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NetBSD/sys/uvm/uvm_swap.c

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/* $NetBSD: uvm_swap.c,v 1.152 2010/07/09 08:13:33 hannken Exp $ */
/*
* Copyright (c) 1995, 1996, 1997, 2009 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.
*
* 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_swap.c,v 1.152 2010/07/09 08:13:33 hannken Exp $");
#include "opt_uvmhist.h"
#include "opt_compat_netbsd.h"
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/bufq.h>
#include <sys/conf.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/vmem.h>
#include <sys/blist.h>
#include <sys/mount.h>
#include <sys/pool.h>
#include <sys/syscallargs.h>
#include <sys/swap.h>
#include <sys/kauth.h>
#include <sys/sysctl.h>
#include <sys/workqueue.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.
*
* locking:
* - swap_syscall_lock (krwlock_t): 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).
* - uvm_swap_data_lock (kmutex_t): this lock protects all swap data
* structures including the priority list, the swapdev structures,
* and the swapmap arena.
*
* 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
*
* 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. The actual work is done
* in the uvm_swap_stats(9) function.
* [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")
*/
/*
* 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 {
dev_t swd_dev; /* device id */
int swd_flags; /* flags:inuse/enable/fake */
int swd_priority; /* our priority */
int swd_nblks; /* blocks in this device */
char *swd_path; /* saved pathname of device */
int swd_pathlen; /* length of pathname */
int swd_npages; /* #pages we can use */
int swd_npginuse; /* #pages in use */
int swd_npgbad; /* #pages bad */
int swd_drumoffset; /* page0 offset in drum */
int swd_drumsize; /* #pages in drum */
blist_t swd_blist; /* blist for this swapdev */
struct vnode *swd_vp; /* backing vnode */
CIRCLEQ_ENTRY(swapdev) swd_next; /* priority circleq */
int swd_bsize; /* blocksize (bytes) */
int swd_maxactive; /* max active i/o reqs */
struct bufq_state *swd_tab; /* buffer list */
int swd_active; /* number of active buffers */
};
/*
* 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 */
};
/*
* 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;
};
/*
* NetBSD 1.3 swapctl(SWAP_STATS, ...) swapent structure; uses 32 bit
* dev_t and has no se_path[] member.
*/
struct swapent13 {
int32_t se13_dev; /* device id */
int se13_flags; /* flags */
int se13_nblks; /* total blocks */
int se13_inuse; /* blocks in use */
int se13_priority; /* priority of this device */
};
/*
* NetBSD 5.0 swapctl(SWAP_STATS, ...) swapent structure; uses 32 bit
* dev_t.
*/
struct swapent50 {
int32_t se50_dev; /* device id */
int se50_flags; /* flags */
int se50_nblks; /* total blocks */
int se50_inuse; /* blocks in use */
int se50_priority; /* priority of this device */
char se50_path[PATH_MAX+1]; /* path name */
};
/*
* We keep a of pool vndbuf's and vndxfer structures.
*/
static struct pool vndxfer_pool, vndbuf_pool;
/*
* local variables
*/
MALLOC_DEFINE(M_VMSWAP, "VM swap", "VM swap structures");
static vmem_t *swapmap; /* controls the mapping of /dev/drum */
/* list of all active swap devices [by priority] */
LIST_HEAD(swap_priority, swappri);
static struct swap_priority swap_priority;
/* locks */
static krwlock_t swap_syscall_lock;
/* workqueue and use counter for swap to regular files */
static int sw_reg_count = 0;
static struct workqueue *sw_reg_workqueue;
/* tuneables */
u_int uvm_swapisfull_factor = 99;
/*
* prototypes
*/
static struct swapdev *swapdrum_getsdp(int);
static struct swapdev *swaplist_find(struct vnode *, bool);
static void swaplist_insert(struct swapdev *,
struct swappri *, int);
static void swaplist_trim(void);
static int swap_on(struct lwp *, struct swapdev *);
static int swap_off(struct lwp *, struct swapdev *);
static void uvm_swap_stats_locked(int, struct swapent *, int, register_t *);
static void sw_reg_strategy(struct swapdev *, struct buf *, int);
static void sw_reg_biodone(struct buf *);
static void sw_reg_iodone(struct work *wk, void *dummy);
static void sw_reg_start(struct swapdev *);
static int uvm_swap_io(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(void)
{
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;
rw_init(&swap_syscall_lock);
mutex_init(&uvm_swap_data_lock, MUTEX_DEFAULT, IPL_NONE);
if (bdevvp(swapdev, &swapdev_vp))
panic("%s: can't get vnode for swap device", __func__);
if (vn_lock(swapdev_vp, LK_EXCLUSIVE | LK_RETRY))
panic("%s: can't lock swap device", __func__);
if (VOP_OPEN(swapdev_vp, FREAD | FWRITE, NOCRED))
panic("%s: can't open swap device", __func__);
VOP_UNLOCK(swapdev_vp);
/*
* 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 = vmem_create("swapmap", 1, INT_MAX - 1, 1, NULL, NULL, NULL, 0,
VM_NOSLEEP, IPL_NONE);
if (swapmap == 0) {
panic("%s: vmem_create failed", __func__);
}
pool_init(&vndxfer_pool, sizeof(struct vndxfer), 0, 0, 0, "swp vnx",
NULL, IPL_BIO);
pool_init(&vndbuf_pool, sizeof(struct vndbuf), 0, 0, 0, "swp vnd",
NULL, IPL_BIO);
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 uvm_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(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.
