1 /* $OpenBSD: vfs_biomem.c,v 1.4 2008/11/08 23:20:50 pedro Exp $ */ 2 /* 3 * Copyright (c) 2007 Artur Grabowski <art@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 19 #include <sys/param.h> 20 #include <sys/systm.h> 21 #include <sys/buf.h> 22 #include <sys/pool.h> 23 #include <sys/mount.h> 24 25 #include <uvm/uvm_extern.h> 26 #include <uvm/uvm.h> 27 28 vaddr_t buf_kva_start, buf_kva_end; 29 int buf_needva; 30 TAILQ_HEAD(,buf) buf_valist; 31 32 int buf_nkvmsleep; 33 34 extern struct bcachestats bcstats; 35 36 /* 37 * Pages are allocated from a uvm object (we only use it for page storage, 38 * all pages are wired). Since every buffer contains a contiguous range of 39 * pages, reusing the pages could be very painful. Fortunately voff_t is 40 * 64 bits, so we can just increment buf_page_offset all the time and ignore 41 * wraparound. Even if you reuse 4GB worth of buffers every second 42 * you'll still run out of time_t faster than buffers. 43 * 44 * XXX - the spl locking in here is extreme paranoia right now until I figure 45 * it all out. 46 */ 47 voff_t buf_page_offset; 48 struct uvm_object *buf_object, buf_object_store; 49 50 vaddr_t buf_unmap(struct buf *); 51 52 void 53 buf_mem_init(vsize_t size) 54 { 55 TAILQ_INIT(&buf_valist); 56 57 buf_kva_start = vm_map_min(kernel_map); 58 if (uvm_map(kernel_map, &buf_kva_start, size, NULL, 59 UVM_UNKNOWN_OFFSET, PAGE_SIZE, UVM_MAPFLAG(UVM_PROT_NONE, 60 UVM_PROT_NONE, UVM_INH_NONE, UVM_ADV_NORMAL, 0))) 61 panic("bufinit: can't reserve VM for buffers"); 62 buf_kva_end = buf_kva_start + size; 63 64 buf_object = &buf_object_store; 65 66 buf_object->pgops = NULL; 67 TAILQ_INIT(&buf_object->memq); 68 buf_object->uo_npages = 0; 69 buf_object->uo_refs = 1; 70 } 71 72 /* 73 * buf_acquire and buf_release manage the kvm mappings of buffers. 74 */ 75 void 76 buf_acquire(struct buf *bp) 77 { 78 vaddr_t va; 79 int s; 80 81 KASSERT((bp->b_flags & B_BUSY) == 0); 82 83 s = splbio(); 84 /* 85 * Busy before waiting for kvm. 86 */ 87 SET(bp->b_flags, B_BUSY); 88 89 if (bp->b_data == NULL) { 90 unsigned long i; 91 92 /* 93 * First, just use the pre-allocated space until we run out. 94 */ 95 if (buf_kva_start < buf_kva_end) { 96 va = buf_kva_start; 97 buf_kva_start += MAXPHYS; 98 } else { 99 struct buf *vbp; 100 101 /* 102 * Find some buffer we can steal the space from. 103 */ 104 while ((vbp = TAILQ_FIRST(&buf_valist)) == NULL) { 105 buf_needva++; 106 buf_nkvmsleep++; 107 tsleep(&buf_needva, PRIBIO, "buf_needva", 0); 108 } 109 va = buf_unmap(vbp); 110 } 111 112 for (i = 0; i < atop(bp->b_bufsize); i++) { 113 struct vm_page *pg = uvm_pagelookup(bp->b_pobj, 114 bp->b_poffs + ptoa(i)); 115 116 KASSERT(pg != NULL); 117 118 pmap_kenter_pa(va + ptoa(i), VM_PAGE_TO_PHYS(pg), 119 VM_PROT_READ|VM_PROT_WRITE); 120 pmap_update(pmap_kernel()); 121 } 122 bp->b_data = (caddr_t)va; 123 } else { 124 TAILQ_REMOVE(&buf_valist, bp, b_valist); 125 } 126 splx(s); 127 } 128 129 /* 130 * Busy a buffer, but don't map it. 131 * If it has a mapping, we keep it, but we also keep the mapping on 132 * the list since we assume that it won't be used anymore. 