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NetBSD/sys/uvm/uvm_swap.c

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/* $NetBSD: uvm_swap.c,v 1.13 1998/07/24 18:46:02 thorpej Exp $ */
/*
* Copyright (c) 1995, 1996, 1997 Matthew R. Green
* 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. 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.
*
* from: NetBSD: vm_swap.c,v 1.52 1997/12/02 13:47:37 pk Exp
* from: Id: uvm_swap.c,v 1.1.2.42 1998/02/02 20:38:06 chuck Exp
*/
#include "fs_nfs.h"
#include "opt_uvmhist.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/disklabel.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/extent.h>
#include <sys/mount.h>
#include <sys/pool.h>
#include <sys/syscallargs.h>
#include <vm/vm.h>
#include <vm/vm_swap.h>
#include <vm/vm_conf.h>
#include <uvm/uvm.h>
#include <miscfs/specfs/specdev.h>
/*
* uvm_swap.c: manage configuration and i/o to swap space.
*/
/*
* swap space is managed in the following way:
*
* each swap partition or file is described by a "swapdev" structure.
* each "swapdev" structure contains a "swapent" structure which contains
* information that is passed up to the user (via system calls).
*
* each swap partition is assigned a "priority" (int) which controls
* swap parition usage.
*
* the system maintains a global data structure describing all swap
* partitions/files. there is a sorted LIST of "swappri" structures
* which describe "swapdev"'s at that priority. this LIST is headed
* by the "swap_priority" global var. each "swappri" contains a
* CIRCLEQ of "swapdev" structures at that priority.
*
* the system maintains a fixed pool of "swapbuf" structures for use
* at swap i/o time. a swapbuf includes a "buf" structure and an
* "aiodone" [we want to avoid malloc()'ing anything at swapout time
* since memory may be low].
*
* locking:
* - swap_syscall_lock (sleep lock): this lock serializes the swapctl
* system call and prevents the swap priority list from changing
* while we are in the middle of a system call (e.g. SWAP_STATS).
* - swap_data_lock (simple_lock): this lock protects all swap data
* structures including the priority list, the swapdev structures,
* and the swapmap extent.
* - swap_buf_lock (simple_lock): this lock protects the free swapbuf
* pool.
*
* each swap device has the following info:
* - swap device in use (could be disabled, preventing future use)
* - swap enabled (allows new allocations on swap)
* - map info in /dev/drum
* - vnode pointer
* for swap files only:
* - block size
* - max byte count in buffer
* - buffer
* - credentials to use when doing i/o to file
*
* userland controls and configures swap with the swapctl(2) system call.
* the sys_swapctl performs the following operations:
* [1] SWAP_NSWAP: returns the number of swap devices currently configured
* [2] SWAP_STATS: given a pointer to an array of swapent structures
* (passed in via "arg") of a size passed in via "misc" ... we load
* the current swap config into the array.
* [3] SWAP_ON: given a pathname in arg (could be device or file) and a
* priority in "misc", start swapping on it.
* [4] SWAP_OFF: as SWAP_ON, but stops swapping to a device
* [5] SWAP_CTL: changes the priority of a swap device (new priority in
* "misc")
*/
/*
* SWAP_TO_FILES: allows swapping to plain files.
*/
#define SWAP_TO_FILES
/*
* swapdev: describes a single swap partition/file
*
* note the following should be true:
* swd_inuse <= swd_nblks [number of blocks in use is <= total blocks]
* swd_nblks <= swd_mapsize [because mapsize includes miniroot+disklabel]
*/
struct swapdev {
struct swapent swd_se; /* swap entry struct */
#define swd_dev swd_se.se_dev /* dev_t for this dev */
#define swd_flags swd_se.se_flags /* flags:inuse/enable/fake*/
#define swd_priority swd_se.se_priority /* our priority */
/* also: swd_se.se_nblks, swd_se.se_inuse */
int swd_npages; /* #pages we can use */
int swd_npginuse; /* #pages in use */
int swd_drumoffset; /* page0 offset in drum */
int swd_drumsize; /* #pages in drum */
struct extent *swd_ex; /* extent for this swapdev*/
struct vnode *swd_vp; /* backing vnode */
CIRCLEQ_ENTRY(swapdev) swd_next; /* priority circleq */
#ifdef SWAP_TO_FILES
int swd_bsize; /* blocksize (bytes) */
int swd_maxactive; /* max active i/o reqs */
struct buf swd_tab; /* buffer list */
struct ucred *swd_cred; /* cred for file access */
#endif
};
/*
* swap device priority entry; the list is kept sorted on `spi_priority'.
*/
struct swappri {
int spi_priority; /* priority */
CIRCLEQ_HEAD(spi_swapdev, swapdev) spi_swapdev;
/* circleq of swapdevs at this priority */
LIST_ENTRY(swappri) spi_swappri; /* global list of pri's */
};
/*
* swapbuf, swapbuffer plus async i/o info
*/
struct swapbuf {
struct buf sw_buf; /* a buffer structure */
struct uvm_aiodesc sw_aio; /* aiodesc structure, used if ASYNC */
SIMPLEQ_ENTRY(swapbuf) sw_sq; /* free list pointer */
};
/*
* The following two structures are used to keep track of data transfers
* on swap devices associated with regular files.
* NOTE: this code is more or less a copy of vnd.c; we use the same
* structure names here to ease porting..
*/
struct vndxfer {
struct buf *vx_bp; /* Pointer to parent buffer */
struct swapdev *vx_sdp;
int vx_error;
int vx_pending; /* # of pending aux buffers */
int vx_flags;
#define VX_BUSY 1
#define VX_DEAD 2
};
struct vndbuf {
struct buf vb_buf;
struct vndxfer *vb_xfer;
};
/*
* We keep a of pool vndbuf's and vndxfer structures.
*/
struct pool *vndxfer_pool;
struct pool *vndbuf_pool;
#define getvndxfer(vnx) do { \
int s = splbio(); \
vnx = (struct vndxfer *) \
pool_get(vndxfer_pool, PR_MALLOCOK|PR_WAITOK); \
splx(s); \
} while (0)
#define putvndxfer(vnx) { \
pool_put(vndxfer_pool, (void *)(vnx)); \
}
#define getvndbuf(vbp) do { \
int s = splbio(); \
vbp = (struct vndbuf *) \
pool_get(vndbuf_pool, PR_MALLOCOK|PR_WAITOK); \
splx(s); \
} while (0)
#define putvndbuf(vbp) { \
pool_put(vndbuf_pool, (void *)(vbp)); \
}
/*
* local variables
*/
static struct extent *swapmap; /* controls the mapping of /dev/drum */
SIMPLEQ_HEAD(swapbufhead, swapbuf);
struct pool *swapbuf_pool;
/* list of all active swap devices [by priority] */
LIST_HEAD(swap_priority, swappri);
static struct swap_priority swap_priority;
/* locks */
lock_data_t swap_syscall_lock;
static simple_lock_data_t swap_data_lock;
/*
* prototypes
*/
static void swapdrum_add __P((struct swapdev *, int));
static struct swapdev *swapdrum_getsdp __P((int));
static struct swapdev *swaplist_find __P((struct vnode *, int));
static void swaplist_insert __P((struct swapdev *,
struct swappri *, int));
static void swaplist_trim __P((void));
static int swap_on __P((struct proc *, struct swapdev *));
#ifdef SWAP_OFF_WORKS
static int swap_off __P((struct proc *, struct swapdev *));
#endif
#ifdef SWAP_TO_FILES
static void sw_reg_strategy __P((struct swapdev *, struct buf *, int));
static void sw_reg_iodone __P((struct buf *));
static void sw_reg_start __P((struct swapdev *));
#endif
static void uvm_swap_aiodone __P((struct uvm_aiodesc *));
static void uvm_swap_bufdone __P((struct buf *));
static int uvm_swap_io __P((struct vm_page **, int, int, int));
/*
* uvm_swap_init: init the swap system data structures and locks
*
* => called at boot time from init_main.c after the filesystems
* are brought up (which happens after uvm_init())
*/
void
uvm_swap_init()
{
UVMHIST_FUNC("uvm_swap_init");
UVMHIST_CALLED(pdhist);
/*
* first, init the swap list, its counter, and its lock.
