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Extend m_copyback() to support unmapped mbufs.

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Reviewed by:	gallatin, markj
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D30133
This commit is contained in:
John Baldwin 2021-05-25 16:59:18 -07:00
parent 3c7a01d773
commit 3f9dac85cc
1 changed files with 28 additions and 2 deletions
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30
sys/kern/uipc_mbuf.c
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@ -1139,6 +1139,29 @@ m_devget(char *buf, int totlen, int off, struct ifnet *ifp,
return (top);
}
static void
m_copytounmapped(const struct mbuf *m, int off, int len, c_caddr_t cp)
{
struct iovec iov;
struct uio uio;
int error;
KASSERT(off >= 0, ("m_copytounmapped: negative off %d", off));
KASSERT(len >= 0, ("m_copytounmapped: negative len %d", len));
KASSERT(off < m->m_len, ("m_copytounmapped: len exceeds mbuf length"));
iov.iov_base = __DECONST(caddr_t, cp);
iov.iov_len = len;
uio.uio_resid = len;
uio.uio_iov = &iov;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_iovcnt = 1;
uio.uio_offset = 0;
uio.uio_rw = UIO_WRITE;
error = m_unmappedtouio(m, off, &uio, len);
KASSERT(error == 0, ("m_unmappedtouio failed: off %d, len %d", off,
len));
}
/*
* Copy data from a buffer back into the indicated mbuf chain,
* starting "off" bytes from the beginning, extending the mbuf
@ -1172,7 +1195,10 @@ m_copyback(struct mbuf *m0, int off, int len, c_caddr_t cp)
M_TRAILINGSPACE(m));
}
mlen = min (m->m_len - off, len);
bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
if ((m->m_flags & M_EXTPG) != 0)
m_copytounmapped(m, off, mlen, cp);
else
bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
cp += mlen;
len -= mlen;
mlen += off;
@ -1870,7 +1896,7 @@ m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
}
/*
* Copy data from an unmapped mbuf into a uio limited by len if set.
* Copy data to/from an unmapped mbuf into a uio limited by len if set.
*/
int
m_unmappedtouio(const struct mbuf *m, int m_off, struct uio *uio, int len)