Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
NetBSD/sys/miscfs/genfs/genfs_io.c

1705 lines
43 KiB
C
Raw Blame History

/* $NetBSD: genfs_io.c,v 1.6 2008/04/19 11:53:13 hannken Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. 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.
* 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. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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>
__KERNEL_RCSID(0, "$NetBSD: genfs_io.c,v 1.6 2008/04/19 11:53:13 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/kmem.h>
#include <sys/poll.h>
#include <sys/mman.h>
#include <sys/file.h>
#include <sys/kauth.h>
#include <sys/fstrans.h>
#include <miscfs/genfs/genfs.h>
#include <miscfs/genfs/genfs_node.h>
#include <miscfs/specfs/specdev.h>
#include <uvm/uvm.h>
#include <uvm/uvm_pager.h>
static int genfs_do_directio(struct vmspace *, vaddr_t, size_t, struct vnode *,
off_t, enum uio_rw);
static void genfs_dio_iodone(struct buf *);
static int genfs_do_io(struct vnode *, off_t, vaddr_t, size_t, int, enum uio_rw,
void (*)(struct buf *));
static inline void genfs_rel_pages(struct vm_page **, int);
#define MAX_READ_PAGES 16 /* XXXUBC 16 */
int genfs_maxdio = MAXPHYS;
static inline void
genfs_rel_pages(struct vm_page **pgs, int npages)
{
int i;
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[i];
if (pg == NULL || pg == PGO_DONTCARE)
continue;
if (pg->flags & PG_FAKE) {
pg->flags |= PG_RELEASED;
}
}
mutex_enter(&uvm_pageqlock);
uvm_page_unbusy(pgs, npages);
mutex_exit(&uvm_pageqlock);
}
/*
* generic VM getpages routine.
* Return PG_BUSY pages for the given range,
* reading from backing store if necessary.
*/
int
genfs_getpages(void *v)
{
struct vop_getpages_args /* {
struct vnode *a_vp;
voff_t a_offset;
struct vm_page **a_m;
int *a_count;
int a_centeridx;
vm_prot_t a_access_type;
int a_advice;
int a_flags;
} */ *ap = v;
off_t newsize, diskeof, memeof;
off_t offset, origoffset, startoffset, endoffset;
daddr_t lbn, blkno;
int i, error, npages, orignpages, npgs, run, ridx, pidx, pcount;
int fs_bshift, fs_bsize, dev_bshift;
int flags = ap->a_flags;
size_t bytes, iobytes, tailstart, tailbytes, totalbytes, skipbytes;
vaddr_t kva;
struct buf *bp, *mbp;
struct vnode *vp = ap->a_vp;
struct vnode *devvp;
struct genfs_node *gp = VTOG(vp);
struct uvm_object *uobj = &vp->v_uobj;
struct vm_page *pg, **pgs, *pgs_onstack[MAX_READ_PAGES];
int pgs_size;
kauth_cred_t cred = curlwp->l_cred; /* XXXUBC curlwp */
bool async = (flags & PGO_SYNCIO) == 0;
bool write = (ap->a_access_type & VM_PROT_WRITE) != 0;
bool sawhole = false;
bool has_trans = false;
bool overwrite = (flags & PGO_OVERWRITE) != 0;
bool blockalloc = write && (flags & PGO_NOBLOCKALLOC) == 0;
voff_t origvsize;
UVMHIST_FUNC("genfs_getpages"); UVMHIST_CALLED(ubchist);
UVMHIST_LOG(ubchist, "vp %p off 0x%x/%x count %d",
vp, ap->a_offset >> 32, ap->a_offset, *ap->a_count);
KASSERT(vp->v_type == VREG || vp->v_type == VDIR ||
vp->v_type == VLNK || vp->v_type == VBLK);
/* XXXUBC temp limit */
if (*ap->a_count > MAX_READ_PAGES) {
panic("genfs_getpages: too many pages");
}
pgs = pgs_onstack;
pgs_size = sizeof(pgs_onstack);
startover:
error = 0;
origvsize = vp->v_size;
origoffset = ap->a_offset;
orignpages = *ap->a_count;
GOP_SIZE(vp, origvsize, &diskeof, 0);
if (flags & PGO_PASTEOF) {
#if defined(DIAGNOSTIC)
off_t writeeof;
#endif /* defined(DIAGNOSTIC) */
newsize = MAX(origvsize,
origoffset + (orignpages << PAGE_SHIFT));
GOP_SIZE(vp, newsize, &memeof, GOP_SIZE_MEM);
#if defined(DIAGNOSTIC)
GOP_SIZE(vp, vp->v_writesize, &writeeof, GOP_SIZE_MEM);
if (newsize > round_page(writeeof)) {
panic("%s: past eof", __func__);
}
#endif /* defined(DIAGNOSTIC) */
} else {
GOP_SIZE(vp, origvsize, &memeof, GOP_SIZE_MEM);
}
KASSERT(ap->a_centeridx >= 0 || ap->a_centeridx <= orignpages);
KASSERT((origoffset & (PAGE_SIZE - 1)) == 0 && origoffset >= 0);
KASSERT(orignpages > 0);
/*
* Bounds-check the request.
*/
if (origoffset + (ap->a_centeridx << PAGE_SHIFT) >= memeof) {
if ((flags & PGO_LOCKED) == 0) {
mutex_exit(&uobj->vmobjlock);
}
UVMHIST_LOG(ubchist, "off 0x%x count %d goes past EOF 0x%x",
origoffset, *ap->a_count, memeof,0);
error = EINVAL;
goto out_err;
}
/* uobj is locked */
if ((flags & PGO_NOTIMESTAMP) == 0 &&
(vp->v_type != VBLK ||
(vp->v_mount->mnt_flag & MNT_NODEVMTIME) == 0)) {
int updflags = 0;
if ((vp->v_mount->mnt_flag & MNT_NOATIME) == 0) {
updflags = GOP_UPDATE_ACCESSED;
}
if (write) {
updflags |= GOP_UPDATE_MODIFIED;
}
if (updflags != 0) {
GOP_MARKUPDATE(vp, updflags);
}
}
if (write) {
gp->g_dirtygen++;
if ((vp->v_iflag & VI_ONWORKLST) == 0) {
vn_syncer_add_to_worklist(vp, filedelay);
}
if ((vp->v_iflag & (VI_WRMAP|VI_WRMAPDIRTY)) == VI_WRMAP) {
vp->v_iflag |= VI_WRMAPDIRTY;
}
}
/*
* For PGO_LOCKED requests, just return whatever's in memory.
