journal: return mapped size from mmap_cache_get()

If requested, return the actual mapping size to the caller in
addition to the address.

journal_file_move_to_object() often performs two successive
mmap_cache_get() calls via journal_file_move_to(); one to get the
object header, then another to get the entire object when it's
larger than the header's size.

If mmap_cache_get() returned the actual mapping's size, it's
probable that the second mmap_cache_get() could be skipped when
the established mapping already encompassed the desired size.

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 4ff38de2e6a9a94d386fee007593bf93c9468ae1..05cbf08a35aeaba6320a51ffdde07604e8377653 100644 (file)
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -749,7 +749,7 @@ static int journal_file_move_to(JournalFile *f, ObjectType type, bool keep_alway
                         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);
+        return mmap_cache_get(f->mmap, f->cache_fd, f->prot, type_to_context(type), keep_always, offset, size, &f->last_stat, ret, NULL);
 }
 
 static uint64_t minimum_header_size(Object *o) {
@@ -991,7 +991,7 @@ int journal_file_map_data_hash_table(JournalFile *f) {
                                  OBJECT_DATA_HASH_TABLE,
                                  true,
                                  p, s,
-                                 &t);
+                                 &t, NULL);
         if (r < 0)
                 return r;
 
@@ -1017,7 +1017,7 @@ int journal_file_map_field_hash_table(JournalFile *f) {
                                  OBJECT_FIELD_HASH_TABLE,
                                  true,
                                  p, s,
-                                 &t);
+                                 &t, NULL);
         if (r < 0)
                 return r;
 
@@ -3196,7 +3196,7 @@ 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);
+        r = mmap_cache_get(f->mmap, f->cache_fd, f->prot, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h, NULL);
         if (r < 0)
                 goto fail;
 

diff --git a/src/journal/journal-verify.c b/src/journal/journal-verify.c
index 9feb5b5ae6974d5cddee030f7082176d3ce42dd9..3f4c38ccde1bc3b4e1d6986ca6b4b846371e008c 100644 (file)
--- a/src/journal/journal-verify.c
+++ b/src/journal/journal-verify.c
@@ -392,7 +392,7 @@ 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);
+                r = mmap_cache_get(m, f, PROT_READ|PROT_WRITE, 0, false, c * sizeof(uint64_t), sizeof(uint64_t), NULL, (void **) &z, NULL);
                 if (r < 0)
                         return r;
 

diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
index 5dfda73c56a7d7d7f3503c23c31631e7eea3f1e0..546710cdc9f16e98c4fe97cf802a47e4ec884544 100644 (file)
--- a/src/journal/mmap-cache.c
+++ b/src/journal/mmap-cache.c
@@ -338,7 +338,8 @@ static int try_context(
                 bool keep_always,
                 uint64_t offset,
                 size_t size,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         Context *c;
 
@@ -370,6 +371,9 @@ static int try_context(
         c->window->keep_always = c->window->keep_always || keep_always;
 
         *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+        if (ret_size)
+                *ret_size = c->window->size - (offset - c->window->offset);
+
         return 1;
 }
 
@@ -381,7 +385,8 @@ static int find_mmap(
                 bool keep_always,
                 uint64_t offset,
                 size_t size,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         Window *w;
         Context *c;
@@ -409,6 +414,9 @@ static int find_mmap(
         w->keep_always = w->keep_always || keep_always;
 
         *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (ret_size)
+                *ret_size = w->size - (offset - w->offset);
+
         return 1;
 }
 
@@ -448,7 +456,8 @@ static int add_mmap(
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         uint64_t woffset, wsize;
         Context *c;
@@ -508,6 +517,9 @@ static int add_mmap(
         LIST_PREPEND(by_window, w->contexts, c);
 
         *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (ret_size)
+                *ret_size = w->size - (offset - w->offset);
+
         return 1;
 
 outofmem:
@@ -524,7 +536,8 @@ int mmap_cache_get(
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         int r;
 
@@ -536,14 +549,14 @@ 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);
+        r = try_context(m, f, prot, context, keep_always, offset, size, ret, ret_size);
         if (r != 0) {
                 m->n_hit++;
                 return r;
         }
 
         /* Search for a matching mmap */
-        r = find_mmap(m, f, prot, context, keep_always, offset, size, ret);
+        r = find_mmap(m, f, prot, context, keep_always, offset, size, ret, ret_size);
         if (r != 0) {
                 m->n_hit++;
                 return r;
@@ -552,7 +565,7 @@ int mmap_cache_get(
         m->n_missed++;
 
         /* Create a new mmap */
-        return add_mmap(m, f, prot, context, keep_always, offset, size, st, ret);
+        return add_mmap(m, f, prot, context, keep_always, offset, size, st, ret, ret_size);
 }
 
 unsigned mmap_cache_get_hit(MMapCache *m) {

diff --git a/src/journal/mmap-cache.h b/src/journal/mmap-cache.h
index 7b332185636c401418cc8f43b872479828020ecf..cf6af1906a8f960023cd246424fdb637b9ae2a6c 100644 (file)
--- a/src/journal/mmap-cache.h
+++ b/src/journal/mmap-cache.h
@@ -41,7 +41,8 @@ int mmap_cache_get(
         uint64_t offset,
         size_t size,
         struct stat *st,
-        void **ret);
+        void **ret,
+        size_t *ret_size);
 MMapFileDescriptor * mmap_cache_add_fd(MMapCache *m, int fd);
 void mmap_cache_free_fd(MMapCache *m, MMapFileDescriptor *f);
 

diff --git a/src/journal/test-mmap-cache.c b/src/journal/test-mmap-cache.c
index c51b069f8bd200eb90703c0d2c6ad1d4908e528c..702434efd239445bcc1da35beca301d725513eab 100644 (file)
--- a/src/journal/test-mmap-cache.c
+++ b/src/journal/test-mmap-cache.c
@@ -51,23 +51,23 @@ 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);
+        r = mmap_cache_get(m, fx, PROT_READ, 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);
+        r = mmap_cache_get(m, fx, PROT_READ, 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);
+        r = mmap_cache_get(m, fx, PROT_READ, 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);
+        r = mmap_cache_get(m, fx, PROT_READ, 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);
+        r = mmap_cache_get(m, fx, PROT_READ, 1, false, 16ULL*1024ULL*1024ULL+1, 2, NULL, &q, NULL);
         assert_se(r >= 0);
 
         assert_se((uint8_t*) p + 1 == (uint8_t*) q);