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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..68dbe7015b
--- /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 <assert.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
+
+#include "mmap-cache.h"
+
+#define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
+#define WINDOWS_MAX 32
+
+typedef struct Window {
+ int fd;
+ void *ptr;
+ uint64_t offset;
+ uint64_t size;
+
+ unsigned n_ref;
+ unsigned lru_prev;
+ unsigned lru_next;
+
+ unsigned by_fd_prev;
+ unsigned by_fd_next;
+} Window;
+
+typedef struct FileDescriptor {
+ int fd;
+ unsigned windows;
+} FileDescriptor;
+
+struct MMapCache {
+ unsigned n_ref;
+
+ unsigned contexts_max;
+ unsigned windows_max;
+ unsigned fds_max;
+
+ unsigned n_windows;
+ unsigned n_fds;
+
+ unsigned lru_first, lru_last;
+
+ Window *windows;
+ unsigned *by_context;
+ FileDescriptor *by_fd;
+};
+
+static void mmap_cache_window_unmap(MMapCache *m, unsigned w) {
+ Window *v;
+
+ assert(m);
+ assert(w < m->n_windows);
+
+ v = m->windows + w;
+ if (!v->ptr)
+ return;
+
+ munmap(v->ptr, v->size);
+ v->ptr = NULL;
+}
+
+static void mmap_cache_window_add_lru(MMapCache *m, unsigned w) {
+ Window *v;
+
+ assert(m);
+ assert(w < m->n_windows);
+
+ v = m->windows + w;
+ v->lru_prev = m->lru_last;
+ v->lru_next = (unsigned) -1;
+
+ m->lru_last = w;
+ if (m->lru_first == (unsigned) -1)
+ m->lru_first = w;
+}
+
+static void mmap_cache_window_remove_lru(MMapCache *m, unsigned w) {
+ Window *v;
+
+ assert(m);
+ assert(w < m->n_windows);
+
+ v = m->windows + w;
+
+ if (v->lru_prev == (unsigned) -1)
+ m->lru_first = v->lru_next;
+ else
+ m->windows[v->lru_prev].lru_next = v->lru_next;
+
+ if (v->lru_next == (unsigned) -1)
+ m->lru_last = v->lru_prev;
+ else
+ m->windows[v->lru_next].lru_prev = v->lru_prev;
+}
+
+static void mmap_cache_fd_add(MMapCache *m, unsigned fd_index, unsigned w) {
+ Window *v;
+
+ assert(m);
+ assert(fd_index < m->n_fds);
+
+ v = m->windows + w;
+ v->by_fd_next = m->by_fd[fd_index].windows;
+ v->by_fd_prev = (unsigned) -1;
+
+ m->by_fd[fd_index].windows = w;
+}
+
+static void mmap_cache_fd_remove(MMapCache *m, unsigned fd_index, unsigned w) {
+ Window *v;
+
+ assert(m);
+ assert(fd_index < m->n_fds);
+
+ v = m->windows + w;
+ if (v->by_fd_prev == (unsigned) -1)
+ m->by_fd[fd_index].windows = v->by_fd_next;
+ else
+ m->windows[v->by_fd_prev].by_fd_next = v->by_fd_next;
+
+ if (v->by_fd_next != (unsigned) -1)
+ m->windows[v->by_fd_next].by_fd_prev = v->by_fd_prev;
+}
+
+static void mmap_cache_context_unset(MMapCache *m, unsigned c) {
+ Window *v;
+ unsigned w;
+
+ assert(m);
+ assert(c < m->contexts_max);
+
+ if (m->by_context[c] == (unsigned) -1)
+ return;
+
+ w = m->by_context[c];
+ m->by_context[c] = (unsigned) -1;
+
+ v = m->windows + w;
+ assert(v->n_ref > 0);
+ v->n_ref --;
+
+ if (v->n_ref == 0)
+ mmap_cache_window_add_lru(m, w);
+}
+
+static void mmap_cache_context_set(MMapCache *m, unsigned c, unsigned w) {
+ Window *v;
+
+ assert(m);
+ assert(c < m->contexts_max);
+ assert(w < m->n_windows);
+
+ if (m->by_context[c] == w)
+ return;
+
+ mmap_cache_context_unset(m, c);
+
+ m->by_context[c] = w;
+
+ v = m->windows + w;
+ v->n_ref ++;
+ if (v->n_ref == 1)
+ mmap_cache_window_remove_lru(m, w);
+}
+
+static void mmap_cache_free(MMapCache *m) {
+
+ assert(m);
+
+ if (m->windows) {
+ unsigned w;
+
+ for (w = 0; w < m->n_windows; w++)
