/*
* Copy a binary buffer from kernel space to user space.
*
* Returns 0 on success, EFAULT on failure.
*/
int
copyout(const void *kaddr, void *udaddr, size_t len)
{
struct vmspace *vm = curproc->p_vmspace;
struct lwbuf *lwb;
struct lwbuf lwb_cache;
vm_page_t m;
int error;
size_t n;
error = 0;
while (len) {
m = vm_fault_page(&vm->vm_map, trunc_page((vm_offset_t)udaddr),
VM_PROT_READ|VM_PROT_WRITE,
VM_FAULT_NORMAL, &error);
if (error)
break;
n = PAGE_SIZE - ((vm_offset_t)udaddr & PAGE_MASK);
if (n > len)
n = len;
lwb = lwbuf_alloc(m, &lwb_cache);
bcopy(kaddr, (char *)lwbuf_kva(lwb) +
((vm_offset_t)udaddr & PAGE_MASK), n);
len -= n;
udaddr = (char *)udaddr + n;
kaddr = (const char *)kaddr + n;
vm_page_dirty(m);
lwbuf_free(lwb);
vm_page_unhold(m);
}
return (error);
}
/*
* Copy the specified number of bytes from userland to the xio.
* Return an error code or 0 on success.
*
* uoffset is the abstracted starting offset in the XIO, not the actual
* offset, and usually starts at 0.
*
* Data in pages backing the XIO will be modified.
*/
int
xio_copy_utox(xio_t xio, int uoffset, const void *uptr, int bytes)
{
int i;
int n;
int error;
int offset;
vm_page_t m;
struct lwbuf *lwb;
struct lwbuf lwb_cache;
if (uoffset + bytes > xio->xio_bytes)
return(EFAULT);
offset = (xio->xio_offset + uoffset) & PAGE_MASK;
if ((n = PAGE_SIZE - offset) > bytes)
n = bytes;
error = 0;
for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT;
i < xio->xio_npages;
++i
) {
m = xio->xio_pages[i];
lwb = lwbuf_alloc(m, &lwb_cache);
error = copyin(uptr, (char *)lwbuf_kva(lwb) + offset, n);
lwbuf_free(lwb);
if (error)
break;
bytes -= n;
uptr = (const char *)uptr + n;
if (bytes == 0)
break;
if ((n = bytes) > PAGE_SIZE)
n = PAGE_SIZE;
offset = 0;
}
return(error);
}
/*
* Copy the specified number of bytes from the xio to a kernel
* buffer. Return an error code or 0 on success.
*
* uoffset is the abstracted starting offset in the XIO, not the actual
* offset, and usually starts at 0.
*
* The XIO is not modified.
*/
int
xio_copy_xtok(xio_t xio, int uoffset, void *kptr, int bytes)
{
int i;
int n;
int error;
int offset;
vm_page_t m;
struct lwbuf *lwb;
struct lwbuf lwb_cache;
if (bytes + uoffset > xio->xio_bytes)
return(EFAULT);
offset = (xio->xio_offset + uoffset) & PAGE_MASK;
if ((n = PAGE_SIZE - offset) > bytes)
n = bytes;
error = 0;
for (i = (xio->xio_offset + uoffset) >> PAGE_SHIFT;
i < xio->xio_npages;
++i
) {
m = xio->xio_pages[i];
lwb = lwbuf_alloc(m, &lwb_cache);
bcopy((char *)lwbuf_kva(lwb) + offset, kptr, n);
lwbuf_free(lwb);
bytes -= n;
kptr = (char *)kptr + n;
if (bytes == 0)
break;
if ((n = bytes) > PAGE_SIZE)
n = PAGE_SIZE;
offset = 0;
}
return(error);
}
/*
* Implement uiomove(9) from physical memory using lwbuf's to reduce
* the creation and destruction of ephemeral mappings.
*/
int
uiomove_fromphys(vm_page_t *ma, vm_offset_t offset, size_t n, struct uio *uio)
{
struct lwbuf lwb_cache;
struct lwbuf *lwb;
struct thread *td = curthread;
struct iovec *iov;
void *cp;
vm_offset_t page_offset;
vm_page_t m;
size_t cnt;
int error = 0;
int save = 0;
KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
("uiomove_fromphys: mode"));
KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
("uiomove_fromphys proc"));
crit_enter();
save = td->td_flags & TDF_DEADLKTREAT;
td->td_flags |= TDF_DEADLKTREAT;
crit_exit();
while (n > 0 && uio->uio_resid) {
iov = uio->uio_iov;
cnt = iov->iov_len;
if (cnt == 0) {
uio->uio_iov++;
uio->uio_iovcnt--;
continue;
}
if (cnt > n)
cnt = n;
page_offset = offset & PAGE_MASK;
cnt = min(cnt, PAGE_SIZE - page_offset);
m = ma[offset >> PAGE_SHIFT];
lwb = lwbuf_alloc(m, &lwb_cache);
cp = (char *)lwbuf_kva(lwb) + page_offset;
switch (uio->uio_segflg) {
case UIO_USERSPACE:
/*
* note: removed uioyield (it was the wrong place to
* put it).
