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(Window, by_fd, w->fd->windows, w);
116 if (w->cache->last_unused == w)
117 w->cache->last_unused = w->unused_prev;
119 LIST_REMOVE(Window, 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(Context, by_window, w->contexts, c);
185 if (!w->contexts && !w->keep_always) {
186 /* Not used anymore? */
187 LIST_PREPEND(Window, 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(Window, 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(Context, 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 while ((f = hashmap_first(m->fds)))
314 window_free(m->unused);
319 MMapCache* mmap_cache_unref(MMapCache *m) {
321 assert(m->n_ref > 0);
330 static int make_room(MMapCache *m) {
336 window_free(m->last_unused);
340 static int try_context(
353 assert(m->n_ref > 0);
358 c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
362 assert(c->id == context);
367 if (!window_matches(c->window, fd, prot, offset, size)) {
369 /* Drop the reference to the window, since it's unnecessary now */
370 context_detach_window(c);
374 c->window->keep_always = c->window->keep_always || keep_always;
376 *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
380 static int find_mmap(
395 assert(m->n_ref > 0);
400 f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
406 LIST_FOREACH(by_fd, w, f->windows)
407 if (window_matches(w, fd, prot, offset, size))
413 c = context_add(m, context);
417 context_attach_window(c, w);
418 w->keep_always = w->keep_always || keep_always;
420 *ret = (uint8_t*) w->ptr + (offset - w->offset);
435 uint64_t woffset, wsize;
443 assert(m->n_ref > 0);
448 woffset = offset & ~((uint64_t) page_size() - 1ULL);
449 wsize = size + (offset - woffset);
450 wsize = PAGE_ALIGN(wsize);
452 if (wsize < WINDOW_SIZE) {
455 delta = PAGE_ALIGN((WINDOW_SIZE - wsize) / 2);
466 /* Memory maps that are larger then the files
467 underneath have undefined behavior. Hence, clamp
468 things to the file size if we know it */
470 if (woffset >= (uint64_t) st->st_size)
471 return -EADDRNOTAVAIL;
473 if (woffset + wsize > (uint64_t) st->st_size)
474 wsize = PAGE_ALIGN(st->st_size - woffset);
478 d = mmap(NULL, wsize, prot, MAP_SHARED, fd, woffset);
491 c = context_add(m, context);
503 w->keep_always = keep_always;
510 LIST_PREPEND(Window, by_fd, f->windows, w);
512 context_detach_window(c);
514 LIST_PREPEND(Context, by_window, w->contexts, c);
516 *ret = (uint8_t*) w->ptr + (offset - w->offset);
534 assert(m->n_ref > 0);
539 /* Check whether the current context is the right one already */
540 r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
544 /* Search for a matching mmap */
545 r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);
549 /* Create a new mmap */
550 return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
553 void mmap_cache_close_fd(MMapCache *m, int fd) {
559 f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
566 void mmap_cache_close_context(MMapCache *m, unsigned context) {
571 c = hashmap_get(m->contexts, UINT_TO_PTR(context + 1));