*/
pspp = NULL;
LIST_FOREACH(spp, &swap_priority, spi_swappri) {
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++;
}
/*
* swaplist_find: find and optionally remove a swap device from the
* global list.
*
* => caller must hold both swap_syscall_lock and uvm_swap_data_lock
* => we return the swapdev we found (and removed)
*/
static struct swapdev *
swaplist_find(struct vnode *vp, bool remove)
{
struct swapdev *sdp;
struct swappri *spp;
/*
* search the lists for the requested vp
*/
LIST_FOREACH(spp, &swap_priority, spi_swappri) {
CIRCLEQ_FOREACH(sdp, &spp->spi_swapdev, swd_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 uvm_swap_data_lock
*/
static void
swaplist_trim(void)
{
struct swappri *spp, *nextspp;
for (spp = LIST_FIRST(&swap_priority); spp != NULL; spp = nextspp) {
nextspp = LIST_NEXT(spp, spi_swappri);
if (CIRCLEQ_FIRST(&spp->spi_swapdev) !=
(void *)&spp->spi_swapdev)
continue;
LIST_REMOVE(spp, spi_swappri);
free(spp, M_VMSWAP);
}
}
/*
* 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 uvm_swap_data_lock
*/
static struct swapdev *
swapdrum_getsdp(int pgno)
{
struct swapdev *sdp;
struct swappri *spp;
LIST_FOREACH(spp, &swap_priority, spi_swappri) {
CIRCLEQ_FOREACH(sdp, &spp->spi_swapdev, swd_next) {
if (sdp->swd_flags & SWF_FAKE)
continue;
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(struct lwp *l, const struct sys_swapctl_args *uap, register_t *retval)
{
/* {
syscallarg(int) cmd;
syscallarg(void *) arg;
syscallarg(int) misc;
} */
struct vnode *vp;
struct nameidata nd;
struct swappri *spp;
struct swapdev *sdp;
struct swapent *sep;
#define SWAP_PATH_MAX (PATH_MAX + 1)
char *userpath;
size_t len;
int 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
*/
rw_enter(&swap_syscall_lock, RW_WRITER);
userpath = malloc(SWAP_PATH_MAX, M_TEMP, M_WAITOK);
/*
* 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;
error = 0;
goto out;
}
/*
* 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 uvm_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
#if defined(COMPAT_50)
|| SCARG(uap, cmd) == SWAP_STATS50
#endif
#if defined(COMPAT_13)
|| SCARG(uap, cmd) == SWAP_STATS13
#endif
) {
if ((size_t)misc > (size_t)uvmexp.nswapdev)
misc = uvmexp.nswapdev;
#if defined(COMPAT_13)
if (SCARG(uap, cmd) == SWAP_STATS13)
len = sizeof(struct swapent13) * misc;
else
#endif
#if defined(COMPAT_50)
if (SCARG(uap, cmd) == SWAP_STATS50)
len = sizeof(struct swapent50) * misc;
else
#endif
len = sizeof(struct swapent) * misc;
sep = (struct swapent *)malloc(len, M_TEMP, M_WAITOK);
uvm_swap_stats_locked(SCARG(uap, cmd), sep, misc, retval);
error = copyout(sep, SCARG(uap, arg), len);
free(sep, M_TEMP);
UVMHIST_LOG(pdhist, "<- done SWAP_STATS", 0, 0, 0, 0);
goto out;
}
if (SCARG(uap, cmd) == SWAP_GETDUMPDEV) {
dev_t *devp = (dev_t *)SCARG(uap, arg);
error = copyout(&dumpdev, devp, sizeof(dumpdev));
goto out;
}
/*
* all other requests require superuser privs. verify.
