freebsd-dev/sys/fs/pseudofs/pseudofs.c
Konstantin Belousov 29ffb32ccd Remove Giant asserts. Update comment.
Owning Giant in the init/uninit is accidental due to the moment where
VFS modules initialization is performed, and is not enforced by the
VFS interface.  The Giant lock does not prevent a parallel execution
of the code, it is VFS which implements the proper protocol.

Approved by:	des (pseudofs maintainer)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-08-03 08:57:15 +00:00

455 lines
9.9 KiB
C

/*-
* Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_pseudofs.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <fs/pseudofs/pseudofs.h>
#include <fs/pseudofs/pseudofs_internal.h>
static MALLOC_DEFINE(M_PFSNODES, "pfs_nodes", "pseudofs nodes");
SYSCTL_NODE(_vfs, OID_AUTO, pfs, CTLFLAG_RW, 0,
"pseudofs");
#ifdef PSEUDOFS_TRACE
int pfs_trace;
SYSCTL_INT(_vfs_pfs, OID_AUTO, trace, CTLFLAG_RW, &pfs_trace, 0,
"enable tracing of pseudofs vnode operations");
#endif
#if PFS_FSNAMELEN != MFSNAMELEN
#error "PFS_FSNAMELEN is not equal to MFSNAMELEN"
#endif
/*
* Allocate and initialize a node
*/
static struct pfs_node *
pfs_alloc_node(struct pfs_info *pi, const char *name, pfs_type_t type)
{
struct pfs_node *pn;
KASSERT(strlen(name) < PFS_NAMELEN,
("%s(): node name is too long", __func__));
pn = malloc(sizeof *pn,
M_PFSNODES, M_WAITOK|M_ZERO);
mtx_init(&pn->pn_mutex, "pfs_node", NULL, MTX_DEF | MTX_DUPOK);
strlcpy(pn->pn_name, name, sizeof pn->pn_name);
pn->pn_type = type;
pn->pn_info = pi;
return (pn);
}
/*
* Add a node to a directory
*/
static void
pfs_add_node(struct pfs_node *parent, struct pfs_node *pn)
{
#ifdef INVARIANTS
struct pfs_node *iter;
#endif
KASSERT(parent != NULL,
("%s(): parent is NULL", __func__));
KASSERT(pn->pn_parent == NULL,
("%s(): node already has a parent", __func__));
KASSERT(parent->pn_info != NULL,
("%s(): parent has no pn_info", __func__));
KASSERT(parent->pn_type == pfstype_dir ||
parent->pn_type == pfstype_procdir ||
parent->pn_type == pfstype_root,
("%s(): parent is not a directory", __func__));
#ifdef INVARIANTS
/* XXX no locking! */
if (pn->pn_type == pfstype_procdir)
for (iter = parent; iter != NULL; iter = iter->pn_parent)
KASSERT(iter->pn_type != pfstype_procdir,
("%s(): nested process directories", __func__));
for (iter = parent->pn_nodes; iter != NULL; iter = iter->pn_next) {
KASSERT(strcmp(pn->pn_name, iter->pn_name) != 0,
("%s(): homonymous siblings", __func__));
if (pn->pn_type == pfstype_procdir)
KASSERT(iter->pn_type != pfstype_procdir,
("%s(): sibling process directories", __func__));
}
#endif
pn->pn_parent = parent;
pfs_fileno_alloc(pn);
pfs_lock(parent);
pn->pn_next = parent->pn_nodes;
if ((parent->pn_flags & PFS_PROCDEP) != 0)
pn->pn_flags |= PFS_PROCDEP;
parent->pn_nodes = pn;
pfs_unlock(parent);
}
/*
* Detach a node from its aprent
*/
static void
pfs_detach_node(struct pfs_node *pn)
{
struct pfs_node *parent = pn->pn_parent;
struct pfs_node **iter;
KASSERT(parent != NULL, ("%s(): node has no parent", __func__));
KASSERT(parent->pn_info == pn->pn_info,
("%s(): parent has different pn_info", __func__));
pfs_lock(parent);
iter = &parent->pn_nodes;
while (*iter != NULL) {
if (*iter == pn) {
*iter = pn->pn_next;
break;
}
iter = &(*iter)->pn_next;
}
pn->pn_parent = NULL;
pfs_unlock(parent);
}
/*
* Add . and .. to a directory
*/
static void
pfs_fixup_dir(struct pfs_node *parent)
{
struct pfs_node *pn;
pn = pfs_alloc_node(parent->pn_info, ".", pfstype_this);
pfs_add_node(parent, pn);
pn = pfs_alloc_node(parent->pn_info, "..", pfstype_parent);
pfs_add_node(parent, pn);
}
/*
* Create a directory
*/
struct pfs_node *
pfs_create_dir(struct pfs_node *parent, const char *name,
pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
int flags)
{
struct pfs_node *pn;
pn = pfs_alloc_node(parent->pn_info, name,
(flags & PFS_PROCDEP) ? pfstype_procdir : pfstype_dir);
pn->pn_attr = attr;
pn->pn_vis = vis;
pn->pn_destroy = destroy;
pn->pn_flags = flags;
pfs_add_node(parent, pn);
pfs_fixup_dir(pn);
return (pn);
}
/*
* Create a file
*/
struct pfs_node *
pfs_create_file(struct pfs_node *parent, const char *name, pfs_fill_t fill,
pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
int flags)
{
struct pfs_node *pn;
pn = pfs_alloc_node(parent->pn_info, name, pfstype_file);
