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-rw-r--r--src/journal/mmap-cache.c577
1 files changed, 577 insertions, 0 deletions
diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
new file mode 100644
index 0000000000..251aefe121
--- /dev/null
+++ b/src/journal/mmap-cache.c
@@ -0,0 +1,577 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2012 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <string.h>
+
+#include "hashmap.h"
+#include "list.h"
+#include "log.h"
+#include "util.h"
+#include "macro.h"
+#include "mmap-cache.h"
+
+typedef struct Window Window;
+typedef struct Context Context;
+typedef struct FileDescriptor FileDescriptor;
+
+struct Window {
+ MMapCache *cache;
+
+ bool keep_always;
+ bool in_unused;
+
+ void *ptr;
+ uint64_t offset;
+ int prot;
+ size_t size;
+
+ FileDescriptor *fd;
+
+ LIST_FIELDS(Window, by_fd);
+ LIST_FIELDS(Window, unused);
+
+ LIST_HEAD(Context, contexts);
+};
+
+struct Context {
+ MMapCache *cache;
+ unsigned id;
+ Window *window;
+
+ LIST_FIELDS(Context, by_window);
+};
+
+struct FileDescriptor {
+ MMapCache *cache;
+ int fd;
+ LIST_HEAD(Window, windows);
+};
+
+struct MMapCache {
+ int n_ref;
+
+ Hashmap *fds;
+ Hashmap *contexts;
+
+ unsigned n_windows;
+
+ LIST_HEAD(Window, unused);
+ Window *last_unused;
+};
+
+#define WINDOWS_MIN 64
+#define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
+
+MMapCache* mmap_cache_new(void) {
+ MMapCache *m;
+
+ m = new0(MMapCache, 1);
+ if (!m)
+ return NULL;
+
+ m->n_ref = 1;
+ return m;
+}
+
+MMapCache* mmap_cache_ref(MMapCache *m) {
+ assert(m);
+ assert(m->n_ref > 0);
+
+ m->n_ref ++;
+ return m;
+}
+
+static void window_unlink(Window *w) {
+ Context *c;
+
+ assert(w);
+
+ if (w->ptr)
+ munmap(w->ptr, w->size);
+
+ if (w->fd)
+ LIST_REMOVE(Window, by_fd, w->fd->windows, w);
+
+ if (w->in_unused) {
+ if (w->cache->last_unused == w)
+ w->cache->last_unused = w->unused_prev;
+
+ LIST_REMOVE(Window, unused, w->cache->unused, w);
+ }
+
+ LIST_FOREACH(by_window, c, w->contexts) {
+ assert(c->window == w);
+ c->window = NULL;
+ }
+}
+
+static void window_free(Window *w) {
+ assert(w);
+
+ window_unlink(w);
+ w->cache->n_windows--;
+ free(w);
+}
+
+static bool window_matches(Window *w, int fd, int prot, uint64_t offset, size_t size) {
+ assert(w);
+ assert(fd >= 0);
+ assert(size > 0);
+
+ return
+ w->fd &&
+ fd == w->fd->fd &&
+ prot == w->prot &&
+ offset >= w->offset &&
+ offset + size <= w->offset + w->size;
+}
+
+static Window *window_add(MMapCache *m) {
+ Window *w;
+
+ assert(m);
+
+ if (!m->last_unused || m->n_windows <= WINDOWS_MIN) {
+
+ /* Allocate a new window */
+ w = new0(Window, 1);
+ if (!w)
+ return NULL;
+ m->n_windows++;
+ } else {
+
+ /* Reuse an existing one */
+ w = m->last_unused;
+ window_unlink(w);
+ zero(*w);
+ }
+
+ w->cache = m;
+ return w;
+}
+
+static void context_detach_window(Context *c) {
+ Window *w;
+
+ assert(c);
+
+ if (!c->window)
+ return;
+
+ w = c->window;
+ c->window = NULL;
+ LIST_REMOVE(Context, by_window, w->contexts, c);
+
+ if (!w->contexts && !w->keep_always) {
+ /* Not used anymore? */
+ LIST_PREPEND(Window, unused, c->cache->unused, w);
+ if (!c->cache->last_unused)
+ c->cache->last_unused = w;
+
+ w->in_unused = true;
+ }
+}
+
+static void context_attach_window(Context *c, Window *w) {
