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ufs/suspend: deny suspension if the calling process has a file from mp opened for write

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Also deny suspension if we cannot check the above condition race-free
because there is more than one thread in the calling process.

PR:	267628, 267630
Reviewed by:	mckusick
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D37896
This commit is contained in:
Konstantin Belousov 2022-12-28 20:14:52 +02:00
parent 6891270170
commit 701b36961c
1 changed files with 11 additions and 0 deletions
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11
sys/ufs/ffs/ffs_suspend.c
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@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/filedesc.h>
#include <sys/ioccom.h>
#include <sys/jail.h>
#include <sys/mount.h>
@ -302,6 +303,16 @@ ffs_susp_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
vfs_rel(mp);
if (error != 0)
break;
/*
* Require single-thread curproc so that the check is not racey.
* XXXKIB: might consider to singlethread curproc instead.
*/
error = curproc->p_numthreads > 1 ? EDEADLK :
descrip_check_write_mp(curproc->p_fd, mp);
if (error != 0)
break;
error = ffs_susp_suspend(mp);
if (error != 0) {
vfs_unbusy(mp);