Centralize the logic in vfs_vmio_unwire() and sendfile_free_page().

Both of these functions atomically unwire a page, optionally attempt
to free the page, and enqueue or requeue the page.  Add functions
vm_page_release() and vm_page_release_locked() to perform the same task.
The latter must be called with the page's object lock held.

As a side effect of this refactoring, the buffer cache will no longer
attempt to free mapped pages when completing direct I/O.  This is
consistent with the handling of pages by sendfile(SF_NOCACHE).

Reviewed by:	alc, kib
MFC after:	2 weeks
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D20986

1 files changed, 5 insertions, 2 deletions

diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index 3edde63abb9b..58f181d599c5 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -562,8 +562,12 @@ bool vm_page_reclaim_contig(int req, u_long npages, vm_paddr_t low,
 bool vm_page_reclaim_contig_domain(int domain, int req, u_long npages,
     vm_paddr_t low, vm_paddr_t high, u_long alignment, vm_paddr_t boundary);
 void vm_page_reference(vm_page_t m);
+#define	VPR_TRYFREE	0x01
+#define	VPR_NOREUSE	0x02
+void vm_page_release(vm_page_t m, int flags);
+void vm_page_release_locked(vm_page_t m, int flags);
 bool vm_page_remove(vm_page_t);
-int vm_page_rename (vm_page_t, vm_object_t, vm_pindex_t);
+int vm_page_rename(vm_page_t, vm_object_t, vm_pindex_t);
 vm_page_t vm_page_replace(vm_page_t mnew, vm_object_t object,
     vm_pindex_t pindex);
 void vm_page_requeue(vm_page_t m);
@@ -574,7 +578,6 @@ void vm_page_set_valid_range(vm_page_t m, int base, int size);
 int vm_page_sleep_if_busy(vm_page_t m, const char *msg);
 vm_offset_t vm_page_startup(vm_offset_t vaddr);
 void vm_page_sunbusy(vm_page_t m);
-bool vm_page_try_to_free(vm_page_t m);
 int vm_page_trysbusy(vm_page_t m);
 void vm_page_unhold_pages(vm_page_t *ma, int count);
 void vm_page_unswappable(vm_page_t m);