/* $NetBSD: uvm_swap.c,v 1.64 2002/05/09 21:43:44 fredette 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 __KERNEL_RCSID(0, "$NetBSD: uvm_swap.c,v 1.64 2002/05/09 21:43:44 fredette Exp $"); #include "fs_nfs.h" #include "opt_uvmhist.h" #include "opt_compat_netbsd.h" #include "opt_ddb.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 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 (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). * - uvm.swap_data_lock (simple_lock): this lock protects all swap data * structures including the priority list, the swapdev structures, * and the swapmap extent. * * 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 { struct oswapent swd_ose; #define swd_dev swd_ose.ose_dev /* device id */ #define swd_flags swd_ose.ose_flags /* flags:inuse/enable/fake */ #define swd_priority swd_ose.ose_priority /* our priority */ /* also: swd_ose.ose_nblks, swd_ose.ose_inuse */ 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 */ struct extent *swd_ex; /* extent for this swapdev */ char swd_exname[12]; /* name of extent above */ 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 buf_queue 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; }; /* * We keep a of pool vndbuf's and vndxfer structures. */ static struct pool vndxfer_pool; static struct pool vndbuf_pool; #define getvndxfer(vnx) do { \ int s = splbio(); \ vnx = pool_get(&vndxfer_pool, PR_WAITOK); \ splx(s); \ } while (0) #define putvndxfer(vnx) { \ pool_put(&vndxfer_pool, (void *)(vnx)); \ } #define getvndbuf(vbp) do { \ int s = splbio(); \ vbp = pool_get(&vndbuf_pool, PR_WAITOK); \ splx(s); \ } while (0) #define putvndbuf(vbp) { \ pool_put(&vndbuf_pool, (void *)(vbp)); \ } /* /dev/drum */ bdev_decl(sw); cdev_decl(sw); /* * local variables */ static struct extent *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 */ struct lock swap_syscall_lock; /* * prototypes */ 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 *)); static int swap_off __P((struct proc *, struct swapdev *)); 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 *)); 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(&uvm.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 pools for structures used for swapping to files. */ pool_init(&vndxfer_pool, sizeof(struct vndxfer), 0, 0, 0, "swp vnx", NULL); pool_init(&vndbuf_pool, sizeof(struct vndbuf), 0, 0, 0, "swp vnd", NULL); /* * 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 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(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. */ 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(vp, remove) struct vnode *vp; boolean_t 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() { 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(pgno) 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(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; char userpath[PATH_MAX + 1]; 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 */ lockmgr(&swap_syscall_lock, LK_EXCLUSIVE, NULL); /* * 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_13) || SCARG(uap, cmd) == SWAP_OSTATS #endif ) { misc = MIN(uvmexp.nswapdev, misc); #if defined(COMPAT_13) if (SCARG(uap, cmd) == SWAP_OSTATS) len = sizeof(struct oswapent) * misc; else #endif len = sizeof(struct swapent) * misc; sep = (struct swapent *)malloc(len, M_TEMP, M_WAITOK); uvm_swap_stats(SCARG(uap, cmd), sep, misc, retval); error = copyout(sep, (void *)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 = suser(p->p_ucred, &p->p_acflag))) 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 */ if (vget(vp, LK_EXCLUSIVE)) { error = EBUSY; goto out; } if (SCARG(uap, cmd) == SWAP_ON && copystr("miniroot", userpath, sizeof userpath, &len)) panic("swapctl: miniroot copy failed"); } else { int space; char *where; if (SCARG(uap, cmd) == SWAP_ON) { if ((error = copyinstr(SCARG(uap, arg), userpath, sizeof userpath, &len))) goto out; space = UIO_SYSSPACE; where = userpath; } else { space = UIO_USERSPACE; where = (char *)SCARG(uap, arg); } NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, space, where, p); 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; } dumpdev = vp->v_rdev; 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); simple_lock(&uvm.swap_data_lock); if ((sdp = swaplist_find(vp, 1)) == NULL) { error = ENOENT; } else { swaplist_insert(sdp, spp, priority); swaplist_trim(); } simple_unlock(&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); simple_lock(&uvm.swap_data_lock); if (swaplist_find(vp, 0) != NULL) { error = EBUSY; simple_unlock(&uvm.swap_data_lock); free(sdp, M_VMSWAP); free(spp, M_VMSWAP); break; } memset(sdp, 0, sizeof(*sdp)); sdp->swd_flags = SWF_FAKE; /* placeholder only */ sdp->swd_vp = vp; sdp->swd_dev = (vp->v_type == VBLK) ? vp->v_rdev : NODEV; BUFQ_INIT(&sdp->swd_tab); swaplist_insert(sdp, spp, priority); simple_unlock(&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(p, sdp)) != 0) { simple_lock(&uvm.swap_data_lock); (void) swaplist_find(vp, 