git: b730fd30b78f - main - vm: Add KPI to dynamically register pagers
Konstantin Belousov
kib at FreeBSD.org
Thu May 13 17:14:17 UTC 2021
The branch main has been updated by kib:
URL: https://cgit.FreeBSD.org/src/commit/?id=b730fd30b78f502ed5dd08e5285cb2c951495d65
commit b730fd30b78f502ed5dd08e5285cb2c951495d65
Author: Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-05-07 19:06:16 +0000
Commit: Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-05-13 17:12:29 +0000
vm: Add KPI to dynamically register pagers
Pager is allowed to inherit part of its implementation from the existing
pager, which is done by copying non-NULL virtual method slots.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D30168
---
sys/vm/vm.h | 1 +
sys/vm/vm_object.c | 15 +++++++++-
sys/vm/vm_object.h | 1 +
sys/vm/vm_pager.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++-------
sys/vm/vm_pager.h | 3 ++
5 files changed, 91 insertions(+), 11 deletions(-)
diff --git a/sys/vm/vm.h b/sys/vm/vm.h
index 2aae787d7f58..ca310b15b43c 100644
--- a/sys/vm/vm.h
+++ b/sys/vm/vm.h
@@ -98,6 +98,7 @@ enum obj_type {
OBJT_SG,
OBJT_MGTDEVICE,
OBJT_SWAP_TMPFS,
+ OBJT_FIRST_DYN,
};
typedef u_char objtype_t;
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 8cb4c0006c59..73cbdfb1ece4 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -430,7 +430,8 @@ vm_object_allocate(objtype_t type, vm_pindex_t size)
flags = 0;
break;
default:
- panic("vm_object_allocate: type %d is undefined", type);
+ panic("vm_object_allocate: type %d is undefined or dynamic",
+ type);
}
object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
_vm_object_allocate(type, size, flags, object, NULL);
@@ -438,6 +439,18 @@ vm_object_allocate(objtype_t type, vm_pindex_t size)
return (object);
}
+vm_object_t
+vm_object_allocate_dyn(objtype_t dyntype, vm_pindex_t size, u_short flags)
+{
+ vm_object_t object;
+
+ MPASS(dyntype >= OBJT_FIRST_DYN /* && dyntype < nitems(pagertab) */);
+ object = (vm_object_t)uma_zalloc(obj_zone, M_WAITOK);
+ _vm_object_allocate(dyntype, size, flags, object, NULL);
+
+ return (object);
+}
+
/*
* vm_object_allocate_anon:
*
diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
index 0e1ed321255f..7e99288e0ff2 100644
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -356,6 +356,7 @@ extern int umtx_shm_vnobj_persistent;
vm_object_t vm_object_allocate (objtype_t, vm_pindex_t);
vm_object_t vm_object_allocate_anon(vm_pindex_t, vm_object_t, struct ucred *,
vm_size_t);
+vm_object_t vm_object_allocate_dyn(objtype_t, vm_pindex_t, u_short);
boolean_t vm_object_coalesce(vm_object_t, vm_ooffset_t, vm_size_t, vm_size_t,
boolean_t);
void vm_object_collapse (vm_object_t);
diff --git a/sys/vm/vm_pager.c b/sys/vm/vm_pager.c
index 9476058a75bf..432a948cfe81 100644
--- a/sys/vm/vm_pager.c
+++ b/sys/vm/vm_pager.c
@@ -165,7 +165,7 @@ static const struct pagerops deadpagerops = {
.pgo_getvp = dead_pager_getvp,
};
-const struct pagerops *pagertab[] __read_mostly = {
+const struct pagerops *pagertab[16] __read_mostly = {
[OBJT_DEFAULT] = &defaultpagerops,
[OBJT_SWAP] = &swappagerops,
[OBJT_VNODE] = &vnodepagerops,
@@ -176,18 +176,24 @@ const struct pagerops *pagertab[] __read_mostly = {
[OBJT_MGTDEVICE] = &mgtdevicepagerops,
[OBJT_SWAP_TMPFS] = &swaptmpfspagerops,
};
+static struct mtx pagertab_lock;
void
vm_pager_init(void)
{
const struct pagerops **pgops;
+ int i;
+
+ mtx_init(&pagertab_lock, "dynpag", NULL, MTX_DEF);
/*
* Initialize known pagers
*/
- for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++)
+ for (i = 0; i < OBJT_FIRST_DYN; i++) {
+ pgops = &pagertab[i];
if ((*pgops)->pgo_init != NULL)
(*(*pgops)->pgo_init)();
+ }
}
static int nswbuf_max;