*/
if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_SWAPCTL,
0, NULL, NULL, NULL)))
goto out;
if (SCARG(uap, cmd) == SWAP_DUMPOFF) {
/* drop the current dump device */
dumpdev = NODEV;
dumpcdev = NODEV;
cpu_dumpconf();
goto out;
}
/*
* 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 */
vref(vp);
if (vn_lock(vp, LK_EXCLUSIVE)) {
vrele(vp);
error = EBUSY;
goto out;
}
if (SCARG(uap, cmd) == SWAP_ON &&
copystr("miniroot", userpath, SWAP_PATH_MAX, &len))
panic("swapctl: miniroot copy failed");
} else {
int space;
char *where;
if (SCARG(uap, cmd) == SWAP_ON) {
if ((error = copyinstr(SCARG(uap, arg), userpath,
SWAP_PATH_MAX, &len)))
goto out;
space = UIO_SYSSPACE;
where = userpath;
} else {
space = UIO_USERSPACE;
where = (char *)SCARG(uap, arg);
}
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | TRYEMULROOT,
space, where);
if ((error = namei(&nd)))
goto out;
vp = nd.ni_vp;
}
/* note: "vp" is referenced and locked */
error = 0; /* assume no error */
switch(SCARG(uap, cmd)) {
case SWAP_DUMPDEV:
if (vp->v_type != VBLK) {
error = ENOTBLK;
break;
}
if (bdevsw_lookup(vp->v_rdev)) {
dumpdev = vp->v_rdev;
dumpcdev = devsw_blk2chr(dumpdev);
} else
dumpdev = NODEV;
cpu_dumpconf();
break;
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 = malloc(sizeof *spp, M_VMSWAP, M_WAITOK);
mutex_enter(&uvm_swap_data_lock);
if ((sdp = swaplist_find(vp, true)) == NULL) {
error = ENOENT;
} else {
swaplist_insert(sdp, spp, priority);
swaplist_trim();
}
mutex_exit(&uvm_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);
sdp = malloc(sizeof *sdp, M_VMSWAP, M_WAITOK);
spp = malloc(sizeof *spp, M_VMSWAP, M_WAITOK);
memset(sdp, 0, sizeof(*sdp));
sdp->swd_flags = SWF_FAKE;
sdp->swd_vp = vp;
sdp->swd_dev = (vp->v_type == VBLK) ? vp->v_rdev : NODEV;
bufq_alloc(&sdp->swd_tab, "disksort", BUFQ_SORT_RAWBLOCK);
mutex_enter(&uvm_swap_data_lock);
if (swaplist_find(vp, false) != NULL) {
error = EBUSY;
mutex_exit(&uvm_swap_data_lock);
bufq_free(sdp->swd_tab);
free(sdp, M_VMSWAP);
free(spp, M_VMSWAP);
break;
}
swaplist_insert(sdp, spp, priority);
mutex_exit(&uvm_swap_data_lock);
sdp->swd_pathlen = len;
sdp->swd_path = malloc(sdp->swd_pathlen, M_VMSWAP, M_WAITOK);
if (copystr(userpath, sdp->swd_path, sdp->swd_pathlen, 0) != 0)
panic("swapctl: copystr");
/*
* 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(l, sdp)) != 0) {
mutex_enter(&uvm_swap_data_lock);
(void) swaplist_find(vp, true); /* kill fake entry */
swaplist_trim();
mutex_exit(&uvm_swap_data_lock);
bufq_free(sdp->swd_tab);
free(sdp->swd_path, M_VMSWAP);
free(sdp, M_VMSWAP);
break;
}
break;
case SWAP_OFF:
mutex_enter(&uvm_swap_data_lock);
if ((sdp = swaplist_find(vp, false)) == NULL) {
mutex_exit(&uvm_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) {
mutex_exit(&uvm_swap_data_lock);
error = EBUSY;
break;
}
/*
* do the real work.
*/
error = swap_off(l, sdp);
break;
default:
error = EINVAL;
}
/*
* done! release the ref gained by namei() and unlock.
*/
vput(vp);
out:
free(userpath, M_TEMP);
rw_exit(&swap_syscall_lock);
UVMHIST_LOG(pdhist, "<- done! error=%d", error, 0, 0, 0);
return (error);
}
/*
* swap_stats: implements swapctl(SWAP_STATS). The function is kept
* away from sys_swapctl() in order to allow COMPAT_* swapctl()
* emulation to use it directly without going through sys_swapctl().
* The problem with using sys_swapctl() there is that it involves
* copying the swapent array to the stackgap, and this array's size
* is not known at build time. Hence it would not be possible to
* ensure it would fit in the stackgap in any case.
*/
void
uvm_swap_stats(int cmd, struct swapent *sep, int sec, register_t *retval)
{
rw_enter(&swap_syscall_lock, RW_READER);
uvm_swap_stats_locked(cmd, sep, sec, retval);
rw_exit(&swap_syscall_lock);
}
static void
uvm_swap_stats_locked(int cmd, struct swapent *sep, int sec, register_t *retval)
{
struct swappri *spp;
struct swapdev *sdp;
int count = 0;
LIST_FOREACH(spp, &swap_priority, spi_swappri) {
for (sdp = CIRCLEQ_FIRST(&spp->spi_swapdev);
sdp != (void *)&spp->spi_swapdev && sec-- > 0;
sdp = CIRCLEQ_NEXT(sdp, swd_next)) {
int inuse;
/*
* backwards compatibility for system call.