+ assert(c);
+ assert(w);
+
+ if (c->window == w)
+ return;
+
+ context_detach_window(c);
+
+ if (w->in_unused) {
+ /* Used again? */
+ LIST_REMOVE(Window, unused, c->cache->unused, w);
+ if (c->cache->last_unused == w)
+ c->cache->last_unused = w->unused_prev;
+
+ w->in_unused = false;
+ }
+
+ c->window = w;
+ LIST_PREPEND(Context, by_window, w->contexts, c);
+}
+
+static Context *context_add(MMapCache *m, unsigned id) {
+ Context *c;
+ int r;
+
+ assert(m);
+
+ c = hashmap_get(m->contexts, UINT_TO_PTR(id + 1));
+ if (c)
+ return c;
+
+ r = hashmap_ensure_allocated(&m->contexts, trivial_hash_func, trivial_compare_func);
+ if (r < 0)
+ return NULL;
+
+ c = new0(Context, 1);
+ if (!c)
+ return NULL;
+
+ c->cache = m;
+ c->id = id;
+
+ r = hashmap_put(m->contexts, UINT_TO_PTR(id + 1), c);
+ if (r < 0) {
+ free(c);
+ return NULL;
+ }
+
+ return c;
+}
+
+static void context_free(Context *c) {
+ assert(c);
+
+ context_detach_window(c);
+
+ if (c->cache)
+ assert_se(hashmap_remove(c->cache->contexts, UINT_TO_PTR(c->id + 1)));
+
+ free(c);
+}
+
+static void fd_free(FileDescriptor *f) {
+ assert(f);
+
+ while (f->windows)
+ window_free(f->windows);
+
+ if (f->cache)
+ assert_se(hashmap_remove(f->cache->fds, INT_TO_PTR(f->fd + 1)));
+
+ free(f);
+}
+
+static FileDescriptor* fd_add(MMapCache *m, int fd) {
+ FileDescriptor *f;
+ int r;
+
+ assert(m);
+ assert(fd >= 0);
+
+ f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
+ if (f)
+ return f;
+
+ r = hashmap_ensure_allocated(&m->fds, trivial_hash_func, trivial_compare_func);
+ if (r < 0)
+ return NULL;
+
+ f = new0(FileDescriptor, 1);
+ if (!f)
+ return NULL;
+
+ f->cache = m;
+ f->fd = fd;
+
+ r = hashmap_put(m->fds, UINT_TO_PTR(fd + 1), f);
+ if (r < 0) {
+ free(f);
+ return NULL;
+ }
+
+ return f;
+}
+
+static void mmap_cache_free(MMapCache *m) {
+ Context *c;
+ FileDescriptor *f;
+
+ assert(m);
+
+ while ((c = hashmap_first(m->contexts)))
+ context_free(c);
+
+ while ((f = hashmap_first(m->fds)))
+ fd_free(f);
+
+ while (m->unused)
+ window_free(m->unused);
+
+ free(m);
+}
+
+MMapCache* mmap_cache_unref(MMapCache *m) {
+ assert(m);
+ assert(m->n_ref > 0);
+
+ m->n_ref --;
+ if (m->n_ref == 0)
+ mmap_cache_free(m);
+
+ return NULL;
+}
+
+static int make_room(MMapCache *m) {
+ assert(m);
+
+ if (!m->last_unused)
+ return 0;
+
+ window_free(m->last_unused);
+ return 1;
+}
+
+static int try_context(
+ MMapCache *m,
+ int fd,
+ int prot,
+ unsigned context,
+ bool keep_always,
+ uint64_t offset,
+ size_t size,
+ void **ret) {
+
+ Context *c;
+
+ assert(m);
+ assert(m->n_ref > 0);
+ assert(fd >= 0);
+ assert(size > 0);
+ assert(ret);
+
+ c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
+ if (!c)
+ return 0;
+
+ assert(c->id == context);
+
+ if (!c->window)
+ return 0;
+
+ if (!window_matches(c->window, fd, prot, offset, size)) {
+
+ /* Drop the reference to the window, since it's unnecessary now */
+ context_detach_window(c);
+ return 0;
+ }
+
+ c->window->keep_always = c->window->keep_always || keep_always;
+
+ *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+ return 1;
+}
+
+static int find_mmap(
+ MMapCache *m,
+ int fd,
+ int prot,
+ unsigned context,
+ bool keep_always,
+ uint64_t offset,
+ size_t size,
+ void **ret) {
+
+ FileDescriptor *f;
+ Window *w;
+ Context *c;
+
+ assert(m);