+ mmap_cache_window_unmap(m, w);
+
+ free(m->windows);
+ }
+
+ free(m->by_context);
+ free(m->by_fd);
+ free(m);
+}
+
+MMapCache* mmap_cache_new(unsigned contexts_max, unsigned fds_max) {
+ MMapCache *m;
+
+ assert(contexts_max > 0);
+ assert(fds_max > 0);
+
+ m = new0(MMapCache, 1);
+ if (!m)
+ return NULL;
+
+ m->contexts_max = contexts_max;
+ m->fds_max = fds_max;
+ m->windows_max = MAX(m->contexts_max, WINDOWS_MAX);
+ m->n_ref = 1;
+ m->lru_first = (unsigned) -1;
+ m->lru_last = (unsigned) -1;
+
+ m->windows = new(Window, m->windows_max);
+ if (!m->windows) {
+ mmap_cache_free(m);
+ return NULL;
+ }
+
+ m->by_context = new(unsigned, m->contexts_max);
+ if (!m->by_context) {
+ mmap_cache_free(m);
+ return NULL;
+ }
+
+ memset(m->by_context, -1, m->contexts_max * sizeof(unsigned));
+
+ m->by_fd = new(FileDescriptor, m->fds_max);
+ if (!m->by_fd) {
+ mmap_cache_free(m);
+ return NULL;
+ }
+
+ return m;
+}
+
+MMapCache* mmap_cache_ref(MMapCache *m) {
+ assert(m);
+ assert(m->n_ref > 0);
+
+ m->n_ref++;
+ return m;
+}
+
+MMapCache* mmap_cache_unref(MMapCache *m) {
+ assert(m);
+ assert(m->n_ref > 0);
+
+ if (m->n_ref == 1)
+ mmap_cache_free(m);
+ else
+ m->n_ref--;
+
+ return NULL;
+}
+
+static int mmap_cache_allocate_window(MMapCache *m, unsigned *w) {
+ assert(m);
+ assert(w);
+
+ if (m->n_windows < m->windows_max) {
+ *w = m->n_windows ++;
+ return 0;
+ }
+
+ if (m->lru_first == (unsigned) -1)
+ return -E2BIG;
+
+ *w = m->lru_first;
+ mmap_cache_window_unmap(m, *w);
+ mmap_cache_window_remove_lru(m, *w);
+
+ return 0;
+}
+
+static int mmap_cache_make_room(MMapCache *m) {
+ unsigned w;
+
+ assert(m);
+
+ w = m->lru_first;
+ while (w != (unsigned) -1) {
+ Window *v;
+
+ v = m->windows + w;
+
+ if (v->ptr) {
+ mmap_cache_window_unmap(m, w);
+ return 1;
+ }
+
+ w = v->lru_next;
+ }
+
+ return 0;
+}
+
+static int mmap_cache_put(
+ MMapCache *m,
+ int fd,
+ unsigned fd_index,
+ int prot,
+ unsigned context,
+ uint64_t offset,
+ uint64_t size,
+ void **ret) {
+
+ unsigned w;
+ Window *v;
+ void *d;
+ uint64_t woffset, wsize;
+ int r;
+
+ assert(m);
+ assert(fd >= 0);
+ assert(context < m->contexts_max);
+ 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 = (WINDOW_SIZE - wsize) / 2;
+
+ if (delta > offset)
+ woffset = 0;
+ else
+ woffset -= delta;
+
+ wsize = WINDOW_SIZE;
+ }
+
+ for (;;) {
+ d = mmap(NULL, wsize, prot, MAP_SHARED, fd, woffset);
+ if (d != MAP_FAILED)
+ break;
+ if (errno != ENOMEM)
+ return -errno;
+
+ r = mmap_cache_make_room(m);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -ENOMEM;
+ }
+
+ r = mmap_cache_allocate_window(m, &w);
+ if (r < 0) {
+ munmap(d, wsize);
+ return r;
+ }
+
+ v = m->windows + w;
+ v->fd = fd;
+ v->ptr = d;
+ v->offset = woffset;
+ v->size = wsize;
+
+ v->n_ref = 0;
+ v->lru_prev = v->lru_next = (unsigned) -1;
+
+ mmap_cache_fd_add(m, fd_index, w);
+ mmap_cache_context_set(m, context, w);
+
+ *ret = (uint8_t*) d + (offset - woffset);
+ return 1;
+}
+
+static int fd_cmp(const void *_a, const void *_b) {
+ const FileDescriptor *a = _a, *b = _b;
+
+ if (a->fd < b->fd)
+ return -1;
+ if (a->fd > b->fd)
+ return 1;
+
+ return 0;
+}
+
+static int mmap_cache_get_fd_index(MMapCache *m, int fd, unsigned *fd_index) {
+ FileDescriptor *j;
+
+ assert(m);
+ assert(fd >= 0);
+ assert(fd_index);
+
+ j = bsearch(&fd, m->by_fd, m->n_fds, sizeof(m->by_fd[0]), fd_cmp);
+ if (!j) {
+ if (m->n_fds >= m->fds_max)
+ return -E2BIG;
+
