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swap_pager: Removing handling for objects with OBJ_SWAP clear

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With the removal of OBJT_DEFAULT, we can assume that pager operations
provide an object with OBJ_SWAP set.  Also, we do not need to convert
objects from type OBJT_DEFAULT.  Thus, remove checks for OBJ_SWAP and
remove code which modifies the object type.  In some places, replace the
check for OBJ_SWAP with a check for whether any swap blocks are
assigned.

Reviewed by:	alc, kib
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D35786
This commit is contained in:
Mark Johnston 2022-07-16 11:28:09 -04:00
parent 5d32157d4e
commit cb6757c0a6
1 changed files with 13 additions and 63 deletions
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76
sys/vm/swap_pager.c
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@ -1018,9 +1018,11 @@ swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject,
daddr_t dstaddr __diagused;
KASSERT((srcobject->flags & OBJ_SWAP) != 0,
("%s: Srcobject not swappable", __func__));
if ((dstobject->flags & OBJ_SWAP) != 0 &&
swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) {
("%s: srcobject not swappable", __func__));
KASSERT((dstobject->flags & OBJ_SWAP) != 0,
("%s: dstobject not swappable", __func__));
if (swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) {
/* Caller should destroy the source block. */
return (false);
}
@ -1051,8 +1053,6 @@ swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject,
*
* The source object contains no vm_page_t's (which is just as well)
*
* The source object is of type OBJT_SWAP.
*
* The source and destination objects must be locked.
* Both object locks may temporarily be released.
*/
@ -1060,7 +1060,6 @@ void
swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
vm_pindex_t offset, int destroysource)
{
VM_OBJECT_ASSERT_WLOCKED(srcobject);
VM_OBJECT_ASSERT_WLOCKED(dstobject);
@ -1087,21 +1086,9 @@ swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
/*
* Free left over swap blocks in source.
*
* We have to revert the type to OBJT_DEFAULT so we do not accidentally
* double-remove the object from the swap queues.
*/
if (destroysource) {
if (destroysource)
swp_pager_meta_free_all(srcobject);
/*
* Reverting the type is not necessary, the caller is going
* to destroy srcobject directly, but I'm doing it here
* for consistency since we've removed the object from its
* queues.
*/
srcobject->type = OBJT_DEFAULT;
vm_object_clear_flag(srcobject, OBJ_SWAP);
}
}
/*
@ -1454,9 +1441,6 @@ swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count,
*
* Assign swap (if necessary) and initiate I/O on the specified pages.
*
* We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects
* are automatically converted to SWAP objects.
*
* In a low memory situation we may block in VOP_STRATEGY(), but the new
* vm_page reservation system coupled with properly written VFS devices
* should ensure that no low-memory deadlock occurs. This is an area
@ -1485,23 +1469,11 @@ swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count,
("%s: object mismatch %p/%p",
__func__, object, ma[0]->object));
/*
* Step 1
*
* Turn object into OBJT_SWAP. Force sync if not a pageout process.
*/
if ((object->flags & OBJ_SWAP) == 0) {
addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE);
KASSERT(addr == SWAPBLK_NONE,
("unexpected object swap block"));
}
VM_OBJECT_WUNLOCK(object);
async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0;
swp_pager_init_freerange(&s_free, &n_free);
/*
* Step 2
*
* Assign swap blocks and issue I/O. We reallocate swap on the fly.
* The page is left dirty until the pageout operation completes
* successfully.
@ -1795,7 +1767,8 @@ swap_pager_swapped_pages(vm_object_t object)
int i;
VM_OBJECT_ASSERT_LOCKED(object);
if ((object->flags & OBJ_SWAP) == 0)
if (pctrie_is_empty(&object->un_pager.swp.swp_blks))
return (0);
for (res = 0, pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
@ -2025,9 +1998,6 @@ swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb)
/*
* SWP_PAGER_META_BUILD() - add swap block to swap meta data for object
*
* We first convert the object to a swap object if it is a default
* object.
*
* The specified swapblk is added to the object's swap metadata. If
* the swapblk is not valid, it is freed instead. Any previously
* assigned swapblk is returned.
@ -2043,27 +2013,6 @@ swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk)
VM_OBJECT_ASSERT_WLOCKED(object);
/*
* Convert default object to swap object if necessary
*/
if ((object->flags & OBJ_SWAP) == 0) {
pctrie_init(&object->un_pager.swp.swp_blks);
/*
* Ensure that swap_pager_swapoff()'s iteration over
* object_list does not see a garbage pctrie.
*/
atomic_thread_fence_rel();
object->type = OBJT_SWAP;
vm_object_set_flag(object, OBJ_SWAP);
object->un_pager.swp.writemappings = 0;
KASSERT((object->flags & OBJ_ANON) != 0 ||
object->handle == NULL,
("default pager %p with handle %p",
object, object->handle));
}
rdpi = rounddown(pindex, SWAP_META_PAGES);
sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi);
if (sb == NULL) {
@ -2165,7 +2114,7 @@ swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject,
int i, limit, start;
VM_OBJECT_ASSERT_WLOCKED(srcobject);
if ((srcobject->flags & OBJ_SWAP) == 0 || count == 0)
if (count == 0 || pctrie_is_empty(&srcobject->un_pager.swp.swp_blks))
return;
swp_pager_init_freerange(&s_free, &n_free);
@ -2232,7 +2181,8 @@ swp_pager_meta_free_all(vm_object_t object)
int i;
VM_OBJECT_ASSERT_WLOCKED(object);
if ((object->flags & OBJ_SWAP) == 0)
if (pctrie_is_empty(&object->un_pager.swp.swp_blks))
return;
swp_pager_init_freerange(&s_free, &n_free);
@ -2296,9 +2246,9 @@ swap_pager_find_least(vm_object_t object, vm_pindex_t pindex)
int i;
VM_OBJECT_ASSERT_LOCKED(object);
if ((object->flags & OBJ_SWAP) == 0)
return (object->size);
if (pctrie_is_empty(&object->un_pager.swp.swp_blks))
return (object->size);
sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks,
rounddown(pindex, SWAP_META_PAGES));
if (sb == NULL)