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- Move nfs_realign() from the NFS client to the shared NFS code and

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remove the NFS server version in order to reduce code duplication.
  The shared version now uses a second parameter how, which is passed
  on to m_get(9) and m_getcl(9) as the server used M_WAIT while the
  client requires M_DONTWAIT, and replaces the the previously unused
  parameter hsiz.
- Change nfs_realign() to use nfsm_aligned() so as with other NFS code
  the alignment check isn't actually performed on platforms without
  strict alignment requirements for performance reasons because as the
  comment suggests unaligned data only occasionally occurs with TCP.
- Change fha_extract_info() to use nfs_realign() with M_DONTWAIT rather
  than M_WAIT because it's called with the RPC sp_lock held.

Reviewed by:	jhb, rmacklem
MFC after:	1 week
This commit is contained in:
Marius Strobl 2010-02-09 23:45:14 +00:00
parent be03f0b907
commit 9ea01fedc0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=203732
6 changed files with 73 additions and 126 deletions
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67
sys/nfs/nfs_common.c
View File

@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/sysent.h>
#include <sys/syscall.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_object.h>
@ -78,6 +79,16 @@ nfstype nfsv3_type[9] = {
static void *nfsm_dissect_xx_sub(int s, struct mbuf **md, caddr_t *dpos,
int how);
SYSCTL_DECL(_vfs_nfs);
static int nfs_realign_test;
SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_test, CTLFLAG_RD, &nfs_realign_test,
0, "Number of realign tests done");
static int nfs_realign_count;
SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_count, CTLFLAG_RD, &nfs_realign_count,
0, "Number of mbuf realignments done");
u_quad_t
nfs_curusec(void)
{
@ -337,3 +348,59 @@ nfsm_adv_xx(int s, struct mbuf **md, caddr_t *dpos)
return (t1);
return (0);
}
/*
* Check for badly aligned mbuf data and realign by copying the unaligned
* portion of the data into a new mbuf chain and freeing the portions of the
* old chain that were replaced.
*
* We cannot simply realign the data within the existing mbuf chain because
* the underlying buffers may contain other rpc commands and we cannot afford
* to overwrite them.
*
* We would prefer to avoid this situation entirely. The situation does not
* occur with NFS/UDP and is supposed to only occassionally occur with TCP.
* Use vfs.nfs.realign_count and realign_test to check this.
*/
int
nfs_realign(struct mbuf **pm, int how)
{
struct mbuf *m, *n;
int off;
++nfs_realign_test;
while ((m = *pm) != NULL) {
if (!nfsm_aligned(m->m_len, u_int32_t) ||
!nfsm_aligned(mtod(m, intptr_t), u_int32_t)) {
/*
* NB: we can't depend on m_pkthdr.len to help us
* decide what to do here. May not be worth doing
* the m_length calculation as m_copyback will
* expand the mbuf chain below as needed.
*/
if (m_length(m, NULL) >= MINCLSIZE) {
/* NB: m_copyback handles space > MCLBYTES */
n = m_getcl(how, MT_DATA, 0);
} else
n = m_get(how, MT_DATA);
if (n == NULL)
return (ENOMEM);
/*
* Align the remainder of the mbuf chain.
*/
n->m_len = 0;
off = 0;
while (m != NULL) {
m_copyback(n, off, m->m_len, mtod(m, caddr_t));
off += m->m_len;
m = m->m_next;
}
m_freem(*pm);
*pm = n;
++nfs_realign_count;
break;
}
pm = &m->m_next;
}
return (0);
}

1
sys/nfs/nfs_common.h
View File

@ -48,6 +48,7 @@ extern nfstype nfsv3_type[];
int nfs_adv(struct mbuf **, caddr_t *, int, int);
u_quad_t nfs_curusec(void);
void *nfsm_disct(struct mbuf **, caddr_t *, int, int, int);
int nfs_realign(struct mbuf **, int);
/* ****************************** */
/* Build request/reply phase macros */

67
sys/nfsclient/nfs_krpc.c
View File

@ -87,8 +87,6 @@ uint32_t nfsclient_nfs3_start_probes[NFS_NPROCS];
uint32_t nfsclient_nfs3_done_probes[NFS_NPROCS];
#endif
static int nfs_realign_test;
static int nfs_realign_count;
static int nfs_bufpackets = 4;
static int nfs_reconnects;
static int nfs3_jukebox_delay = 10;
@ -97,10 +95,6 @@ static int fake_wchan;
SYSCTL_DECL(_vfs_nfs);
SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_test, CTLFLAG_RW, &nfs_realign_test, 0,
"Number of realign tests done");
SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_count, CTLFLAG_RW, &nfs_realign_count, 0,
"Number of mbuf realignments done");
SYSCTL_INT(_vfs_nfs, OID_AUTO, bufpackets, CTLFLAG_RW, &nfs_bufpackets, 0,
"Buffer reservation size 2 < x < 64");
SYSCTL_INT(_vfs_nfs, OID_AUTO, reconnects, CTLFLAG_RD, &nfs_reconnects, 0,
@ -402,65 +396,6 @@ nfs_feedback(int type, int proc, void *arg)
}
}
/*
* nfs_realign:
*
* Check for badly aligned mbuf data and realign by copying the unaligned
* portion of the data into a new mbuf chain and freeing the portions
* of the old chain that were replaced.
*
* We cannot simply realign the data within the existing mbuf chain
* because the underlying buffers may contain other rpc commands and
* we cannot afford to overwrite them.
*
* We would prefer to avoid this situation entirely. The situation does
* not occur with NFS/UDP and is supposed to only occassionally occur
* with TCP. Use vfs.nfs.realign_count and realign_test to check this.
*
*/
static int
nfs_realign(struct mbuf **pm, int hsiz)
{
struct mbuf *m, *n;
int off, space;
++nfs_realign_test;
while ((m = *pm) != NULL) {
if ((m->m_len & 0x3) || (mtod(m, intptr_t) & 0x3)) {
/*
* NB: we can't depend on m_pkthdr.len to help us
* decide what to do here. May not be worth doing
* the m_length calculation as m_copyback will
* expand the mbuf chain below as needed.
*/
space = m_length(m, NULL);
if (space >= MINCLSIZE) {
/* NB: m_copyback handles space > MCLBYTES */
n = m_getcl(M_DONTWAIT, MT_DATA, 0);
} else
n = m_get(M_DONTWAIT, MT_DATA);
if (n == NULL)
return (ENOMEM);
/*
* Align the remainder of the mbuf chain.
*/
n->m_len = 0;
off = 0;
while (m != NULL) {
m_copyback(n, off, m->m_len, mtod(m, caddr_t));
off += m->m_len;
m = m->m_next;
}
m_freem(*pm);
*pm = n;
++nfs_realign_count;
break;
}
pm = &m->m_next;
}
return (0);
}
/*
* nfs_request - goes something like this
* - fill in request struct
@ -589,7 +524,7 @@ nfs_request(struct vnode *vp, struct mbuf *mreq, int procnum,
* These could cause pointer alignment problems, so copy them to
* well aligned mbufs.
*/
error = nfs_realign(&mrep, 2 * NFSX_UNSIGNED);
error = nfs_realign(&mrep, M_DONTWAIT);
if (error == ENOMEM) {
m_freem(mrep);
AUTH_DESTROY(auth);

