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authorRusty Russell <rusty@rustcorp.com.au>2012-06-22 09:44:40 +0930
committerRusty Russell <rusty@rustcorp.com.au>2012-06-22 07:35:17 +0200
commit0a34f342c3facace0767ff08f05532c9f161e305 (patch)
treec227f755f1933e797ac49f74a856c8d60b11539d
parent66d151d6893657b31c419d422bffeefc506e2319 (diff)
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ntdb: enhancement to allow direct access to the ntdb map during expansion.
This means keeping the old mmap around when we expand the database. We could revert to read/write, except for platforms with incoherent mmap (ie. OpenBSD), where we need to use mmap for all accesses. Thus we keep a linked list of old maps, and unmap them when the last access finally goes away. This is required if we want ntdb_parse_record() callbacks to be able to expand the database. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--lib/ntdb/free.c3
-rw-r--r--lib/ntdb/io.c80
-rw-r--r--lib/ntdb/ntdb.c10
-rw-r--r--lib/ntdb/open.c7
-rw-r--r--lib/ntdb/private.h19
5 files changed, 86 insertions, 33 deletions
diff --git a/lib/ntdb/free.c b/lib/ntdb/free.c
index 971436f5a3..470c3765d9 100644
--- a/lib/ntdb/free.c
+++ b/lib/ntdb/free.c
@@ -958,9 +958,6 @@ ntdb_off_t alloc(struct ntdb_context *ntdb, size_t keylen, size_t datalen,
{
ntdb_off_t off;
- /* We can't hold pointers during this: we could unmap! */
- assert(!ntdb->direct_access);
-
for (;;) {
enum NTDB_ERROR ecode;
off = get_free(ntdb, keylen, datalen, growing, magic);
diff --git a/lib/ntdb/io.c b/lib/ntdb/io.c
index a54f1a661c..6749d282d9 100644
--- a/lib/ntdb/io.c
+++ b/lib/ntdb/io.c
@@ -28,17 +28,48 @@
#include "private.h"
#include <ccan/likely/likely.h>
-void ntdb_munmap(struct ntdb_file *file)
+static void free_old_mmaps(struct ntdb_context *ntdb)
{
- if (file->fd == -1)
- return;
+ struct ntdb_old_mmap *i;
- if (file->map_ptr) {
- munmap(file->map_ptr, file->map_size);
- file->map_ptr = NULL;
+ assert(ntdb->file->direct_count == 0);
+
+ while ((i = ntdb->file->old_mmaps) != NULL) {
+ ntdb->file->old_mmaps = i->next;
+ munmap(i->map_ptr, i->map_size);
+ ntdb->free_fn(i, ntdb->alloc_data);
}
}
+enum NTDB_ERROR ntdb_munmap(struct ntdb_context *ntdb)
+{
+ if (ntdb->file->fd == -1) {
+ return NTDB_SUCCESS;
+ }
+
+ if (!ntdb->file->map_ptr) {
+ return NTDB_SUCCESS;
+ }
+
+ /* We can't unmap now if there are accessors. */
+ if (ntdb->file->direct_count) {
+ struct ntdb_old_mmap *old
+ = ntdb->alloc_fn(ntdb, sizeof(*old), ntdb->alloc_data);
+ if (!old) {
+ return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
+ "ntdb_munmap alloc failed");
+ }
+ old->next = ntdb->file->old_mmaps;
+ old->map_ptr = ntdb->file->map_ptr;
+ old->map_size = ntdb->file->map_size;
+ ntdb->file->old_mmaps = old;
+ } else {