+ j = m->by_fd + m->n_fds ++;
+ j->fd = fd;
+ j->windows = (unsigned) -1;
+
+ qsort(m->by_fd, m->n_fds, sizeof(m->by_fd[0]), fd_cmp);
+ j = bsearch(&fd, m->by_fd, m->n_fds, sizeof(m->by_fd[0]), fd_cmp);
+ }
+
+ *fd_index = (unsigned) (j - m->by_fd);
+ return 0;
+}
+
+static bool mmap_cache_test_window(
+ MMapCache *m,
+ unsigned w,
+ uint64_t offset,
+ uint64_t size) {
+ Window *v;
+
+ assert(m);
+ assert(w < m->n_windows);
+ assert(size > 0);
+
+ v = m->windows + w;
+
+ return offset >= v->offset &&
+ offset + size <= v->offset + v->size;
+}
+
+static int mmap_cache_current(
+ MMapCache *m,
+ int fd,
+ unsigned context,
+ uint64_t offset,
+ uint64_t size,
+ void **ret) {
+
+ Window *v;
+ unsigned w;
+
+ assert(m);
+ assert(fd >= 0);
+ assert(context < m->contexts_max);
+ assert(size > 0);
+ assert(ret);
+
+ if (m->by_context[context] == (unsigned) -1)
+ return 0;
+
+ w = m->by_context[context];
+ v = m->windows + w;
+
+ if (v->fd != fd)
+ return 0;
+
+ if (!mmap_cache_test_window(m, w, offset, size))
+ return 0;
+
+ *ret = (uint8_t*) v->ptr + (offset - v->offset);
+ return 1;
+}
+
+static int mmap_cache_find(
+ MMapCache *m,
+ unsigned fd_index,
+ unsigned context,
+ uint64_t offset,
+ uint64_t size,
+ void **ret) {
+
+ Window *v = NULL;
+ unsigned w;
+
+ assert(m);
+ assert(fd_index < m->n_fds);
+ assert(context < m->contexts_max);
+ assert(size > 0);
+ assert(ret);
+
+ w = m->by_fd[fd_index].windows;
+ while (w != (unsigned) -1) {
+ if (mmap_cache_test_window(m, w, offset, size))
+ break;
+
+ w = m->windows[w].by_fd_next;
+ }
+
+ if (w == (unsigned) -1)
+ return 0;
+
+ mmap_cache_context_set(m, context, w);
+
+ v = m->windows + w;
+ *ret = (uint8_t*) v->ptr + (offset - v->offset);
+ return 1;
+}
+
+int mmap_cache_get(
+ MMapCache *m,
+ int fd,
+ int prot,
+ unsigned context,
+ uint64_t offset,
+ uint64_t size,
+ void **ret) {
+
+ unsigned fd_index;
+ int r;
+
+ assert(m);
+ assert(fd >= 0);
+ assert(context < m->contexts_max);
+ assert(size > 0);
+ assert(ret);
+
+ /* Maybe the current pointer for this context is already the
+ * right one? */
+ r = mmap_cache_current(m, fd, context, offset, size, ret);
+ if (r != 0)
+ return r;
+
+ /* OK, let's find the chain for this FD */
+ r = mmap_cache_get_fd_index(m, fd, &fd_index);
+ if (r < 0)
+ return r;
+
+ /* And let's look through the available mmaps */
+ r = mmap_cache_find(m, fd_index, context, offset, size, ret);
+ if (r != 0)
+ return r;
+
+ /* Not found? Then, let's add it */
+ return mmap_cache_put(m, fd, fd_index, prot, context, offset, size, ret);
+}
+
+void mmap_cache_close_fd(MMapCache *m, int fd) {
+ FileDescriptor *j;
+ unsigned fd_index, c, w;
+
+ assert(m);
+ assert(fd > 0);
+
+ j = bsearch(&fd, m->by_fd, m->n_fds, sizeof(m->by_fd[0]), fd_cmp);
+ if (!j)
+ return;
+ fd_index = (unsigned) (j - m->by_fd);
+
+ for (c = 0; c < m->contexts_max; c++) {
+ w = m->by_context[c];
+ if (w == (unsigned) -1)
+ continue;
+
+ if (m->windows[w].fd == fd)
+ mmap_cache_context_unset(m, c);
+ }
+
+ w = m->by_fd[fd_index].windows;
+ while (w != (unsigned) -1) {
+
+ mmap_cache_fd_remove(m, fd_index, w);
+ mmap_cache_window_unmap(m, w);
+
+ w = m->by_fd[fd_index].windows;
+ }
+
+ memmove(m->by_fd + fd_index, m->by_fd + fd_index + 1, (m->n_fds - (fd_index + 1)) * sizeof(FileDescriptor));
+ m->n_fds --;
+}
+
+void mmap_cache_close_context(MMapCache *m, unsigned context) {
+ mmap_cache_context_unset(m, context);
+}