* For NetBSD 1.3 and 5.0, we have to use
* the 32 bit dev_t. For 5.0 and -current
* we have to add the path.
*/
inuse = btodb((uint64_t)sdp->swd_npginuse <<
PAGE_SHIFT);
#if defined(COMPAT_13) || defined(COMPAT_50)
if (cmd == SWAP_STATS) {
#endif
sep->se_dev = sdp->swd_dev;
sep->se_flags = sdp->swd_flags;
sep->se_nblks = sdp->swd_nblks;
sep->se_inuse = inuse;
sep->se_priority = sdp->swd_priority;
memcpy(&sep->se_path, sdp->swd_path,
sizeof sep->se_path);
sep++;
#if defined(COMPAT_13)
} else if (cmd == SWAP_STATS13) {
struct swapent13 *sep13 =
(struct swapent13 *)sep;
sep13->se13_dev = sdp->swd_dev;
sep13->se13_flags = sdp->swd_flags;
sep13->se13_nblks = sdp->swd_nblks;
sep13->se13_inuse = inuse;
sep13->se13_priority = sdp->swd_priority;
sep = (struct swapent *)(sep13 + 1);
#endif
#if defined(COMPAT_50)
} else if (cmd == SWAP_STATS50) {
struct swapent50 *sep50 =
(struct swapent50 *)sep;
sep50->se50_dev = sdp->swd_dev;
sep50->se50_flags = sdp->swd_flags;
sep50->se50_nblks = sdp->swd_nblks;
sep50->se50_inuse = inuse;
sep50->se50_priority = sdp->swd_priority;
memcpy(&sep50->se50_path, sdp->swd_path,
sizeof sep50->se50_path);
sep = (struct swapent *)(sep50 + 1);
#endif
#if defined(COMPAT_13) || defined(COMPAT_50)
}
#endif
count++;
}
}
*retval = count;
return;
}
/*
* 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 uvm_swap_data_lock unlocked, we may lock it
* if needed.
*/
static int
swap_on(struct lwp *l, struct swapdev *sdp)
{
struct vnode *vp;
int error, npages, nblocks, size;
long addr;
u_long result;
struct vattr va;
const struct bdevsw *bdev;
dev_t dev;
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, l->l_cred)))
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:
bdev = bdevsw_lookup(dev);
if (bdev == NULL || bdev->d_psize == NULL ||
(nblocks = (*bdev->d_psize)(dev)) == -1) {
error = ENXIO;
goto bad;
}
break;
case VREG:
if ((error = VOP_GETATTR(vp, &va, l->l_cred)))
goto bad;
nblocks = (int)btodb(va.va_size);
sdp->swd_bsize = 1 << vp->v_mount->mnt_fs_bshift;
/*
* limit the max # of outstanding I/O requests we issue
* at any one time. take it easy on NFS servers.
*/
if (vp->v_tag == VT_NFS)
sdp->swd_maxactive = 2; /* XXX */
else
sdp->swd_maxactive = 8; /* XXX */
break;
default:
error = ENXIO;
goto bad;
}
/*
* save nblocks in a safe place and convert to pages.
*/
sdp->swd_nblks = nblocks;
npages = dbtob((uint64_t)nblocks) >> PAGE_SHIFT;
/*
* for block special files, we want to make sure that leave
* the disklabel and bootblocks alone, so we arrange to skip
* over them (arbitrarily 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
*/
sdp->swd_blist = blist_create(npages);
/* mark all expect the `saved' region free. */
blist_free(sdp->swd_blist, addr, size);
/*
* 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 statvfs *sp;
int rootblocks, rootpages;
mp = rootvnode->v_mount;
sp = &mp->mnt_stat;
rootblocks = sp->f_blocks * btodb(sp->f_frsize);
/*
* XXX: sp->f_blocks isn't the total number of
* blocks in the filesystem, it's the number of
* data blocks. so, our rootblocks almost
* definitely underestimates the total size
* of the filesystem - how badly depends on the
* details of the filesystem type. there isn't
* an obvious way to deal with this cleanly
* and perfectly, so for now we just pad our
* rootblocks estimate with an extra 5 percent.
*/
rootblocks += (rootblocks >> 5) +
(rootblocks >> 6) +
(rootblocks >> 7);
rootpages = round_page(dbtob(rootblocks)) >> PAGE_SHIFT;
if (rootpages > size)
panic("swap_on: miniroot larger than swap?");
if (rootpages != blist_fill(sdp->swd_blist, addr, rootpages)) {
panic("swap_on: unable to preserve miniroot");
}
size -= rootpages;
printf("Preserved %d pages of miniroot ", rootpages);
printf("leaving %d pages of swap\n", size);
}
/*
* add a ref to vp to reflect usage as a swap device.
*/
vref(vp);
/*
* now add the new swapdev to the drum and enable.
