Author: rmacklem
Date: Wed Jun 10 02:51:39 2020
New Revision: 361998
URL: https://svnweb.freebsd.org/changeset/base/361998
Log:
Add two functions that create M_EXTPG mbufs with anonymous pages.
These two functions are needed by nfs-over-tls, but could also be
useful for other purposes.
mb_alloc_ext_plus_pages() - Allocates a M_EXTPG mbuf and enough anonymous
pages to store "len" data bytes.
mb_mapped_to_unmapped() - Copies the data from a list of mapped (non-M_EXTPG)
mbufs into a list of M_EXTPG mbufs allocated with anonymous pages.
This is roughly the inverse of mb_unmapped_to_ext().
Reviewed by: gallatin
Differential Revision: https://reviews.freebsd.org/D25182
Modified:
head/sys/kern/kern_mbuf.c
head/sys/sys/mbuf.h
Modified: head/sys/kern/kern_mbuf.c
==============================================================================
--- head/sys/kern/kern_mbuf.c Wed Jun 10 02:50:25 2020 (r361997)
+++ head/sys/kern/kern_mbuf.c Wed Jun 10 02:51:39 2020 (r361998)
@@ -60,6 +60,7 @@ __FBSDID("$FreeBSD$");
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
+#include <vm/vm_pageout.h>
#include <vm/vm_map.h>
#include <vm/uma.h>
#include <vm/uma_dbg.h>
@@ -1536,4 +1537,105 @@ m_snd_tag_destroy(struct m_snd_tag *mst)
ifp->if_snd_tag_free(mst);
if_rele(ifp);
counter_u64_add(snd_tag_count, -1);
+}
+
+/*
+ * Allocate an mbuf with anonymous external pages.
+ */
+struct mbuf *
+mb_alloc_ext_plus_pages(int len, int how)
+{
+ struct mbuf *m;
+ vm_page_t pg;
+ int i, npgs;
+
+ m = mb_alloc_ext_pgs(how, mb_free_mext_pgs);
+ if (m == NULL)
+ return (NULL);
+ m->m_epg_flags |= EPG_FLAG_ANON;
+ npgs = howmany(len, PAGE_SIZE);
+ for (i = 0; i < npgs; i++) {
+ do {
+ pg = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
+ VM_ALLOC_NOOBJ | VM_ALLOC_NODUMP | VM_ALLOC_WIRED);
+ if (pg == NULL) {
+ if (how == M_NOWAIT) {
+ m->m_epg_npgs = i;
+ m_free(m);
+ return (NULL);
+ }
+ vm_wait(NULL);
+ }
+ } while (pg == NULL);
+ m->m_epg_pa[i] = VM_PAGE_TO_PHYS(pg);
+ }
+ m->m_epg_npgs = npgs;
+ return (m);
+}
+
+/*
+ * Copy the data in the mbuf chain to a chain of mbufs with anonymous external
+ * unmapped pages.
+ * len is the length of data in the input mbuf chain.
+ * mlen is the maximum number of bytes put into each ext_page mbuf.
+ */
+struct mbuf *
+mb_mapped_to_unmapped(struct mbuf *mp, int len, int mlen, int how,
+ struct mbuf **mlast)
+{
+ struct mbuf *m, *mout;
+ char *pgpos, *mbpos;
+ int i, mblen, mbufsiz, pglen, xfer;
+
+ if (len == 0)
+ return (NULL);
+ mbufsiz = min(mlen, len);
+ m = mout = mb_alloc_ext_plus_pages(mbufsiz, how);
+ if (m == NULL)
+ return (m);
+ pgpos = (char *)(void *)PHYS_TO_DMAP(m->m_epg_pa[0]);
+ pglen = PAGE_SIZE;
+ mblen = 0;
+ i = 0;
+ do {
+ if (pglen == 0) {
+ if (++i == m->m_epg_npgs) {
+ m->m_epg_last_len = PAGE_SIZE;
+ mbufsiz = min(mlen, len);
+ m->m_next = mb_alloc_ext_plus_pages(mbufsiz,
+ how);
+ m = m->m_next;
+ if (m == NULL) {
+ m_freem(mout);
+ return (m);
+ }
+ i = 0;
+ }
+ pgpos = (char *)(void *)PHYS_TO_DMAP(m->m_epg_pa[i]);
+ pglen = PAGE_SIZE;
+ }
+ while (mblen == 0) {
+ if (mp == NULL) {
+ m_freem(mout);
+ return (NULL);
+ }
+ KASSERT((mp->m_flags & M_EXTPG) == 0,
+ ("mb_copym_ext_pgs: ext_pgs input mbuf"));
+ mbpos = mtod(mp, char *);
+ mblen = mp->m_len;
+ mp = mp->m_next;
+ }
+ xfer = min(mblen, pglen);
+ memcpy(pgpos, mbpos, xfer);
+ pgpos += xfer;
+ mbpos += xfer;
+ pglen -= xfer;
+ mblen -= xfer;
+ len -= xfer;
+ m->m_len += xfer;
+ } while (len > 0);
+ m->m_epg_last_len = PAGE_SIZE - pglen;
+ if (mlast != NULL)
+ *mlast = m;
+ return (mout);
}
Modified: head/sys/sys/mbuf.h
==============================================================================
--- head/sys/sys/mbuf.h Wed Jun 10 02:50:25 2020 (r361997)
+++ head/sys/sys/mbuf.h Wed Jun 10 02:51:39 2020 (r361998)
@@ -741,6 +741,9 @@ void mb_free_ext(struct mbuf *);
void mb_free_extpg(struct mbuf *);
void mb_free_mext_pgs(struct mbuf *);
struct mbuf *mb_alloc_ext_pgs(int, m_ext_free_t);
+struct mbuf *mb_alloc_ext_plus_pages(int, int);
+struct mbuf *mb_mapped_to_unmapped(struct mbuf *, int, int, int,
+ struct mbuf **);
int mb_unmapped_compress(struct mbuf *m);
struct mbuf *mb_unmapped_to_ext(struct mbuf *m);
void mb_free_notready(struct mbuf *m, int count);
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