* then get a handle on the vnode for /dev/drum by using
* the its dev_t number ("swapdev", from MD conf.c).
*/
LIST_INIT(&swap_priority);
uvmexp.nswapdev = 0;
lockinit(&swap_syscall_lock, PVM, "swapsys", 0, 0);
simple_lock_init(&swap_data_lock);
if (bdevvp(swapdev, &swapdev_vp))
panic("uvm_swap_init: can't get vnode for swap device");
/*
* create swap block resource map to map /dev/drum. the range
* from 1 to INT_MAX allows 2 gigablocks of swap space. note
* that block 0 is reserved (used to indicate an allocation
* failure, or no allocation).
*/
swapmap = extent_create("swapmap", 1, INT_MAX,
M_VMSWAP, 0, 0, EX_NOWAIT);
if (swapmap == 0)
panic("uvm_swap_init: extent_create failed");
/*
* allocate our private pool of "swapbuf" structures (includes
* a "buf" structure). ["nswbuf" comes from param.c and can
* be adjusted by MD code before we get here].
*/
swapbuf_pool =
pool_create(sizeof(struct swapbuf), 0, 0, 0, "swp buf", 0,
NULL, NULL, 0);
if (swapbuf_pool == NULL)
panic("swapinit: pool_create failed");
/* XXX - set a maximum on swapbuf_pool? */
vndxfer_pool =
pool_create(sizeof(struct vndxfer), 0, 0, 0, "swp vnx", 0,
NULL, NULL, 0);
if (vndxfer_pool == NULL)
panic("swapinit: pool_create failed");
vndbuf_pool =
pool_create(sizeof(struct vndbuf), 0, 0, 0, "swp vnd", 0,
NULL, NULL, 0);
if (vndbuf_pool == NULL)
panic("swapinit: pool_create failed");
/*
* done!
*/
UVMHIST_LOG(pdhist, "<- done", 0, 0, 0, 0);
}
/*
* swaplist functions: functions that operate on the list of swap
* devices on the system.
*/
/*
* swaplist_insert: insert swap device "sdp" into the global list
*
* => caller must hold both swap_syscall_lock and swap_data_lock
* => caller must provide a newly malloc'd swappri structure (we will
* FREE it if we don't need it... this it to prevent malloc blocking
* here while adding swap)
*/
static void
swaplist_insert(sdp, newspp, priority)
struct swapdev *sdp;
struct swappri *newspp;
int priority;
{
struct swappri *spp, *pspp;
UVMHIST_FUNC("swaplist_insert"); UVMHIST_CALLED(pdhist);
/*
* find entry at or after which to insert the new device.
*/
for (pspp = NULL, spp = swap_priority.lh_first; spp != NULL;
spp = spp->spi_swappri.le_next) {
if (priority <= spp->spi_priority)
break;
pspp = spp;
}
/*
* new priority?
*/
if (spp == NULL || spp->spi_priority != priority) {
spp = newspp; /* use newspp! */
UVMHIST_LOG(pdhist, "created new swappri = %d", priority, 0, 0, 0);
spp->spi_priority = priority;
CIRCLEQ_INIT(&spp->spi_swapdev);
if (pspp)
LIST_INSERT_AFTER(pspp, spp, spi_swappri);
else
LIST_INSERT_HEAD(&swap_priority, spp, spi_swappri);
} else {
/* we don't need a new priority structure, free it */
FREE(newspp, M_VMSWAP);
}
/*
* priority found (or created). now insert on the priority's
* circleq list and bump the total number of swapdevs.
*/
sdp->swd_priority = priority;
CIRCLEQ_INSERT_TAIL(&spp->spi_swapdev, sdp, swd_next);
uvmexp.nswapdev++;
/*
* done!
*/
}
/*
* swaplist_find: find and optionally remove a swap device from the
* global list.
*
* => caller must hold both swap_syscall_lock and swap_data_lock
* => we return the swapdev we found (and removed)
*/
static struct swapdev *
swaplist_find(vp, remove)
struct vnode *vp;
boolean_t remove;
{
struct swapdev *sdp;
struct swappri *spp;
/*
* search the lists for the requested vp
*/
for (spp = swap_priority.lh_first; spp != NULL;
spp = spp->spi_swappri.le_next) {
for (sdp = spp->spi_swapdev.cqh_first;
sdp != (void *)&spp->spi_swapdev;
sdp = sdp->swd_next.cqe_next)
if (sdp->swd_vp == vp) {
if (remove) {
CIRCLEQ_REMOVE(&spp->spi_swapdev,
sdp, swd_next);
uvmexp.nswapdev--;
}
return(sdp);
}
}
return (NULL);
}
/*
* swaplist_trim: scan priority list for empty priority entries and kill
* them.
*
* => caller must hold both swap_syscall_lock and swap_data_lock
*/
static void
swaplist_trim()
{
struct swappri *spp, *nextspp;
for (spp = swap_priority.lh_first; spp != NULL; spp = nextspp) {
nextspp = spp->spi_swappri.le_next;
if (spp->spi_swapdev.cqh_first != (void *)&spp->spi_swapdev)
continue;
LIST_REMOVE(spp, spi_swappri);
free((caddr_t)spp, M_VMSWAP);
}
}
/*
* swapdrum_add: add a "swapdev"'s blocks into /dev/drum's area.
*
* => caller must hold swap_syscall_lock
* => swap_data_lock should be unlocked (we may sleep)
*/
static void
swapdrum_add(sdp, npages)
struct swapdev *sdp;
int npages;
{
u_long result;
if (extent_alloc(swapmap, npages, EX_NOALIGN, EX_NOBOUNDARY,
EX_WAITOK, &result))
panic("swapdrum_add");
sdp->swd_drumoffset = result;
sdp->swd_drumsize = npages;
}
/*
* swapdrum_getsdp: given a page offset in /dev/drum, convert it back
* to the "swapdev" that maps that section of the drum.
