/
genfs_io.c
1934 lines (1709 loc) · 48.7 KB
/
genfs_io.c
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/* $NetBSD: genfs_io.c,v 1.76 2019/10/06 05:48:00 mlelstv 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 1.76 2019/10/06 05:48:00 mlelstv Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/kmem.h>
#include <sys/kauth.h>
#include <sys/fstrans.h>
#include <sys/buf.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_getpages_read(struct vnode *, struct vm_page **, int, off_t,
off_t, bool, bool, bool, bool);
static int genfs_do_io(struct vnode *, off_t, vaddr_t, size_t, int, enum uio_rw,
void (*)(struct buf *));
static void genfs_rel_pages(struct vm_page **, unsigned int);
static void genfs_markdirty(struct vnode *);
int genfs_maxdio = MAXPHYS;
static void
genfs_rel_pages(struct vm_page **pgs, unsigned int npages)
{
unsigned int i;
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[i];
if (pg == NULL || pg == PGO_DONTCARE)
continue;
KASSERT(uvm_page_locked_p(pg));
if (pg->flags & PG_FAKE) {
pg->flags |= PG_RELEASED;
}
}
mutex_enter(&uvm_pageqlock);
uvm_page_unbusy(pgs, npages);
mutex_exit(&uvm_pageqlock);
}
static void
genfs_markdirty(struct vnode *vp)
{
struct genfs_node * const gp = VTOG(vp);
KASSERT(mutex_owned(vp->v_interlock));
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;
}
}
/*
* 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;
} */ * const ap = v;
off_t diskeof, memeof;
int i, error, npages;
const int flags = ap->a_flags;
struct vnode * const vp = ap->a_vp;
struct uvm_object * const uobj = &vp->v_uobj;
const bool async = (flags & PGO_SYNCIO) == 0;
const bool memwrite = (ap->a_access_type & VM_PROT_WRITE) != 0;
const bool overwrite = (flags & PGO_OVERWRITE) != 0;
const bool blockalloc = memwrite && (flags & PGO_NOBLOCKALLOC) == 0;
const bool need_wapbl = (vp->v_mount->mnt_wapbl &&
(flags & PGO_JOURNALLOCKED) == 0);
const bool glocked = (flags & PGO_GLOCKHELD) != 0;
bool holds_wapbl = false;
struct mount *trans_mount = NULL;
UVMHIST_FUNC("genfs_getpages"); UVMHIST_CALLED(ubchist);
UVMHIST_LOG(ubchist, "vp %#jx off 0x%jx/%jx count %jd",
(uintptr_t)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);
#ifdef DIAGNOSTIC
if ((flags & PGO_JOURNALLOCKED) && vp->v_mount->mnt_wapbl)
WAPBL_JLOCK_ASSERT(vp->v_mount);
#endif
error = vdead_check(vp, VDEAD_NOWAIT);
if (error) {
if ((flags & PGO_LOCKED) == 0)
mutex_exit(uobj->vmobjlock);
return error;
}
startover:
error = 0;
const voff_t origvsize = vp->v_size;
const off_t origoffset = ap->a_offset;
const int orignpages = *ap->a_count;
GOP_SIZE(vp, origvsize, &diskeof, 0);
if (flags & PGO_PASTEOF) {
off_t newsize;
#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: %" PRId64 " vs. %" PRId64,
__func__, newsize, round_page(writeeof));
}
#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%jx count %jd goes past EOF 0x%jx",
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 (memwrite) {
updflags |= GOP_UPDATE_MODIFIED;
}
if (updflags != 0) {
GOP_MARKUPDATE(vp, updflags);
}
}
/*
* For PGO_LOCKED requests, just return whatever's in memory.
*/
if (flags & PGO_LOCKED) {
int nfound;
struct vm_page *pg;
KASSERT(!glocked);
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|(memwrite ? UFP_NORDONLY : 0));
KASSERT(npages == *ap->a_count);
if (nfound == 0) {
error = EBUSY;
goto out_err;
}
if (!genfs_node_rdtrylock(vp)) {
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;
}
KASSERT(ap->a_m[i] == NULL ||
ap->a_m[i] == PGO_DONTCARE);
}
} else {
genfs_node_unlock(vp);
}
error = (ap->a_m[ap->a_centeridx] == NULL ? EBUSY : 0);
if (error == 0 && memwrite) {
genfs_markdirty(vp);
}
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.
