/*
* Run the chain and if the bottom-most object is a vnode-type lock the
* underlying vnode. A locked vnode or NULL is returned.
*/
struct vnode *
vnode_pager_lock(vm_object_t object)
{
struct vnode *vp = NULL;
vm_object_t lobject;
vm_object_t tobject;
int error;
if (object == NULL)
return(NULL);
ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
lobject = object;
while (lobject->type != OBJT_VNODE) {
if (lobject->flags & OBJ_DEAD)
break;
tobject = lobject->backing_object;
if (tobject == NULL)
break;
vm_object_hold_shared(tobject);
if (tobject == lobject->backing_object) {
if (lobject != object) {
vm_object_lock_swap();
vm_object_drop(lobject);
}
lobject = tobject;
} else {
vm_object_drop(tobject);
}
}
while (lobject->type == OBJT_VNODE &&
(lobject->flags & OBJ_DEAD) == 0) {
/*
* Extract the vp
*/
vp = lobject->handle;
error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE);
if (error == 0) {
if (lobject->handle == vp)
break;
vput(vp);
} else {
kprintf("vnode_pager_lock: vp %p error %d "
"lockstatus %d, retrying\n",
vp, error,
lockstatus(&vp->v_lock, curthread));
tsleep(object->handle, 0, "vnpgrl", hz);
}
vp = NULL;
}
if (lobject != object)
vm_object_drop(lobject);
return (vp);
}
/*
* The map entries can *almost* be read with programs like cat. However,
* large maps need special programs to read. It is not easy to implement
* a program that can sense the required size of the buffer, and then
* subsequently do a read with the appropriate size. This operation cannot
* be atomic. The best that we can do is to allow the program to do a read
* with an arbitrarily large buffer, and return as much as we can. We can
* return an error code if the buffer is too small (EFBIG), then the program
* can try a bigger buffer.
*/
int
procfs_domap(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
struct uio *uio)
{
struct proc *p = lp->lwp_proc;
int len;
struct vnode *vp;
char *fullpath, *freepath;
int error;
vm_map_t map = &p->p_vmspace->vm_map;
pmap_t pmap = vmspace_pmap(p->p_vmspace);
vm_map_entry_t entry;
char mebuffer[MEBUFFERSIZE];
if (uio->uio_rw != UIO_READ)
return (EOPNOTSUPP);
if (uio->uio_offset != 0)
return (0);
error = 0;
vm_map_lock_read(map);
for (entry = map->header.next;
((uio->uio_resid > 0) && (entry != &map->header));
entry = entry->next) {
vm_object_t obj, tobj, lobj;
int ref_count, shadow_count, flags;
vm_offset_t addr;
vm_offset_t ostart;
int resident, privateresident;
char *type;
if (entry->maptype != VM_MAPTYPE_NORMAL &&
entry->maptype != VM_MAPTYPE_VPAGETABLE) {
continue;
}
obj = entry->object.vm_object;
if (obj)
vm_object_hold(obj);
if (obj && (obj->shadow_count == 1))
privateresident = obj->resident_page_count;
else
privateresident = 0;
/*
* Use map->hint as a poor man's ripout detector.
*/
map->hint = entry;
ostart = entry->start;
/*
* Count resident pages (XXX can be horrible on 64-bit)
*/
resident = 0;
addr = entry->start;
while (addr < entry->end) {
if (pmap_extract(pmap, addr))
resident++;
addr += PAGE_SIZE;
}
if (obj) {
lobj = obj;
while ((tobj = lobj->backing_object) != NULL) {
KKASSERT(tobj != obj);
vm_object_hold(tobj);
if (tobj == lobj->backing_object) {
if (lobj != obj) {
vm_object_lock_swap();
vm_object_drop(lobj);
}
lobj = tobj;
} else {
vm_object_drop(tobj);
}
}
} else {
lobj = NULL;
}
freepath = NULL;
fullpath = "-";
if (lobj) {
switch(lobj->type) {
default:
case OBJT_DEFAULT:
type = "default";
vp = NULL;
break;
case OBJT_VNODE:
type = "vnode";
vp = lobj->handle;
vref(vp);
break;
case OBJT_SWAP:
type = "swap";
vp = NULL;
break;
case OBJT_DEVICE:
type = "device";
vp = NULL;
break;
}
flags = obj->flags;
ref_count = obj->ref_count;
shadow_count = obj->shadow_count;
if (vp != NULL) {
vn_fullpath(p, vp, &fullpath, &freepath, 1);
vrele(vp);
}
if (lobj != obj)
vm_object_drop(lobj);
} else {
type = "none";
flags = 0;
ref_count = 0;
shadow_count = 0;
}
/*
* format:
* start, end, res, priv res, cow, access, type, (fullpath).
*/
ksnprintf(mebuffer, sizeof(mebuffer),
#if LONG_BIT == 64
"0x%016lx 0x%016lx %d %d %p %s%s%s %d %d "
#else
"0x%08lx 0x%08lx %d %d %p %s%s%s %d %d "
#endif
"0x%04x %s %s %s %s\n",
(u_long)entry->start, (u_long)entry->end,
resident, privateresident, obj,
(entry->protection & VM_PROT_READ)?"r":"-",
(entry->protection & VM_PROT_WRITE)?"w":"-",
(entry->protection & VM_PROT_EXECUTE)?"x":"-",
ref_count, shadow_count, flags,
(entry->eflags & MAP_ENTRY_COW)?"COW":"NCOW",
(entry->eflags & MAP_ENTRY_NEEDS_COPY)?"NC":"NNC",
type, fullpath);
if (obj)
vm_object_drop(obj);
if (freepath != NULL) {
kfree(freepath, M_TEMP);
freepath = NULL;
}
len = strlen(mebuffer);
if (len > uio->uio_resid) {
error = EFBIG;
break;
}
/*
* We cannot safely hold the map locked while accessing
* userspace as a VM fault might recurse the locked map.
*/
vm_map_unlock_read(map);
error = uiomove(mebuffer, len, uio);
vm_map_lock_read(map);
if (error)
break;
/*
* We use map->hint as a poor man's ripout detector. If
* it does not match the entry we set it to prior to
* unlocking the map the entry MIGHT now be stale. In
* this case we do an expensive lookup to find our place
* in the iteration again.
*/
if (map->hint != entry) {
vm_map_entry_t reentry;
vm_map_lookup_entry(map, ostart, &reentry);
entry = reentry;
}
}
vm_map_unlock_read(map);
return error;
}
