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mmap-cache: bind prot(ection) to MMapFileDescriptor 

There are no mmap_cache_get() users that actually deviate prot
from the JournalFile's f->prot.

So there's no point in making this a separate parameter to
mmap_cache_get(), nor is there any need to store it in
JournalFile's f->prot.

Instead just pass it to mmap_cache_add_fd() at MMapFileDescriptor
creation, storing it in there for the mmap() callers, which
already receive MMapFileDescriptor *.

For functions receiving both an MMapFileDescriptor * and prot,
the prot argument has been simply removed and call sites updated.

Formalizing this fd:prot binding at the public API also enables
discarding the prot check in window_matches(), which is a hot
function on long window lists, so a minor CPU efficiency gain
should be had there as seen with the past removal of the fd
check.  Unnoticable for uncached journals, but maybe a little
runtime improvement when cached in specific circumstances.

window_matches_fd() has also been simplified to treat the
MMapFileDescrptor * as equivalent to its fd and prot.
This commit is contained in:
Vito Caputo 2020-12-02 22:11:23 -08:00 committed by Lennart Poettering
parent cca2da15c8
commit 104fc4be11
6 changed files with 33 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
src/journal/journal-file.c
View File

@ -751,7 +751,7 @@ static int journal_file_move_to(
return -EADDRNOTAVAIL;
}
return mmap_cache_get(f->mmap, f->cache_fd, f->prot, type_to_context(type), keep_always, offset, size, &f->last_stat, ret, ret_size);
return mmap_cache_get(f->mmap, f->cache_fd, type_to_context(type), keep_always, offset, size, &f->last_stat, ret, ret_size);
}
static uint64_t minimum_header_size(Object *o) {
@ -3365,7 +3365,6 @@ int journal_file_open(
.mode = mode,
.flags = flags,
.prot = prot_from_flags(flags),
.writable = (flags & O_ACCMODE) != O_RDONLY,
#if HAVE_ZSTD
@ -3464,7 +3463,7 @@ int journal_file_open(
goto fail;
}
f->cache_fd = mmap_cache_add_fd(f->mmap, f->fd);
f->cache_fd = mmap_cache_add_fd(f->mmap, f->fd, prot_from_flags(flags));
if (!f->cache_fd) {
r = -ENOMEM;
goto fail;
@ -3511,7 +3510,7 @@ int journal_file_open(
goto fail;
}
r = mmap_cache_get(f->mmap, f->cache_fd, f->prot, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h, NULL);
r = mmap_cache_get(f->mmap, f->cache_fd, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h, NULL);
if (r == -EINVAL) {
/* Some file systems (jffs2 or p9fs) don't support mmap() properly (or only read-only
* mmap()), and return EINVAL in that case. Let's propagate that as a more recognizable error

1
src/journal/journal-file.h
View File

@ -63,7 +63,6 @@ typedef struct JournalFile {
mode_t mode;
int flags;
int prot;
bool writable:1;
bool compress_xz:1;
bool compress_lz4:1;

8
src/journal/journal-verify.c
View File

@ -377,7 +377,7 @@ static int contains_uint64(MMapCache *m, MMapFileDescriptor *f, uint64_t n, uint
c = (a + b) / 2;
r = mmap_cache_get(m, f, PROT_READ|PROT_WRITE, 0, false, c * sizeof(uint64_t), sizeof(uint64_t), NULL, (void **) &z, NULL);
r = mmap_cache_get(m, f, 0, false, c * sizeof(uint64_t), sizeof(uint64_t), NULL, (void **) &z, NULL);
if (r < 0)
return r;
@ -862,19 +862,19 @@ int journal_file_verify(
goto fail;
}
cache_data_fd = mmap_cache_add_fd(f->mmap, data_fd);
cache_data_fd = mmap_cache_add_fd(f->mmap, data_fd, PROT_READ|PROT_WRITE);
if (!cache_data_fd) {
r = log_oom();
goto fail;
}
cache_entry_fd = mmap_cache_add_fd(f->mmap, entry_fd);
cache_entry_fd = mmap_cache_add_fd(f->mmap, entry_fd, PROT_READ|PROT_WRITE);
if (!cache_entry_fd) {
r = log_oom();
goto fail;
}
cache_entry_array_fd = mmap_cache_add_fd(f->mmap, entry_array_fd);
cache_entry_array_fd = mmap_cache_add_fd(f->mmap, entry_array_fd, PROT_READ|PROT_WRITE);
if (!cache_entry_array_fd) {
r = log_oom();
goto fail;