*
* => each swapdev takes one big contig chunk of the drum
* => caller must hold swap_data_lock
*/
static struct swapdev *
swapdrum_getsdp(pgno)
int pgno;
{
struct swapdev *sdp;
struct swappri *spp;
for (spp = swap_priority.lh_first; spp != NULL;
spp = spp->spi_swappri.le_next)
for (sdp = spp->spi_swapdev.cqh_first;
sdp != (void *)&spp->spi_swapdev;
sdp = sdp->swd_next.cqe_next)
if (pgno >= sdp->swd_drumoffset &&
pgno < (sdp->swd_drumoffset + sdp->swd_drumsize)) {
return sdp;
}
return NULL;
}
/*
* sys_swapctl: main entry point for swapctl(2) system call
* [with two helper functions: swap_on and swap_off]
*/
int
sys_swapctl(p, v, retval)
struct proc *p;
void *v;
register_t *retval;
{
struct sys_swapctl_args /* {
syscallarg(int) cmd;
syscallarg(void *) arg;
syscallarg(int) misc;
} */ *uap = (struct sys_swapctl_args *)v;
struct vnode *vp;
struct nameidata nd;
struct swappri *spp;
struct swapdev *sdp;
struct swapent *sep;
int count, error, misc;
int priority;
UVMHIST_FUNC("sys_swapctl"); UVMHIST_CALLED(pdhist);
misc = SCARG(uap, misc);
/*
* ensure serialized syscall access by grabbing the swap_syscall_lock
*/
lockmgr(&swap_syscall_lock, LK_EXCLUSIVE, (void *)0);
/*
* we handle the non-priv NSWAP and STATS request first.
*
* SWAP_NSWAP: return number of config'd swap devices
* [can also be obtained with uvmexp sysctl]
*/
if (SCARG(uap, cmd) == SWAP_NSWAP) {
UVMHIST_LOG(pdhist, "<- done SWAP_NSWAP=%d", uvmexp.nswapdev,
0, 0, 0);
*retval = uvmexp.nswapdev;
lockmgr(&swap_syscall_lock, LK_RELEASE, (void *)0);
return (0);
}
/*
* SWAP_STATS: get stats on current # of configured swap devs
*
* note that the swap_priority list can't change as long
* as we are holding the swap_syscall_lock. we don't want
* to grab the swap_data_lock because we may fault&sleep during
* copyout() and we don't want to be holding that lock then!
*/
if (SCARG(uap, cmd) == SWAP_STATS) {
sep = (struct swapent *)SCARG(uap, arg);
count = 0;
for (spp = swap_priority.lh_first; spp != NULL;
spp = spp->spi_swappri.le_next) {
for (sdp = spp->spi_swapdev.cqh_first;
sdp != (void *)&spp->spi_swapdev && misc-- > 0;
sdp = sdp->swd_next.cqe_next) {
/* backwards compatibility for system call */
sdp->swd_se.se_inuse =
btodb(sdp->swd_npginuse * PAGE_SIZE);
error = copyout((caddr_t)&sdp->swd_se,
(caddr_t)sep, sizeof(struct swapent));
if (error) {
lockmgr(&swap_syscall_lock,
LK_RELEASE, (void *)0);
return (error);
}
count++;
sep++;
}
}
UVMHIST_LOG(pdhist, "<-done SWAP_STATS", 0, 0, 0, 0);
*retval = count;
lockmgr(&swap_syscall_lock, LK_RELEASE, (void *)0);
return (0);
}
/*
* all other requests require superuser privs. verify.
*/
if ((error = suser(p->p_ucred, &p->p_acflag))) {
lockmgr(&swap_syscall_lock, LK_RELEASE, (void *)0);
return (error);
}
/*
* at this point we expect a path name in arg. we will
* use namei() to gain a vnode reference (vref), and lock
* the vnode (VOP_LOCK).
*
* XXX: a NULL arg means use the root vnode pointer (e.g. for
* miniroot
*/
if (SCARG(uap, arg) == NULL) {
vp = rootvp; /* miniroot */
if (vget(vp, LK_EXCLUSIVE)) {
lockmgr(&swap_syscall_lock, LK_RELEASE,
(void *)0);
return (EBUSY);
}
} else {
NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, UIO_USERSPACE,
SCARG(uap, arg), p);
if ((error = namei(&nd))) {
lockmgr(&swap_syscall_lock, LK_RELEASE,
(void *)0);
return (error);
}
vp = nd.ni_vp;
}
/* note: "vp" is referenced and locked */
error = 0; /* assume no error */
switch(SCARG(uap, cmd)) {
case SWAP_CTL:
/*
* get new priority, remove old entry (if any) and then
* reinsert it in the correct place. finally, prune out
* any empty priority structures.
*/
priority = SCARG(uap, misc);
spp = (struct swappri *)
malloc(sizeof *spp, M_VMSWAP, M_WAITOK);
simple_lock(&swap_data_lock);
if ((sdp = swaplist_find(vp, 1)) == NULL) {
error = ENOENT;
} else {
swaplist_insert(sdp, spp, priority);
swaplist_trim();
}
simple_unlock(&swap_data_lock);
if (error)
free(spp, M_VMSWAP);
break;
case SWAP_ON:
/*
* check for duplicates. if none found, then insert a
* dummy entry on the list to prevent someone else from
* trying to enable this device while we are working on
* it.
*/
priority = SCARG(uap, misc);
simple_lock(&swap_data_lock);
if ((sdp = swaplist_find(vp, 0)) != NULL) {
error = EBUSY;
simple_unlock(&swap_data_lock);
goto bad;
}
sdp = (struct swapdev *)
malloc(sizeof *sdp, M_VMSWAP, M_WAITOK);
spp = (struct swappri *)
malloc(sizeof *spp, M_VMSWAP, M_WAITOK);
bzero(sdp, sizeof(*sdp));
sdp->swd_flags = SWF_FAKE; /* placeholder only */
sdp->swd_vp = vp;
sdp->swd_dev = (vp->v_type == VBLK) ? vp->v_rdev : NODEV;
#ifdef SWAP_TO_FILES
/*
* XXX Is NFS elaboration necessary?
*/
if (vp->v_type == VREG)
sdp->swd_cred = crdup(p->p_ucred);
#endif
swaplist_insert(sdp, spp, priority);
simple_unlock(&swap_data_lock);
/*
* we've now got a FAKE placeholder in the swap list.
* now attempt to enable swap on it. if we fail, undo
* what we've done and kill the fake entry we just inserted.
* if swap_on is a success, it will clear the SWF_FAKE flag
*/
if ((error = swap_on(p, sdp)) != 0) {
simple_lock(&swap_data_lock);
(void) swaplist_find(vp, 1); /* kill fake entry */
swaplist_trim();
simple_unlock(&swap_data_lock);
#ifdef SWAP_TO_FILES
if (vp->v_type == VREG)
crfree(sdp->swd_cred);
#endif
free((caddr_t)sdp, M_VMSWAP);
break;
}
/*
* got it! now add a second reference to vp so that
* we keep a reference to the vnode after we return.
*/
vref(vp);
break;
case SWAP_OFF:
UVMHIST_LOG(pdhist, "someone is using SWAP_OFF...??", 0,0,0,0);
#ifdef SWAP_OFF_WORKS
/*
* find the entry of interest and ensure it is enabled.
*/
simple_lock(&swap_data_lock);
if ((sdp = swaplist_find(vp, 0)) == NULL) {
simple_unlock(&swap_data_lock);
error = ENXIO;
break;
}
/*
* If a device isn't in use or enabled, we
* can't stop swapping from it (again).