*/
if (flags & PGO_LOCKED) {
int nfound;
npages = *ap->a_count;
#if defined(DEBUG)
for (i = 0; i < npages; i++) {
pg = ap->a_m[i];
KASSERT(pg == NULL || pg == PGO_DONTCARE);
}
#endif /* defined(DEBUG) */
nfound = uvn_findpages(uobj, origoffset, &npages,
ap->a_m, UFP_NOWAIT|UFP_NOALLOC|(write ? UFP_NORDONLY : 0));
KASSERT(npages == *ap->a_count);
if (nfound == 0) {
error = EBUSY;
goto out_err;
}
if (!rw_tryenter(&gp->g_glock, RW_READER)) {
genfs_rel_pages(ap->a_m, npages);
/*
* restore the array.
*/
for (i = 0; i < npages; i++) {
pg = ap->a_m[i];
if (pg != NULL || pg != PGO_DONTCARE) {
ap->a_m[i] = NULL;
}
}
} else {
rw_exit(&gp->g_glock);
}
error = (ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0);
goto out_err;
}
mutex_exit(&uobj->vmobjlock);
/*
* find the requested pages and make some simple checks.
* leave space in the page array for a whole block.
*/
if (vp->v_type != VBLK) {
fs_bshift = vp->v_mount->mnt_fs_bshift;
dev_bshift = vp->v_mount->mnt_dev_bshift;
} else {
fs_bshift = DEV_BSHIFT;
dev_bshift = DEV_BSHIFT;
}
fs_bsize = 1 << fs_bshift;
orignpages = MIN(orignpages,
round_page(memeof - origoffset) >> PAGE_SHIFT);
npages = orignpages;
startoffset = origoffset & ~(fs_bsize - 1);
endoffset = round_page((origoffset + (npages << PAGE_SHIFT) +
fs_bsize - 1) & ~(fs_bsize - 1));
endoffset = MIN(endoffset, round_page(memeof));
ridx = (origoffset - startoffset) >> PAGE_SHIFT;
pgs_size = sizeof(struct vm_page *) *
((endoffset - startoffset) >> PAGE_SHIFT);
if (pgs_size > sizeof(pgs_onstack)) {
pgs = kmem_zalloc(pgs_size, async ? KM_NOSLEEP : KM_SLEEP);
if (pgs == NULL) {
pgs = pgs_onstack;
error = ENOMEM;
goto out_err;
}
} else {
/* pgs == pgs_onstack */
memset(pgs, 0, pgs_size);
}
UVMHIST_LOG(ubchist, "ridx %d npages %d startoff %ld endoff %ld",
ridx, npages, startoffset, endoffset);
if (!has_trans) {
fstrans_start(vp->v_mount, FSTRANS_SHARED);
has_trans = true;
}
/*
* hold g_glock to prevent a race with truncate.
*
* check if our idea of v_size is still valid.
*/
if (blockalloc) {
rw_enter(&gp->g_glock, RW_WRITER);
} else {
rw_enter(&gp->g_glock, RW_READER);
}
mutex_enter(&uobj->vmobjlock);
if (vp->v_size < origvsize) {
rw_exit(&gp->g_glock);
if (pgs != pgs_onstack)
kmem_free(pgs, pgs_size);
goto startover;
}
if (uvn_findpages(uobj, origoffset, &npages, &pgs[ridx],
async ? UFP_NOWAIT : UFP_ALL) != orignpages) {
rw_exit(&gp->g_glock);
KASSERT(async != 0);
genfs_rel_pages(&pgs[ridx], orignpages);
mutex_exit(&uobj->vmobjlock);
error = EBUSY;
goto out_err;
}
/*
* if the pages are already resident, just return them.
*/
for (i = 0; i < npages; i++) {
struct vm_page *pg1 = pgs[ridx + i];
if ((pg1->flags & PG_FAKE) ||
(blockalloc && (pg1->flags & PG_RDONLY))) {
break;
}
}
if (i == npages) {
rw_exit(&gp->g_glock);
UVMHIST_LOG(ubchist, "returning cached pages", 0,0,0,0);
npages += ridx;
goto out;
}
/*
* if PGO_OVERWRITE is set, don't bother reading the pages.
*/
if (overwrite) {
rw_exit(&gp->g_glock);
UVMHIST_LOG(ubchist, "PGO_OVERWRITE",0,0,0,0);
for (i = 0; i < npages; i++) {
struct vm_page *pg1 = pgs[ridx + i];
pg1->flags &= ~(PG_RDONLY|PG_CLEAN);
}
npages += ridx;
goto out;
}
/*
* the page wasn't resident and we're not overwriting,
* so we're going to have to do some i/o.
* find any additional pages needed to cover the expanded range.
*/
npages = (endoffset - startoffset) >> PAGE_SHIFT;
if (startoffset != origoffset || npages != orignpages) {
/*
* we need to avoid deadlocks caused by locking
* additional pages at lower offsets than pages we
* already have locked. unlock them all and start over.
*/
genfs_rel_pages(&pgs[ridx], orignpages);
memset(pgs, 0, pgs_size);
UVMHIST_LOG(ubchist, "reset npages start 0x%x end 0x%x",
startoffset, endoffset, 0,0);
npgs = npages;
if (uvn_findpages(uobj, startoffset, &npgs, pgs,
async ? UFP_NOWAIT : UFP_ALL) != npages) {
rw_exit(&gp->g_glock);
KASSERT(async != 0);
genfs_rel_pages(pgs, npages);
mutex_exit(&uobj->vmobjlock);
error = EBUSY;
goto out_err;
}
}
mutex_exit(&uobj->vmobjlock);
/*
* read the desired page(s).
*/
totalbytes = npages << PAGE_SHIFT;
bytes = MIN(totalbytes, MAX(diskeof - startoffset, 0));
tailbytes = totalbytes - bytes;
skipbytes = 0;
kva = uvm_pagermapin(pgs, npages,
UVMPAGER_MAPIN_READ | UVMPAGER_MAPIN_WAITOK);
mbp = getiobuf(vp, true);
mbp->b_bufsize = totalbytes;
mbp->b_data = (void *)kva;
mbp->b_resid = mbp->b_bcount = bytes;
mbp->b_cflags = BC_BUSY;
if (async) {
mbp->b_flags = B_READ | B_ASYNC;
mbp->b_iodone = uvm_aio_biodone;
} else {
mbp->b_flags = B_READ;
mbp->b_iodone = NULL;
}
if (async)
BIO_SETPRIO(mbp, BPRIO_TIMELIMITED);
else
BIO_SETPRIO(mbp, BPRIO_TIMECRITICAL);
/*
* if EOF is in the middle of the range, zero the part past EOF.