+ munmap(ntdb->file->map_ptr, ntdb->file->map_size);
+ ntdb->file->map_ptr = NULL;
+ }
+ return NTDB_SUCCESS;
+}
+
enum NTDB_ERROR ntdb_mmap(struct ntdb_context *ntdb)
{
int mmap_flags;
@@ -98,11 +129,6 @@ static enum NTDB_ERROR ntdb_normal_oob(struct ntdb_context *ntdb,
struct stat st;
enum NTDB_ERROR ecode;
- /* We can't hold pointers during this: we could unmap! */
- assert(!ntdb->direct_access
- || (ntdb->flags & NTDB_NOLOCK)
- || ntdb_has_expansion_lock(ntdb));
-
if (len + off < len) {
if (probe)
return NTDB_SUCCESS;
@@ -149,7 +175,10 @@ static enum NTDB_ERROR ntdb_normal_oob(struct ntdb_context *ntdb,
}
/* Unmap, update size, remap */
- ntdb_munmap(ntdb->file);
+ ecode = ntdb_munmap(ntdb);
+ if (ecode) {
+ return ecode;
+ }
ntdb->file->map_size = st.st_size;
return ntdb_mmap(ntdb);
@@ -418,7 +447,10 @@ static enum NTDB_ERROR ntdb_expand_file(struct ntdb_context *ntdb,
} else {
/* Unmap before trying to write; old NTDB claimed OpenBSD had
* problem with this otherwise. */
- ntdb_munmap(ntdb->file);
+ ecode = ntdb_munmap(ntdb);
+ if (ecode) {
+ return ecode;
+ }
/* If this fails, we try to fill anyway. */
if (ftruncate(ntdb->file->fd, ntdb->file->map_size + addition))
@@ -461,8 +493,9 @@ const void *ntdb_access_read(struct ntdb_context *ntdb,
if (convert) {
ntdb_convert(ntdb, (void *)ret, len);
}
- } else
- ntdb->direct_access++;
+ } else {
+ ntdb->file->direct_count++;
+ }
return ret;
}
@@ -500,9 +533,9 @@ void *ntdb_access_write(struct ntdb_context *ntdb,
ret = hdr + 1;
if (convert)
ntdb_convert(ntdb, (void *)ret, len);
- } else
- ntdb->direct_access++;
-
+ } else {
+ ntdb->file->direct_count++;
+ }
return ret;
}
@@ -525,8 +558,11 @@ void ntdb_access_release(struct ntdb_context *ntdb, const void *p)
hdr = *hp;
*hp = hdr->next;
ntdb->free_fn(hdr, ntdb->alloc_data);
- } else
- ntdb->direct_access--;
+ } else {
+ if (--ntdb->file->direct_count == 0) {
+ free_old_mmaps(ntdb);
+ }
+ }
}
enum NTDB_ERROR ntdb_access_commit(struct ntdb_context *ntdb, void *p)
@@ -543,7 +579,9 @@ enum NTDB_ERROR ntdb_access_commit(struct ntdb_context *ntdb, void *p)
*hp = hdr->next;
ntdb->free_fn(hdr, ntdb->alloc_data);
} else {
- ntdb->direct_access--;
+ if (--ntdb->file->direct_count == 0) {
+ free_old_mmaps(ntdb);
+ }
ecode = NTDB_SUCCESS;
}
diff --git a/lib/ntdb/ntdb.c b/lib/ntdb/ntdb.c
index ddbf7d6e9e..6c75915899 100644
--- a/lib/ntdb/ntdb.c
+++ b/lib/ntdb/ntdb.c
@@ -234,7 +234,7 @@ out:
}
_PUBLIC_ enum NTDB_ERROR ntdb_fetch(struct ntdb_context *ntdb, NTDB_DATA key,
- NTDB_DATA *data)
+ NTDB_DATA *data)
{
ntdb_off_t off;
struct ntdb_used_record rec;
@@ -353,9 +353,15 @@ _PUBLIC_ void ntdb_add_flag(struct ntdb_context *ntdb, unsigned flag)
ntdb->flags |= NTDB_NOLOCK;
break;
case NTDB_NOMMAP:
+ if (ntdb->file->direct_count) {