*/
if ((sdp->swd_flags & (SWF_INUSE|SWF_ENABLE)) == 0) {
simple_unlock(&swap_data_lock);
error = EBUSY;
goto bad;
}
/* XXXCDC: should we call with list locked or unlocked? */
if ((error = swap_off(p, sdp)) != 0)
goto bad;
/* XXXCDC: might need relock here */
/*
* now we can kill the entry.
*/
if ((sdp = swaplist_find(vp, 1)) == NULL) {
error = ENXIO;
break;
}
simple_unlock(&swap_data_lock);
free((caddr_t)sdp, M_VMSWAP);
#else
error = EINVAL;
#endif
break;
default:
UVMHIST_LOG(pdhist, "unhandled command: %#x",
SCARG(uap, cmd), 0, 0, 0);
error = EINVAL;
}
bad:
/*
* done! use vput to drop our reference and unlock
*/
vput(vp);
lockmgr(&swap_syscall_lock, LK_RELEASE, (void *)0);
UVMHIST_LOG(pdhist, "<- done! error=%d", error, 0, 0, 0);
return (error);
}
/*
* swap_on: attempt to enable a swapdev for swapping. note that the
* swapdev is already on the global list, but disabled (marked
* SWF_FAKE).
*
* => we avoid the start of the disk (to protect disk labels)
* => we also avoid the miniroot, if we are swapping to root.
* => caller should leave swap_data_lock unlocked, we may lock it
* if needed.
*/
static int
swap_on(p, sdp)
struct proc *p;
struct swapdev *sdp;
{
static int count = 0; /* static */
struct vnode *vp;
int error, npages, nblocks, size;
long addr;
#ifdef SWAP_TO_FILES
struct vattr va;
#endif
#ifdef NFS
extern int (**nfsv2_vnodeop_p) __P((void *));
#endif /* NFS */
dev_t dev;
char *name;
UVMHIST_FUNC("swap_on"); UVMHIST_CALLED(pdhist);
/*
* we want to enable swapping on sdp. the swd_vp contains
* the vnode we want (locked and ref'd), and the swd_dev
* contains the dev_t of the file, if it a block device.
*/
vp = sdp->swd_vp;
dev = sdp->swd_dev;
/*
* open the swap file (mostly useful for block device files to
* let device driver know what is up).
*
* we skip the open/close for root on swap because the root
* has already been opened when root was mounted (mountroot).
*/
if (vp != rootvp) {
if ((error = VOP_OPEN(vp, FREAD|FWRITE, p->p_ucred, p)))
return (error);
}
/* XXX this only works for block devices */
UVMHIST_LOG(pdhist, " dev=%d, major(dev)=%d", dev, major(dev), 0,0);
/*
* we now need to determine the size of the swap area. for
* block specials we can call the d_psize function.
* for normal files, we must stat [get attrs].
*
* we put the result in nblks.
* for normal files, we also want the filesystem block size
* (which we get with statfs).
*/
switch (vp->v_type) {
case VBLK:
if (bdevsw[major(dev)].d_psize == 0 ||
(nblocks = (*bdevsw[major(dev)].d_psize)(dev)) == -1) {
error = ENXIO;
goto bad;
}
break;
#ifdef SWAP_TO_FILES
case VREG:
if ((error = VOP_GETATTR(vp, &va, p->p_ucred, p)))
goto bad;
nblocks = (int)btodb(va.va_size);
if ((error =
VFS_STATFS(vp->v_mount, &vp->v_mount->mnt_stat, p)) != 0)
goto bad;
sdp->swd_bsize = vp->v_mount->mnt_stat.f_iosize;
/*
* limit the max # of outstanding I/O requests we issue
* at any one time. take it easy on NFS servers.
*/
#ifdef NFS
if (vp->v_op == nfsv2_vnodeop_p)
sdp->swd_maxactive = 2; /* XXX */
else
#endif /* NFS */
sdp->swd_maxactive = 8; /* XXX */
break;
#endif
default:
error = ENXIO;
goto bad;
}
/*
* save nblocks in a safe place and convert to pages.
*/
sdp->swd_se.se_nblks = nblocks;
npages = dbtob((u_int64_t)nblocks) / PAGE_SIZE;
/*
* for block special files, we want to make sure that leave
* the disklabel and bootblocks alone, so we arrange to skip
* over them (randomly choosing to skip PAGE_SIZE bytes).
* note that because of this the "size" can be less than the
* actual number of blocks on the device.
*/
if (vp->v_type == VBLK) {
/* we use pages 1 to (size - 1) [inclusive] */
size = npages - 1;
addr = 1;
} else {
/* we use pages 0 to (size - 1) [inclusive] */
size = npages;
addr = 0;
}
/*
* make sure we have enough blocks for a reasonable sized swap
* area. we want at least one page.
*/
if (size < 1) {
UVMHIST_LOG(pdhist, " size <= 1!!", 0, 0, 0, 0);
error = EINVAL;
goto bad;
}
UVMHIST_LOG(pdhist, " dev=%x: size=%d addr=%ld\n", dev, size, addr, 0);
/*
* now we need to allocate an extent to manage this swap device
*/
name = malloc(12, M_VMSWAP, M_WAITOK);
sprintf(name, "swap0x%04x", count++);
/* note that extent_create's 3rd arg is inclusive, thus "- 1" */
sdp->swd_ex = extent_create(name, 0, npages - 1, M_VMSWAP,
0, 0, EX_WAITOK);
/* allocate the `saved' region from the extent so it won't be used */
if (addr) {
if (extent_alloc_region(sdp->swd_ex, 0, addr, EX_WAITOK))
panic("disklabel region");
sdp->swd_npginuse += addr;
uvmexp.swpginuse += addr;
}
/*
* if the vnode we are swapping to is the root vnode
* (i.e. we are swapping to the miniroot) then we want
* to make sure we don't overwrite it. do a statfs to
* find its size and skip over it.
*/
if (vp == rootvp) {
struct mount *mp;
struct statfs *sp;
int rootblocks, rootpages;
mp = rootvnode->v_mount;
sp = &mp->mnt_stat;
rootblocks = sp->f_blocks * btodb(sp->f_bsize);
rootpages = round_page(dbtob(rootblocks)) / PAGE_SIZE;
if (rootpages > npages)
panic("swap_on: miniroot larger than swap?");
if (extent_alloc_region(sdp->swd_ex, addr,
rootpages, EX_WAITOK))
panic("swap_on: unable to preserve miniroot");
sdp->swd_npginuse += (rootpages - addr);
uvmexp.swpginuse += (rootpages - addr);
printf("Preserved %d pages of miniroot ", rootpages);
printf("leaving %d pages of swap\n", size - rootpages);
}
/*
* now add the new swapdev to the drum and enable.
*/
simple_lock(&swap_data_lock);
swapdrum_add(sdp, npages);
sdp->swd_npages = npages;
sdp->swd_flags &= ~SWF_FAKE; /* going live */
sdp->swd_flags |= (SWF_INUSE|SWF_ENABLE);
simple_unlock(&swap_data_lock);
uvmexp.swpages += npages;
/*
* add anon's to reflect the swap space we added
*/
uvm_anon_add(size);
#if 0
/*
* At this point we could arrange to reserve memory for the
* swap buffer pools.