* skip over pages which are not PG_FAKE since in that case they have
* valid data that we need to preserve.
*/
tailstart = bytes;
while (tailbytes > 0) {
const int len = PAGE_SIZE - (tailstart & PAGE_MASK);
KASSERT(len <= tailbytes);
if ((pgs[tailstart >> PAGE_SHIFT]->flags & PG_FAKE) != 0) {
memset((void *)(kva + tailstart), 0, len);
UVMHIST_LOG(ubchist, "tailbytes %p 0x%x 0x%x",
kva, tailstart, len, 0);
}
tailstart += len;
tailbytes -= len;
}
/*
* now loop over the pages, reading as needed.
*/
bp = NULL;
for (offset = startoffset;
bytes > 0;
offset += iobytes, bytes -= iobytes) {
/*
* skip pages which don't need to be read.
*/
pidx = (offset - startoffset) >> PAGE_SHIFT;
while ((pgs[pidx]->flags & PG_FAKE) == 0) {
size_t b;
KASSERT((offset & (PAGE_SIZE - 1)) == 0);
if ((pgs[pidx]->flags & PG_RDONLY)) {
sawhole = true;
}
b = MIN(PAGE_SIZE, bytes);
offset += b;
bytes -= b;
skipbytes += b;
pidx++;
UVMHIST_LOG(ubchist, "skipping, new offset 0x%x",
offset, 0,0,0);
if (bytes == 0) {
goto loopdone;
}
}
/*
* bmap the file to find out the blkno to read from and
* how much we can read in one i/o. if bmap returns an error,
* skip the rest of the top-level i/o.
*/
lbn = offset >> fs_bshift;
error = VOP_BMAP(vp, lbn, &devvp, &blkno, &run);
if (error) {
UVMHIST_LOG(ubchist, "VOP_BMAP lbn 0x%x -> %d\n",
lbn, error,0,0);
skipbytes += bytes;
goto loopdone;
}
/*
* see how many pages can be read with this i/o.
* reduce the i/o size if necessary to avoid
* overwriting pages with valid data.
*/
iobytes = MIN((((off_t)lbn + 1 + run) << fs_bshift) - offset,
bytes);
if (offset + iobytes > round_page(offset)) {
pcount = 1;
while (pidx + pcount < npages &&
pgs[pidx + pcount]->flags & PG_FAKE) {
pcount++;
}
iobytes = MIN(iobytes, (pcount << PAGE_SHIFT) -
(offset - trunc_page(offset)));
}
/*
* if this block isn't allocated, zero it instead of
* reading it. unless we are going to allocate blocks,
* mark the pages we zeroed PG_RDONLY.
*/
if (blkno < 0) {
int holepages = (round_page(offset + iobytes) -
trunc_page(offset)) >> PAGE_SHIFT;
UVMHIST_LOG(ubchist, "lbn 0x%x -> HOLE", lbn,0,0,0);
sawhole = true;
memset((char *)kva + (offset - startoffset), 0,
iobytes);
skipbytes += iobytes;
for (i = 0; i < holepages; i++) {
if (write) {
pgs[pidx + i]->flags &= ~PG_CLEAN;
}
if (!blockalloc) {
pgs[pidx + i]->flags |= PG_RDONLY;
}
}
continue;
}
/*
* allocate a sub-buf for this piece of the i/o
* (or just use mbp if there's only 1 piece),
* and start it going.
*/
if (offset == startoffset && iobytes == bytes) {
bp = mbp;
} else {
bp = getiobuf(vp, true);
nestiobuf_setup(mbp, bp, offset - startoffset, iobytes);
}
bp->b_lblkno = 0;
/* adjust physical blkno for partial blocks */
bp->b_blkno = blkno + ((offset - ((off_t)lbn << fs_bshift)) >>
dev_bshift);
UVMHIST_LOG(ubchist,
"bp %p offset 0x%x bcount 0x%x blkno 0x%x",
bp, offset, iobytes, bp->b_blkno);
VOP_STRATEGY(devvp, bp);
}
loopdone:
nestiobuf_done(mbp, skipbytes, error);
if (async) {
UVMHIST_LOG(ubchist, "returning 0 (async)",0,0,0,0);
rw_exit(&gp->g_glock);
error = 0;
goto out_err;
}
if (bp != NULL) {
error = biowait(mbp);
}
putiobuf(mbp);
uvm_pagermapout(kva, npages);
/*
* if this we encountered a hole then we have to do a little more work.
* for read faults, we marked the page PG_RDONLY so that future
* write accesses to the page will fault again.
* for write faults, we must make sure that the backing store for
* the page is completely allocated while the pages are locked.
*/
if (!error && sawhole && blockalloc) {
error = GOP_ALLOC(vp, startoffset, npages << PAGE_SHIFT, 0,
cred);
UVMHIST_LOG(ubchist, "gop_alloc off 0x%x/0x%x -> %d",
startoffset, npages << PAGE_SHIFT, error,0);
if (!error) {
for (i = 0; i < npages; i++) {
if (pgs[i] == NULL) {
continue;
}
pgs[i]->flags &= ~(PG_CLEAN|PG_RDONLY);
UVMHIST_LOG(ubchist, "mark dirty pg %p",
pgs[i],0,0,0);
}
}
}
rw_exit(&gp->g_glock);
mutex_enter(&uobj->vmobjlock);
/*
* we're almost done! release the pages...
* for errors, we free the pages.
* otherwise we activate them and mark them as valid and clean.
* also, unbusy pages that were not actually requested.
*/
if (error) {
for (i = 0; i < npages; i++) {
if (pgs[i] == NULL) {
continue;
}
UVMHIST_LOG(ubchist, "examining pg %p flags 0x%x",
pgs[i], pgs[i]->flags, 0,0);
if (pgs[i]->flags & PG_FAKE) {
pgs[i]->flags |= PG_RELEASED;
}
}
mutex_enter(&uvm_pageqlock);
uvm_page_unbusy(pgs, npages);
mutex_exit(&uvm_pageqlock);
mutex_exit(&uobj->vmobjlock);
UVMHIST_LOG(ubchist, "returning error %d", error,0,0,0);
goto out_err;
}
out:
UVMHIST_LOG(ubchist, "succeeding, npages %d", npages,0,0,0);
error = 0;
mutex_enter(&uvm_pageqlock);
for (i = 0; i < npages; i++) {
pg = pgs[i];
if (pg == NULL) {
continue;
}
UVMHIST_LOG(ubchist, "examining pg %p flags 0x%x",
pg, pg->flags, 0,0);
if (pg->flags & PG_FAKE && !overwrite) {
pg->flags &= ~(PG_FAKE);
pmap_clear_modify(pgs[i]);
}
KASSERT(!write || !blockalloc || (pg->flags & PG_RDONLY) == 0);
if (i < ridx || i >= ridx + orignpages || async) {
UVMHIST_LOG(ubchist, "unbusy pg %p offset 0x%x",
pg, pg->offset,0,0);
if (pg->flags & PG_WANTED) {
wakeup(pg);
}
if (pg->flags & PG_FAKE) {
KASSERT(overwrite);
uvm_pagezero(pg);
}
if (pg->flags & PG_RELEASED) {
uvm_pagefree(pg);
continue;
}
uvm_pageenqueue(pg);
pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
}
}
mutex_exit(&uvm_pageqlock);
mutex_exit(&uobj->vmobjlock);
if (ap->a_m != NULL) {
memcpy(ap->a_m, &pgs[ridx],
orignpages * sizeof(struct vm_page *));
}
out_err:
if (pgs != pgs_onstack)
kmem_free(pgs, pgs_size);
if (has_trans)
fstrans_done(vp->v_mount);
return (error);
}
/*
* generic VM putpages routine.