*/
result = vmem_alloc(swapmap, npages, VM_BESTFIT | VM_SLEEP);
if (result == 0)
panic("swapdrum_add");
/*
* If this is the first regular swap create the workqueue.
* => Protected by swap_syscall_lock.
*/
if (vp->v_type != VBLK) {
if (sw_reg_count++ == 0) {
KASSERT(sw_reg_workqueue == NULL);
if (workqueue_create(&sw_reg_workqueue, "swapiod",
sw_reg_iodone, NULL, PRIBIO, IPL_BIO, 0) != 0)
panic("%s: workqueue_create failed", __func__);
}
}
sdp->swd_drumoffset = (int)result;
sdp->swd_drumsize = npages;
sdp->swd_npages = size;
mutex_enter(&uvm_swap_data_lock);
sdp->swd_flags &= ~SWF_FAKE; /* going live */
sdp->swd_flags |= (SWF_INUSE|SWF_ENABLE);
uvmexp.swpages += size;
uvmexp.swpgavail += size;
mutex_exit(&uvm_swap_data_lock);
return (0);
/*
* failure: clean up and return error.
*/
bad:
if (sdp->swd_blist) {
blist_destroy(sdp->swd_blist);
}
if (vp != rootvp) {
(void)VOP_CLOSE(vp, FREAD|FWRITE, l->l_cred);
}
return (error);
}
/*
* swap_off: stop swapping on swapdev
*
* => swap data should be locked, we will unlock.
*/
static int
swap_off(struct lwp *l, struct swapdev *sdp)
{
int npages = sdp->swd_npages;
int error = 0;
UVMHIST_FUNC("swap_off"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, " dev=%x, npages=%d", sdp->swd_dev,npages,0,0);
/* disable the swap area being removed */
sdp->swd_flags &= ~SWF_ENABLE;
uvmexp.swpgavail -= npages;
mutex_exit(&uvm_swap_data_lock);
/*
* the idea is to find all the pages that are paged out to this
* device, and page them all in. in uvm, swap-backed pageable
* memory can take two forms: aobjs and anons. call the
* swapoff hook for each subsystem to bring in pages.
*/
if (uao_swap_off(sdp->swd_drumoffset,
sdp->swd_drumoffset + sdp->swd_drumsize) ||
amap_swap_off(sdp->swd_drumoffset,
sdp->swd_drumoffset + sdp->swd_drumsize)) {
error = ENOMEM;
} else if (sdp->swd_npginuse > sdp->swd_npgbad) {
error = EBUSY;
}
if (error) {
mutex_enter(&uvm_swap_data_lock);
sdp->swd_flags |= SWF_ENABLE;
uvmexp.swpgavail += npages;
mutex_exit(&uvm_swap_data_lock);
return error;
}
/*
* If this is the last regular swap destroy the workqueue.
* => Protected by swap_syscall_lock.
*/
if (sdp->swd_vp->v_type != VBLK) {
KASSERT(sw_reg_count > 0);
KASSERT(sw_reg_workqueue != NULL);
if (--sw_reg_count == 0) {
workqueue_destroy(sw_reg_workqueue);
sw_reg_workqueue = NULL;
}
}
/*
* done with the vnode.
* drop our ref on the vnode before calling VOP_CLOSE()
* so that spec_close() can tell if this is the last close.
*/
vrele(sdp->swd_vp);
if (sdp->swd_vp != rootvp) {
(void) VOP_CLOSE(sdp->swd_vp, FREAD|FWRITE, l->l_cred);
}
mutex_enter(&uvm_swap_data_lock);
uvmexp.swpages -= npages;
uvmexp.swpginuse -= sdp->swd_npgbad;
if (swaplist_find(sdp->swd_vp, true) == NULL)
panic("%s: swapdev not in list", __func__);
swaplist_trim();
mutex_exit(&uvm_swap_data_lock);
/*
* free all resources!
*/
vmem_free(swapmap, sdp->swd_drumoffset, sdp->swd_drumsize);
blist_destroy(sdp->swd_blist);
bufq_free(sdp->swd_tab);
free(sdp, M_VMSWAP);
return (0);
}
/*
* /dev/drum interface and i/o functions
*/
/*
* swstrategy: perform I/O on the drum
*
* => we must map the i/o request from the drum to the correct swapdev.
*/
static void
swstrategy(struct buf *bp)
{
struct swapdev *sdp;
struct vnode *vp;
int pageno, 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((int64_t)bp->b_blkno) >> PAGE_SHIFT;
mutex_enter(&uvm_swap_data_lock);
sdp = swapdrum_getsdp(pageno);
mutex_exit(&uvm_swap_data_lock);
if (sdp == NULL) {
bp->b_error = EINVAL;
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 -= sdp->swd_drumoffset; /* page # on swapdev */
bn = btodb((uint64_t)pageno << PAGE_SHIFT); /* convert to diskblock */
UVMHIST_LOG(pdhist, " %s: mapoff=%x bn=%x bcount=%ld",
((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 delegate
* to sw_reg_strategy().
