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Implemented an nfs_node hash list lock, similar to what was implemented

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in ffs_vget(), and for the same reason: to prevent a race condition that
results in duplicate vnodes/NFSnodes being allocated.
This commit is contained in:
David Greenman 1995-07-21 10:25:13 +00:00
parent 44918dfed7
commit f5526ddb48
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=9604
2 changed files with 62 additions and 2 deletions
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32
sys/nfs/nfs_node.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE. * SUCH DAMAGE.
* *
* @(#)nfs_node.c 8.2 (Berkeley) 12/30/93 * @(#)nfs_node.c 8.2 (Berkeley) 12/30/93
* $Id: nfs_node.c,v 1.8 1995/03/16 18:15:36 bde Exp $ * $Id: nfs_node.c,v 1.9 1995/06/27 11:06:35 dfr Exp $
*/ */
#include <sys/param.h> #include <sys/param.h>
@ -99,6 +99,8 @@ nfs_hash(fhp, fhsize)
* In all cases, a pointer to a * In all cases, a pointer to a
* nfsnode structure is returned. * nfsnode structure is returned.
*/ */
int nfs_node_hash_lock;
int int
nfs_nget(mntp, fhp, fhsize, npp) nfs_nget(mntp, fhp, fhsize, npp)
struct mount *mntp; struct mount *mntp;
@ -124,8 +126,28 @@ loop:
*npp = np; *npp = np;
return(0); return(0);
} }
/*
* Obtain a lock to prevent a race condition if the getnewvnode
* or malloc below happen to block.
*/
if (nfs_node_hash_lock) {
while (nfs_node_hash_lock) {
nfs_node_hash_lock = -1;
tsleep(&nfs_node_hash_lock, PVM, "ffsvgt", 0);
}
goto loop;
}
nfs_node_hash_lock = 1;
error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp); error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp);
if (error) { if (error) {
/*
* Wakeup anyone blocked on our lock.
*/
if (nfs_node_hash_lock < 0) {
wakeup(&nfs_node_hash_lock);
}
nfs_node_hash_lock = 0;
*npp = 0; *npp = 0;
return (error); return (error);
} }
@ -146,6 +168,14 @@ loop:
np->n_fhsize = fhsize; np->n_fhsize = fhsize;
*npp = np; *npp = np;
/*
* Wakeup anyone blocked on our lock
*/
if (nfs_node_hash_lock < 0) {
wakeup(&nfs_node_hash_lock);
}
nfs_node_hash_lock = 0;
/* /*
* Lock the new nfsnode. * Lock the new nfsnode.
*/ */

32
sys/nfsclient/nfs_node.c
View File

@ -34,7 +34,7 @@
* SUCH DAMAGE. * SUCH DAMAGE.
* *
* @(#)nfs_node.c 8.2 (Berkeley) 12/30/93 * @(#)nfs_node.c 8.2 (Berkeley) 12/30/93
* $Id: nfs_node.c,v 1.8 1995/03/16 18:15:36 bde Exp $ * $Id: nfs_node.c,v 1.9 1995/06/27 11:06:35 dfr Exp $
*/ */
#include <sys/param.h> #include <sys/param.h>
@ -99,6 +99,8 @@ nfs_hash(fhp, fhsize)
* In all cases, a pointer to a * In all cases, a pointer to a
* nfsnode structure is returned. * nfsnode structure is returned.
*/ */
int nfs_node_hash_lock;
int int
nfs_nget(mntp, fhp, fhsize, npp) nfs_nget(mntp, fhp, fhsize, npp)
struct mount *mntp; struct mount *mntp;
@ -124,8 +126,28 @@ loop:
*npp = np; *npp = np;
return(0); return(0);
} }
/*
* Obtain a lock to prevent a race condition if the getnewvnode
* or malloc below happen to block.
*/
if (nfs_node_hash_lock) {
while (nfs_node_hash_lock) {
nfs_node_hash_lock = -1;
tsleep(&nfs_node_hash_lock, PVM, "ffsvgt", 0);
}
goto loop;
}
nfs_node_hash_lock = 1;
error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp); error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp);
if (error) { if (error) {
/*
* Wakeup anyone blocked on our lock.
*/
if (nfs_node_hash_lock < 0) {
wakeup(&nfs_node_hash_lock);
}
nfs_node_hash_lock = 0;
*npp = 0; *npp = 0;
return (error); return (error);
} }
@ -146,6 +168,14 @@ loop:
np->n_fhsize = fhsize; np->n_fhsize = fhsize;
*npp = np; *npp = np;
/*
* Wakeup anyone blocked on our lock
*/
if (nfs_node_hash_lock < 0) {
wakeup(&nfs_node_hash_lock);
}
nfs_node_hash_lock = 0;
/* /*
* Lock the new nfsnode. * Lock the new nfsnode.
*/ */