* Write the given range of pages to backing store.
*
* => "offhi == 0" means flush all pages at or after "offlo".
* => object should be locked by caller. we return with the
* object unlocked.
* => if PGO_CLEANIT or PGO_SYNCIO is set, we may block (due to I/O).
* thus, a caller might want to unlock higher level resources
* (e.g. vm_map) before calling flush.
* => if neither PGO_CLEANIT nor PGO_SYNCIO is set, we will not block
* => if PGO_ALLPAGES is set, then all pages in the object will be processed.
* => NOTE: we rely on the fact that the object's memq is a TAILQ and
* that new pages are inserted on the tail end of the list. thus,
* we can make a complete pass through the object in one go by starting
* at the head and working towards the tail (new pages are put in
* front of us).
* => NOTE: we are allowed to lock the page queues, so the caller
* must not be holding the page queue lock.
*
* note on "cleaning" object and PG_BUSY pages:
* this routine is holding the lock on the object. the only time
* that it can run into a PG_BUSY page that it does not own is if
* some other process has started I/O on the page (e.g. either
* a pagein, or a pageout). if the PG_BUSY page is being paged
* in, then it can not be dirty (!PG_CLEAN) because no one has
* had a chance to modify it yet. if the PG_BUSY page is being
* paged out then it means that someone else has already started
* cleaning the page for us (how nice!). in this case, if we
* have syncio specified, then after we make our pass through the
* object we need to wait for the other PG_BUSY pages to clear
* off (i.e. we need to do an iosync). also note that once a
* page is PG_BUSY it must stay in its object until it is un-busyed.
*
* note on page traversal:
* we can traverse the pages in an object either by going down the
* linked list in "uobj->memq", or we can go over the address range
* by page doing hash table lookups for each address. depending
* on how many pages are in the object it may be cheaper to do one
* or the other. we set "by_list" to true if we are using memq.
* if the cost of a hash lookup was equal to the cost of the list
* traversal we could compare the number of pages in the start->stop
* range to the total number of pages in the object. however, it
* seems that a hash table lookup is more expensive than the linked
* list traversal, so we multiply the number of pages in the
* range by an estimate of the relatively higher cost of the hash lookup.
*/
int
genfs_putpages(void *v)
{
struct vop_putpages_args /* {
struct vnode *a_vp;
voff_t a_offlo;
voff_t a_offhi;
int a_flags;
} */ *ap = v;
return genfs_do_putpages(ap->a_vp, ap->a_offlo, ap->a_offhi,
ap->a_flags, NULL);
}
int
genfs_do_putpages(struct vnode *vp, off_t startoff, off_t endoff,
int origflags, struct vm_page **busypg)
{
struct uvm_object *uobj = &vp->v_uobj;
kmutex_t *slock = &uobj->vmobjlock;
off_t off;
/* Even for strange MAXPHYS, the shift rounds down to a page */
#define maxpages (MAXPHYS >> PAGE_SHIFT)
int i, error, npages, nback;
int freeflag;
struct vm_page *pgs[maxpages], *pg, *nextpg, *tpg, curmp, endmp;
bool wasclean, by_list, needs_clean, yld;
bool async = (origflags & PGO_SYNCIO) == 0;
bool pagedaemon = curlwp == uvm.pagedaemon_lwp;
struct lwp *l = curlwp ? curlwp : &lwp0;
struct genfs_node *gp = VTOG(vp);
int flags;
int dirtygen;
bool modified;
bool has_trans;
bool cleanall;
bool onworklst;
UVMHIST_FUNC("genfs_putpages"); UVMHIST_CALLED(ubchist);
KASSERT(origflags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE));
KASSERT((startoff & PAGE_MASK) == 0 && (endoff & PAGE_MASK) == 0);
KASSERT(startoff < endoff || endoff == 0);
UVMHIST_LOG(ubchist, "vp %p pages %d off 0x%x len 0x%x",
vp, uobj->uo_npages, startoff, endoff - startoff);
has_trans = false;
retry:
modified = false;
flags = origflags;
KASSERT((vp->v_iflag & VI_ONWORKLST) != 0 ||
(vp->v_iflag & VI_WRMAPDIRTY) == 0);
if (uobj->uo_npages == 0) {
if (vp->v_iflag & VI_ONWORKLST) {
vp->v_iflag &= ~VI_WRMAPDIRTY;
if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL)
vn_syncer_remove_from_worklist(vp);
}
if (has_trans)
fstrans_done(vp->v_mount);
mutex_exit(slock);
return (0);
}
/*
* the vnode has pages, set up to process the request.
*/
if (!has_trans && (flags & PGO_CLEANIT) != 0) {
mutex_exit(slock);
if (pagedaemon) {
error = fstrans_start_nowait(vp->v_mount, FSTRANS_LAZY);
if (error)
return error;
} else
fstrans_start(vp->v_mount, FSTRANS_LAZY);
has_trans = true;
mutex_enter(slock);
goto retry;
}
error = 0;
wasclean = (vp->v_numoutput == 0);
off = startoff;
if (endoff == 0 || flags & PGO_ALLPAGES) {
endoff = trunc_page(LLONG_MAX);
}
by_list = (uobj->uo_npages <=
((endoff - startoff) >> PAGE_SHIFT) * UVM_PAGE_HASH_PENALTY);
#if !defined(DEBUG)
/*
* if this vnode is known not to have dirty pages,
* don't bother to clean it out.