*/
if (uio->uio_rw == UIO_READ)
error = copyout(cp, iov->iov_base, cnt);
else
error = copyin(iov->iov_base, cp, cnt);
if (error) {
lwbuf_free(lwb);
goto out;
}
break;
case UIO_SYSSPACE:
if (uio->uio_rw == UIO_READ)
bcopy(cp, iov->iov_base, cnt);
else
bcopy(iov->iov_base, cp, cnt);
break;
case UIO_NOCOPY:
break;
}
lwbuf_free(lwb);
iov->iov_base = (char *)iov->iov_base + cnt;
iov->iov_len -= cnt;
uio->uio_resid -= cnt;
uio->uio_offset += cnt;
offset += cnt;
n -= cnt;
}
out:
if (save == 0) {
crit_enter();
td->td_flags &= ~TDF_DEADLKTREAT;
crit_exit();
}
return (error);
}
/*
* Lets the VM system know about a change in size for a file.
* We adjust our own internal size and flush any cached pages in
* the associated object that are affected by the size change.
*
* NOTE: This routine may be invoked as a result of a pager put
* operation (possibly at object termination time), so we must be careful.
*
* NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that
* we do not blow up on the case. nsize will always be >= 0, however.
*/
void
vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
{
vm_pindex_t nobjsize;
vm_pindex_t oobjsize;
vm_object_t object;
object = vp->v_object;
if (object == NULL)
return;
vm_object_hold(object);
KKASSERT(vp->v_object == object);
/*
* Hasn't changed size
*/
if (nsize == vp->v_filesize) {
vm_object_drop(object);
return;
}
/*
* Has changed size. Adjust the VM object's size and v_filesize
* before we start scanning pages to prevent new pages from being
* allocated during the scan.
*/
nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
oobjsize = object->size;
object->size = nobjsize;
/*
* File has shrunk. Toss any cached pages beyond the new EOF.
*/
if (nsize < vp->v_filesize) {
vp->v_filesize = nsize;
if (nobjsize < oobjsize) {
vm_object_page_remove(object, nobjsize, oobjsize,
FALSE);
}
/*
* This gets rid of garbage at the end of a page that is now
* only partially backed by the vnode. Since we are setting
* the entire page valid & clean after we are done we have
* to be sure that the portion of the page within the file
* bounds is already valid. If it isn't then making it
* valid would create a corrupt block.
*/
if (nsize & PAGE_MASK) {
vm_offset_t kva;
vm_page_t m;
m = vm_page_lookup_busy_wait(object, OFF_TO_IDX(nsize),
TRUE, "vsetsz");
if (m && m->valid) {
int base = (int)nsize & PAGE_MASK;
int size = PAGE_SIZE - base;
struct lwbuf *lwb;
struct lwbuf lwb_cache;
/*
* Clear out partial-page garbage in case
* the page has been mapped.
*
* This is byte aligned.
*/
lwb = lwbuf_alloc(m, &lwb_cache);
kva = lwbuf_kva(lwb);
bzero((caddr_t)kva + base, size);
lwbuf_free(lwb);
/*
* XXX work around SMP data integrity race
* by unmapping the page from user processes.
* The garbage we just cleared may be mapped
* to a user process running on another cpu
* and this code is not running through normal
* I/O channels which handle SMP issues for
* us, so unmap page to synchronize all cpus.
*
* XXX should vm_pager_unmap_page() have
* dealt with this?
*/
vm_page_protect(m, VM_PROT_NONE);
/*
* Clear out partial-page dirty bits. This
* has the side effect of setting the valid
* bits, but that is ok. There are a bunch
* of places in the VM system where we expected
* m->dirty == VM_PAGE_BITS_ALL. The file EOF
* case is one of them. If the page is still
* partially dirty, make it fully dirty.
*
* NOTE: We do not clear out the valid
* bits. This would prevent bogus_page
* replacement from working properly.
*
* NOTE: We do not want to clear the dirty
* bit for a partial DEV_BSIZE'd truncation!
* This is DEV_BSIZE aligned!
*/
vm_page_clear_dirty_beg_nonincl(m, base, size);
if (m->dirty != 0)
m->dirty = VM_PAGE_BITS_ALL;
vm_page_wakeup(m);
} else if (m) {
vm_page_wakeup(m);
}
}
} else {
vp->v_filesize = nsize;
}
vm_object_drop(object);
}
/*
* A VFS can call this function to try to dispose of a read request
* directly from the VM system, pretty much bypassing almost all VFS
* overhead except for atime updates.
*
* If 0 is returned some or all of the uio was handled. The caller must
* check the uio and handle the remainder.
*
* The caller must fail on a non-zero error.