*
* I don't think this is necessary, since swapping starts well
* ahead of serious memory deprivation and the memory resource
* pools hold on to actively used memory. This should ensure
* we always have some resources to continue operation.
*/
int s = splbio();
int n = 8 * sdp->swd_maxactive;
(void)pool_prime(swapbuf_pool, n, 0);
if (vp->v_type == VREG) {
/* Allocate additional vnx and vnd buffers */
/*
* Allocation Policy:
* (8 * swd_maxactive) vnx headers per swap dev
* (16 * swd_maxactive) vnd buffers per swap dev
*/
n = 8 * sdp->swd_maxactive;
(void)pool_prime(vndxfer_pool, n, 0);
n = 16 * sdp->swd_maxactive;
(void)pool_prime(vndbuf_pool, n, 0);
}
splx(s);
#endif
return (0);
bad:
/*
* failure: close device if necessary and return error.
*/
if (vp != rootvp)
(void)VOP_CLOSE(vp, FREAD|FWRITE, p->p_ucred, p);
return (error);
}
#ifdef SWAP_OFF_WORKS
/*
* swap_off: stop swapping on swapdev
*
* XXXCDC: what conditions go here?
*/
static int
swap_off(p, sdp)
struct proc *p;
struct swapdev *sdp;
{
char *name;
UVMHIST_FUNC("swap_off"); UVMHIST_CALLED(pdhist);
/* turn off the enable flag */
sdp->swd_flags &= ~SWF_ENABLE;
UVMHIST_LOG(pdhist, " dev=%x", sdp->swd_dev);
/*
* XXX write me
*
* the idea is to find out which processes are using this swap
* device, and page them all in.
*
* eventually, we should try to move them out to other swap areas
* if available.
*
* The alternative is to create a redirection map for this swap
* device. This should work by moving all the pages of data from
* the ex-swap device to another one, and making an entry in the
* redirection map for it. locking is going to be important for
* this!
*
* XXXCDC: also need to shrink anon pool
*/
/* until the above code is written, we must ENODEV */
return ENODEV;
extent_free(swapmap, sdp->swd_mapoffset, sdp->swd_mapsize, EX_WAITOK);
name = sdp->swd_ex->ex_name;
extent_destroy(sdp->swd_ex);
free(name, M_VMSWAP);
free((caddr_t)sdp->swd_ex, M_VMSWAP);
if (sdp->swp_vp != rootvp)
(void) VOP_CLOSE(sdp->swd_vp, FREAD|FWRITE, p->p_ucred, p);
if (sdp->swd_vp)
vrele(sdp->swd_vp);
free((caddr_t)sdp, M_VMSWAP);
return (0);
}
#endif
/*
* /dev/drum interface and i/o functions
*/
/*
* swread: the read function for the drum (just a call to physio)
*/
/*ARGSUSED*/
int
swread(dev, uio, ioflag)
dev_t dev;
struct uio *uio;
int ioflag;
{
UVMHIST_FUNC("swread"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, " dev=%x offset=%qx", dev, uio->uio_offset, 0, 0);
return (physio(swstrategy, NULL, dev, B_READ, minphys, uio));
}
/*
* swwrite: the write function for the drum (just a call to physio)
*/
/*ARGSUSED*/
int
swwrite(dev, uio, ioflag)
dev_t dev;
struct uio *uio;
int ioflag;
{
UVMHIST_FUNC("swwrite"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, " dev=%x offset=%qx", dev, uio->uio_offset, 0, 0);
return (physio(swstrategy, NULL, dev, B_WRITE, minphys, uio));
}
/*
* swstrategy: perform I/O on the drum
*
* => we must map the i/o request from the drum to the correct swapdev.
*/
void
swstrategy(bp)
struct buf *bp;
{
struct swapdev *sdp;
struct vnode *vp;
int pageno;
int bn;
UVMHIST_FUNC("swstrategy"); UVMHIST_CALLED(pdhist);
/*
* convert block number to swapdev. note that swapdev can't
* be yanked out from under us because we are holding resources
* in it (i.e. the blocks we are doing I/O on).
*/
pageno = dbtob(bp->b_blkno) / PAGE_SIZE;
simple_lock(&swap_data_lock);
sdp = swapdrum_getsdp(pageno);
simple_unlock(&swap_data_lock);
if (sdp == NULL) {
bp->b_error = EINVAL;
bp->b_flags |= B_ERROR;
biodone(bp);
UVMHIST_LOG(pdhist, " failed to get swap device", 0, 0, 0, 0);
return;
}
/*
* convert drum page number to block number on this swapdev.
*/
pageno = pageno - sdp->swd_drumoffset; /* page # on swapdev */
bn = btodb(pageno * PAGE_SIZE); /* convert to diskblock */
UVMHIST_LOG(pdhist, " %s: mapoff=%x bn=%x bcount=%ld\n",
((bp->b_flags & B_READ) == 0) ? "write" : "read",
sdp->swd_drumoffset, bn, bp->b_bcount);
/*
* for block devices we finish up here.
* for regular files we have to do more work which we deligate
* to sw_reg_strategy().
*/
switch (sdp->swd_vp->v_type) {
default:
panic("swstrategy: vnode type 0x%x", sdp->swd_vp->v_type);
case VBLK:
/*
* must convert "bp" from an I/O on /dev/drum to an I/O
* on the swapdev (sdp).
*/
bp->b_blkno = bn; /* swapdev block number */
vp = sdp->swd_vp; /* swapdev vnode pointer */
bp->b_dev = sdp->swd_dev; /* swapdev dev_t */
VHOLD(vp); /* "hold" swapdev vp for i/o */
/*
* if we are doing a write, we have to redirect the i/o on
* drum's v_numoutput counter to the swapdevs.
*/
if ((bp->b_flags & B_READ) == 0) {
int s = splbio();
vwakeup(bp); /* kills one 'v_numoutput' on drum */
vp->v_numoutput++; /* put it on swapdev */
splx(s);
}
/*
* dissassocate buffer with /dev/drum vnode
* [could be null if buf was from physio]
*/
if (bp->b_vp != NULLVP)
brelvp(bp);
/*
* finally plug in swapdev vnode and start I/O
*/
bp->b_vp = vp;
VOP_STRATEGY(bp);
return;
#ifdef SWAP_TO_FILES
case VREG:
/*
* deligate to sw_reg_strategy function.
*/
sw_reg_strategy(sdp, bp, bn);
return;
#endif
}
/* NOTREACHED */
}
#ifdef SWAP_TO_FILES
/*
* sw_reg_strategy: handle swap i/o to regular files
*/
static void
sw_reg_strategy(sdp, bp, bn)
struct swapdev *sdp;
struct buf *bp;
int bn;
{
struct vnode *vp;
struct vndxfer *vnx;
daddr_t nbn, byteoff;
caddr_t addr;
int s, off, nra, error, sz, resid;
UVMHIST_FUNC("sw_reg_strategy"); UVMHIST_CALLED(pdhist);
/*
* allocate a vndxfer head for this transfer and point it to
* our buffer.
*/
getvndxfer(vnx);
vnx->vx_flags = VX_BUSY;
vnx->vx_error = 0;
vnx->vx_pending = 0;
vnx->vx_bp = bp;
vnx->vx_sdp = sdp;
/*
* setup for main loop where we read filesystem blocks into
* our buffer.