*/
if ((vp->v_iflag & VI_ONWORKLST) == 0) {
if ((flags & (PGO_FREE|PGO_DEACTIVATE)) == 0) {
goto skip_scan;
}
flags &= ~PGO_CLEANIT;
}
#endif /* !defined(DEBUG) */
/*
* start the loop. when scanning by list, hold the last page
* in the list before we start. pages allocated after we start
* will be added to the end of the list, so we can stop at the
* current last page.
*/
cleanall = (flags & PGO_CLEANIT) != 0 && wasclean &&
startoff == 0 && endoff == trunc_page(LLONG_MAX) &&
(vp->v_iflag & VI_ONWORKLST) != 0;
dirtygen = gp->g_dirtygen;
freeflag = pagedaemon ? PG_PAGEOUT : PG_RELEASED;
if (by_list) {
curmp.uobject = uobj;
curmp.offset = (voff_t)-1;
curmp.flags = PG_BUSY;
endmp.uobject = uobj;
endmp.offset = (voff_t)-1;
endmp.flags = PG_BUSY;
pg = TAILQ_FIRST(&uobj->memq);
TAILQ_INSERT_TAIL(&uobj->memq, &endmp, listq);
uvm_lwp_hold(l);
} else {
pg = uvm_pagelookup(uobj, off);
}
nextpg = NULL;
while (by_list || off < endoff) {
/*
* if the current page is not interesting, move on to the next.
*/
KASSERT(pg == NULL || pg->uobject == uobj);
KASSERT(pg == NULL ||
(pg->flags & (PG_RELEASED|PG_PAGEOUT)) == 0 ||
(pg->flags & PG_BUSY) != 0);
if (by_list) {
if (pg == &endmp) {
break;
}
if (pg->offset < startoff || pg->offset >= endoff ||
pg->flags & (PG_RELEASED|PG_PAGEOUT)) {
if (pg->flags & (PG_RELEASED|PG_PAGEOUT)) {
wasclean = false;
}
pg = TAILQ_NEXT(pg, listq);
continue;
}
off = pg->offset;
} else if (pg == NULL || pg->flags & (PG_RELEASED|PG_PAGEOUT)) {
if (pg != NULL) {
wasclean = false;
}
off += PAGE_SIZE;
if (off < endoff) {
pg = uvm_pagelookup(uobj, off);
}
continue;
}
/*
* if the current page needs to be cleaned and it's busy,
* wait for it to become unbusy.
*/
yld = (l->l_cpu->ci_schedstate.spc_flags &
SPCF_SHOULDYIELD) && !pagedaemon;
if (pg->flags & PG_BUSY || yld) {
UVMHIST_LOG(ubchist, "busy %p", pg,0,0,0);
if (flags & PGO_BUSYFAIL && pg->flags & PG_BUSY) {
UVMHIST_LOG(ubchist, "busyfail %p", pg, 0,0,0);
error = EDEADLK;
if (busypg != NULL)
*busypg = pg;
break;
}
if (pagedaemon) {
/*
* someone has taken the page while we
* dropped the lock for fstrans_start.
*/
break;
}
if (by_list) {
TAILQ_INSERT_BEFORE(pg, &curmp, listq);
UVMHIST_LOG(ubchist, "curmp next %p",
TAILQ_NEXT(&curmp, listq), 0,0,0);
}
if (yld) {
mutex_exit(slock);
preempt();
mutex_enter(slock);
} else {
pg->flags |= PG_WANTED;
UVM_UNLOCK_AND_WAIT(pg, slock, 0, "genput", 0);
mutex_enter(slock);
}
if (by_list) {
UVMHIST_LOG(ubchist, "after next %p",
TAILQ_NEXT(&curmp, listq), 0,0,0);
pg = TAILQ_NEXT(&curmp, listq);
TAILQ_REMOVE(&uobj->memq, &curmp, listq);
} else {
pg = uvm_pagelookup(uobj, off);
}
continue;
}
/*
* if we're freeing, remove all mappings of the page now.
* if we're cleaning, check if the page is needs to be cleaned.
*/
if (flags & PGO_FREE) {
pmap_page_protect(pg, VM_PROT_NONE);
} else if (flags & PGO_CLEANIT) {
/*
* if we still have some hope to pull this vnode off
* from the syncer queue, write-protect the page.
*/
if (cleanall && wasclean &&
gp->g_dirtygen == dirtygen) {
/*
* uobj pages get wired only by uvm_fault
* where uobj is locked.
*/
if (pg->wire_count == 0) {
pmap_page_protect(pg,
VM_PROT_READ|VM_PROT_EXECUTE);
} else {
cleanall = false;
}
}
}
if (flags & PGO_CLEANIT) {
needs_clean = pmap_clear_modify(pg) ||
(pg->flags & PG_CLEAN) == 0;
pg->flags |= PG_CLEAN;
} else {
needs_clean = false;
}
/*
* if we're cleaning, build a cluster.
* the cluster will consist of pages which are currently dirty,
* but they will be returned to us marked clean.
* if not cleaning, just operate on the one page.
*/
if (needs_clean) {
KDASSERT((vp->v_iflag & VI_ONWORKLST));
wasclean = false;
memset(pgs, 0, sizeof(pgs));
pg->flags |= PG_BUSY;
UVM_PAGE_OWN(pg, "genfs_putpages");
/*
* first look backward.
*/
npages = MIN(maxpages >> 1, off >> PAGE_SHIFT);
nback = npages;
uvn_findpages(uobj, off - PAGE_SIZE, &nback, &pgs[0],
UFP_NOWAIT|UFP_NOALLOC|UFP_DIRTYONLY|UFP_BACKWARD);
if (nback) {
memmove(&pgs[0], &pgs[npages - nback],
nback * sizeof(pgs[0]));
if (npages - nback < nback)
memset(&pgs[nback], 0,
(npages - nback) * sizeof(pgs[0]));
else
memset(&pgs[npages - nback], 0,
nback * sizeof(pgs[0]));
}
/*
* then plug in our page of interest.
*/
pgs[nback] = pg;
/*
* then look forward to fill in the remaining space in
* the array of pages.
*/
npages = maxpages - nback - 1;
uvn_findpages(uobj, off + PAGE_SIZE, &npages,
&pgs[nback + 1],
UFP_NOWAIT|UFP_NOALLOC|UFP_DIRTYONLY);
npages += nback + 1;
} else {
pgs[0] = pg;
npages = 1;
nback = 0;
}
/*
* apply FREE or DEACTIVATE options if requested.
