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Merge pull request #29439 from yuwata/mmap-cache-cleanups-part2

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mmap-cache: several cleanups (part2)
This commit is contained in:
Daan De Meyer
2023-10-05 14:49:48 +02:00
committed by GitHub
parent 289c816952 0073f6c623
commit 32a1d321d4
1 changed files with 63 additions and 156 deletions
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219
src/libsystemd/sd-journal/mmap-cache.c
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@@ -19,7 +19,7 @@ typedef struct Window Window;
typedef struct Context Context;
struct Window {
MMapCache *cache;
MMapFileDescriptor *fd;
bool invalidated:1;
bool keep_always:1;
@@ -29,9 +29,7 @@ struct Window {
uint64_t offset;
size_t size;
MMapFileDescriptor *fd;
LIST_FIELDS(Window, by_fd);
LIST_FIELDS(Window, windows);
LIST_FIELDS(Window, unused);
LIST_HEAD(Context, contexts);
@@ -110,7 +108,7 @@ static Window* window_unlink(Window *w) {
c->window = NULL;
}
return LIST_REMOVE(by_fd, w->fd->windows, w);
return LIST_REMOVE(windows, w->fd->windows, w);
}
static void window_invalidate(Window *w) {
@@ -132,37 +130,26 @@ static Window* window_free(Window *w) {
return NULL;
window_unlink(w);
w->cache->n_windows--;
w->fd->cache->n_windows--;
return mfree(w);
}
static bool window_matches(Window *w, uint64_t offset, size_t size) {
assert(w);
static bool window_matches(Window *w, MMapFileDescriptor *f, uint64_t offset, size_t size) {
assert(size > 0);
return
w &&
f == w->fd &&
offset >= w->offset &&
offset + size <= w->offset + w->size;
}
static bool window_matches_fd(Window *w, MMapFileDescriptor *f, uint64_t offset, size_t size) {
assert(w);
assert(f);
return
w->fd == f &&
window_matches(w, offset, size);
}
static Window *window_add(MMapCache *m, MMapFileDescriptor *f, bool keep_always, uint64_t offset, size_t size, void *ptr) {
static Window* window_add(MMapFileDescriptor *f, uint64_t offset, size_t size, void *ptr) {
MMapCache *m = mmap_cache_fd_cache(f);
Window *w;
assert(m);
assert(f);
if (!m->last_unused || m->n_windows <= WINDOWS_MIN) {
/* Allocate a new window */
w = new(Window, 1);
if (!w)
@@ -173,17 +160,13 @@ static Window *window_add(MMapCache *m, MMapFileDescriptor *f, bool keep_always,
w = window_unlink(m->last_unused);
*w = (Window) {
.cache = m,
.fd = f,
.keep_always = keep_always,
.offset = offset,
.size = size,
.ptr = ptr,
};
LIST_PREPEND(by_fd, f->windows, w);
return w;
return LIST_PREPEND(windows, f->windows, w);
}
static void context_detach_window(MMapCache *m, Context *c) {
@@ -254,123 +237,37 @@ static MMapCache* mmap_cache_free(MMapCache *m) {
DEFINE_TRIVIAL_REF_UNREF_FUNC(MMapCache, mmap_cache, mmap_cache_free);
static int make_room(MMapCache *m) {
assert(m);
static int mmap_try_harder(MMapFileDescriptor *f, void *addr, int flags, uint64_t offset, size_t size, void **ret) {
MMapCache *m = mmap_cache_fd_cache(f);
if (!m->last_unused)
return 0;
window_free(m->last_unused);
return 1;
}
static int try_context(
MMapFileDescriptor *f,
Context *c,
bool keep_always,
uint64_t offset,
size_t size,
void **ret) {
assert(f);
assert(f->cache);
assert(f->cache->n_ref > 0);
assert(c);
assert(size > 0);
assert(ret);
if (!c->window)
return 0;
if (!window_matches_fd(c->window, f, offset, size)) {
/* Drop the reference to the window, since it's unnecessary now */
context_detach_window(f->cache, c);
return 0;
}
if (c->window->fd->sigbus)
return -EIO;
c->window->keep_always = c->window->keep_always || keep_always;
*ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
f->cache->n_context_cache_hit++;
return 1;
}
static int find_mmap(
MMapFileDescriptor *f,
Context *c,
bool keep_always,
uint64_t offset,
size_t size,
void **ret) {