*/
error = 0;
bp->b_resid = bp->b_bcount; /* nothing transfered yet! */
addr = bp->b_data; /* current position in buffer */
byteoff = dbtob(bn);
for (resid = bp->b_resid; resid; resid -= sz) {
struct vndbuf *nbp;
/*
* translate byteoffset into block number. return values:
* vp = vnode of underlying device
* nbn = new block number (on underlying vnode dev)
* nra = num blocks we can read-ahead (excludes requested
* block)
*/
nra = 0;
error = VOP_BMAP(sdp->swd_vp, byteoff / sdp->swd_bsize,
&vp, &nbn, &nra);
if (error == 0 && (long)nbn == -1)
error = EIO; /* failure */
/*
* punt if there was an error or a hole in the file.
* we must wait for any i/o ops we have already started
* to finish before returning.
*
* XXX we could deal with holes here but it would be
* a hassle (in the write case).
*/
if (error) {
s = splbio();
vnx->vx_error = error; /* pass error up */
goto out;
}
/*
* compute the size ("sz") of this transfer (in bytes).
* XXXCDC: ignores read-ahead for non-zero offset
*/
if ((off = (byteoff % sdp->swd_bsize)) != 0)
sz = sdp->swd_bsize - off;
else
sz = (1 + nra) * sdp->swd_bsize;
if (resid < sz)
sz = resid;
UVMHIST_LOG(pdhist, "sw_reg_strategy: vp %p/%p offset 0x%x/0x%x",
sdp->swd_vp, vp, byteoff, nbn);
/*
* now get a buf structure. note that the vb_buf is
* at the front of the nbp structure so that you can
* cast pointers between the two structure easily.
*/
getvndbuf(nbp);
nbp->vb_buf.b_flags = bp->b_flags | B_CALL;
nbp->vb_buf.b_bcount = sz;
#if 0
nbp->vb_buf.b_bufsize = bp->b_bufsize; /* XXXCDC: really? */
#endif
nbp->vb_buf.b_bufsize = sz;
nbp->vb_buf.b_error = 0;
nbp->vb_buf.b_data = addr;
nbp->vb_buf.b_blkno = nbn + btodb(off);
nbp->vb_buf.b_proc = bp->b_proc;
nbp->vb_buf.b_iodone = sw_reg_iodone;
nbp->vb_buf.b_vp = NULLVP;
nbp->vb_buf.b_vnbufs.le_next = NOLIST;
nbp->vb_buf.b_rcred = sdp->swd_cred;
nbp->vb_buf.b_wcred = sdp->swd_cred;
/*
* set b_dirtyoff/end and b_validoff/end. this is
* required by the NFS client code (otherwise it will
* just discard our I/O request).
*/
if (bp->b_dirtyend == 0) {
nbp->vb_buf.b_dirtyoff = 0;
nbp->vb_buf.b_dirtyend = sz;
} else {
nbp->vb_buf.b_dirtyoff =
max(0, bp->b_dirtyoff - (bp->b_bcount-resid));
nbp->vb_buf.b_dirtyend =
min(sz,
max(0, bp->b_dirtyend - (bp->b_bcount-resid)));
}
if (bp->b_validend == 0) {
nbp->vb_buf.b_validoff = 0;
nbp->vb_buf.b_validend = sz;
} else {
nbp->vb_buf.b_validoff =
max(0, bp->b_validoff - (bp->b_bcount-resid));
nbp->vb_buf.b_validend =
min(sz,
max(0, bp->b_validend - (bp->b_bcount-resid)));
}
nbp->vb_xfer = vnx; /* patch it back in to vnx */
/*
* Just sort by block number
*/
nbp->vb_buf.b_cylinder = nbp->vb_buf.b_blkno;
s = splbio();
if (vnx->vx_error != 0) {
putvndbuf(nbp);
goto out;
}
vnx->vx_pending++;
/* assoc new buffer with underlying vnode */
bgetvp(vp, &nbp->vb_buf);
/* sort it in and start I/O if we are not over our limit */
disksort(&sdp->swd_tab, &nbp->vb_buf);
sw_reg_start(sdp);
splx(s);
/*
* advance to the next I/O
*/
byteoff += sz;
addr += sz;
}
s = splbio();
out: /* Arrive here at splbio */
vnx->vx_flags &= ~VX_BUSY;
if (vnx->vx_pending == 0) {
if (vnx->vx_error != 0) {
bp->b_error = vnx->vx_error;
bp->b_flags |= B_ERROR;
}
putvndxfer(vnx);
biodone(bp);
}
splx(s);
}
/*
* sw_reg_start: start an I/O request on the requested swapdev
*
* => reqs are sorted by disksort (above)
*/
static void
sw_reg_start(sdp)
struct swapdev *sdp;
{
struct buf *bp;
UVMHIST_FUNC("sw_reg_start"); UVMHIST_CALLED(pdhist);
/* recursion control */
if ((sdp->swd_flags & SWF_BUSY) != 0)
return;
sdp->swd_flags |= SWF_BUSY;
while (sdp->swd_tab.b_active < sdp->swd_maxactive) {
bp = sdp->swd_tab.b_actf;
if (bp == NULL)
break;
sdp->swd_tab.b_actf = bp->b_actf;
sdp->swd_tab.b_active++;
UVMHIST_LOG(pdhist,
"sw_reg_start: bp %p vp %p blkno %p cnt %lx",
bp, bp->b_vp, bp->b_blkno, bp->b_bcount);
if ((bp->b_flags & B_READ) == 0)
bp->b_vp->v_numoutput++;
VOP_STRATEGY(bp);
}
sdp->swd_flags &= ~SWF_BUSY;
}
/*
* sw_reg_iodone: one of our i/o's has completed and needs post-i/o cleanup
*
* => note that we can recover the vndbuf struct by casting the buf ptr
*/
static void
sw_reg_iodone(bp)
struct buf *bp;
{
struct vndbuf *vbp = (struct vndbuf *) bp;
struct vndxfer *vnx = vbp->vb_xfer;
struct buf *pbp = vnx->vx_bp; /* parent buffer */
struct swapdev *sdp = vnx->vx_sdp;
int s, resid;
UVMHIST_FUNC("sw_reg_iodone"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, " vbp=%p vp=%p blkno=%x addr=%p",
vbp, vbp->vb_buf.b_vp, vbp->vb_buf.b_blkno, vbp->vb_buf.b_data);
UVMHIST_LOG(pdhist, " cnt=%lx resid=%lx",
vbp->vb_buf.b_bcount, vbp->vb_buf.b_resid, 0, 0);
/*
* protect vbp at splbio and update.
*/
s = splbio();
resid = vbp->vb_buf.b_bcount - vbp->vb_buf.b_resid;
pbp->b_resid -= resid;
vnx->vx_pending--;
if (vbp->vb_buf.b_error) {
UVMHIST_LOG(pdhist, " got error=%d !",
vbp->vb_buf.b_error, 0, 0, 0);
/* pass error upward */
vnx->vx_error = vbp->vb_buf.b_error;
}
/*
* drop "hold" reference to vnode (if one)
* XXXCDC: always set to NULLVP, this is useless, right?