*/
if (flags & (PGO_DEACTIVATE|PGO_FREE)) {
mutex_enter(&uvm_pageqlock);
}
for (i = 0; i < npages; i++) {
tpg = pgs[i];
KASSERT(tpg->uobject == uobj);
if (by_list && tpg == TAILQ_NEXT(pg, listq))
pg = tpg;
if (tpg->offset < startoff || tpg->offset >= endoff)
continue;
if (flags & PGO_DEACTIVATE && tpg->wire_count == 0) {
uvm_pagedeactivate(tpg);
} else if (flags & PGO_FREE) {
pmap_page_protect(tpg, VM_PROT_NONE);
if (tpg->flags & PG_BUSY) {
tpg->flags |= freeflag;
if (pagedaemon) {
uvm_pageout_start(1);
uvm_pagedequeue(tpg);
}
} else {
/*
* ``page is not busy''
* implies that npages is 1
* and needs_clean is false.
*/
nextpg = TAILQ_NEXT(tpg, listq);
uvm_pagefree(tpg);
if (pagedaemon)
uvmexp.pdfreed++;
}
}
}
if (flags & (PGO_DEACTIVATE|PGO_FREE)) {
mutex_exit(&uvm_pageqlock);
}
if (needs_clean) {
modified = true;
/*
* start the i/o. if we're traversing by list,
* keep our place in the list with a marker page.
*/
if (by_list) {
TAILQ_INSERT_AFTER(&uobj->memq, pg, &curmp,
listq);
}
mutex_exit(slock);
error = GOP_WRITE(vp, pgs, npages, flags);
mutex_enter(slock);
if (by_list) {
pg = TAILQ_NEXT(&curmp, listq);
TAILQ_REMOVE(&uobj->memq, &curmp, listq);
}
if (error) {
break;
}
if (by_list) {
continue;
}
}
/*
* find the next page and continue if there was no error.
*/
if (by_list) {
if (nextpg) {
pg = nextpg;
nextpg = NULL;
} else {
pg = TAILQ_NEXT(pg, listq);
}
} else {
off += (npages - nback) << PAGE_SHIFT;
if (off < endoff) {
pg = uvm_pagelookup(uobj, off);
}
}
}
if (by_list) {
TAILQ_REMOVE(&uobj->memq, &endmp, listq);
uvm_lwp_rele(l);
}
if (modified && (vp->v_iflag & VI_WRMAPDIRTY) != 0 &&
(vp->v_type != VBLK ||
(vp->v_mount->mnt_flag & MNT_NODEVMTIME) == 0)) {
GOP_MARKUPDATE(vp, GOP_UPDATE_MODIFIED);
}
/*
* if we're cleaning and there was nothing to clean,
* take us off the syncer list. if we started any i/o
* and we're doing sync i/o, wait for all writes to finish.
*/
if (cleanall && wasclean && gp->g_dirtygen == dirtygen &&
(vp->v_iflag & VI_ONWORKLST) != 0) {
#if defined(DEBUG)
TAILQ_FOREACH(pg, &uobj->memq, listq) {
if ((pg->flags & PG_CLEAN) == 0) {
printf("%s: %p: !CLEAN\n", __func__, pg);
}
if (pmap_is_modified(pg)) {
printf("%s: %p: modified\n", __func__, pg);
}
}
#endif /* defined(DEBUG) */
vp->v_iflag &= ~VI_WRMAPDIRTY;
if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL)
vn_syncer_remove_from_worklist(vp);
}
#if !defined(DEBUG)
skip_scan:
#endif /* !defined(DEBUG) */
/* Wait for output to complete. */
if (!wasclean && !async && vp->v_numoutput != 0) {
while (vp->v_numoutput != 0)
cv_wait(&vp->v_cv, slock);
}
onworklst = (vp->v_iflag & VI_ONWORKLST) != 0;
mutex_exit(slock);
if ((flags & PGO_RECLAIM) != 0 && onworklst) {
/*
* in the case of PGO_RECLAIM, ensure to make the vnode clean.
* retrying is not a big deal because, in many cases,
* uobj->uo_npages is already 0 here.
*/
mutex_enter(slock);
goto retry;
}
if (has_trans)
fstrans_done(vp->v_mount);
return (error);
}
int
genfs_gop_write(struct vnode *vp, struct vm_page **pgs, int npages, int flags)
{
off_t off;
vaddr_t kva;
size_t len;
int error;
UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
UVMHIST_LOG(ubchist, "vp %p pgs %p npages %d flags 0x%x",
vp, pgs, npages, flags);
off = pgs[0]->offset;
kva = uvm_pagermapin(pgs, npages,
UVMPAGER_MAPIN_WRITE | UVMPAGER_MAPIN_WAITOK);
len = npages << PAGE_SHIFT;
error = genfs_do_io(vp, off, kva, len, flags, UIO_WRITE,
uvm_aio_biodone);
return error;
}
/*
* Backend routine for doing I/O to vnode pages. Pages are already locked
* and mapped into kernel memory. Here we just look up the underlying
* device block addresses and call the strategy routine.