*/
vp = sdp->swd_vp; /* swapdev vnode pointer */
switch (vp->v_type) {
default:
panic("%s: vnode type 0x%x", __func__, 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 */
bp->b_dev = sdp->swd_dev; /* swapdev dev_t */
/*
* 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) {
mutex_enter(bp->b_objlock);
vwakeup(bp); /* kills one 'v_numoutput' on drum */
mutex_exit(bp->b_objlock);
mutex_enter(&vp->v_interlock);
vp->v_numoutput++; /* put it on swapdev */
mutex_exit(&vp->v_interlock);
}
/*
* finally plug in swapdev vnode and start I/O
*/
bp->b_vp = vp;
bp->b_objlock = &vp->v_interlock;
VOP_STRATEGY(vp, bp);
return;
case VREG:
/*
* delegate to sw_reg_strategy function.
*/
sw_reg_strategy(sdp, bp, bn);
return;
}
/* NOTREACHED */
}
/*
* swread: the read function for the drum (just a call to physio)
*/
/*ARGSUSED*/
static int
swread(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*/
static int
swwrite(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));
}
const struct bdevsw swap_bdevsw = {
nullopen, nullclose, swstrategy, noioctl, nodump, nosize, D_OTHER,
};
const struct cdevsw swap_cdevsw = {
nullopen, nullclose, swread, swwrite, noioctl,
nostop, notty, nopoll, nommap, nokqfilter, D_OTHER,
};
/*
* sw_reg_strategy: handle swap i/o to regular files
*/
static void
sw_reg_strategy(struct swapdev *sdp, struct buf *bp, int bn)
{
struct vnode *vp;
struct vndxfer *vnx;
daddr_t nbn;
char *addr;
off_t byteoff;
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.
*/
vnx = pool_get(&vndxfer_pool, PR_WAITOK);
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((uint64_t)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 && nbn == (daddr_t)-1) {
/*
* this used to just set error, but that doesn't
* do the right thing. Instead, it causes random
* memory errors. The panic() should remain until
* this condition doesn't destabilize the system.
*/
#if 1
panic("%s: swap to sparse file", __func__);
#else
error = EIO; /* failure */
#endif
}
/*
* 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).
*/
off = byteoff % sdp->swd_bsize;
sz = (1 + nra) * sdp->swd_bsize - off;
if (sz > resid)
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.
*/
nbp = pool_get(&vndbuf_pool, PR_WAITOK);
buf_init(&nbp->vb_buf);
nbp->vb_buf.b_flags = bp->b_flags;
nbp->vb_buf.b_cflags = bp->b_cflags;
nbp->vb_buf.b_oflags = bp->b_oflags;
nbp->vb_buf.b_bcount = sz;
nbp->vb_buf.b_bufsize = sz;
nbp->vb_buf.b_error = 0;
nbp->vb_buf.b_data = addr;
nbp->vb_buf.b_lblkno = 0;
nbp->vb_buf.b_blkno = nbn + btodb(off);
nbp->vb_buf.b_rawblkno = nbp->vb_buf.b_blkno;
nbp->vb_buf.b_iodone = sw_reg_biodone;
nbp->vb_buf.b_vp = vp;
nbp->vb_buf.b_objlock = &vp->v_interlock;
if (vp->v_type == VBLK) {
nbp->vb_buf.b_dev = vp->v_rdev;
}
nbp->vb_xfer = vnx; /* patch it back in to vnx */
/*
* Just sort by block number
*/
s = splbio();
if (vnx->vx_error != 0) {
buf_destroy(&nbp->vb_buf);
pool_put(&vndbuf_pool, nbp);
goto out;
}
vnx->vx_pending++;
/* sort it in and start I/O if we are not over our limit */
/* XXXAD locking */
bufq_put(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) {
error = vnx->vx_error;
pool_put(&vndxfer_pool, vnx);
bp->b_error = error;
biodone(bp);
}
splx(s);
}
/*
* sw_reg_start: start an I/O request on the requested swapdev
*
* => reqs are sorted by b_rawblkno (above)
*/
static void
sw_reg_start(struct swapdev *sdp)
{
struct buf *bp;
struct vnode *vp;
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_active < sdp->swd_maxactive) {
bp = bufq_get(sdp->swd_tab);
if (bp == NULL)
break;
sdp->swd_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);
vp = bp->b_vp;
KASSERT(bp->b_objlock == &vp->v_interlock);
if ((bp->b_flags & B_READ) == 0) {
mutex_enter(&vp->v_interlock);
vp->v_numoutput++;
mutex_exit(&vp->v_interlock);
}
VOP_STRATEGY(vp, bp);
}
sdp->swd_flags &= ~SWF_BUSY;
}
/*
* sw_reg_biodone: one of our i/o's has completed
*/