43
src/journal/mmap-cache.c
View File

@ -25,7 +25,6 @@ struct Window {
bool keep_always:1;
bool in_unused:1;
int prot;
void *ptr;
uint64_t offset;
size_t size;
@ -49,6 +48,7 @@ struct Context {
struct MMapFileDescriptor {
MMapCache *cache;
int fd;
int prot;
bool sigbus;
LIST_HEAD(Window, windows);
};
@ -112,6 +112,7 @@ static void window_unlink(Window *w) {
static void window_invalidate(Window *w) {
assert(w);
assert(w->fd);
if (w->invalidated)
return;
@ -121,7 +122,7 @@ static void window_invalidate(Window *w) {
* trigger any further SIGBUS, possibly overrunning the sigbus
* queue. */
assert_se(mmap(w->ptr, w->size, w->prot, MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0) == w->ptr);
assert_se(mmap(w->ptr, w->size, w->fd->prot, MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0) == w->ptr);
w->invalidated = true;
}
@ -133,27 +134,25 @@ static void window_free(Window *w) {
free(w);
}
_pure_ static bool window_matches(Window *w, int prot, uint64_t offset, size_t size) {
_pure_ static bool window_matches(Window *w, uint64_t offset, size_t size) {
assert(w);
assert(size > 0);
return
prot == w->prot &&
offset >= w->offset &&
offset + size <= w->offset + w->size;
}
_pure_ static bool window_matches_fd(Window *w, MMapFileDescriptor *f, int prot, uint64_t offset, size_t size) {
_pure_ static bool window_matches_fd(Window *w, MMapFileDescriptor *f, uint64_t offset, size_t size) {
assert(w);
assert(f);
return
w->fd &&
f->fd == w->fd->fd &&
window_matches(w, prot, offset, size);
w->fd == f &&
window_matches(w, offset, size);
}
static Window *window_add(MMapCache *m, MMapFileDescriptor *f, int prot, bool keep_always, uint64_t offset, size_t size, void *ptr) {
static Window *window_add(MMapCache *m, MMapFileDescriptor *f, bool keep_always, uint64_t offset, size_t size, void *ptr) {
Window *w;
assert(m);
@ -176,7 +175,6 @@ static Window *window_add(MMapCache *m, MMapFileDescriptor *f, int prot, bool ke
*w = (Window) {
.cache = m,
.fd = f,
.prot = prot,
.keep_always = keep_always,
.offset = offset,
.size = size,
@ -304,7 +302,6 @@ static int make_room(MMapCache *m) {
static int try_context(
MMapCache *m,
MMapFileDescriptor *f,
int prot,
unsigned context,
bool keep_always,
uint64_t offset,
@ -329,7 +326,7 @@ static int try_context(
if (!c->window)
return 0;
if (!window_matches_fd(c->window, f, prot, offset, size)) {
if (!window_matches_fd(c->window, f, offset, size)) {
/* Drop the reference to the window, since it's unnecessary now */
context_detach_window(c);
@ -351,7 +348,6 @@ static int try_context(
static int find_mmap(
MMapCache *m,
MMapFileDescriptor *f,
int prot,
unsigned context,
bool keep_always,
uint64_t offset,
@ -371,7 +367,7 @@ static int find_mmap(
return -EIO;
LIST_FOREACH(by_fd, w, f->windows)
if (window_matches(w, prot, offset, size))
if (window_matches(w, offset, size))
break;
if (!w)
@ -391,7 +387,7 @@ static int find_mmap(
return 1;
}
static int mmap_try_harder(MMapCache *m, void *addr, MMapFileDescriptor *f, int prot, int flags, uint64_t offset, size_t size, void **res) {
static int mmap_try_harder(MMapCache *m, void *addr, MMapFileDescriptor *f, int flags, uint64_t offset, size_t size, void **res) {
void *ptr;
assert(m);
@ -401,7 +397,7 @@ static int mmap_try_harder(MMapCache *m, void *addr, MMapFileDescriptor *f, int
for (;;) {
int r;
ptr = mmap(addr, size, prot, flags, f->fd, offset);
ptr = mmap(addr, size, f->prot, flags, f->fd, offset);
if (ptr != MAP_FAILED)
break;
if (errno != ENOMEM)
@ -421,7 +417,6 @@ static int mmap_try_harder(MMapCache *m, void *addr, MMapFileDescriptor *f, int
static int add_mmap(
MMapCache *m,
MMapFileDescriptor *f,
int prot,
unsigned context,
bool keep_always,
uint64_t offset,
@ -471,7 +466,7 @@ static int add_mmap(
wsize = PAGE_ALIGN(st->st_size - woffset);
}
r = mmap_try_harder(m, NULL, f, prot, MAP_SHARED, woffset, wsize, &d);
r = mmap_try_harder(m, NULL, f, MAP_SHARED, woffset, wsize, &d);
if (r < 0)
return r;
@ -479,7 +474,7 @@ static int add_mmap(
if (!c)
goto outofmem;
w = window_add(m, f, prot, keep_always, woffset, wsize, d);
w = window_add(m, f, keep_always, woffset, wsize, d);
if (!w)
goto outofmem;
@ -499,7 +494,6 @@ outofmem:
int mmap_cache_get(
MMapCache *m,
MMapFileDescriptor *f,
int prot,
unsigned context,
bool keep_always,
uint64_t offset,
@ -518,14 +512,14 @@ int mmap_cache_get(
assert(context < MMAP_CACHE_MAX_CONTEXTS);
/* Check whether the current context is the right one already */
r = try_context(m, f, prot, context, keep_always, offset, size, ret, ret_size);
r = try_context(m, f, context, keep_always, offset, size, ret, ret_size);
if (r != 0) {
m->n_context_cache_hit++;
return r;
}
/* Search for a matching mmap */
r = find_mmap(m, f, prot, context, keep_always, offset, size, ret, ret_size);
r = find_mmap(m, f, context, keep_always, offset, size, ret, ret_size);
if (r != 0) {
m->n_window_list_hit++;
return r;
@ -534,7 +528,7 @@ int mmap_cache_get(
m->n_missed++;
/* Create a new mmap */
return add_mmap(m, f, prot, context, keep_always, offset, size, st, ret, ret_size);
return add_mmap(m, f, context, keep_always, offset, size, st, ret, ret_size);
}
void mmap_cache_stats_log_debug(MMapCache *m) {
@ -614,7 +608,7 @@ bool mmap_cache_got_sigbus(MMapCache *m, MMapFileDescriptor *f) {
return f->sigbus;
}
MMapFileDescriptor* mmap_cache_add_fd(MMapCache *m, int fd) {
MMapFileDescriptor* mmap_cache_add_fd(MMapCache *m, int fd, int prot) {
MMapFileDescriptor *f;
int r;
@ -635,6 +629,7 @@ MMapFileDescriptor* mmap_cache_add_fd(MMapCache *m, int fd) {
f->cache = m;
f->fd = fd;
f->prot = prot;
r = hashmap_put(m->fds, FD_TO_PTR(fd), f);
if (r < 0)

