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Diffstat (limited to 'source4/lib/tdb/common/freelist.c')
-rw-r--r--source4/lib/tdb/common/freelist.c85
1 files changed, 43 insertions, 42 deletions
diff --git a/source4/lib/tdb/common/freelist.c b/source4/lib/tdb/common/freelist.c
index c086c151fa..2f2a4c379b 100644
--- a/source4/lib/tdb/common/freelist.c
+++ b/source4/lib/tdb/common/freelist.c
@@ -208,62 +208,61 @@ update:
}
+
/*
the core of tdb_allocate - called when we have decided which
free list entry to use
+
+ Note that we try to allocate by grabbing data from the end of an existing record,
+ not the beginning. This is so the left merge in a free is more likely to be
+ able to free up the record without fragmentation
*/
-static tdb_off_t tdb_allocate_ofs(struct tdb_context *tdb, tdb_len_t length, tdb_off_t rec_ptr,
- struct list_struct *rec, tdb_off_t last_ptr)
+static tdb_off_t tdb_allocate_ofs(struct tdb_context *tdb,
+ tdb_len_t length, tdb_off_t rec_ptr,
+ struct list_struct *rec, tdb_off_t last_ptr)
{
- struct list_struct newrec;
- tdb_off_t newrec_ptr;
+#define MIN_REC_SIZE (sizeof(struct list_struct) + sizeof(tdb_off_t) + 8)
- memset(&newrec, '\0', sizeof(newrec));
+ if (rec->rec_len < length + MIN_REC_SIZE) {
+ /* we have to grab the whole record */
- /* found it - now possibly split it up */
- if (rec->rec_len > length + MIN_REC_SIZE) {
- /* Length of left piece */
- length = TDB_ALIGN(length, TDB_ALIGNMENT);
-
- /* Right piece to go on free list */
- newrec.rec_len = rec->rec_len - (sizeof(*rec) + length);
- newrec_ptr = rec_ptr + sizeof(*rec) + length;
-
- /* And left record is shortened */
- rec->rec_len = length;
- } else {
- newrec_ptr = 0;
+ /* unlink it from the previous record */
+ if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1) {
+ return 0;
+ }
+
+ /* mark it not free */
+ rec->magic = TDB_MAGIC;
+ if (tdb_rec_write(tdb, rec_ptr, rec) == -1) {
+ return 0;
+ }
+ return rec_ptr;
+ }
+
+ /* we're going to just shorten the existing record */
+ rec->rec_len -= (length + sizeof(*rec));
+ if (tdb_rec_write(tdb, rec_ptr, rec) == -1) {
+ return 0;
}
-
- /* Remove allocated record from the free list */
- if (tdb_ofs_write(tdb, last_ptr, &rec->next) == -1) {
+ if (update_tailer(tdb, rec_ptr, rec) == -1) {
return 0;
}
-
- /* Update header: do this before we drop alloc
- lock, otherwise tdb_free() might try to
- merge with us, thinking we're free.
- (Thanks Jeremy Allison). */
+
+ /* and setup the new record */
+ rec_ptr += sizeof(*rec) + rec->rec_len;
+
+ memset(rec, '\0', sizeof(*rec));
+ rec->rec_len = length;
rec->magic = TDB_MAGIC;
+
if (tdb_rec_write(tdb, rec_ptr, rec) == -1) {
return 0;
}
-
- /* Did we create new block? */
- if (newrec_ptr) {
- /* Update allocated record tailer (we
- shortened it). */
- if (update_tailer(tdb, rec_ptr, rec) == -1) {
- return 0;
- }
-
- /* Free new record */
- if (tdb_free(tdb, newrec_ptr, &newrec) == -1) {
- return 0;
- }
+
+ if (update_tailer(tdb, rec_ptr, rec) == -1) {
+ return 0;
}
-
- /* all done - return the new record offset */
+
return rec_ptr;
}
@@ -287,6 +286,7 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct list_st
/* Extra bytes required for tailer */
length += sizeof(tdb_off_t);
+ length = TDB_ALIGN(length, TDB_ALIGNMENT);
again:
last_ptr = FREELIST_TOP;
@@ -343,7 +343,8 @@ tdb_off_t tdb_allocate(struct tdb_context *tdb, tdb_len_t length, struct list_st
goto fail;
}
- newrec_ptr = tdb_allocate_ofs(tdb, length, bestfit.rec_ptr, rec, bestfit.last_ptr);
+ newrec_ptr = tdb_allocate_ofs(tdb, length, bestfit.rec_ptr,
+ rec, bestfit.last_ptr);
tdb_unlock(tdb, -1, F_WRLCK);
return newrec_ptr;
}