1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2012 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
32 #include "mmap-cache.h"
34 typedef struct Window Window;
35 typedef struct Context Context;
36 typedef struct FileDescriptor FileDescriptor;
51 LIST_FIELDS(Window, by_fd);
52 LIST_FIELDS(Window, unused);
54 LIST_HEAD(Context, contexts);
62 LIST_FIELDS(Context, by_window);
65 struct FileDescriptor {
68 LIST_HEAD(Window, windows);
78 LIST_HEAD(Window, unused);
82 #define WINDOWS_MIN 64
83 #define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
85 MMapCache* mmap_cache_new(void) {
88 m = new0(MMapCache, 1);
96 MMapCache* mmap_cache_ref(MMapCache *m) {
104 static void window_unlink(Window *w) {
110 munmap(w->ptr, w->size);
113 LIST_REMOVE(by_fd, w->fd->windows, w);
116 if (w->cache->last_unused == w)
117 w->cache->last_unused = w->unused_prev;
119 LIST_REMOVE(unused, w->cache->unused, w);
122 LIST_FOREACH(by_window, c, w->contexts) {
123 assert(c->window == w);
128 static void window_free(Window *w) {
132 w->cache->n_windows--;
136 _pure_ static bool window_matches(Window *w, int fd, int prot, uint64_t offset, size_t size) {
145 offset >= w->offset &&
146 offset + size <= w->offset + w->size;
149 static Window *window_add(MMapCache *m) {
154 if (!m->last_unused || m->n_windows <= WINDOWS_MIN) {
156 /* Allocate a new window */
163 /* Reuse an existing one */
173 static void context_detach_window(Context *c) {
183 LIST_REMOVE(by_window, w->contexts, c);
185 if (!w->contexts && !w->keep_always) {
186 /* Not used anymore? */
187 LIST_PREPEND(unused, c->cache->unused, w);
188 if (!c->cache->last_unused)
189 c->cache->last_unused = w;
195 static void context_attach_window(Context *c, Window *w) {
202 context_detach_window(c);
206 LIST_REMOVE(unused, c->cache->unused, w);
207 if (c->cache->last_unused == w)
208 c->cache->last_unused = w->unused_prev;
210 w->in_unused = false;
214 LIST_PREPEND(by_window, w->contexts, c);
217 static Context *context_add(MMapCache *m, unsigned id) {
223 c = hashmap_get(m->contexts, UINT_TO_PTR(id + 1));
227 r = hashmap_ensure_allocated(&m->contexts, trivial_hash_func, trivial_compare_func);
231 c = new0(Context, 1);
238 r = hashmap_put(m->contexts, UINT_TO_PTR(id + 1), c);
247 static void context_free(Context *c) {
250 context_detach_window(c);
253 assert_se(hashmap_remove(c->cache->contexts, UINT_TO_PTR(c->id + 1)));
258 static void fd_free(FileDescriptor *f) {
262 window_free(f->windows);
265 assert_se(hashmap_remove(f->cache->fds, INT_TO_PTR(f->fd + 1)));
270 static FileDescriptor* fd_add(MMapCache *m, int fd) {
277 f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
281 r = hashmap_ensure_allocated(&m->fds, trivial_hash_func, trivial_compare_func);
285 f = new0(FileDescriptor, 1);
292 r = hashmap_put(m->fds, UINT_TO_PTR(fd + 1), f);
301 static void mmap_cache_free(MMapCache *m) {
307 while ((c = hashmap_first(m->contexts)))
310 hashmap_free(m->contexts);
312 while ((f = hashmap_first(m->fds)))
315 hashmap_free(m->fds);
318 window_free(m->unused);
323 MMapCache* mmap_cache_unref(MMapCache *m) {
325 assert(m->n_ref > 0);
334 static int make_room(MMapCache *m) {
340 window_free(m->last_unused);
344 static int try_context(
357 assert(m->n_ref > 0);
362 c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
366 assert(c->id == context);
371 if (!window_matches(c->window, fd, prot, offset, size)) {
373 /* Drop the reference to the window, since it's unnecessary now */
374 context_detach_window(c);
378 c->window->keep_always = c->window->keep_always || keep_always;
380 *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
384 static int find_mmap(
399 assert(m->n_ref > 0);
404 f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
410 LIST_FOREACH(by_fd, w, f->windows)
411 if (window_matches(w, fd, prot, offset, size))
417 c = context_add(m, context);
421 context_attach_window(c, w);
422 w->keep_always = w->keep_always || keep_always;
424 *ret = (uint8_t*) w->ptr + (offset - w->offset);
439 uint64_t woffset, wsize;
447 assert(m->n_ref > 0);
452 woffset = offset & ~((uint64_t) page_size() - 1ULL);
453 wsize = size + (offset - woffset);
454 wsize = PAGE_ALIGN(wsize);
456 if (wsize < WINDOW_SIZE) {
459 delta = PAGE_ALIGN((WINDOW_SIZE - wsize) / 2);
470 /* Memory maps that are larger then the files
471 underneath have undefined behavior. Hence, clamp
472 things to the file size if we know it */
474 if (woffset >= (uint64_t) st->st_size)
475 return -EADDRNOTAVAIL;
477 if (woffset + wsize > (uint64_t) st->st_size)
478 wsize = PAGE_ALIGN(st->st_size - woffset);
482 d = mmap(NULL, wsize, prot, MAP_SHARED, fd, woffset);
495 c = context_add(m, context);
507 w->keep_always = keep_always;
514 LIST_PREPEND(by_fd, f->windows, w);
516 context_detach_window(c);
518 LIST_PREPEND(by_window, w->contexts, c);
520 *ret = (uint8_t*) w->ptr + (offset - w->offset);
538 assert(m->n_ref > 0);
543 /* Check whether the current context is the right one already */
544 r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
548 /* Search for a matching mmap */
549 r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);
553 /* Create a new mmap */
554 return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
557 void mmap_cache_close_fd(MMapCache *m, int fd) {
563 f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
570 void mmap_cache_close_context(MMapCache *m, unsigned context) {
575 c = hashmap_get(m->contexts, UINT_TO_PTR(context + 1));