1); /* kill fake entry */ swaplist_trim(); simple_unlock(&uvm.swap_data_lock); free(sdp->swd_path, M_VMSWAP); free(sdp, M_VMSWAP); break; } break; case SWAP_OFF: simple_lock(&uvm.swap_data_lock); if ((sdp = swaplist_find(vp, 0)) == NULL) { simple_unlock(&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) { simple_unlock(&uvm.swap_data_lock); error = EBUSY; break; } /* * do the real work. */ error = swap_off(p, sdp); break; default: error = EINVAL; } /* * done! release the ref gained by namei() and unlock. */ vput(vp); out: lockmgr(&swap_syscall_lock, LK_RELEASE, NULL); 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(cmd, sep, sec, retval) 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)) { /* * backwards compatibility for system call. * note that we use 'struct oswapent' as an * overlay into both 'struct swapdev' and * the userland 'struct swapent', as we * want to retain backwards compatibility * with NetBSD 1.3. */ sdp->swd_ose.ose_inuse = btodb((u_int64_t)sdp->swd_npginuse << PAGE_SHIFT); (void)memcpy(sep, &sdp->swd_ose, sizeof(struct oswapent)); /* now copy out the path if necessary */ #if defined(COMPAT_13) if (cmd == SWAP_STATS) #endif (void)memcpy(&sep->se_path, sdp->swd_path, sdp->swd_pathlen); count++; #if defined(COMPAT_13) if (cmd == SWAP_OSTATS) sep = (struct swapent *) ((struct oswapent *)sep + 1); else #endif sep++; } } *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(p, sdp) struct proc *p; struct swapdev *sdp; { static int count = 0; /* static */ struct vnode *vp; int error, npages, nblocks, size; long addr; u_long result; struct vattr va; #ifdef NFS extern int (**nfsv2_vnodeop_p) __P((void *)); #endif /* NFS */ 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, 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; 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; default: error = ENXIO; goto bad; } /* * save nblocks in a safe place and convert to pages. */ sdp->swd_ose.ose_nblks = nblocks; npages = dbtob((u_int64_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 */ snprintf(sdp->swd_exname, sizeof(sdp->swd_exname), "swap0x%04x", count++); /* note that extent_create's 3rd arg is inclusive, thus "- 1" */ sdp->swd_ex = extent_create(sdp->swd_exname, 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"); } /* * 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); /* * 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 (extent_alloc_region(sdp->swd_ex, addr, rootpages, EX_WAITOK)) panic("swap_on: unable to preserve miniroot"); size -= rootpages; printf("Preserved %d pages of miniroot ", rootpages); printf("leaving %d pages of swap\n", size); } /* * try to add anons to reflect the new swap space. */ error = uvm_anon_add(size); if (error) { goto bad; } /* * add a ref to vp to reflect usage as a swap device. */ vref(vp); /* * now add the new swapdev to the drum and enable. */ if (extent_alloc(swapmap, npages, EX_NOALIGN, EX_NOBOUNDARY, EX_WAITOK, &result)) panic("swapdrum_add"); sdp->swd_drumoffset = (int)result; sdp->swd_drumsize = npages; sdp->swd_npages = size; simple_lock(&uvm.swap_data_lock); sdp->swd_flags &= ~SWF_FAKE; /* going live */ sdp->swd_flags |= (SWF_INUSE|SWF_ENABLE); uvmexp.swpages += size; simple_unlock(&uvm.swap_data_lock); return (0); /* * failure: clean up and return error. */ bad: if (sdp->swd_ex) { extent_destroy(sdp->swd_ex); } if (vp != rootvp) { (void)VOP_CLOSE(vp, FREAD|FWRITE, p->p_ucred, p); } return (error); } /* * swap_off: stop swapping on swapdev * * => swap data should be locked, we will unlock. */ static int swap_off(p, sdp) struct proc *p; struct swapdev *sdp; { UVMHIST_FUNC("swap_off"); UVMHIST_CALLED(pdhist); UVMHIST_LOG(pdhist, " dev=%x", sdp->swd_dev,0,0,0); /* disable the swap area being removed */ sdp->swd_flags &= ~SWF_ENABLE; simple_unlock(&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) || anon_swap_off(sdp->swd_drumoffset, sdp->swd_drumoffset + sdp->swd_drumsize)) { simple_lock(&uvm.swap_data_lock); sdp->swd_flags |= SWF_ENABLE; simple_unlock(&uvm.swap_data_lock); return ENOMEM; } KASSERT(sdp->swd_npginuse == sdp->swd_npgbad); /* * 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, p->p_ucred, p); } /* remove anons from the system */ uvm_anon_remove(sdp->swd_npages); simple_lock(&uvm.swap_data_lock); uvmexp.swpages -= sdp->swd_npages; if (swaplist_find(sdp->swd_vp, 1) == NULL) panic("swap_off: swapdev not in list\n"); swaplist_trim(); simple_unlock(&uvm.swap_data_lock); /* * free all resources! */ extent_free(swapmap, sdp->swd_drumoffset, sdp->swd_drumsize, EX_WAITOK); extent_destroy(sdp->swd_ex); free(sdp, M_VMSWAP); return (0); } /* * /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 s, 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; simple_lock(&uvm.swap_data_lock); sdp = swapdrum_getsdp(pageno); simple_unlock(&uvm.