133 */ 134 void 135 buf_acquire_unmapped(struct buf *bp) 136 { 137 int s; 138 139 s = splbio(); 140 SET(bp->b_flags, B_BUSY|B_NOTMAPPED); 141 splx(s); 142 } 143 144 void 145 buf_release(struct buf *bp) 146 { 147 int s; 148 149 KASSERT(bp->b_flags & B_BUSY); 150 KASSERT((bp->b_data != NULL) || (bp->b_flags & B_NOTMAPPED)); 151 152 s = splbio(); 153 if (bp->b_data) { 154 TAILQ_INSERT_TAIL(&buf_valist, bp, b_valist); 155 if (buf_needva) { 156 buf_needva--; 157 wakeup_one(&buf_needva); 158 } 159 } 160 CLR(bp->b_flags, B_BUSY|B_NOTMAPPED); 161 splx(s); 162 } 163 164 /* 165 * Deallocate all memory resources for this buffer. We need to be careful 166 * to not drop kvm since we have no way to reclaim it. So, if the buffer 167 * has kvm, we need to free it later. We put it on the front of the 168 * freelist just so it gets picked up faster. 169 * 170 * Also, lots of assertions count on bp->b_data being NULL, so we 171 * set it temporarily to NULL. 172 * 173 * Return non-zero if we take care of the freeing later. 174 */ 175 int 176 buf_dealloc_mem(struct buf *bp) 177 { 178 caddr_t data; 179 int s; 180 181 s = splbio(); 182 183 data = bp->b_data; 184 bp->b_data = NULL; 185 186 if (data) { 187 pmap_kremove((vaddr_t)data, bp->b_bufsize); 188 pmap_update(pmap_kernel()); 189 } 190 191 if (bp->b_pobj) 192 buf_free_pages(bp); 193 194 if (data == NULL) { 195 splx(s); 196 return (0); 197 } 198 199 bp->b_data = data; 200 if (!(bp->b_flags & B_BUSY)) /* XXX - need better test */ 201 TAILQ_REMOVE(&buf_valist, bp, b_valist); 202 else 203 CLR(bp->b_flags, B_BUSY); 204 SET(bp->b_flags, B_RELEASED); 205 TAILQ_INSERT_HEAD(&buf_valist, bp, b_valist); 206 207 splx(s); 208 209 return (1); 210 } 211 212 vaddr_t 213 buf_unmap(struct buf *bp) 214 { 215 vaddr_t va; 216 int s; 217 218 KASSERT((bp->b_flags & B_BUSY) == 0); 219 KASSERT(bp->b_data != NULL); 220 221 s = splbio(); 222 TAILQ_REMOVE(&buf_valist, bp, b_valist); 223 va = (vaddr_t)bp->b_data; 224 bp->b_data = 0; 225 pmap_kremove(va, bp->b_bufsize); 226 pmap_update(pmap_kernel()); 227 228 if (bp->b_flags & B_RELEASED) 229 pool_put(&bufpool, bp); 230 231 splx(s); 232 233 return (va); 234 } 235 236 void 237 buf_alloc_pages(struct buf *bp, vsize_t size) 238 { 239 struct vm_page *pg; 240 voff_t offs, i; 241 int s; 242 243 KASSERT(size == round_page(size)); 244 KASSERT(bp->b_pobj == NULL); 245 KASSERT(bp->b_data == NULL); 246 247 s = splbio(); 248 249 offs = buf_page_offset; 250 buf_page_offset += size; 251 252 KASSERT(buf_page_offset > 0); 253 254 for (i = 0; i < atop(size); i++) { 255 #if defined(DEBUG) || 1 256 if ((pg = uvm_pagelookup(buf_object, offs + ptoa(i)))) 257 panic("buf_alloc_pages: overlap buf: %p page: %p", 258 bp, pg); 259 #endif 260 261 while ((pg = uvm_pagealloc(buf_object, offs + ptoa(i), 262 NULL, 0)) == NULL) { 263 uvm_wait("buf_alloc_pages"); 264 } 265 pg->wire_count = 1; 266 atomic_clearbits_int(&pg->pg_flags, PG_BUSY); 267 bcstats.numbufpages++; 268 } 269 270 bp->b_pobj = buf_object; 271 bp->b_poffs = offs; 272 bp->b_bufsize = size; 273 splx(s); 274 } 275 276 void 277 buf_free_pages(struct buf *bp) 278 { 279 struct uvm_object *uobj = bp->b_pobj; 280 struct vm_page *pg; 281 voff_t off, i; 282 int s; 283 284 KASSERT(bp->b_data == NULL); 285 KASSERT(uobj != NULL); 286 287 s = splbio(); 288 289 off = bp->b_poffs; 290 bp->b_pobj = NULL; 291 bp->b_poffs = 0; 292 293 for (i = 0; i < atop(bp->b_bufsize); i++) { 294 pg = uvm_pagelookup(uobj, off + ptoa(i)); 295 KASSERT(pg != NULL); 296 KASSERT(pg->wire_count == 1); 297 pg->wire_count = 0; 298 uvm_pagefree(pg); 299 bcstats.numbufpages--; 300 } 301 splx(s); 302 } 303 304 /* 305 * XXX - it might make sense to make a buf_realloc_pages to avoid 306 * bouncing through the free list all the time. 307 */ 308