+ assert(m->n_ref > 0);
+ assert(fd >= 0);
+ assert(size > 0);
+ assert(ret);
+
+ f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
+ if (!f)
+ return 0;
+
+ assert(f->fd == fd);
+
+ LIST_FOREACH(by_fd, w, f->windows)
+ if (window_matches(w, fd, prot, offset, size))
+ break;
+
+ if (!w)
+ return 0;
+
+ c = context_add(m, context);
+ if (!c)
+ return -ENOMEM;
+
+ context_attach_window(c, w);
+ w->keep_always = w->keep_always || keep_always;
+
+ *ret = (uint8_t*) w->ptr + (offset - w->offset);
+ return 1;
+}
+
+static int add_mmap(
+ MMapCache *m,
+ int fd,
+ int prot,
+ unsigned context,
+ bool keep_always,
+ uint64_t offset,
+ size_t size,
+ struct stat *st,
+ void **ret) {
+
+ uint64_t woffset, wsize;
+ Context *c;
+ FileDescriptor *f;
+ Window *w;
+ void *d;
+ int r;
+
+ assert(m);
+ assert(m->n_ref > 0);
+ assert(fd >= 0);
+ assert(size > 0);
+ assert(ret);
+
+ woffset = offset & ~((uint64_t) page_size() - 1ULL);
+ wsize = size + (offset - woffset);
+ wsize = PAGE_ALIGN(wsize);
+
+ if (wsize < WINDOW_SIZE) {
+ uint64_t delta;
+
+ delta = PAGE_ALIGN((WINDOW_SIZE - wsize) / 2);
+
+ if (delta > offset)
+ woffset = 0;
+ else
+ woffset -= delta;
+
+ wsize = WINDOW_SIZE;
+ }
+
+ if (st) {
+ /* Memory maps that are larger then the files
+ underneath have undefined behavior. Hence, clamp
+ things to the file size if we know it */
+
+ if (woffset >= (uint64_t) st->st_size)
+ return -EADDRNOTAVAIL;
+
+ if (woffset + wsize > (uint64_t) st->st_size)
+ wsize = PAGE_ALIGN(st->st_size - woffset);
+ }
+
+ for (;;) {
+ d = mmap(NULL, wsize, prot, MAP_SHARED, fd, woffset);
+ if (d != MAP_FAILED)
+ break;
+ if (errno != ENOMEM)
+ return -errno;
+
+ r = make_room(m);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -ENOMEM;
+ }
+
+ c = context_add(m, context);
+ if (!c)
+ return -ENOMEM;
+
+ f = fd_add(m, fd);
+ if (!f)
+ return -ENOMEM;
+
+ w = window_add(m);
+ if (!w)
+ return -ENOMEM;
+
+ w->keep_always = keep_always;
+ w->ptr = d;
+ w->offset = woffset;
+ w->prot = prot;
+ w->size = wsize;
+ w->fd = f;
+
+ LIST_PREPEND(Window, by_fd, f->windows, w);
+
+ context_detach_window(c);
+ c->window = w;
+ LIST_PREPEND(Context, by_window, w->contexts, c);
+
+ *ret = (uint8_t*) w->ptr + (offset - w->offset);
+ return 1;
+}
+
+int mmap_cache_get(
+ MMapCache *m,
+ int fd,
+ int prot,
+ unsigned context,
+ bool keep_always,
+ uint64_t offset,
+ size_t size,
+ struct stat *st,
+ void **ret) {
+
+ int r;
+
+ assert(m);
+ assert(m->n_ref > 0);
+ assert(fd >= 0);
+ assert(size > 0);
+ assert(ret);
+
+ /* Check whether the current context is the right one already */
+ r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
+ if (r != 0)
+ return r;
+
+ /* Search for a matching mmap */
+ r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);
+ if (r != 0)
+ return r;
+
+ /* Create a new mmap */
+ return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
+}
+
+void mmap_cache_close_fd(MMapCache *m, int fd) {
+ FileDescriptor *f;
+
+ assert(m);
+ assert(fd >= 0);
+
+ f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
+ if (!f)
+ return;
+
+ fd_free(f);
+}
+
+void mmap_cache_close_context(MMapCache *m, unsigned context) {
+ Context *c;
+
+ assert(m);
+
+ c = hashmap_get(m->contexts, UINT_TO_PTR(context + 1));
+ if (!c)
+ return;
+
+ context_free(c);
+}