*/
if (vbp->vb_buf.b_vp != NULLVP)
brelvp(&vbp->vb_buf);
/*
* kill vbp structure
*/
putvndbuf(vbp);
/*
* wrap up this transaction if it has run to completion or, in
* case of an error, when all auxiliary buffers have returned.
*/
if (vnx->vx_error != 0) {
/* pass error upward */
pbp->b_flags |= B_ERROR;
pbp->b_error = vnx->vx_error;
if ((vnx->vx_flags & VX_BUSY) == 0 && vnx->vx_pending == 0) {
putvndxfer(vnx);
biodone(pbp);
}
} else if (pbp->b_resid == 0) {
#ifdef DIAGNOSTIC
if (vnx->vx_pending != 0)
panic("sw_reg_iodone: vnx pending: %d",vnx->vx_pending);
#endif
if ((vnx->vx_flags & VX_BUSY) == 0) {
UVMHIST_LOG(pdhist, " iodone error=%d !",
pbp, vnx->vx_error, 0, 0);
putvndxfer(vnx);
biodone(pbp);
}
}
/*
* done! start next swapdev I/O if one is pending
*/
sdp->swd_tab.b_active--;
sw_reg_start(sdp);
splx(s);
}
#endif /* SWAP_TO_FILES */
/*
* uvm_swap_alloc: allocate space on swap
*
* => allocation is done "round robin" down the priority list, as we
* allocate in a priority we "rotate" the circle queue.
* => space can be freed with uvm_swap_free
* => we return the page slot number in /dev/drum (0 == invalid slot)
* => we lock swap_data_lock
* => XXXMRG: "LESSOK" INTERFACE NEEDED TO EXTENT SYSTEM
*/
int
uvm_swap_alloc(nslots, lessok)
int *nslots; /* IN/OUT */
boolean_t lessok;
{
struct swapdev *sdp;
struct swappri *spp;
u_long result;
UVMHIST_FUNC("uvm_swap_alloc"); UVMHIST_CALLED(pdhist);
/*
* no swap devices configured yet? definite failure.
*/
if (uvmexp.nswapdev < 1)
return 0;
/*
* lock data lock, convert slots into blocks, and enter loop
*/
simple_lock(&swap_data_lock);
ReTry: /* XXXMRG */
for (spp = swap_priority.lh_first; spp != NULL;
spp = spp->spi_swappri.le_next) {
for (sdp = spp->spi_swapdev.cqh_first;
sdp != (void *)&spp->spi_swapdev;
sdp = sdp->swd_next.cqe_next) {
/* if it's not enabled, then we can't swap from it */
if ((sdp->swd_flags & SWF_ENABLE) == 0)
continue;
if (sdp->swd_npginuse + *nslots > sdp->swd_npages)
continue;
if (extent_alloc(sdp->swd_ex, *nslots, EX_NOALIGN,
EX_NOBOUNDARY, EX_MALLOCOK|EX_NOWAIT,
&result) != 0) {
continue;
}
/*
* successful allocation! now rotate the circleq.
*/
CIRCLEQ_REMOVE(&spp->spi_swapdev, sdp, swd_next);
CIRCLEQ_INSERT_TAIL(&spp->spi_swapdev, sdp, swd_next);
sdp->swd_npginuse += *nslots;
uvmexp.swpginuse += *nslots;
simple_unlock(&swap_data_lock);
/* done! return drum slot number */
UVMHIST_LOG(pdhist,
"success! returning %d slots starting at %d",
*nslots, result + sdp->swd_drumoffset, 0, 0);
#if 0
{
struct swapdev *sdp2;
sdp2 = swapdrum_getsdp(result + sdp->swd_drumoffset);
if (sdp2 == NULL) {
printf("uvm_swap_alloc: nslots=%d, dev=%x, drumoff=%d, result=%ld",
*nslots, sdp->swd_dev, sdp->swd_drumoffset, result);
panic("uvm_swap_alloc: allocating unmapped swap block!");
}
}
#endif
return(result + sdp->swd_drumoffset);
}
}
/* XXXMRG: BEGIN HACK */
if (*nslots > 1 && lessok) {
*nslots = 1;
goto ReTry; /* XXXMRG: ugh! extent should support this for us */
}
/* XXXMRG: END HACK */
simple_unlock(&swap_data_lock);
return 0; /* failed */
}
/*
* uvm_swap_free: free swap slots
*
* => this can be all or part of an allocation made by uvm_swap_alloc
* => we lock swap_data_lock
*/
void
uvm_swap_free(startslot, nslots)
int startslot;
int nslots;
{
struct swapdev *sdp;
UVMHIST_FUNC("uvm_swap_free"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "freeing %d slots starting at %d", nslots,
startslot, 0, 0);
/*
* convert drum slot offset back to sdp, free the blocks
* in the extent, and return. must hold pri lock to do
* lookup and access the extent.
*/
simple_lock(&swap_data_lock);
sdp = swapdrum_getsdp(startslot);
#ifdef DIAGNOSTIC
if (uvmexp.nswapdev < 1)
panic("uvm_swap_free: uvmexp.nswapdev < 1\n");
if (sdp == NULL) {
printf("uvm_swap_free: startslot %d, nslots %d\n", startslot,
nslots);
panic("uvm_swap_free: unmapped address\n");
}
#endif
if (extent_free(sdp->swd_ex, startslot - sdp->swd_drumoffset, nslots,
EX_MALLOCOK|EX_NOWAIT) != 0)
printf("warning: resource shortage: %d slots of swap lost\n",
nslots);
sdp->swd_npginuse -= nslots;
uvmexp.swpginuse -= nslots;
#ifdef DIAGNOSTIC
if (sdp->swd_npginuse < 0)
panic("uvm_swap_free: inuse < 0");
#endif
simple_unlock(&swap_data_lock);
}
/*
* uvm_swap_put: put any number of pages into a contig place on swap
*
* => can be sync or async
* => XXXMRG: consider making it an inline or macro
*/
int
uvm_swap_put(swslot, ppsp, npages, flags)
int swslot;
struct vm_page **ppsp;
int npages;
int flags;
{
int result;
#if 0
flags |= PGO_SYNCIO; /* XXXMRG: tmp, force sync */
#endif
result = uvm_swap_io(ppsp, swslot, npages, B_WRITE |
((flags & PGO_SYNCIO) ? 0 : B_ASYNC));
return (result);
}
/*
* uvm_swap_get: get a single page from swap
*
* => usually a sync op (from fault)
* => XXXMRG: consider making it an inline or macro
*/
int
uvm_swap_get(page, swslot, flags)
struct vm_page *page;
int swslot, flags;
{
int result;
uvmexp.nswget++;
#ifdef DIAGNOSTIC
if ((flags & PGO_SYNCIO) == 0)
printf("uvm_swap_get: ASYNC get requested?\n");
#endif
result = uvm_swap_io(&page, swslot, 1, B_READ |
((flags & PGO_SYNCIO) ? 0 : B_ASYNC));
return (result);
}
/*
* uvm_swap_io: do an i/o operation to swap
*/
static int
uvm_swap_io(pps, startslot, npages, flags)
struct vm_page **pps;
int startslot, npages, flags;
{
daddr_t startblk;
struct swapbuf *sbp;
struct buf *bp;
vm_offset_t kva;
int result, s, waitf, pflag;
UVMHIST_FUNC("uvm_swap_io"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "<- called, startslot=%d, npages=%d, flags=%d",
startslot, npages, flags, 0);
/*
* convert starting drum slot to block number
*/
startblk = btodb(startslot * PAGE_SIZE);
/*
* first, map the pages into the kernel (XXX: currently required
* by buffer system). note that we don't let pagermapin alloc
* an aiodesc structure because we don't want to chance a malloc.
