Convert page cache read to VOP.

There are several negative side-effects of not calling into VOP layer
at all for page cache reads.  The biggest is the missed activation of
EVFILT_READ knotes.

Also, it allows filesystem to make more fine grained decision to
refuse read from page cache.

Keep VIRF_PGREAD flag around, it is still useful for nullfs, and for
asserts.

Reviewed by:	markj
Tested by:	pho
Discussed with:	mjg
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D26346

1 files changed, 9 insertions, 0 deletions

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 34f35f3638d0..6956a8f55e89 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -5839,6 +5839,15 @@ vop_read_post(void *ap, int rc)
 }
 
 void
+vop_read_pgcache_post(void *ap, int rc)
+{
+	struct vop_read_pgcache_args *a = ap;
+
+	if (!rc)
+		VFS_KNOTE_UNLOCKED(a->a_vp, NOTE_READ);
+}
+
+void
 vop_readdir_post(void *ap, int rc)
 {
 	struct vop_readdir_args *a = ap;