*/
int
vop_helper_read_shortcut(struct vop_read_args *ap)
{
struct vnode *vp;
struct uio *uio;
struct lwbuf *lwb;
struct lwbuf lwb_cache;
vm_object_t obj;
vm_page_t m;
int offset;
int n;
int error;
vp = ap->a_vp;
uio = ap->a_uio;
/*
* We can't short-cut if there is no VM object or this is a special
* UIO_NOCOPY read (typically from VOP_STRATEGY()). We also can't
* do this if we cannot extract the filesize from the vnode.
*/
if (vm_read_shortcut_enable == 0)
return(0);
if (vp->v_object == NULL || uio->uio_segflg == UIO_NOCOPY)
return(0);
if (vp->v_filesize == NOOFFSET)
return(0);
if (uio->uio_resid == 0)
return(0);
/*
* Iterate the uio on a page-by-page basis
*
* XXX can we leave the object held shared during the uiomove()?
*/
++vm_read_shortcut_count;
obj = vp->v_object;
vm_object_hold_shared(obj);
error = 0;
while (uio->uio_resid && error == 0) {
offset = (int)uio->uio_offset & PAGE_MASK;
n = PAGE_SIZE - offset;
if (n > uio->uio_resid)
n = uio->uio_resid;
if (vp->v_filesize < uio->uio_offset)
break;
if (uio->uio_offset + n > vp->v_filesize)
n = vp->v_filesize - uio->uio_offset;
if (n == 0)
break; /* hit EOF */
m = vm_page_lookup_busy_try(obj, OFF_TO_IDX(uio->uio_offset),
FALSE, &error);
if (error || m == NULL) {
++vm_read_shortcut_failed;
error = 0;
break;
}
if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
++vm_read_shortcut_failed;
vm_page_wakeup(m);
break;
}
lwb = lwbuf_alloc(m, &lwb_cache);
/*
* Use a no-fault uiomove() to avoid deadlocking against
* our VM object (which could livelock on the same object
* due to shared-vs-exclusive), or deadlocking against
* our busied page. Returns EFAULT on any fault which
* winds up diving a vnode.
*/
error = uiomove_nofault((char *)lwbuf_kva(lwb) + offset,
n, uio);
vm_page_flag_set(m, PG_REFERENCED);
lwbuf_free(lwb);
vm_page_wakeup(m);
}
vm_object_drop(obj);
/*
* Ignore EFAULT since we used uiomove_nofault(), causes caller
* to fall-back to normal code for this case.
*/
if (error == EFAULT)
error = 0;
return (error);
}
/*
* MPSAFE thread
*/
static void
vm_pagezero(void *arg)
{
vm_page_t m = NULL;
struct lwbuf *lwb = NULL;
struct lwbuf lwb_cache;
enum zeroidle_state state = STATE_IDLE;
char *pg = NULL;
int npages = 0;
int sleep_time;
int i = 0;
int cpu = (int)(intptr_t)arg;
int zero_state = 0;
/*
* Adjust thread parameters before entering our loop. The thread
* is started with the MP lock held and with normal kernel thread
* priority.
*
* Also put us on the last cpu for now.
*
* For now leave the MP lock held, the VM routines cannot be called
* with it released until tokenization is finished.
*/
lwkt_setpri_self(TDPRI_IDLE_WORK);
lwkt_setcpu_self(globaldata_find(cpu));
sleep_time = DEFAULT_SLEEP_TIME;
/*
* Loop forever
*/
for (;;) {
int zero_count;
switch(state) {
case STATE_IDLE:
/*
* Wait for work.
*/
tsleep(&zero_state, 0, "pgzero", sleep_time);
if (vm_page_zero_check(&zero_count, &zero_state))
npages = idlezero_rate / 10;
sleep_time = vm_page_zero_time(zero_count);
if (npages)
state = STATE_GET_PAGE; /* Fallthrough */
break;
case STATE_GET_PAGE:
/*
* Acquire page to zero
*/
if (--npages == 0) {
state = STATE_IDLE;
} else {
m = vm_page_free_fromq_fast();
if (m == NULL) {
state = STATE_IDLE;
} else {
state = STATE_ZERO_PAGE;
lwb = lwbuf_alloc(m, &lwb_cache);
pg = (char *)lwbuf_kva(lwb);
i = 0;
}
}
break;
case STATE_ZERO_PAGE:
/*
* Zero-out the page
*/
while (i < PAGE_SIZE) {
if (idlezero_nocache == 1)
bzeront(&pg[i], IDLEZERO_RUN);
else
bzero(&pg[i], IDLEZERO_RUN);
i += IDLEZERO_RUN;
lwkt_yield();
}
state = STATE_RELEASE_PAGE;
break;
case STATE_RELEASE_PAGE:
lwbuf_free(lwb);
vm_page_flag_set(m, PG_ZERO);
vm_page_free_toq(m);
state = STATE_GET_PAGE;
++idlezero_count; /* non-locked, SMP race ok */
break;
}
lwkt_yield();
}
}