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 -= sdp->swd_drumoffset; /* page # on swapdev */ bn = btodb((u_int64_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(). */ 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). */ s = splbio(); bp->b_blkno = bn; /* swapdev block number */ vp = sdp->swd_vp; /* swapdev vnode pointer */ 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) { vwakeup(bp); /* kills one 'v_numoutput' on drum */ vp->v_numoutput++; /* put it on swapdev */ } /* * finally plug in swapdev vnode and start I/O */ bp->b_vp = vp; splx(s); VOP_STRATEGY(bp); return; case VREG: /* * delegate to sw_reg_strategy function. */ sw_reg_strategy(sdp, bp, bn); return; } /* NOTREACHED */ } /* * 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; caddr_t 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. */ 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((u_int64_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("sw_reg_strategy: swap to sparse file"); #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. */ getvndbuf(nbp); nbp->vb_buf.b_flags = bp->b_flags | B_CALL; 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_iodone; nbp->vb_buf.b_vp = vp; if (vp->v_type == VBLK) { nbp->vb_buf.b_dev = vp->v_rdev; } LIST_INIT(&nbp->vb_buf.b_dep); nbp->vb_xfer = vnx; /* patch it back in to vnx */ /* * Just sort by block number */ s = splbio(); if (vnx->vx_error != 0) { putvndbuf(nbp); goto out; } vnx->vx_pending++; /* sort it in and start I/O if we are not over our limit */ disksort_blkno(&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_active < sdp->swd_maxactive) { bp = BUFQ_FIRST(&sdp->swd_tab); if (bp == NULL) break; BUFQ_REMOVE(&sdp->swd_tab, bp); 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); 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; } /* * 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) { KASSERT(vnx->vx_pending == 0); 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_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(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(&uvm.swap_data_lock); ReTry: /* XXXMRG */ LIST_FOREACH(spp, &swap_priority, spi_swappri) { CIRCLEQ_FOREACH(sdp, &spp->spi_swapdev, swd_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(&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; goto ReTry; /* XXXMRG: ugh! extent should support this for us */ } /* XXXMRG: END HACK */ simple_unlock(&uvm.swap_data_lock); return 0; } /* * 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(startslot, nslots) int startslot; int nslots; { struct swapdev *sdp; UVMHIST_FUNC("uvm_swap_markbad"); UVMHIST_CALLED(pdhist); simple_lock(&uvm.swap_data_lock); sdp = swapdrum_getsdp(startslot); /* * 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. */ sdp->swd_npgbad += nslots; UVMHIST_LOG(pdhist, "now %d bad", sdp->swd_npgbad, 0,0,0); simple_unlock(&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(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); /* * 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. */ simple_lock(&uvm.swap_data_lock); sdp = swapdrum_getsdp(startslot); KASSERT(uvmexp.nswapdev >= 1); KASSERT(sdp != NULL); KASSERT(sdp->swd_npginuse >= nslots); if (extent_free(sdp->swd_ex, startslot - sdp->swd_drumoffset, nslots, EX_MALLOCOK|EX_NOWAIT) != 0) { printf("warning: resource shortage: %d pages of swap lost\n", nslots); } sdp->swd_npginuse -= nslots; uvmexp.swpginuse -= nslots; simple_unlock(&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(swslot, ppsp, npages, flags) 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(page, swslot, flags) struct vm_page *page; int swslot, 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. */ simple_lock(&uvm.swap_data_lock); KASSERT(uvmexp.swpgonly > 0); uvmexp.swpgonly--; simple_unlock(&uvm.swap_data_lock); } return error; } /* * 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 buf *bp; vaddr_t kva; int error, s, mapinflags; boolean_t 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; /* * convert starting drum slot to block number */ startblk = btodb((u_int64_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); /* * now allocate a buf for the i/o. */ s = splbio(); bp = pool_get(&bufpool, PR_WAITOK); splx(s); /* * fill in the bp/sbp. we currently route our i/o through * /dev/drum's vnode [swapdev_vp]. */ bp->b_flags = B_BUSY | B_NOCACHE | (flags & (B_READ|B_ASYNC)); bp->b_proc = &proc0; /* XXX */ bp->b_vnbufs.le_next = NOLIST; bp->b_data = (caddr_t)kva; bp->b_blkno = startblk; bp->b_vp = swapdev_vp; bp->b_dev = swapdev_vp->v_rdev; bp->b_bufsize = bp->b_bcount = npages << PAGE_SHIFT; LIST_INIT(&bp->b_dep); /* * bump v_numoutput (counter of number of active outputs). */ if (write) { s = splbio(); swapdev_vp->v_numoutput++; splx(s); } /* * for async ops we must set up the iodone handler. */ if (async) { bp->b_flags |= B_CALL; bp->b_iodone = uvm_aio_biodone; UVMHIST_LOG(pdhist, "doing async!", 0, 0, 0, 0); } 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(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. */ s = splbio(); if (write) vwakeup(bp); pool_put(&bufpool, bp); splx(s); UVMHIST_LOG(pdhist, "<- done (sync) error=%d", error, 0, 0, 0); return (error); }