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devtmpfs regression fix: reconfigure on each mount

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commit a6097180d884ddab769fb25588ea8598589c218c upstream.

Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
mount options as "remount" options, so it updates the configuration of
the single super_block on each mount.

Since that was changed, the mount options used for devtmpfs are ignored.
This is a regression which affect systemd - which mounts devtmpfs with
"-o mode=755,size=4m,nr_inodes=1m".

This patch restores the "remount" effect by calling reconfigure_single()

Fixes: d401727ea0 ("devtmpfs: don't mix {ramfs,shmem}_fill_super() with mount_single()")
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
NeilBrown 2022-01-17 09:07:26 +11:00 committed by Greg Kroah-Hartman
parent c117b116e6
commit 5d6af67307
3 changed files with 12 additions and 2 deletions
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8
drivers/base/devtmpfs.c
View File

@ -25,6 +25,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/fs_context.h>
#include <uapi/linux/mount.h>
#include "base.h"
@ -62,8 +63,15 @@ static struct dentry *public_dev_mount(struct file_system_type *fs_type, int fla
const char *dev_name, void *data)
{
struct super_block *s = mnt->mnt_sb;
int err;
atomic_inc(&s->s_active);
down_write(&s->s_umount);
err = reconfigure_single(s, flags, data);
if (err < 0) {
deactivate_locked_super(s);
return ERR_PTR(err);
}
return dget(s->s_root);
}

4
fs/super.c
View File

@ -1470,8 +1470,8 @@ struct dentry *mount_nodev(struct file_system_type *fs_type,
}
EXPORT_SYMBOL(mount_nodev);
static int reconfigure_single(struct super_block *s,
int flags, void *data)
int reconfigure_single(struct super_block *s,
int flags, void *data)
{
struct fs_context *fc;
int ret;

2
include/linux/fs_context.h
View File

@ -135,6 +135,8 @@ extern int generic_parse_monolithic(struct fs_context *fc, void *data);
extern int vfs_get_tree(struct fs_context *fc);
extern void put_fs_context(struct fs_context *fc);
extern void fc_drop_locked(struct fs_context *fc);
int reconfigure_single(struct super_block *s,
int flags, void *data);
/*
* sget() wrappers to be called from the ->get_tree() op.