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* add a rant about why MPSAFE isn't enabled even though puffs code is 

* predict_false that we are mounting when calling statvfs
* KNF
This commit is contained in:
pooka 2010-02-17 14:32:08 +00:00
parent 27e0e1c809
commit 65dca8eead
1 changed files with 30 additions and 4 deletions
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34
sys/fs/puffs/puffs_vfsops.c
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@ -1,4 +1,4 @@
/* $NetBSD: puffs_vfsops.c,v 1.86 2010/01/14 19:50:07 pooka Exp $ */ /* $NetBSD: puffs_vfsops.c,v 1.87 2010/02/17 14:32:08 pooka Exp $ */
/* /*
* Copyright (c) 2005, 2006 Antti Kantee. All Rights Reserved. * Copyright (c) 2005, 2006 Antti Kantee. All Rights Reserved.
@ -30,7 +30,7 @@
*/ */
#include <sys/cdefs.h> #include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: puffs_vfsops.c,v 1.86 2010/01/14 19:50:07 pooka Exp $"); __KERNEL_RCSID(0, "$NetBSD: puffs_vfsops.c,v 1.87 2010/02/17 14:32:08 pooka Exp $");
#include <sys/param.h> #include <sys/param.h>
#include <sys/mount.h> #include <sys/mount.h>
@ -222,13 +222,39 @@ puffs_vfsop_mount(struct mount *mp, const char *path, void *data,
mp->mnt_flag &= ~MNT_LOCAL; /* we don't really know, so ... */ mp->mnt_flag &= ~MNT_LOCAL; /* we don't really know, so ... */
mp->mnt_data = pmp; mp->mnt_data = pmp;
#if 0
/*
* XXX: puffs code is MPSAFE. However, VFS really isn't.
* Currently, there is nothing which protects an inode from
* reclaim while there are threads inside the file system.
* This means that in the event of a server crash, an MPSAFE
* mount is likely to end up accessing invalid memory. For the
* non-mpsafe case, the kernel lock, general structure of
* puffs and pmp_refcount protect the threads during escape.
*
* Fixing this will require:
* a) fixing vfs
* OR
* b) adding a small sleep to puffs_msgif_close() between
* userdead() and dounmount().
* (well, this isn't really a fix, but would solve
* 99.999% of the race conditions).
*
* Also, in the event of "b", unmount -f should be used,
* like with any other file system, sparingly and only when
* it is "known" to be safe.
*/
mp->mnt_iflags |= IMNT_MPSAFE;
#endif
pmp->pmp_status = PUFFSTAT_MOUNTING; pmp->pmp_status = PUFFSTAT_MOUNTING;
pmp->pmp_mp = mp; pmp->pmp_mp = mp;
pmp->pmp_msg_maxsize = args->pa_maxmsglen; pmp->pmp_msg_maxsize = args->pa_maxmsglen;
pmp->pmp_args = *args; pmp->pmp_args = *args;
pmp->pmp_npnodehash = args->pa_nhashbuckets; pmp->pmp_npnodehash = args->pa_nhashbuckets;
pmp->pmp_pnodehash = kmem_alloc(BUCKETALLOC(pmp->pmp_npnodehash), KM_SLEEP); pmp->pmp_pnodehash = kmem_alloc(BUCKETALLOC(pmp->pmp_npnodehash),
KM_SLEEP);
for (i = 0; i < pmp->pmp_npnodehash; i++) for (i = 0; i < pmp->pmp_npnodehash; i++)
LIST_INIT(&pmp->pmp_pnodehash[i]); LIST_INIT(&pmp->pmp_pnodehash[i]);
LIST_INIT(&pmp->pmp_newcookie); LIST_INIT(&pmp->pmp_newcookie);
@ -435,7 +461,7 @@ puffs_vfsop_statvfs(struct mount *mp, struct statvfs *sbp)
* requesting statvfs from userspace would mean a deadlock. * requesting statvfs from userspace would mean a deadlock.
* Compensate. * Compensate.
*/ */
if (pmp->pmp_status == PUFFSTAT_MOUNTING) if (__predict_false(pmp->pmp_status == PUFFSTAT_MOUNTING))
return EINPROGRESS; return EINPROGRESS;
PUFFS_MSG_ALLOC(vfs, statvfs); PUFFS_MSG_ALLOC(vfs, statvfs);