* we've got our own pool of aiodesc structures (in swapbuf).
*/
waitf = (flags & B_ASYNC) ? M_NOWAIT : M_WAITOK;
kva = uvm_pagermapin(pps, npages, NULL, waitf);
if (kva == NULL)
return (VM_PAGER_AGAIN);
/*
* now allocate a swap buffer off of freesbufs
* [make sure we don't put the pagedaemon to sleep...]
*/
s = splbio();
pflag = ((flags & B_ASYNC) != 0 || curproc == uvm.pagedaemon_proc)
? 0
: PR_WAITOK;
sbp = pool_get(swapbuf_pool, pflag);
splx(s); /* drop splbio */
/*
* if we failed to get a swapbuf, return "try again"
*/
if (sbp == NULL)
return (VM_PAGER_AGAIN);
/*
* fill in the bp/sbp. we currently route our i/o through
* /dev/drum's vnode [swapdev_vp].
*/
bp = &sbp->sw_buf;
bp->b_flags = B_BUSY | (flags & (B_READ|B_ASYNC));
bp->b_proc = &proc0; /* XXX */
bp->b_rcred = bp->b_wcred = proc0.p_ucred;
bp->b_vnbufs.le_next = NOLIST;
bp->b_data = (caddr_t)kva;
bp->b_blkno = startblk;
VHOLD(swapdev_vp);
bp->b_vp = swapdev_vp;
/* XXXCDC: isn't swapdev_vp always a VCHR? */
/* XXXMRG: probably -- this is obviously something inherited... */
if (swapdev_vp->v_type == VBLK)
bp->b_dev = swapdev_vp->v_rdev;
bp->b_bcount = npages * PAGE_SIZE;
/*
* for pageouts we must set "dirtyoff" [NFS client code needs it].
* and we bump v_numoutput (counter of number of active outputs).
*/
if ((bp->b_flags & B_READ) == 0) {
bp->b_dirtyoff = 0;
bp->b_dirtyend = npages * PAGE_SIZE;
s = splbio();
swapdev_vp->v_numoutput++;
splx(s);
}
/*
* for async ops we must set up the aiodesc and setup the callback
* XXX: we expect no async-reads, but we don't prevent it here.
*/
if (flags & B_ASYNC) {
sbp->sw_aio.aiodone = uvm_swap_aiodone;
sbp->sw_aio.kva = kva;
sbp->sw_aio.npages = npages;
sbp->sw_aio.pd_ptr = sbp; /* backpointer */
bp->b_flags |= B_CALL; /* set callback */
bp->b_iodone = uvm_swap_bufdone;/* "buf" iodone function */
UVMHIST_LOG(pdhist, "doing async!", 0, 0, 0, 0);
}
UVMHIST_LOG(pdhist,
"about to start io: data = 0x%p blkno = 0x%x, bcount = %ld",
bp->b_data, bp->b_blkno, bp->b_bcount, 0);
/*
* now we start the I/O, and if async, return.
*/
VOP_STRATEGY(bp);
if (flags & B_ASYNC)
return (VM_PAGER_PEND);
/*
* must be sync i/o. wait for it to finish
*/
bp->b_error = biowait(bp);
result = (bp->b_flags & B_ERROR) ? VM_PAGER_ERROR : VM_PAGER_OK;
/*
* kill the pager mapping
*/
uvm_pagermapout(kva, npages);
/*
* now dispose of the swap buffer
*/
s = splbio();
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_PAGET|B_UAREA|B_DIRTY);
if (bp->b_vp)
brelvp(bp);
pool_put(swapbuf_pool, sbp);
splx(s);
/*
* finally return.
*/
UVMHIST_LOG(pdhist, "<- done (sync) result=%d", result, 0, 0, 0);
return (result);
}
/*
* uvm_swap_bufdone: called from the buffer system when the i/o is done
*/
static void
uvm_swap_bufdone(bp)
struct buf *bp;
{
struct swapbuf *sbp = (struct swapbuf *) bp;
int s = splbio();
UVMHIST_FUNC("uvm_swap_bufdone"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "cleaning buf %p", buf, 0, 0, 0);
#ifdef DIAGNOSTIC
/*
* sanity check: swapbufs are private, so they shouldn't be wanted
*/
if (bp->b_flags & B_WANTED)
panic("uvm_swap_bufdone: private buf wanted");
#endif
/*
* drop buffers reference to the vnode and its flags.
*/
bp->b_flags &= ~(B_BUSY|B_WANTED|B_PHYS|B_PAGET|B_UAREA|B_DIRTY);
if (bp->b_vp)
brelvp(bp);
/*
* now put the aio on the uvm.aio_done list and wake the
* pagedaemon (which will finish up our job in its context).
*/
simple_lock(&uvm.pagedaemon_lock); /* locks uvm.aio_done */
TAILQ_INSERT_TAIL(&uvm.aio_done, &sbp->sw_aio, aioq);
simple_unlock(&uvm.pagedaemon_lock);
thread_wakeup(&uvm.pagedaemon);
splx(s);
}
/*
* uvm_swap_aiodone: aiodone function for anonymous memory
*
* => this is called in the context of the pagedaemon (but with the
* page queues unlocked!)
* => our "aio" structure must be part of a "swapbuf"
*/
static void
uvm_swap_aiodone(aio)
struct uvm_aiodesc *aio;
{
struct swapbuf *sbp = aio->pd_ptr;
/* XXXMRG: does this work if PAGE_SIZE is a variable, eg SUN4C&&SUN4 */
/* XXX it does with GCC */
struct vm_page *pps[MAXBSIZE/PAGE_SIZE];
int lcv, s;
vm_offset_t addr;
UVMHIST_FUNC("uvm_swap_aiodone"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "done with aio %p", aio, 0, 0, 0);
#ifdef DIAGNOSTIC
/*
* sanity check
*/
if (aio->npages > (MAXBSIZE/PAGE_SIZE))
panic("uvm_swap_aiodone: aio too big!");
#endif
/*
* first, we have to recover the page pointers (pps) by poking in the
* kernel pmap (XXX: should be saved in the buf structure).
*/
for (addr = aio->kva, lcv = 0 ; lcv < aio->npages ;
addr += PAGE_SIZE, lcv++) {
pps[lcv] = uvm_pageratop(addr);
}
/*
* now we can dispose of the kernel mappings of the buffer
*/
uvm_pagermapout(aio->kva, aio->npages);
/*
* now we can dispose of the pages by using the dropcluster function
* [note that we have no "page of interest" so we pass in null]
*/
uvm_pager_dropcluster(NULL, NULL, pps, &aio->npages,
PGO_PDFREECLUST, 0);
/*
* finally, we can dispose of the swapbuf
*/
s = splbio();
pool_put(swapbuf_pool, sbp);
splx(s);
/*
* done!
*/
}
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