@@ -245,15 +251,9 @@ vm_object_t
vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
{
- vm_object_t ret;
- const struct pagerops *ops;
+ MPASS(type < nitems(pagertab));
- ops = pagertab[type];
- if (ops)
- ret = (*ops->pgo_alloc)(handle, size, prot, off, cred);
- else
- ret = NULL;
- return (ret);
+ return ((*pagertab[type]->pgo_alloc)(handle, size, prot, off, cred));
}
/*
@@ -264,6 +264,7 @@ vm_pager_deallocate(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
+ MPASS(object->type < nitems(pagertab));
(*pagertab[object->type]->pgo_dealloc) (object);
}
@@ -315,6 +316,7 @@ vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
#endif
int r;
+ MPASS(object->type < nitems(pagertab));
vm_pager_assert_in(object, m, count);
r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind,
@@ -348,6 +350,7 @@ vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count,
int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
{
+ MPASS(object->type < nitems(pagertab));
vm_pager_assert_in(object, m, count);
return ((*pagertab[object->type]->pgo_getpages_async)(object, m,
@@ -385,6 +388,60 @@ vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
return (object);
}
+int
+vm_pager_alloc_dyn_type(struct pagerops *ops, int base_type)
+{
+ int res;
+
+ mtx_lock(&pagertab_lock);
+ MPASS(base_type == -1 ||
+ (base_type >= OBJT_DEFAULT && base_type < nitems(pagertab)));
+ for (res = OBJT_FIRST_DYN; res < nitems(pagertab); res++) {
+ if (pagertab[res] == NULL)
+ break;
+ }
+ if (res == nitems(pagertab)) {
+ mtx_unlock(&pagertab_lock);
+ return (-1);
+ }
+ if (base_type != -1) {
+ MPASS(pagertab[base_type] != NULL);
+#define FIX(n) \
+ if (ops->pgo_##n == NULL) \
+ ops->pgo_##n = pagertab[base_type]->pgo_##n
+ FIX(init);
+ FIX(alloc);
+ FIX(dealloc);
+ FIX(getpages);
+ FIX(getpages_async);
+ FIX(putpages);
+ FIX(haspage);
+ FIX(populate);
+ FIX(pageunswapped);
+ FIX(update_writecount);
+ FIX(release_writecount);
+ FIX(set_writeable_dirty);
+ FIX(mightbedirty);
+ FIX(getvp);
+ FIX(freespace);
+#undef FIX
+ }
+ pagertab[res] = ops; /* XXXKIB should be rel, but acq is too much */
+ mtx_unlock(&pagertab_lock);
+ return (res);
+}
+
+void
+vm_pager_free_dyn_type(objtype_t type)
+{
+ MPASS(type >= OBJT_FIRST_DYN && type < nitems(pagertab));
+
+ mtx_lock(&pagertab_lock);
+ MPASS(pagertab[type] != NULL);
+ pagertab[type] = NULL;
+ mtx_unlock(&pagertab_lock);
+}
+
static int
pbuf_ctor(void *mem, int size, void *arg, int flags)
{
@@ -517,6 +574,8 @@ vm_object_set_writeable_dirty(vm_object_t object)
{
pgo_set_writeable_dirty_t *method;
+ MPASS(object->type < nitems(pagertab));
+
method = pagertab[object->type]->pgo_set_writeable_dirty;
if (method != NULL)
method(object);
@@ -527,6 +586,8 @@ vm_object_mightbedirty(vm_object_t object)
{
pgo_mightbedirty_t *method;
+ MPASS(object->type < nitems(pagertab));
+
method = pagertab[object->type]->pgo_mightbedirty;
if (method == NULL)
return (false);
@@ -541,6 +602,7 @@ int
vm_object_kvme_type(vm_object_t object, struct vnode **vpp)
{
VM_OBJECT_ASSERT_LOCKED(object);
+ MPASS(object->type < nitems(pagertab));
if (vpp != NULL)
*vpp = vm_object_vnode(object);
diff --git a/sys/vm/vm_pager.h b/sys/vm/vm_pager.h
index 5e0261f818cf..098d48ea3d9d 100644
--- a/sys/vm/vm_pager.h
+++ b/sys/vm/vm_pager.h
@@ -249,6 +249,9 @@ vm_pager_freespace(vm_object_t object, vm_pindex_t start,
method(object, start, size);
}
+int vm_pager_alloc_dyn_type(struct pagerops *ops, int base_type);
+void vm_pager_free_dyn_type(objtype_t type);
+
struct cdev_pager_ops {
int (*cdev_pg_fault)(vm_object_t vm_obj, vm_ooffset_t offset,
int prot, vm_page_t *mres);
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