*/
const int fs_bshift = (vp->v_type != VBLK) ?
vp->v_mount->mnt_fs_bshift : DEV_BSHIFT;
const int fs_bsize = 1 << fs_bshift;
#define blk_mask (fs_bsize - 1)
#define trunc_blk(x) ((x) & ~blk_mask)
#define round_blk(x) (((x) + blk_mask) & ~blk_mask)
const int orignmempages = MIN(orignpages,
round_page(memeof - origoffset) >> PAGE_SHIFT);
npages = orignmempages;
const off_t startoffset = trunc_blk(origoffset);
const off_t endoffset = MIN(
round_page(round_blk(origoffset + (npages << PAGE_SHIFT))),
round_page(memeof));
const int ridx = (origoffset - startoffset) >> PAGE_SHIFT;
const int pgs_size = sizeof(struct vm_page *) *
((endoffset - startoffset) >> PAGE_SHIFT);
struct vm_page **pgs, *pgs_onstack[UBC_MAX_PAGES];
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;
(void)memset(pgs, 0, pgs_size);
}
UVMHIST_LOG(ubchist, "ridx %jd npages %jd startoff %jd endoff %jd",
ridx, npages, startoffset, endoffset);
if (trans_mount == NULL) {
trans_mount = vp->v_mount;
fstrans_start(trans_mount);
/*
* check if this vnode is still valid.
*/
mutex_enter(vp->v_interlock);
error = vdead_check(vp, 0);
mutex_exit(vp->v_interlock);
if (error)
goto out_err_free;
/*
* XXX: This assumes that we come here only via
* the mmio path
*/
if (blockalloc && need_wapbl) {
error = WAPBL_BEGIN(trans_mount);
if (error)
goto out_err_free;
holds_wapbl = true;
}
}
/*
* hold g_glock to prevent a race with truncate.
*
* check if our idea of v_size is still valid.
*/
KASSERT(!glocked || genfs_node_wrlocked(vp));
if (!glocked) {
if (blockalloc) {
genfs_node_wrlock(vp);
} else {
genfs_node_rdlock(vp);
}
}
mutex_enter(uobj->vmobjlock);
if (vp->v_size < origvsize) {
if (!glocked) {
genfs_node_unlock(vp);
}
if (pgs != pgs_onstack)
kmem_free(pgs, pgs_size);
goto startover;
}
if (uvn_findpages(uobj, origoffset, &npages, &pgs[ridx],
async ? UFP_NOWAIT : UFP_ALL) != orignmempages) {
if (!glocked) {
genfs_node_unlock(vp);
}
KASSERT(async != 0);
genfs_rel_pages(&pgs[ridx], orignmempages);
mutex_exit(uobj->vmobjlock);
error = EBUSY;
goto out_err_free;
}
/*
* if the pages are already resident, just return them.
