svn commit: r250793 - user/attilio/vmobj-readlock/sys/vm
Attilio Rao
attilio at FreeBSD.org
Sat May 18 23:49:46 UTC 2013
Author: attilio
Date: Sat May 18 23:49:45 2013
New Revision: 250793
URL: http://svnweb.freebsd.org/changeset/base/250793
Log:
Per-object swp_bcount can be protected by both per-object lock held in
write mode or per-object lock held in read mode and swhash_mtx held
at the same time.
Sponsored by: EMC / Isilon storage division
Discussed with: alc
Modified:
user/attilio/vmobj-readlock/sys/vm/swap_pager.c
Modified: user/attilio/vmobj-readlock/sys/vm/swap_pager.c
==============================================================================
--- user/attilio/vmobj-readlock/sys/vm/swap_pager.c Sat May 18 23:36:21 2013 (r250792)
+++ user/attilio/vmobj-readlock/sys/vm/swap_pager.c Sat May 18 23:49:45 2013 (r250793)
@@ -128,6 +128,21 @@ __FBSDID("$FreeBSD$");
#endif
/*
+ * Per-object swp_bcount must be protected by a write lock on the object
+ * itself or a read lock in combination with swhash_mtx held at the same time.
+ */
+#ifdef INVARIANTS
+#define VM_OBJECT_BCOUNT_ASSERT_LOCKED(object) do { \
+ if (mtx_owned(&swhash_mtx)) \
+ VM_OBJECT_ASSERT_LOCKED(object); \
+ else \
+ VM_OBJECT_ASSERT_WLOCKED(object); \
+} while (0)
+#else
+#define VM_OBJECT_BCOUNT_ASSERT_LOCKED(object)
+#endif
+
+/*
* The swblock structure maps an object and a small, fixed-size range
* of page indices to disk addresses within a swap area.
* The collection of these mappings is implemented as a hash table.
@@ -827,7 +842,7 @@ void
swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size)
{
- VM_OBJECT_ASSERT_LOCKED(object);
+ VM_OBJECT_BCOUNT_ASSERT_LOCKED(object);
swp_pager_meta_free(object, start, size);
}
@@ -999,7 +1014,7 @@ swap_pager_haspage(vm_object_t object, v
{
daddr_t blk0;
- VM_OBJECT_ASSERT_LOCKED(object);
+ VM_OBJECT_BCOUNT_ASSERT_LOCKED(object)
/*
* do we have good backing store at the requested index ?
*/
@@ -1070,7 +1085,7 @@ static void
swap_pager_unswapped(vm_page_t m)
{
- VM_OBJECT_ASSERT_LOCKED(m->object);
+ VM_OBJECT_BCOUNT_ASSERT_LOCKED(m->object);
swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE);
}
@@ -1924,7 +1939,7 @@ static void
swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count)
{
- VM_OBJECT_ASSERT_LOCKED(object);
+ VM_OBJECT_BCOUNT_ASSERT_LOCKED(object);
if (object->type != OBJT_SWAP)
return;
@@ -1970,15 +1985,15 @@ swp_pager_meta_free_all(vm_object_t obje
{
daddr_t index = 0;
- VM_OBJECT_ASSERT_LOCKED(object);
+ VM_OBJECT_BCOUNT_ASSERT_LOCKED(object);
if (object->type != OBJT_SWAP)
return;
- mtx_lock(&swhash_mtx);
while (object->un_pager.swp.swp_bcount) {
struct swblock **pswap;
struct swblock *swap;
+ mtx_lock(&swhash_mtx);
pswap = swp_pager_hash(object, index);
if ((swap = *pswap) != NULL) {
int i;
@@ -1996,9 +2011,9 @@ swp_pager_meta_free_all(vm_object_t obje
uma_zfree(swap_zone, swap);
--object->un_pager.swp.swp_bcount;
}
+ mtx_unlock(&swhash_mtx);
index += SWAP_META_PAGES;
}
- mtx_unlock(&swhash_mtx);
}
/*
@@ -2029,7 +2044,7 @@ swp_pager_meta_ctl(vm_object_t object, v
daddr_t r1;
int idx;
- VM_OBJECT_ASSERT_LOCKED(object);
+ VM_OBJECT_BCOUNT_ASSERT_LOCKED(object);
/*
* The meta data only exists of the object is OBJT_SWAP
* and even then might not be allocated yet.
@@ -2484,16 +2499,14 @@ vmspace_swap_count(struct vmspace *vmspa
for (cur = map->header.next; cur != &map->header; cur = cur->next) {
if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
(object = cur->object.vm_object) != NULL) {
- VM_OBJECT_RLOCK(object);
- mtx_lock(&swhash_mtx);
+ VM_OBJECT_WLOCK(object);
if (object->type == OBJT_SWAP &&
object->un_pager.swp.swp_bcount != 0) {
n = (cur->end - cur->start) / PAGE_SIZE;
count += object->un_pager.swp.swp_bcount *
SWAP_META_PAGES * n / object->size + 1;
}
- mtx_unlock(&swhash_mtx);
- VM_OBJECT_RUNLOCK(object);
+ VM_OBJECT_WUNLOCK(object);
}
}
return (count);
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