static void
sw_reg_biodone(struct buf *bp)
{
workqueue_enqueue(sw_reg_workqueue, &bp->b_work, NULL);
}
/*
* 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(struct work *wk, void *dummy)
{
struct vndbuf *vbp = (void *)wk;
struct vndxfer *vnx = vbp->vb_xfer;
struct buf *pbp = vnx->vx_bp; /* parent buffer */
struct swapdev *sdp = vnx->vx_sdp;
int s, resid, error;
KASSERT(&vbp->vb_buf.b_work == wk);
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 != 0) {
/* pass error upward */
error = vbp->vb_buf.b_error ? vbp->vb_buf.b_error : EIO;
UVMHIST_LOG(pdhist, " got error=%d !", error, 0, 0, 0);
vnx->vx_error = error;
}
/*
* kill vbp structure
*/
buf_destroy(&vbp->vb_buf);
pool_put(&vndbuf_pool, 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 */
error = vnx->vx_error;
if ((vnx->vx_flags & VX_BUSY) == 0 && vnx->vx_pending == 0) {
pbp->b_error = error;
biodone(pbp);
pool_put(&vndxfer_pool, vnx);
}
} else if (pbp->b_resid == 0) {
KASSERT(vnx->vx_pending == 0);
if ((vnx->vx_flags & VX_BUSY) == 0) {
UVMHIST_LOG(pdhist, " iodone error=%d !",
pbp, vnx->vx_error, 0, 0);
biodone(pbp);
pool_put(&vndxfer_pool, vnx);
}
}
/*
* done! start next swapdev I/O if one is pending
*/
sdp->swd_active--;
sw_reg_start(sdp);
splx(s);
}
/*
* 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 uvm_swap_data_lock
* => XXXMRG: "LESSOK" INTERFACE NEEDED TO EXTENT SYSTEM
*/
int
uvm_swap_alloc(int *nslots /* IN/OUT */, bool lessok)
{
struct swapdev *sdp;
struct swappri *spp;
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
*/
mutex_enter(&uvm_swap_data_lock);
ReTry: /* XXXMRG */
LIST_FOREACH(spp, &swap_priority, spi_swappri) {
CIRCLEQ_FOREACH(sdp, &spp->spi_swapdev, swd_next) {
uint64_t result;
/* 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;
result = blist_alloc(sdp->swd_blist, *nslots);
if (result == BLIST_NONE) {
continue;
}
KASSERT(result < sdp->swd_drumsize);
/*
* 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;
mutex_exit(&uvm_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);
return (result + sdp->swd_drumoffset);
}
}
/* XXXMRG: BEGIN HACK */
if (*nslots > 1 && lessok) {
*nslots = 1;
/* XXXMRG: ugh! blist should support this for us */
goto ReTry;
}
/* XXXMRG: END HACK */
mutex_exit(&uvm_swap_data_lock);
return 0;
}
/*
* uvm_swapisfull: return true if most of available swap is allocated
* and in use. we don't count some small portion as it may be inaccessible
* to us at any given moment, for example if there is lock contention or if
* pages are busy.
*/
bool
uvm_swapisfull(void)
{
int swpgonly;
bool rv;
mutex_enter(&uvm_swap_data_lock);
KASSERT(uvmexp.swpgonly <= uvmexp.swpages);
swpgonly = (int)((uint64_t)uvmexp.swpgonly * 100 /
uvm_swapisfull_factor);
rv = (swpgonly >= uvmexp.swpgavail);
mutex_exit(&uvm_swap_data_lock);
return (rv);
}
/*
* uvm_swap_markbad: keep track of swap ranges where we've had i/o errors
*
* => we lock uvm_swap_data_lock
*/
void
uvm_swap_markbad(int startslot, int nslots)
{
struct swapdev *sdp;
UVMHIST_FUNC("uvm_swap_markbad"); UVMHIST_CALLED(pdhist);
mutex_enter(&uvm_swap_data_lock);
sdp = swapdrum_getsdp(startslot);
KASSERT(sdp != NULL);
/*
* we just keep track of how many pages have been marked bad
* in this device, to make everything add up in swap_off().
* we assume here that the range of slots will all be within
* one swap device.
*/
KASSERT(uvmexp.swpgonly >= nslots);
uvmexp.swpgonly -= nslots;
sdp->swd_npgbad += nslots;
UVMHIST_LOG(pdhist, "now %d bad", sdp->swd_npgbad, 0,0,0);
mutex_exit(&uvm_swap_data_lock);
}
/*
* uvm_swap_free: free swap slots
*
* => this can be all or part of an allocation made by uvm_swap_alloc
* => we lock uvm_swap_data_lock
*/
void
uvm_swap_free(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);
/*
* ignore attempts to free the "bad" slot.
*/
if (startslot == SWSLOT_BAD) {
return;
}
/*
* 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.
