,20 @@ static inline struct user_namespace *file_mnt_user_ns(struct file *file)
{
return mnt_user_ns(file->f_path.mnt);
}
/**
* is_idmapped_mnt - check whether a mount is mapped
* @mnt: the mount to check
*
* If @mnt has an idmapping attached to it @mnt is mapped.
*
* Return: true if mount is mapped, false if not.
*/
static inline bool is_idmapped_mnt(const struct vfsmount *mnt)
{
return mnt_user_ns(mnt) != &init_user_ns;
}
extern long vfs_truncate(const struct path *, loff_t);
int do_truncate(struct user_namespace *, struct dentry *, loff_t start,
unsigned int time_attrs, struct file *filp);