diff options
Diffstat (limited to 'vm/vm_object.c')
| -rw-r--r-- | vm/vm_object.c | 53 |
1 files changed, 40 insertions, 13 deletions
diff --git a/vm/vm_object.c b/vm/vm_object.c index e01c1856..c238cce4 100644 --- a/vm/vm_object.c +++ b/vm/vm_object.c @@ -2687,15 +2687,16 @@ void vm_object_page_remove( /* * Routine: vm_object_coalesce - * Function: Coalesces two objects backing up adjoining - * regions of memory into a single object. - * - * returns TRUE if objects were combined. - * - * NOTE: Only works at the moment if one of the objects is NULL - * or if the objects are the same - otherwise, which - * object do we lock first? - * + * Purpose: + * Tries to coalesce two objects backing up adjoining + * regions of memory into a single object. + * + * NOTE: Only works at the moment if one of the objects + * is NULL or if the objects are the same - otherwise, + * which object do we lock first? + * Returns: + * TRUE if objects have been coalesced. + * FALSE the objects could not be coalesced. * Parameters: * prev_object First object to coalesce * prev_offset Offset into prev_object @@ -2705,8 +2706,14 @@ void vm_object_page_remove( * prev_size Size of reference to prev_object * next_size Size of reference to next_object * + * new_object Resulting colesced object + * new_offset Offset into the resulting object * Conditions: - * The object must *not* be locked. + * The objects must *not* be locked. + * + * If the objects are coalesced successfully, the caller's + * references for both objects are consumed, and the caller + * gains a reference for the new object. */ boolean_t vm_object_coalesce( @@ -2715,7 +2722,9 @@ boolean_t vm_object_coalesce( vm_offset_t prev_offset, vm_offset_t next_offset, vm_size_t prev_size, - vm_size_t next_size) + vm_size_t next_size, + vm_object_t *new_object, /* OUT */ + vm_offset_t *new_offset) /* OUT */ { vm_object_t object; vm_size_t newsize; @@ -2725,10 +2734,23 @@ boolean_t vm_object_coalesce( * If neither object actually exists, * the offsets don't matter. */ - if (prev_object == VM_OBJECT_NULL) + if (prev_object == VM_OBJECT_NULL) { + *new_object = VM_OBJECT_NULL; + *new_offset = 0; return TRUE; + } - return prev_offset + prev_size == next_offset; + if (prev_offset + prev_size == next_offset) { + *new_object = prev_object; + *new_offset = prev_offset; + /* + * Deallocate one of the two references. + */ + vm_object_deallocate(prev_object); + return TRUE; + } + + return FALSE; } if (next_object != VM_OBJECT_NULL) { @@ -2785,6 +2807,8 @@ boolean_t vm_object_coalesce( newsize = prev_offset + prev_size + next_size; if (newsize > object->size) object->size = newsize; + + *new_offset = prev_offset; } else { /* * Check if we have enough space in the object @@ -2802,9 +2826,12 @@ boolean_t vm_object_coalesce( vm_object_page_remove(object, next_offset - prev_size, next_offset); + + *new_offset = next_offset - prev_size; } vm_object_unlock(object); + *new_object = object; return TRUE; } |