*/
static int
genfs_do_io(struct vnode *vp, off_t off, vaddr_t kva, size_t len, int flags,
enum uio_rw rw, void (*iodone)(struct buf *))
{
int s, error, run;
int fs_bshift, dev_bshift;
off_t eof, offset, startoffset;
size_t bytes, iobytes, skipbytes;
daddr_t lbn, blkno;
struct buf *mbp, *bp;
struct vnode *devvp;
bool async = (flags & PGO_SYNCIO) == 0;
bool write = rw == UIO_WRITE;
int brw = write ? B_WRITE : B_READ;
UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
UVMHIST_LOG(ubchist, "vp %p kva %p len 0x%x flags 0x%x",
vp, kva, len, flags);
KASSERT(vp->v_size <= vp->v_writesize);
GOP_SIZE(vp, vp->v_writesize, &eof, 0);
if (vp->v_type != VBLK) {
fs_bshift = vp->v_mount->mnt_fs_bshift;
dev_bshift = vp->v_mount->mnt_dev_bshift;
} else {
fs_bshift = DEV_BSHIFT;
dev_bshift = DEV_BSHIFT;
}
error = 0;
startoffset = off;
bytes = MIN(len, eof - startoffset);
skipbytes = 0;
KASSERT(bytes != 0);
if (write) {
mutex_enter(&vp->v_interlock);
vp->v_numoutput += 2;
mutex_exit(&vp->v_interlock);
}
mbp = getiobuf(vp, true);
UVMHIST_LOG(ubchist, "vp %p mbp %p num now %d bytes 0x%x",
vp, mbp, vp->v_numoutput, bytes);
mbp->b_bufsize = len;
mbp->b_data = (void *)kva;
mbp->b_resid = mbp->b_bcount = bytes;
mbp->b_cflags = BC_BUSY | BC_AGE;
if (async) {
mbp->b_flags = brw | B_ASYNC;
mbp->b_iodone = iodone;
} else {
mbp->b_flags = brw;
mbp->b_iodone = NULL;
}
if (curlwp == uvm.pagedaemon_lwp)
BIO_SETPRIO(mbp, BPRIO_TIMELIMITED);
else if (async)
BIO_SETPRIO(mbp, BPRIO_TIMENONCRITICAL);
else
BIO_SETPRIO(mbp, BPRIO_TIMECRITICAL);
bp = NULL;
for (offset = startoffset;
bytes > 0;
offset += iobytes, bytes -= iobytes) {
lbn = offset >> fs_bshift;
error = VOP_BMAP(vp, lbn, &devvp, &blkno, &run);
if (error) {
UVMHIST_LOG(ubchist, "VOP_BMAP() -> %d", error,0,0,0);
skipbytes += bytes;
bytes = 0;
break;
}
iobytes = MIN((((off_t)lbn + 1 + run) << fs_bshift) - offset,
bytes);
if (blkno == (daddr_t)-1) {
if (!write) {
memset((char *)kva + (offset - startoffset), 0,
iobytes);
}
skipbytes += iobytes;
continue;
}
/* if it's really one i/o, don't make a second buf */
if (offset == startoffset && iobytes == bytes) {
bp = mbp;
} else {
UVMHIST_LOG(ubchist, "vp %p bp %p num now %d",
vp, bp, vp->v_numoutput, 0);
bp = getiobuf(vp, true);
nestiobuf_setup(mbp, bp, offset - startoffset, iobytes);
}
bp->b_lblkno = 0;
/* adjust physical blkno for partial blocks */
bp->b_blkno = blkno + ((offset - ((off_t)lbn << fs_bshift)) >>
dev_bshift);
UVMHIST_LOG(ubchist,
"vp %p offset 0x%x bcount 0x%x blkno 0x%x",
vp, offset, bp->b_bcount, bp->b_blkno);
VOP_STRATEGY(devvp, bp);
}
if (skipbytes) {
UVMHIST_LOG(ubchist, "skipbytes %d", skipbytes, 0,0,0);
}
nestiobuf_done(mbp, skipbytes, error);
if (async) {
UVMHIST_LOG(ubchist, "returning 0 (async)", 0,0,0,0);
return (0);
}
UVMHIST_LOG(ubchist, "waiting for mbp %p", mbp,0,0,0);
error = biowait(mbp);
s = splbio();
(*iodone)(mbp);
splx(s);
UVMHIST_LOG(ubchist, "returning, error %d", error,0,0,0);
return (error);
}
/*
* VOP_PUTPAGES() for vnodes which never have pages.
*/
int
genfs_null_putpages(void *v)
{
struct vop_putpages_args /* {
struct vnode *a_vp;
voff_t a_offlo;
voff_t a_offhi;
int a_flags;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
KASSERT(vp->v_uobj.uo_npages == 0);
mutex_exit(&vp->v_interlock);
return (0);
}
int
genfs_compat_getpages(void *v)
{
struct vop_getpages_args /* {
struct vnode *a_vp;
voff_t a_offset;
struct vm_page **a_m;
int *a_count;
int a_centeridx;
vm_prot_t a_access_type;
int a_advice;
int a_flags;
} */ *ap = v;
off_t origoffset;
struct vnode *vp = ap->a_vp;
struct uvm_object *uobj = &vp->v_uobj;
struct vm_page *pg, **pgs;
vaddr_t kva;
int i, error, orignpages, npages;
struct iovec iov;
struct uio uio;
kauth_cred_t cred = curlwp->l_cred;
bool write = (ap->a_access_type & VM_PROT_WRITE) != 0;
error = 0;
origoffset = ap->a_offset;
orignpages = *ap->a_count;
pgs = ap->a_m;
if (write && (vp->v_iflag & VI_ONWORKLST) == 0) {
vn_syncer_add_to_worklist(vp, filedelay);
}
if (ap->a_flags & PGO_LOCKED) {
uvn_findpages(uobj, origoffset, ap->a_count, ap->a_m,
UFP_NOWAIT|UFP_NOALLOC| (write ? UFP_NORDONLY : 0));
return (ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0);
}
if (origoffset + (ap->a_centeridx << PAGE_SHIFT) >= vp->v_size) {
mutex_exit(&uobj->vmobjlock);
return (EINVAL);
}
if ((ap->a_flags & PGO_SYNCIO) == 0) {
mutex_exit(&uobj->vmobjlock);
return 0;
}
npages = orignpages;
uvn_findpages(uobj, origoffset, &npages, pgs, UFP_ALL);
mutex_exit(&uobj->vmobjlock);
kva = uvm_pagermapin(pgs, npages,
UVMPAGER_MAPIN_READ | UVMPAGER_MAPIN_WAITOK);
for (i = 0; i < npages; i++) {
pg = pgs[i];
if ((pg->flags & PG_FAKE) == 0) {
continue;
}
iov.iov_base = (char *)kva + (i << PAGE_SHIFT);
iov.iov_len = PAGE_SIZE;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = origoffset + (i << PAGE_SHIFT);
uio.uio_rw = UIO_READ;
uio.uio_resid = PAGE_SIZE;
UIO_SETUP_SYSSPACE(&uio);
/* XXX vn_lock */
error = VOP_READ(vp, &uio, 0, cred);
if (error) {
break;
}
if (uio.uio_resid) {
memset(iov.iov_base, 0, uio.uio_resid);
}
}
uvm_pagermapout(kva, npages);
mutex_enter(&uobj->vmobjlock);
mutex_enter(&uvm_pageqlock);
for (i = 0; i < npages; i++) {
pg = pgs[i];
if (error && (pg->flags & PG_FAKE) != 0) {
pg->flags |= PG_RELEASED;
} else {
pmap_clear_modify(pg);
uvm_pageactivate(pg);
}
}
if (error) {
uvm_page_unbusy(pgs, npages);
}
mutex_exit(&uvm_pageqlock);
mutex_exit(&uobj->vmobjlock);
return (error);
}
int
genfs_compat_gop_write(struct vnode *vp, struct vm_page **pgs, int npages,
int flags)
{
off_t offset;
struct iovec iov;
struct uio uio;
kauth_cred_t cred = curlwp->l_cred;
struct buf *bp;
vaddr_t kva;
int error;
offset = pgs[0]->offset;
kva = uvm_pagermapin(pgs, npages,
UVMPAGER_MAPIN_WRITE | UVMPAGER_MAPIN_WAITOK);
iov.iov_base = (void *)kva;
iov.iov_len = npages << PAGE_SHIFT;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = offset;
uio.uio_rw = UIO_WRITE;
uio.uio_resid = npages << PAGE_SHIFT;
UIO_SETUP_SYSSPACE(&uio);
/* XXX vn_lock */
error = VOP_WRITE(vp, &uio, 0, cred);
mutex_enter(&vp->v_interlock);
vp->v_numoutput++;
mutex_exit(&vp->v_interlock);
bp = getiobuf(vp, true);
bp->b_cflags = BC_BUSY | BC_AGE;
bp->b_lblkno = offset >> vp->v_mount->mnt_fs_bshift;
bp->b_data = (char *)kva;
bp->b_bcount = npages << PAGE_SHIFT;
bp->b_bufsize = npages << PAGE_SHIFT;
bp->b_resid = 0;
bp->b_error = error;
uvm_aio_aiodone(bp);
return (error);
}
/*
* Process a uio using direct I/O. If we reach a part of the request
* which cannot be processed in this fashion for some reason, just return.
