projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 4e0c95d7 | 1 | /* vm_swap.c 4.1 %G% */ |
| 013037be BJ |
2 | |
| 3 | #include "../h/param.h" | |
| 4 | #include "../h/systm.h" | |
| 5 | #include "../h/buf.h" | |
| 6 | #include "../h/conf.h" | |
| 7 | #include "../h/dir.h" | |
| 8 | #include "../h/user.h" | |
| 9 | #include "../h/inode.h" | |
| 10 | #include "../h/map.h" | |
| 11 | ||
| 12 | struct buf rswbuf; | |
| 13 | /* | |
| 14 | * Indirect driver for multi-controller paging. | |
| 15 | */ | |
| 16 | swstrategy(bp) | |
| 17 | register struct buf *bp; | |
| 18 | { | |
| 19 | int sz, off, seg; | |
| 20 | dev_t dev; | |
| 21 | ||
| 22 | sz = (bp->b_bcount+511)/512; | |
| 23 | off = bp->b_blkno % DMMAX; | |
| 24 | if (bp->b_blkno+sz > nswap || off+sz > DMMAX) { | |
| 25 | bp->b_flags |= B_ERROR; | |
| 26 | iodone(bp); | |
| 27 | return; | |
| 28 | } | |
| 29 | seg = bp->b_blkno / DMMAX; | |
| 30 | dev = swdevt[seg % nswdev].sw_dev; | |
| 31 | seg /= nswdev; | |
| 32 | bp->b_blkno = seg*DMMAX + off; | |
| 33 | bp->b_dev = dev; | |
| 34 | if (dev == 0) | |
| 35 | panic("swstrategy"); | |
| 36 | (*bdevsw[major(dev)].d_strategy)(bp); | |
| 37 | } | |
| 38 | ||
| 39 | swread(dev) | |
| 40 | { | |
| 41 | ||
| 42 | physio(swstrategy, &rswbuf, dev, B_READ, minphys); | |
| 43 | } | |
| 44 | ||
| 45 | swwrite(dev) | |
| 46 | { | |
| 47 | ||
| 48 | physio(swstrategy, &rswbuf, dev, B_WRITE, minphys); | |
| 49 | } | |
| 50 | ||
| 51 | /* | |
| 52 | * System call swapon(name) enables swapping on device name, | |
| 53 | * which must be in the swdevsw. Return EBUSY | |
| 54 | * if already swapping on this device. | |
| 55 | */ | |
| 56 | vswapon() | |
| 57 | { | |
| 58 | register struct a { | |
| 59 | char *sname; | |
| 60 | } *uap; | |
| 61 | register struct inode *ip; | |
| 62 | dev_t dev; | |
| 63 | register struct swdevt *sp; | |
| 64 | ||
| 65 | uap = (struct a *)u.u_ap; | |
| 66 | ip = namei(uchar, 0); | |
| 67 | if (ip == NULL) | |
| 68 | return; | |
| 69 | if ((ip->i_mode&IFMT) != IFBLK) { | |
| 70 | u.u_error = ENOTBLK; | |
| 71 | iput(ip); | |
| 72 | return; | |
| 73 | } | |
| 74 | dev = (dev_t)ip->i_un.i_rdev; | |
| 75 | iput(ip); | |
| 76 | if (major(dev) >= nblkdev) { | |
| 77 | u.u_error = ENXIO; | |
| 78 | return; | |
| 79 | } | |
| 80 | /* | |
| 81 | * Search starting at second table entry, | |
| 82 | * since first (primary swap area) is freed at boot. | |
| 83 | */ | |
| 84 | for (sp = &swdevt[1]; sp->sw_dev; sp++) | |
| 85 | if (sp->sw_dev == dev) { | |
| 86 | if (sp->sw_freed) { | |
| 87 | u.u_error = EBUSY; | |
| 88 | return; | |
| 89 | } | |
| 90 | swfree(sp - swdevt); | |
| 91 | return; | |
| 92 | } | |
| 93 | u.u_error = ENODEV; | |
| 94 | } | |
| 95 | ||
| 96 | /* | |
| 97 | * Swfree(index) frees the index'th portion of the swap map. | |
| 98 | * Each of the nswdev devices provides 1/nswdev'th of the swap | |
| 99 | * space, which is laid out with blocks of DMMAX pages circularly | |
| 100 | * among the devices. | |
| 101 | */ | |
| 102 | swfree(index) | |
| 103 | int index; | |
| 104 | { | |
| 105 | register swblk_t vsbase; | |
| 106 | register int blk; | |
| 107 | ||
| 108 | swdevt[index].sw_freed = 1; | |
| 109 | for (vsbase = index*DMMAX; vsbase < nswap; vsbase += nswdev*DMMAX) { | |
| 110 | blk = nswap - vsbase; | |
| 111 | if (blk > DMMAX) | |
| 112 | blk = DMMAX; | |
| 113 | if (vsbase == 0) { | |
| 114 | /* | |
| 115 | * Can't free a block starting at 0 in the swapmap | |
| 116 | * but need some space for argmap so use this | |
| 117 | * hunk which needs special treatment anyways. | |
| 118 | */ | |
| 119 | argdev = swdevt[0].sw_dev; | |
| 120 | mfree(argmap, blk-CLSIZE, vsbase+CLSIZE); | |
| 121 | } else | |
| 122 | mfree(swapmap, blk, vsbase); | |
| 123 | } | |
| 124 | } |