Date: Sun, 8 Mar 2020 18:52:05 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r358768 - in projects/nfs-over-tls/sys: kern sys Message-ID: <202003081852.028Iq5GA030143@repo.freebsd.org>
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Author: rmacklem Date: Sun Mar 8 18:52:04 2020 New Revision: 358768 URL: https://svnweb.freebsd.org/changeset/base/358768 Log: Add mb_splitatpos_extpgs() to kern_mbuf.c. It is similar to m_split(), but handles ext_pgs mbufs with anonymous pages. It does not duplicate the m_pkthdr mbuf, since that could result in an mbuf with m_len == 0 and npgs == 0, which does not seem to be allowed by certain sanity checks on ext_pgs mbuf chains. For my uses, I do not need an m_pkthdr mbuf. Modified: projects/nfs-over-tls/sys/kern/kern_mbuf.c projects/nfs-over-tls/sys/sys/mbuf.h Modified: projects/nfs-over-tls/sys/kern/kern_mbuf.c ============================================================================== --- projects/nfs-over-tls/sys/kern/kern_mbuf.c Sun Mar 8 18:48:01 2020 (r358767) +++ projects/nfs-over-tls/sys/kern/kern_mbuf.c Sun Mar 8 18:52:04 2020 (r358768) @@ -1679,6 +1679,8 @@ mb_copym_ext_pgs(struct mbuf *mp, int len, int mlen, i m_freem(mout); return (NULL); } + KASSERT((mp->m_flags & M_NOMAP) == 0, + ("mb_copym_ext_pgs: ext_pgs input mbuf")); mbpos = mtod(mp, char *); mblen = mp->m_len; mp = mp->m_next; @@ -1696,4 +1698,120 @@ mb_copym_ext_pgs(struct mbuf *mp, int len, int mlen, i if (mlast != NULL) *mlast = m; return (mout); +} + +/* + * Split an ext_pgs mbuf list into two lists at len bytes. + * Similar to m_split(), but for ext_pgs mbufs with + * anonymous pages. + */ +struct mbuf * +mb_splitatpos_ext(struct mbuf *m0, int len, int how) +{ + struct mbuf *m, *mp; + struct mbuf_ext_pgs *pgs, *pgs0; + vm_page_t pg; + int i, j, left, pgno, plen, trim; + char *cp, *cp0; + + /* Nothing to do. */ + if (len == 0) + return (NULL); + + /* Find the correct mbuf to split at. */ + for (mp = m0; mp != NULL && len > mp->m_len; mp = mp->m_next) + len -= mp->m_len; + if (mp == NULL) + return (NULL); + + /* If len == mp->m_len, we can just split the mbuf list. */ + if (len == mp->m_len) { + m = mp->m_next; + mp->m_next = NULL; + return (m); + } + + /* Find the page to split at. */ + KASSERT((mp->m_flags & (M_EXT | M_NOMAP)) == + (M_EXT | M_NOMAP), + ("mb_splitatpos_ext: m0 not ext_pgs")); + pgs = mp->m_ext.ext_pgs; + KASSERT((pgs->flags & MBUF_PEXT_FLAG_ANON) != 0, + ("mb_splitatpos_ext: not anonymous pages")); + pgno = 0; + left = len; + do { + if (pgno == 0) + plen = mbuf_ext_pg_len(pgs, 0, + pgs->first_pg_off); + else + plen = mbuf_ext_pg_len(pgs, pgno, 0); + if (left <= plen) + break; + left -= plen; + pgno++; + } while (pgno < pgs->npgs); + if (pgno == pgs->npgs) + panic("mb_splitatpos_ext"); + mp->m_len = len; + + m = mb_alloc_ext_pgs(how, false, mb_free_mext_pgs); + if (m == NULL) + return (NULL); + pgs0 = m->m_ext.ext_pgs; + pgs0->flags |= MBUF_PEXT_FLAG_ANON; + + /* + * If left < plen, allocate a new page for the new mbuf + * and copy the data after left in the page to this new + * page. + */ + if (left < plen) { + 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_free(m); + return (NULL); + } + vm_wait(NULL); + } + } while (pg == NULL); + pgs0->pa[0] = VM_PAGE_TO_PHYS(pg); + pgs0->npgs++; + trim = plen - left; + cp = (char *)(void *)PHYS_TO_DMAP(pgs->pa[pgno]); + cp0 = (char *)(void *)PHYS_TO_DMAP(pgs0->pa[0]); + if (pgno == 0) + cp += pgs->first_pg_off; + cp += left; + if (pgno == pgs->npgs - 1) + pgs0->last_pg_len = trim; + else { + pgs0->last_pg_len = pgs->last_pg_len; + pgs0->first_pg_off = PAGE_SIZE - trim; + cp0 += PAGE_SIZE - trim; + } + memcpy(cp0, cp, trim); + m->m_len = trim; + } else + pgs0->last_pg_len = pgs->last_pg_len; + + /* Move the pages beyond pgno to the new mbuf. */ + for (i = pgno + 1, j = pgs0->npgs; i < pgs->npgs; i++, j++) { + pgs0->pa[j] = pgs->pa[i]; + /* Never moves page 0. */ + m->m_len += mbuf_ext_pg_len(pgs, i, 0); + } + pgs0->npgs = j; + pgs->npgs = pgno + 1; + + /* Can now update pgs->last_pg_len. */ + pgs->last_pg_len = left; + + m->m_next = mp->m_next; + mp->m_next = NULL; + return (m); } Modified: projects/nfs-over-tls/sys/sys/mbuf.h ============================================================================== --- projects/nfs-over-tls/sys/sys/mbuf.h Sun Mar 8 18:48:01 2020 (r358767) +++ projects/nfs-over-tls/sys/sys/mbuf.h Sun Mar 8 18:52:04 2020 (r358768) @@ -703,6 +703,7 @@ struct mbuf *mb_alloc_ext_pgs(int, bool, m_ext_free_t) struct mbuf *mb_alloc_ext_plus_pages(int, int, bool, m_ext_free_t); struct mbuf *mb_copym_ext_pgs(struct mbuf *, int, int, int, bool, m_ext_free_t, struct mbuf **); +struct mbuf *mb_splitatpos_ext(struct mbuf *, int, int); 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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