* The caller must handle some additional part of the request using
* buffered I/O before trying direct I/O again.
*/
void
genfs_directio(struct vnode *vp, struct uio *uio, int ioflag)
{
struct vmspace *vs;
struct iovec *iov;
vaddr_t va;
size_t len;
const int mask = DEV_BSIZE - 1;
int error;
/*
* We only support direct I/O to user space for now.
*/
if (VMSPACE_IS_KERNEL_P(uio->uio_vmspace)) {
return;
}
/*
* If the vnode is mapped, we would need to get the getpages lock
* to stabilize the bmap, but then we would get into trouble whil e
* locking the pages if the pages belong to this same vnode (or a
* multi-vnode cascade to the same effect). Just fall back to
* buffered I/O if the vnode is mapped to avoid this mess.
*/
if (vp->v_vflag & VV_MAPPED) {
return;
}
/*
* Do as much of the uio as possible with direct I/O.
*/
vs = uio->uio_vmspace;
while (uio->uio_resid) {
iov = uio->uio_iov;
if (iov->iov_len == 0) {
uio->uio_iov++;
uio->uio_iovcnt--;
continue;
}
va = (vaddr_t)iov->iov_base;
len = MIN(iov->iov_len, genfs_maxdio);
len &= ~mask;
/*
* If the next chunk is smaller than DEV_BSIZE or extends past
* the current EOF, then fall back to buffered I/O.
*/
if (len == 0 || uio->uio_offset + len > vp->v_size) {
return;
}
/*
* Check alignment. The file offset must be at least
* sector-aligned. The exact constraint on memory alignment
* is very hardware-dependent, but requiring sector-aligned
* addresses there too is safe.
*/
if (uio->uio_offset & mask || va & mask) {
return;
}
error = genfs_do_directio(vs, va, len, vp, uio->uio_offset,
uio->uio_rw);
if (error) {
break;
}
iov->iov_base = (char *)iov->iov_base + len;
iov->iov_len -= len;
uio->uio_offset += len;
uio->uio_resid -= len;
}
}
/*
* Iodone routine for direct I/O. We don't do much here since the request is
* always synchronous, so the caller will do most of the work after biowait().
*/
static void
genfs_dio_iodone(struct buf *bp)
{
KASSERT((bp->b_flags & B_ASYNC) == 0);
if ((bp->b_flags & B_READ) == 0 && (bp->b_cflags & BC_AGE) != 0) {
mutex_enter(bp->b_objlock);
vwakeup(bp);
mutex_exit(bp->b_objlock);
}
putiobuf(bp);
}
/*
* Process one chunk of a direct I/O request.
*/
static int
genfs_do_directio(struct vmspace *vs, vaddr_t uva, size_t len, struct vnode *vp,
off_t off, enum uio_rw rw)
{
struct vm_map *map;
struct pmap *upm, *kpm;
size_t klen = round_page(uva + len) - trunc_page(uva);
off_t spoff, epoff;
vaddr_t kva, puva;
paddr_t pa;
vm_prot_t prot;
int error, rv, poff, koff;
const int pgoflags = PGO_CLEANIT | PGO_SYNCIO |
(rw == UIO_WRITE ? PGO_FREE : 0);
/*
* For writes, verify that this range of the file already has fully
* allocated backing store. If there are any holes, just punt and
* make the caller take the buffered write path.
*/
if (rw == UIO_WRITE) {
daddr_t lbn, elbn, blkno;
int bsize, bshift, run;
bshift = vp->v_mount->mnt_fs_bshift;
bsize = 1 << bshift;
lbn = off >> bshift;
elbn = (off + len + bsize - 1) >> bshift;
while (lbn < elbn) {
error = VOP_BMAP(vp, lbn, NULL, &blkno, &run);
if (error) {
return error;
}
if (blkno == (daddr_t)-1) {
return ENOSPC;
}
lbn += 1 + run;
}
}
/*
* Flush any cached pages for parts of the file that we're about to
* access. If we're writing, invalidate pages as well.
*/
spoff = trunc_page(off);
epoff = round_page(off + len);
mutex_enter(&vp->v_interlock);
error = VOP_PUTPAGES(vp, spoff, epoff, pgoflags);
if (error) {
return error;
}
/*
* Wire the user pages and remap them into kernel memory.
*/
prot = rw == UIO_READ ? VM_PROT_READ | VM_PROT_WRITE : VM_PROT_READ;
error = uvm_vslock(vs, (void *)uva, len, prot);
if (error) {
return error;
}
map = &vs->vm_map;
upm = vm_map_pmap(map);
kpm = vm_map_pmap(kernel_map);
kva = uvm_km_alloc(kernel_map, klen, 0,
UVM_KMF_VAONLY | UVM_KMF_WAITVA);
puva = trunc_page(uva);
for (poff = 0; poff < klen; poff += PAGE_SIZE) {
rv = pmap_extract(upm, puva + poff, &pa);
KASSERT(rv);
pmap_enter(kpm, kva + poff, pa, prot, prot | PMAP_WIRED);
}
pmap_update(kpm);
/*
* Do the I/O.
*/
koff = uva - trunc_page(uva);
error = genfs_do_io(vp, off, kva + koff, len, PGO_SYNCIO, rw,
genfs_dio_iodone);
/*
* Tear down the kernel mapping.
*/
pmap_remove(kpm, kva, kva + klen);
pmap_update(kpm);
uvm_km_free(kernel_map, kva, klen, UVM_KMF_VAONLY);
/*
* Unwire the user pages.
*/
uvm_vsunlock(vs, (void *)uva, len);
return error;
}
Reference in New Issue View Git Blame Copy Permalink