Author: mjg
Date: Sat Jan 11 22:59:44 2020
New Revision: 356644
URL: https://svnweb.freebsd.org/changeset/base/356644
Log:
vfs: deduplicate vnode allocation logic
This creates a dedicated routine (vn_alloc) to allocate vnodes.
As a side effect code duplicationw with getnewvnode_reserve is eleminated.
Add vn_free for symmetry.
Modified:
head/sys/kern/vfs_subr.c
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Sat Jan 11 22:58:14 2020 (r356643)
+++ head/sys/kern/vfs_subr.c Sat Jan 11 22:59:44 2020 (r356644)
@@ -1496,7 +1496,7 @@ vcheckspace(void)
* Wait if necessary for space for a new vnode.
*/
static int
-getnewvnode_wait(int suspended)
+vn_alloc_wait(int suspended)
{
mtx_assert(&vnode_free_list_mtx, MA_OWNED);
@@ -1522,81 +1522,12 @@ getnewvnode_wait(int suspended)
return (numvnodes >= desiredvnodes ? ENFILE : 0);
}
-/*
- * This hack is fragile, and probably not needed any more now that the
- * watermark handling works.
- */
-void
-getnewvnode_reserve(void)
+static struct vnode *
+vn_alloc(struct mount *mp)
{
- u_long rnumvnodes, rfreevnodes;
- struct thread *td;
-
- td = curthread;
- MPASS(td->td_vp_reserved == NULL);
-
- mtx_lock(&vnode_free_list_mtx);
- rnumvnodes = atomic_load_long(&numvnodes);
- rfreevnodes = atomic_load_long(&freevnodes);
- if (rnumvnodes + 1 > desiredvnodes && rfreevnodes > wantfreevnodes)
- vnlru_free_locked(ulmin(rnumvnodes + 1 - desiredvnodes,
- rfreevnodes - wantfreevnodes), NULL);
- if (rnumvnodes + 1 > desiredvnodes) {
- while (getnewvnode_wait(0) != 0)
- continue;
- }
- vcheckspace();
- atomic_add_long(&numvnodes, 1);
- mtx_unlock(&vnode_free_list_mtx);
-
- td->td_vp_reserved = uma_zalloc(vnode_zone, M_WAITOK);
-}
-
-/*
- * This hack is fragile, especially if desiredvnodes or wantvnodes are
- * misconfgured or changed significantly. Reducing desiredvnodes below
- * the reserved amount should cause bizarre behaviour like reducing it
- * below the number of active vnodes -- the system will try to reduce
- * numvnodes to match, but should fail, so the subtraction below should
- * not overflow.
- */
-void
-getnewvnode_drop_reserve(void)
-{
- struct thread *td;
-
- td = curthread;
- if (td->td_vp_reserved != NULL) {
- atomic_subtract_long(&numvnodes, 1);
- uma_zfree(vnode_zone, td->td_vp_reserved);
- td->td_vp_reserved = NULL;
- }
-}
-
-/*
- * Return the next vnode from the free list.
- */
-int
-getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
- struct vnode **vpp)
-{
- struct vnode *vp;
- struct thread *td;
- struct lock_object *lo;
static int cyclecount;
int error __unused;
- CTR3(KTR_VFS, "%s: mp %p with tag %s", __func__, mp, tag);
-
- KASSERT(vops->registered,
- ("%s: not registered vector op %p\n", __func__, vops));
-
- td = curthread;
- if (td->td_vp_reserved != NULL) {
- vp = td->td_vp_reserved;
- td->td_vp_reserved = NULL;
- goto init;
- }
mtx_lock(&vnode_free_list_mtx);
if (numvnodes < desiredvnodes)
cyclecount = 0;
@@ -1619,7 +1550,7 @@ getnewvnode(const char *tag, struct mount *mp, struct
else if (freevnodes > 0)
vnlru_free_locked(1, NULL);
else {
- error = getnewvnode_wait(mp != NULL && (mp->mnt_kern_flag &
+ error = vn_alloc_wait(mp != NULL && (mp->mnt_kern_flag &
MNTK_SUSPEND));
#if 0 /* XXX Not all VFS_VGET/ffs_vget callers check returns. */
if (error != 0) {
@@ -1631,8 +1562,40 @@ getnewvnode(const char *tag, struct mount *mp, struct
vcheckspace();
atomic_add_long(&numvnodes, 1);
mtx_unlock(&vnode_free_list_mtx);
- vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK);
-init:
+ return (uma_zalloc(vnode_zone, M_WAITOK));
+}
+
+static void
+vn_free(struct vnode *vp)
+{
+
+ atomic_subtract_long(&numvnodes, 1);
+ uma_zfree(vnode_zone, vp);
+}
+
+/*
+ * Return the next vnode from the free list.
+ */
+int
+getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
+ struct vnode **vpp)
+{
+ struct vnode *vp;
+ struct thread *td;
+ struct lock_object *lo;
+
+ CTR3(KTR_VFS, "%s: mp %p with tag %s", __func__, mp, tag);
+
+ KASSERT(vops->registered,
+ ("%s: not registered vector op %p\n", __func__, vops));
+
+ td = curthread;
+ if (td->td_vp_reserved != NULL) {
+ vp = td->td_vp_reserved;
+ td->td_vp_reserved = NULL;
+ } else {
+ vp = vn_alloc(mp);
+ }
counter_u64_add(vnodes_created, 1);
/*
* Locks are given the generic name "vnode" when created.
@@ -1695,6 +1658,28 @@ init:
return (0);
}
+void
+getnewvnode_reserve(void)
+{
+ struct thread *td;
+
+ td = curthread;
+ MPASS(td->td_vp_reserved == NULL);
+ td->td_vp_reserved = vn_alloc(NULL);
+}
+
+void
+getnewvnode_drop_reserve(void)
+{
+ struct thread *td;
+
+ td = curthread;
+ if (td->td_vp_reserved != NULL) {
+ vn_free(td->td_vp_reserved);
+ td->td_vp_reserved = NULL;
+ }
+}
+
static void
freevnode(struct vnode *vp)
{
@@ -1710,7 +1695,6 @@ freevnode(struct vnode *vp)
* so as not to contaminate the freshly allocated vnode.
*/
CTR2(KTR_VFS, "%s: destroying the vnode %p", __func__, vp);
- atomic_subtract_long(&numvnodes, 1);
bo = &vp->v_bufobj;
VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
("cleaned vnode still on the free list."));
@@ -1751,7 +1735,7 @@ freevnode(struct vnode *vp)
vp->v_iflag = 0;
vp->v_vflag = 0;
bo->bo_flag = 0;
- uma_zfree(vnode_zone, vp);
+ vn_free(vp);
}
/*
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