1
sys/nfsserver/nfs.h
View File

@ -239,7 +239,6 @@ extern int nfs_debug;
#endif
void nfs_realign(struct mbuf **);
struct mbuf *nfs_rephead(int, struct nfsrv_descript *, int, struct mbuf **,
caddr_t *);
void nfsm_srvfattr(struct nfsrv_descript *, struct vattr *,

4
sys/nfsserver/nfs_fha.c
View File

@ -202,7 +202,9 @@ fha_extract_info(struct svc_req *req, struct fha_info *i)
procnum == NFSPROC_NULL)
goto out;
nfs_realign(&req->rq_args);
error = nfs_realign(&req->rq_args, M_DONTWAIT);
if (error)
goto out;
md = req->rq_args;
dpos = mtod(md, caddr_t);

59
sys/nfsserver/nfs_srvkrpc.c
View File

@ -96,8 +96,6 @@ SYSCTL_DECL(_vfs_nfsrv);
SVCPOOL *nfsrv_pool;
int nfsd_waiting = 0;
int nfsrv_numnfsd = 0;
static int nfs_realign_test;
static int nfs_realign_count;
struct callout nfsrv_callout;
static eventhandler_tag nfsrv_nmbclusters_tag;
@ -111,10 +109,6 @@ SYSCTL_INT(_vfs_nfsrv, OID_AUTO, gatherdelay, CTLFLAG_RW,
SYSCTL_INT(_vfs_nfsrv, OID_AUTO, gatherdelay_v3, CTLFLAG_RW,
&nfsrvw_procrastinate_v3, 0,
"Delay in seconds for NFSv3 write gathering");
SYSCTL_INT(_vfs_nfsrv, OID_AUTO, realign_test, CTLFLAG_RW,
&nfs_realign_test, 0, "");
SYSCTL_INT(_vfs_nfsrv, OID_AUTO, realign_count, CTLFLAG_RW,
&nfs_realign_count, 0, "");
static int nfssvc_addsock(struct file *, struct thread *);
static int nfssvc_nfsd(struct thread *, struct nfsd_nfsd_args *);
@ -250,57 +244,6 @@ nfs_rephead(int siz, struct nfsrv_descript *nd, int err,
return (mreq);
}
/*
* nfs_realign:
*
* Check for badly aligned mbuf data and realign by copying the unaligned
* portion of the data into a new mbuf chain and freeing the portions
* of the old chain that were replaced.
*
* We cannot simply realign the data within the existing mbuf chain
* because the underlying buffers may contain other rpc commands and
* we cannot afford to overwrite them.
*
* We would prefer to avoid this situation entirely. The situation does
* not occur with NFS/UDP and is supposed to only occassionally occur
* with TCP. Use vfs.nfs.realign_count and realign_test to check this.
*/
void
nfs_realign(struct mbuf **pm) /* XXX COMMON */
{
struct mbuf *m;
struct mbuf *n = NULL;
int off = 0;
++nfs_realign_test;
while ((m = *pm) != NULL) {
if ((m->m_len & 0x3) || (mtod(m, intptr_t) & 0x3)) {
MGET(n, M_WAIT, MT_DATA);
if (m->m_len >= MINCLSIZE) {
MCLGET(n, M_WAIT);
}
n->m_len = 0;
break;
}
pm = &m->m_next;
}
/*
* If n is non-NULL, loop on m copying data, then replace the
* portion of the chain that had to be realigned.
*/
if (n != NULL) {
++nfs_realign_count;
while (m) {
m_copyback(n, off, m->m_len, mtod(m, caddr_t));
off += m->m_len;
m = m->m_next;
}
m_freem(*pm);
*pm = n;
}
}
static void
nfssvc_program(struct svc_req *rqst, SVCXPRT *xprt)
{
@ -334,7 +277,7 @@ nfssvc_program(struct svc_req *rqst, SVCXPRT *xprt)
mreq = mrep = NULL;
mreq = rqst->rq_args;
rqst->rq_args = NULL;
nfs_realign(&mreq);
(void)nfs_realign(&mreq, M_WAIT);
/*
* Note: we want rq_addr, not svc_getrpccaller for nd_nam2 -