Window *found = NULL;
assert(f);
assert(f->cache);
assert(f->cache->n_ref > 0);
assert(c);
assert(size > 0);
if (f->sigbus)
return -EIO;
LIST_FOREACH(by_fd, w, f->windows)
if (window_matches(w, offset, size)) {
found = w;
break;
}
if (!found)
return 0;
context_attach_window(f->cache, c, found);
found->keep_always = found->keep_always || keep_always;
*ret = (uint8_t*) found->ptr + (offset - found->offset);
f->cache->n_window_list_hit++;
return 1;
}
static int mmap_try_harder(MMapFileDescriptor *f, void *addr, int flags, uint64_t offset, size_t size, void **res) {
void *ptr;
assert(f);
assert(res);
for (;;) {
int r;
void *ptr;
ptr = mmap(addr, size, f->prot, flags, f->fd, offset);
if (ptr != MAP_FAILED)
break;
if (ptr != MAP_FAILED) {
*ret = ptr;
return 0;
}
if (errno != ENOMEM)
return negative_errno();
r = make_room(f->cache);
if (r < 0)
return r;
if (r == 0)
return -ENOMEM;
}
/* When failed with ENOMEM, try again after making a room by freeing an unused window. */
*res = ptr;
return 0;
if (!m->last_unused)
return -ENOMEM; /* no free window, propagate the original error. */
window_free(m->last_unused);
}
}
static int add_mmap(
MMapFileDescriptor *f,
Context *c,
bool keep_always,
uint64_t offset,
size_t size,
struct stat *st,
void **ret) {
Window **ret) {
uint64_t woffset, wsize;
Window *w;
@@ -378,9 +275,6 @@ static int add_mmap(
int r;
assert(f);
assert(f->cache);
assert(f->cache->n_ref > 0);
assert(c);
assert(size > 0);
assert(ret);
@@ -416,19 +310,14 @@ static int add_mmap(
if (r < 0)
return r;
w = window_add(f->cache, f, keep_always, woffset, wsize, d);
if (!w)
goto outofmem;
w = window_add(f, woffset, wsize, d);
if (!w) {
(void) munmap(d, wsize);
return -ENOMEM;
}
context_attach_window(f->cache, c, w);
*ret = (uint8_t*) w->ptr + (offset - w->offset);
return 1;
outofmem:
(void) munmap(d, wsize);
return -ENOMEM;
*ret = w;
return 0;
}
int mmap_cache_fd_get(
@@ -440,32 +329,50 @@ int mmap_cache_fd_get(
struct stat *st,
void **ret) {
MMapCache *m = mmap_cache_fd_cache(f);
Context *c;
Window *w;
int r;
assert(f);
assert(f->cache);
assert(f->cache->n_ref > 0);
assert(context < MMAP_CACHE_MAX_CONTEXTS);
assert(size > 0);
assert(ret);
assert(context < MMAP_CACHE_MAX_CONTEXTS);
if (f->sigbus)
return -EIO;
c = &f->cache->contexts[context];
/* Check whether the current context is the right one already */
r = try_context(f, c, keep_always, offset, size, ret);
if (r != 0)
return r;
if (window_matches(c->window, f, offset, size)) {
m->n_context_cache_hit++;
w = c->window;
goto found;
}
/* Drop the reference to the window, since it's unnecessary now */
context_detach_window(m, c);
/* Search for a matching mmap */
r = find_mmap(f, c, keep_always, offset, size, ret);
if (r != 0)
return r;
LIST_FOREACH(windows, i, f->windows)
if (window_matches(i, f, offset, size)) {
m->n_window_list_hit++;
w = i;
goto found;
}
f->cache->n_missed++;
m->n_missed++;
/* Create a new mmap */
return add_mmap(f, c, keep_always, offset, size, st, ret);
r = add_mmap(f, offset, size, st, &w);
if (r < 0)
return r;
found:
w->keep_always = w->keep_always || keep_always;
context_attach_window(m, c, w);
*ret = (uint8_t*) w->ptr + (offset - w->offset);
return 0;
}
void mmap_cache_stats_log_debug(MMapCache *m) {
@@ -497,7 +404,7 @@ static void mmap_cache_process_sigbus(MMapCache *m) {
ours = false;
HASHMAP_FOREACH(f, m->fds) {
LIST_FOREACH(by_fd, w, f->windows) {
LIST_FOREACH(windows, w, f->windows) {
if ((uint8_t*) addr >= (uint8_t*) w->ptr &&
(uint8_t*) addr < (uint8_t*) w->ptr + w->size) {
found = ours = f->sigbus = true;
@@ -526,7 +433,7 @@ static void mmap_cache_process_sigbus(MMapCache *m) {
if (!f->sigbus)
continue;
LIST_FOREACH(by_fd, w, f->windows)
LIST_FOREACH(windows, w, f->windows)
window_invalidate(w);
}
}