*/
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[ridx + i];
if ((pg->flags & PG_FAKE) ||
(blockalloc && (pg->flags & PG_RDONLY))) {
break;
}
}
if (i == npages) {
if (!glocked) {
genfs_node_unlock(vp);
}
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) {
if (!glocked) {
genfs_node_unlock(vp);
}
UVMHIST_LOG(ubchist, "PGO_OVERWRITE",0,0,0,0);
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[ridx + i];
pg->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 != orignmempages) {
int npgs;
/*
* 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], orignmempages);
memset(pgs, 0, pgs_size);
UVMHIST_LOG(ubchist, "reset npages start 0x%jx end 0x%jx",
startoffset, endoffset, 0,0);
npgs = npages;
if (uvn_findpages(uobj, startoffset, &npgs, pgs,
async ? UFP_NOWAIT : UFP_ALL) != npages) {
if (!glocked) {
genfs_node_unlock(vp);
}
KASSERT(async != 0);
genfs_rel_pages(pgs, npages);
mutex_exit(uobj->vmobjlock);
error = EBUSY;
goto out_err_free;
}
}
mutex_exit(uobj->vmobjlock);
error = genfs_getpages_read(vp, pgs, npages, startoffset, diskeof,
async, memwrite, blockalloc, glocked);
if (!glocked) {
genfs_node_unlock(vp);
}
if (error == 0 && async)
goto out_err_free;
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) {
genfs_rel_pages(pgs, npages);
mutex_exit(uobj->vmobjlock);
UVMHIST_LOG(ubchist, "returning error %jd", error,0,0,0);
goto out_err_free;
}
out:
UVMHIST_LOG(ubchist, "succeeding, npages %jd", npages,0,0,0);
error = 0;
mutex_enter(&uvm_pageqlock);
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[i];
if (pg == NULL) {
continue;
}
UVMHIST_LOG(ubchist, "examining pg %#jx flags 0x%jx",
(uintptr_t)pg, pg->flags, 0,0);
if (pg->flags & PG_FAKE && !overwrite) {
pg->flags &= ~(PG_FAKE);
pmap_clear_modify(pgs[i]);
}
KASSERT(!memwrite || !blockalloc || (pg->flags & PG_RDONLY) == 0);
if (i < ridx || i >= ridx + orignmempages || async) {
UVMHIST_LOG(ubchist, "unbusy pg %#jx offset 0x%jx",
(uintptr_t)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);
if (memwrite) {
genfs_markdirty(vp);
}
mutex_exit(uobj->vmobjlock);
if (ap->a_m != NULL) {
memcpy(ap->a_m, &pgs[ridx],
orignmempages * sizeof(struct vm_page *));
}
out_err_free:
if (pgs != NULL && pgs != pgs_onstack)
kmem_free(pgs, pgs_size);
out_err:
if (trans_mount != NULL) {
if (holds_wapbl)
WAPBL_END(trans_mount);
fstrans_done(trans_mount);
}
return error;
}
/*
* genfs_getpages_read: Read the pages in with VOP_BMAP/VOP_STRATEGY.
*
* "glocked" (which is currently not actually used) tells us not whether
* the genfs_node is locked on entry (it always is) but whether it was
* locked on entry to genfs_getpages.
*/
static int
genfs_getpages_read(struct vnode *vp, struct vm_page **pgs, int npages,
off_t startoffset, off_t diskeof,
bool async, bool memwrite, bool blockalloc, bool glocked)
{
struct uvm_object * const uobj = &vp->v_uobj;
const int fs_bshift = (vp->v_type != VBLK) ?
vp->v_mount->mnt_fs_bshift : DEV_BSHIFT;
const int dev_bshift = (vp->v_type != VBLK) ?
vp->v_mount->mnt_dev_bshift : DEV_BSHIFT;
kauth_cred_t const cred = curlwp->l_cred; /* XXXUBC curlwp */
size_t bytes, iobytes, tailstart, tailbytes, totalbytes, skipbytes;
vaddr_t kva;
struct buf *bp, *mbp;
bool sawhole = false;
int i;
int error = 0;
UVMHIST_FUNC(__func__); UVMHIST_CALLED(ubchist);
/*
* 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 | (async ? 0 : UVMPAGER_MAPIN_WAITOK));
if (kva == 0)
return EBUSY;
if (uvm.aiodone_queue == NULL)
async = 0;
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 %#jx 0x%jx 0x%jx",
(uintptr_t)kva, tailstart, len, 0);
}
tailstart += len;
tailbytes -= len;
}
/*
* now loop over the pages, reading as needed.