pn->pn_fill = fill;
pn->pn_attr = attr;
pn->pn_vis = vis;
pn->pn_destroy = destroy;
pn->pn_flags = flags;
pfs_add_node(parent, pn);
return (pn);
}
/*
* Create a symlink
*/
struct pfs_node *
pfs_create_link(struct pfs_node *parent, const char *name, pfs_fill_t fill,
pfs_attr_t attr, pfs_vis_t vis, pfs_destroy_t destroy,
int flags)
{
struct pfs_node *pn;
pn = pfs_alloc_node(parent->pn_info, name, pfstype_symlink);
pn->pn_fill = fill;
pn->pn_attr = attr;
pn->pn_vis = vis;
pn->pn_destroy = destroy;
pn->pn_flags = flags;
pfs_add_node(parent, pn);
return (pn);
}
/*
* Locate a node by name
*/
struct pfs_node *
pfs_find_node(struct pfs_node *parent, const char *name)
{
struct pfs_node *pn;
pfs_lock(parent);
for (pn = parent->pn_nodes; pn != NULL; pn = pn->pn_next)
if (strcmp(pn->pn_name, name) == 0)
break;
pfs_unlock(parent);
return (pn);
}
/*
* Destroy a node and all its descendants. If the node to be destroyed
* has a parent, the parent's mutex must be held.
*/
int
pfs_destroy(struct pfs_node *pn)
{
struct pfs_node *iter;
KASSERT(pn != NULL,
("%s(): node is NULL", __func__));
KASSERT(pn->pn_info != NULL,
("%s(): node has no pn_info", __func__));
if (pn->pn_parent)
pfs_detach_node(pn);
/* destroy children */
if (pn->pn_type == pfstype_dir ||
pn->pn_type == pfstype_procdir ||
pn->pn_type == pfstype_root) {
pfs_lock(pn);
while (pn->pn_nodes != NULL) {
iter = pn->pn_nodes;
pn->pn_nodes = iter->pn_next;
iter->pn_parent = NULL;
pfs_unlock(pn);
pfs_destroy(iter);
pfs_lock(pn);
}
pfs_unlock(pn);
}
/* revoke vnodes and fileno */
pfs_purge(pn);
/* callback to free any private resources */
if (pn->pn_destroy != NULL)
pn_destroy(pn);
/* destroy the node */
pfs_fileno_free(pn);
mtx_destroy(&pn->pn_mutex);
free(pn, M_PFSNODES);
return (0);
}
/*
* Mount a pseudofs instance
*/
int
pfs_mount(struct pfs_info *pi, struct mount *mp)
{
struct statfs *sbp;
if (mp->mnt_flag & MNT_UPDATE)
return (EOPNOTSUPP);
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_LOCAL;
MNT_IUNLOCK(mp);
mp->mnt_data = pi;
vfs_getnewfsid(mp);
sbp = &mp->mnt_stat;
vfs_mountedfrom(mp, pi->pi_name);
sbp->f_bsize = PAGE_SIZE;
sbp->f_iosize = PAGE_SIZE;
sbp->f_blocks = 1;
sbp->f_bfree = 0;
sbp->f_bavail = 0;
sbp->f_files = 1;
sbp->f_ffree = 0;
return (0);
}
/*
* Compatibility shim for old mount(2) system call
*/
int
pfs_cmount(struct mntarg *ma, void *data, uint64_t flags)
{
int error;
error = kernel_mount(ma, flags);
return (error);
}
/*
* Unmount a pseudofs instance
*/
int
pfs_unmount(struct mount *mp, int mntflags)
{
int error;
error = vflush(mp, 0, (mntflags & MNT_FORCE) ? FORCECLOSE : 0,
curthread);
return (error);
}
/*
* Return a root vnode
*/
int
pfs_root(struct mount *mp, int flags, struct vnode **vpp)
{
struct pfs_info *pi;
pi = (struct pfs_info *)mp->mnt_data;
return (pfs_vncache_alloc(mp, vpp, pi->pi_root, NO_PID));
}
/*
* Return filesystem stats
*/
int
pfs_statfs(struct mount *mp, struct statfs *sbp)
{
/* no-op: always called with mp->mnt_stat */
return (0);
}
/*
* Initialize a pseudofs instance
*/
int
pfs_init(struct pfs_info *pi, struct vfsconf *vfc)
{
struct pfs_node *root;
int error;
pfs_fileno_init(pi);
/* set up the root directory */
root = pfs_alloc_node(pi, "/", pfstype_root);
pi->pi_root = root;
pfs_fileno_alloc(root);
pfs_fixup_dir(root);
/* construct file hierarchy */
error = (pi->pi_init)(pi, vfc);
if (error) {
pfs_destroy(root);
pi->pi_root = NULL;
return (error);
}
if (bootverbose)
printf("%s registered\n", pi->pi_name);
return (0);
}
/*
* Destroy a pseudofs instance
*/
int
pfs_uninit(struct pfs_info *pi, struct vfsconf *vfc)
{
int error;
pfs_destroy(pi->pi_root);
pi->pi_root = NULL;
pfs_fileno_uninit(pi);
if (bootverbose)
printf("%s unregistered\n", pi->pi_name);
error = (pi->pi_uninit)(pi, vfc);
return (error);
}
/*
* Handle load / unload events
*/
static int
pfs_modevent(module_t mod, int evt, void *arg)
{
switch (evt) {
case MOD_LOAD:
pfs_vncache_load();
break;
case MOD_UNLOAD:
case MOD_SHUTDOWN:
pfs_vncache_unload();
break;
default:
return EOPNOTSUPP;
break;
}
return 0;
}
/*
* Module declaration
*/
static moduledata_t pseudofs_data = {
"pseudofs",
pfs_modevent,
NULL
};
DECLARE_MODULE(pseudofs, pseudofs_data, SI_SUB_EXEC, SI_ORDER_FIRST);
MODULE_VERSION(pseudofs, 1);