freebsd-skq/sys/nfsclient/nfsmount.h
green ff904ffb64 Fix a serious deadlock with the NFS client. Given a large enough
atomic write request, it can fill the buffer cache with the entirety
of that write in order to handle retries.  However, it never drops
the vnode lock, or else it wouldn't be atomic, so it ends up waiting
indefinitely for more buf memory that cannot be gotten as it has it
all, and it waits in an uncancellable state.

To fix this, hibufspace is exported and scaled to a reasonable
fraction.  This is used as the limit of how much of an atomic write
request by the NFS client will be handled asynchronously.  If the
request is larger than this, it will be turned into a synchronous
request which won't deadlock the system.  It's possible this value is
far off from what is required by some, so it shall be tunable as soon
as mount_nfs(8) learns of the new field.

The slowdown between an asynchronous and a synchronous write on NFS
appears to be on the order of 2x-4x.

General nod by:	gad
MFC after:	2 weeks
More testing:	wes
PR:		kern/79208
2005-06-10 23:50:41 +00:00

117 lines
4.4 KiB
C

/*-
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Rick Macklem at The University of Guelph.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)nfsmount.h 8.3 (Berkeley) 3/30/95
* $FreeBSD$
*/
#ifndef _NFSCLIENT_NFSMOUNT_H_
#define _NFSCLIENT_NFSMOUNT_H_
struct nfs_tcp_mountstate {
int rpcresid;
#define NFS_TCP_EXPECT_RPCMARKER 0x0001 /* Expect to see a RPC/TCP marker next */
#define NFS_TCP_FORCE_RECONNECT 0x0002 /* Force a TCP reconnect */
int flags;
struct mtx mtx;
};
/*
* Mount structure.
* One allocated on every NFS mount.
* Holds NFS specific information for mount.
*/
struct nfsmount {
int nm_flag; /* Flags for soft/hard... */
int nm_state; /* Internal state flags */
struct mount *nm_mountp; /* Vfs structure for this filesystem */
int nm_numgrps; /* Max. size of groupslist */
u_char nm_fh[NFSX_V4FH]; /* File handle of root dir */
int nm_fhsize; /* Size of root file handle */
struct rpcclnt nm_rpcclnt; /* rpc state */
struct socket *nm_so; /* Rpc socket */
int nm_sotype; /* Type of socket */
int nm_soproto; /* and protocol */
int nm_soflags; /* pr_flags for socket protocol */
struct sockaddr *nm_nam; /* Addr of server */
int nm_timeo; /* Init timer for NFSMNT_DUMBTIMR */
int nm_retry; /* Max retries */
int nm_srtt[4]; /* Timers for rpcs */
int nm_sdrtt[4];
int nm_sent; /* Request send count */
int nm_cwnd; /* Request send window */
int nm_timeouts; /* Request timeouts */
int nm_deadthresh; /* Threshold of timeouts-->dead server*/
int nm_rsize; /* Max size of read rpc */
int nm_wsize; /* Max size of write rpc */
int nm_readdirsize; /* Size of a readdir rpc */
int nm_readahead; /* Num. of blocks to readahead */
int nm_wcommitsize; /* Max size of commit for write */
int nm_acdirmin; /* Directory attr cache min lifetime */
int nm_acdirmax; /* Directory attr cache max lifetime */
int nm_acregmin; /* Reg file attr cache min lifetime */
int nm_acregmax; /* Reg file attr cache max lifetime */
u_char nm_verf[NFSX_V3WRITEVERF]; /* V3 write verifier */
TAILQ_HEAD(, buf) nm_bufq; /* async io buffer queue */
short nm_bufqlen; /* number of buffers in queue */
short nm_bufqwant; /* process wants to add to the queue */
int nm_bufqiods; /* number of iods processing queue */
u_int64_t nm_maxfilesize; /* maximum file size */
struct nfs_rpcops *nm_rpcops;
int nm_tprintf_initial_delay; /* initial delay */
int nm_tprintf_delay; /* interval for messages */
struct nfs_tcp_mountstate nm_nfstcpstate;
/* NFSv4 */
uint64_t nm_clientid;
fsid_t nm_fsid;
u_int nm_lease_time;
time_t nm_last_renewal;
};
#if defined(_KERNEL)
/*
* Convert mount ptr to nfsmount ptr.
*/
#define VFSTONFS(mp) ((struct nfsmount *)((mp)->mnt_data))
#ifndef NFS_TPRINTF_INITIAL_DELAY
#define NFS_TPRINTF_INITIAL_DELAY 12
#endif
#ifndef NFS_TPRINTF_DELAY
#define NFS_TPRINTF_DELAY 30
#endif
#endif
#endif