*/
mutex_enter(&uvm_swap_data_lock);
sdp = swapdrum_getsdp(startslot);
KASSERT(uvmexp.nswapdev >= 1);
KASSERT(sdp != NULL);
KASSERT(sdp->swd_npginuse >= nslots);
blist_free(sdp->swd_blist, startslot - sdp->swd_drumoffset, nslots);
sdp->swd_npginuse -= nslots;
uvmexp.swpginuse -= nslots;
mutex_exit(&uvm_swap_data_lock);
}
/*
* uvm_swap_put: put any number of pages into a contig place on swap
*
* => can be sync or async
*/
int
uvm_swap_put(int swslot, struct vm_page **ppsp, int npages, int flags)
{
int error;
error = uvm_swap_io(ppsp, swslot, npages, B_WRITE |
((flags & PGO_SYNCIO) ? 0 : B_ASYNC));
return error;
}
/*
* uvm_swap_get: get a single page from swap
*
* => usually a sync op (from fault)
*/
int
uvm_swap_get(struct vm_page *page, int swslot, int flags)
{
int error;
uvmexp.nswget++;
KASSERT(flags & PGO_SYNCIO);
if (swslot == SWSLOT_BAD) {
return EIO;
}
error = uvm_swap_io(&page, swslot, 1, B_READ |
((flags & PGO_SYNCIO) ? 0 : B_ASYNC));
if (error == 0) {
/*
* this page is no longer only in swap.
*/
mutex_enter(&uvm_swap_data_lock);
KASSERT(uvmexp.swpgonly > 0);
uvmexp.swpgonly--;
mutex_exit(&uvm_swap_data_lock);
}
return error;
}
/*
* uvm_swap_io: do an i/o operation to swap
*/
static int
uvm_swap_io(struct vm_page **pps, int startslot, int npages, int flags)
{
daddr_t startblk;
struct buf *bp;
vaddr_t kva;
int error, mapinflags;
bool write, async;
UVMHIST_FUNC("uvm_swap_io"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "<- called, startslot=%d, npages=%d, flags=%d",
startslot, npages, flags, 0);
write = (flags & B_READ) == 0;
async = (flags & B_ASYNC) != 0;
/*
* allocate a buf for the i/o.
*/
KASSERT(curlwp != uvm.pagedaemon_lwp || (write && async));
bp = getiobuf(swapdev_vp, curlwp != uvm.pagedaemon_lwp);
if (bp == NULL) {
uvm_aio_aiodone_pages(pps, npages, true, ENOMEM);
return ENOMEM;
}
/*
* convert starting drum slot to block number
*/
startblk = btodb((uint64_t)startslot << PAGE_SHIFT);
/*
* first, map the pages into the kernel.
*/
mapinflags = !write ?
UVMPAGER_MAPIN_WAITOK|UVMPAGER_MAPIN_READ :
UVMPAGER_MAPIN_WAITOK|UVMPAGER_MAPIN_WRITE;
kva = uvm_pagermapin(pps, npages, mapinflags);
/*
* fill in the bp/sbp. we currently route our i/o through
* /dev/drum's vnode [swapdev_vp].
*/
bp->b_cflags = BC_BUSY | BC_NOCACHE;
bp->b_flags = (flags & (B_READ|B_ASYNC));
bp->b_proc = &proc0; /* XXX */
bp->b_vnbufs.le_next = NOLIST;
bp->b_data = (void *)kva;
bp->b_blkno = startblk;
bp->b_bufsize = bp->b_bcount = npages << PAGE_SHIFT;
/*
* bump v_numoutput (counter of number of active outputs).
*/
if (write) {
mutex_enter(&swapdev_vp->v_interlock);
swapdev_vp->v_numoutput++;
mutex_exit(&swapdev_vp->v_interlock);
}
/*
* for async ops we must set up the iodone handler.
*/
if (async) {
bp->b_iodone = uvm_aio_biodone;
UVMHIST_LOG(pdhist, "doing async!", 0, 0, 0, 0);
if (curlwp == uvm.pagedaemon_lwp)
BIO_SETPRIO(bp, BPRIO_TIMECRITICAL);
else
BIO_SETPRIO(bp, BPRIO_TIMELIMITED);
} else {
bp->b_iodone = NULL;
BIO_SETPRIO(bp, BPRIO_TIMECRITICAL);
}
UVMHIST_LOG(pdhist,
"about to start io: data = %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(swapdev_vp, bp);
if (async)
return 0;
/*
* must be sync i/o. wait for it to finish
*/
error = biowait(bp);
/*
* kill the pager mapping
*/
uvm_pagermapout(kva, npages);
/*
* now dispose of the buf and we're done.
*/
if (write) {
mutex_enter(&swapdev_vp->v_interlock);
vwakeup(bp);
mutex_exit(&swapdev_vp->v_interlock);
}
putiobuf(bp);
UVMHIST_LOG(pdhist, "<- done (sync) error=%d", error, 0, 0, 0);
return (error);
}
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