*/
bp = NULL;
off_t offset;
for (offset = startoffset;
bytes > 0;
offset += iobytes, bytes -= iobytes) {
int run;
daddr_t lbn, blkno;
int pidx;
struct vnode *devvp;
/*
* 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%jx",
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%jx -> %jd\n",
lbn,error,0,0);
skipbytes += bytes;
bytes = 0;
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)) {
int pcount;
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 == (daddr_t)-1) {
int holepages = (round_page(offset + iobytes) -
trunc_page(offset)) >> PAGE_SHIFT;
UVMHIST_LOG(ubchist, "lbn 0x%jx -> HOLE", lbn,0,0,0);
sawhole = true;
memset((char *)kva + (offset - startoffset), 0,
iobytes);
skipbytes += iobytes;
mutex_enter(uobj->vmobjlock);
for (i = 0; i < holepages; i++) {
if (memwrite) {
pgs[pidx + i]->flags &= ~PG_CLEAN;
}
if (!blockalloc) {
pgs[pidx + i]->flags |= PG_RDONLY;
}
}
mutex_exit(uobj->vmobjlock);
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 {
UVMHIST_LOG(ubchist, "vp %#jx bp %#jx num now %jd",
(uintptr_t)vp, (uintptr_t)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,
"bp %#jx offset 0x%x bcount 0x%x blkno 0x%x",
(uintptr_t)bp, offset, bp->b_bcount, 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);
return 0;
}
if (bp != NULL) {
error = biowait(mbp);
}
/* Remove the mapping (make KVA available as soon as possible) */
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%jx/0x%jx -> %jd",
startoffset, npages << PAGE_SHIFT, error,0);
if (!error) {
mutex_enter(uobj->vmobjlock);
for (i = 0; i < npages; i++) {
struct vm_page *pg = pgs[i];
if (pg == NULL) {
continue;
}
pg->flags &= ~(PG_CLEAN|PG_RDONLY);
UVMHIST_LOG(ubchist, "mark dirty pg %#jx",
(uintptr_t)pg, 0, 0, 0);
}
mutex_exit(uobj->vmobjlock);
}
}
putiobuf(mbp);
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;
} */ * const 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 * const uobj = &vp->v_uobj;
kmutex_t * const slock = uobj->vmobjlock;
off_t off;
int i, error, npages, nback;
int freeflag;
/*
* This array is larger than it should so that it's size is constant.
* The right size is MAXPAGES.
*/
struct vm_page *pgs[MAXPHYS / MIN_PAGE_SIZE];
#define MAXPAGES (MAXPHYS / PAGE_SIZE)
struct vm_page *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 * const l = curlwp ? curlwp : &lwp0;
struct genfs_node * const gp = VTOG(vp);
struct mount *trans_mp;
int flags;
int dirtygen;
bool modified;
bool holds_wapbl;
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 %#jx pages %jd off 0x%jx len 0x%jx",
(uintptr_t)vp, uobj->uo_npages, startoff, endoff - startoff);
#ifdef DIAGNOSTIC
if ((origflags & PGO_JOURNALLOCKED) && vp->v_mount->mnt_wapbl)
WAPBL_JLOCK_ASSERT(vp->v_mount);
#endif
trans_mp = NULL;
holds_wapbl = 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 (trans_mp) {
if (holds_wapbl)
WAPBL_END(trans_mp);
fstrans_done(trans_mp);
}
mutex_exit(slock);
return (0);
}
/*
* the vnode has pages, set up to process the request.
*/
if (trans_mp == NULL && (flags & PGO_CLEANIT) != 0) {
if (pagedaemon) {
/* Pagedaemon must not sleep here. */
trans_mp = vp->v_mount;
error = fstrans_start_nowait(trans_mp);
if (error) {
mutex_exit(slock);
return error;
}
} else {
/*
* Cannot use vdeadcheck() here as this operation
* usually gets used from VOP_RECLAIM(). Test for
* change of v_mount instead and retry on change.
*/
mutex_exit(slock);
trans_mp = vp->v_mount;
fstrans_start(trans_mp);
if (vp->v_mount != trans_mp) {
fstrans_done(trans_mp);
trans_mp = NULL;
} else {
holds_wapbl = (trans_mp->mnt_wapbl &&
(origflags & PGO_JOURNALLOCKED) == 0);
if (holds_wapbl) {
error = WAPBL_BEGIN(trans_mp);
if (error) {
fstrans_done(trans_mp);
return error;
}
}
}
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_TREE_PENALTY);
/*
* 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 !defined(DEBUG)
if ((flags & (PGO_FREE|PGO_DEACTIVATE)) == 0) {
goto skip_scan;
}
#endif /* !defined(DEBUG) */
flags &= ~PGO_CLEANIT;
}
/*
* 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.flags = PG_MARKER;
endmp.flags = PG_MARKER;
pg = TAILQ_FIRST(&uobj->memq);
TAILQ_INSERT_TAIL(&uobj->memq, &endmp, listq.queue);
} 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->flags & PG_MARKER) != 0 ||
pg->uobject == uobj);