3
src/journal/mmap-cache.h
View File

@ -17,7 +17,6 @@ MMapCache* mmap_cache_unref(MMapCache *m);
int mmap_cache_get(
MMapCache *m,
MMapFileDescriptor *f,
int prot,
unsigned context,
bool keep_always,
uint64_t offset,
@ -25,7 +24,7 @@ int mmap_cache_get(
struct stat *st,
void **ret,
size_t *ret_size);
MMapFileDescriptor * mmap_cache_add_fd(MMapCache *m, int fd);
MMapFileDescriptor * mmap_cache_add_fd(MMapCache *m, int fd, int prot);
void mmap_cache_free_fd(MMapCache *m, MMapFileDescriptor *f);
void mmap_cache_stats_log_debug(MMapCache *m);

12
src/journal/test-mmap-cache.c
View File

@ -24,7 +24,7 @@ int main(int argc, char *argv[]) {
assert_se(x >= 0);
unlink(px);
assert_se(fx = mmap_cache_add_fd(m, x));
assert_se(fx = mmap_cache_add_fd(m, x, PROT_READ));
y = mkostemp_safe(py);
assert_se(y >= 0);
@ -34,23 +34,23 @@ int main(int argc, char *argv[]) {
assert_se(z >= 0);
unlink(pz);
r = mmap_cache_get(m, fx, PROT_READ, 0, false, 1, 2, NULL, &p, NULL);
r = mmap_cache_get(m, fx, 0, false, 1, 2, NULL, &p, NULL);
assert_se(r >= 0);
r = mmap_cache_get(m, fx, PROT_READ, 0, false, 2, 2, NULL, &q, NULL);
r = mmap_cache_get(m, fx, 0, false, 2, 2, NULL, &q, NULL);
assert_se(r >= 0);
assert_se((uint8_t*) p + 1 == (uint8_t*) q);
r = mmap_cache_get(m, fx, PROT_READ, 1, false, 3, 2, NULL, &q, NULL);
r = mmap_cache_get(m, fx, 1, false, 3, 2, NULL, &q, NULL);
assert_se(r >= 0);
assert_se((uint8_t*) p + 2 == (uint8_t*) q);
r = mmap_cache_get(m, fx, PROT_READ, 0, false, 16ULL*1024ULL*1024ULL, 2, NULL, &p, NULL);
r = mmap_cache_get(m, fx, 0, false, 16ULL*1024ULL*1024ULL, 2, NULL, &p, NULL);
assert_se(r >= 0);
r = mmap_cache_get(m, fx, PROT_READ, 1, false, 16ULL*1024ULL*1024ULL+1, 2, NULL, &q, NULL);
r = mmap_cache_get(m, fx, 1, false, 16ULL*1024ULL*1024ULL+1, 2, NULL, &q, NULL);
assert_se(r >= 0);
assert_se((uint8_t*) p + 1 == (uint8_t*) q);