+ ntdb_logerr(ntdb, NTDB_ERR_EINVAL, NTDB_LOG_USE_ERROR,
+ "ntdb_add_flag: Can't get NTDB_NOMMAP from"
+ " ntdb_parse_record!");
+ return;
+ }
ntdb->flags |= NTDB_NOMMAP;
#ifndef HAVE_INCOHERENT_MMAP
- ntdb_munmap(ntdb->file);
+ ntdb_munmap(ntdb);
#endif
break;
case NTDB_NOSYNC:
diff --git a/lib/ntdb/open.c b/lib/ntdb/open.c
index 56c97afe43..abec117236 100644
--- a/lib/ntdb/open.c
+++ b/lib/ntdb/open.c
@@ -99,7 +99,6 @@ static void ntdb_context_init(struct ntdb_context *ntdb)
{
/* Initialize the NTDB fields here */
ntdb_io_init(ntdb);
- ntdb->direct_access = 0;
ntdb->transaction = NULL;
ntdb->access = NULL;
}
@@ -259,6 +258,8 @@ static enum NTDB_ERROR ntdb_new_file(struct ntdb_context *ntdb)
ntdb->file->allrecord_lock.count = 0;
ntdb->file->refcnt = 1;
ntdb->file->map_ptr = NULL;
+ ntdb->file->direct_count = 0;
+ ntdb->file->old_mmaps = NULL;
return NTDB_SUCCESS;
}
@@ -841,7 +842,7 @@ fail_errno:
ntdb->free_fn(ntdb->file->map_ptr,
ntdb->alloc_data);
} else
- ntdb_munmap(ntdb->file);
+ ntdb_munmap(ntdb);
}
if (ntdb->file->fd != -1 && close(ntdb->file->fd) != 0)
ntdb_logerr(ntdb, NTDB_ERR_IO, NTDB_LOG_ERROR,
@@ -875,7 +876,7 @@ _PUBLIC_ int ntdb_close(struct ntdb_context *ntdb)
ntdb->free_fn(ntdb->file->map_ptr,
ntdb->alloc_data);
} else {
- ntdb_munmap(ntdb->file);
+ ntdb_munmap(ntdb);
}
}
ret = close(ntdb->file->fd);
diff --git a/lib/ntdb/private.h b/lib/ntdb/private.h
index 90b782d303..5efd2e0d92 100644
--- a/lib/ntdb/private.h
+++ b/lib/ntdb/private.h
@@ -301,6 +301,14 @@ struct ntdb_access_hdr {
bool convert;
};
+/* mmaps we are keeping around because they are still direct accessed */
+struct ntdb_old_mmap {
+ struct ntdb_old_mmap *next;
+
+ void *map_ptr;
+ ntdb_len_t map_size;
+};
+
struct ntdb_file {
/* How many are sharing us? */
unsigned int refcnt;
@@ -314,6 +322,12 @@ struct ntdb_file {
/* The file descriptor (-1 for NTDB_INTERNAL). */
int fd;
+ /* How many are accessing directly? */
+ unsigned int direct_count;
+
+ /* Old maps, still direct accessed. */
+ struct ntdb_old_mmap *old_mmaps;
+
/* Lock information */
pid_t locker;
struct ntdb_lock allrecord_lock;
@@ -429,7 +443,7 @@ void ntdb_io_init(struct ntdb_context *ntdb);
void *ntdb_convert(const struct ntdb_context *ntdb, void *buf, ntdb_len_t size);
/* Unmap and try to map the ntdb. */
-void ntdb_munmap(struct ntdb_file *file);
+enum NTDB_ERROR ntdb_munmap(struct ntdb_context *ntdb);
enum NTDB_ERROR ntdb_mmap(struct ntdb_context *ntdb);
/* Either alloc a copy, or give direct access. Release frees or noop. */
@@ -576,9 +590,6 @@ struct ntdb_context {
enum NTDB_ERROR (*openhook)(int fd, void *data);
void *openhook_data;
- /* Are we accessing directly? (debugging check). */
- int direct_access;
-
/* Set if we are in a transaction. */
struct ntdb_transaction *transaction;