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Code Issues Releases Activity

Provide the mutual exclusion between the nfs export list modifications

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and nfs requests processing. Lockmgr lock provides the shared locking for
nfs requests, while exclusive mode is used for modifications. The writer
starvation is handled by lockmgr too.

Reported by:	kris, pho, many
Based on the submission by:	mohan
Tested by:	pho
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2008-06-09 10:31:38 +00:00
parent e911e766b1
commit a70537835f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=179670
3 changed files with 7 additions and 0 deletions
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4
sys/kern/vfs_export.c
View File

@ -255,6 +255,7 @@ vfs_export(struct mount *mp, struct export_args *argp)
nep = mp->mnt_export;
error = 0;
lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
if (argp->ex_flags & MNT_DELEXPORT) {
if (nep == NULL) {
error = ENOENT;
@ -294,6 +295,7 @@ vfs_export(struct mount *mp, struct export_args *argp)
}
out:
lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
/*
* Once we have executed the vfs_export() command, we do
* not want to keep the "export" option around in the
@ -443,7 +445,9 @@ vfs_stdcheckexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
{
struct netcred *np;
lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
np = vfs_export_lookup(mp, nam);
lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
if (np == NULL)
return (EACCES);
*extflagsp = np->netc_exflags;

2
sys/kern/vfs_mount.c
View File

@ -452,6 +452,7 @@ mount_init(void *mem, int size, int flags)
mp = (struct mount *)mem;
mtx_init(&mp->mnt_mtx, "struct mount mtx", NULL, MTX_DEF);
lockinit(&mp->mnt_lock, PVFS, "vfslock", 0, 0);
lockinit(&mp->mnt_explock, PVFS, "explock", 0, 0);
return (0);
}
@ -461,6 +462,7 @@ mount_fini(void *mem, int size)
struct mount *mp;
mp = (struct mount *)mem;
lockdestroy(&mp->mnt_explock);
lockdestroy(&mp->mnt_lock);
mtx_destroy(&mp->mnt_mtx);
}

1
sys/sys/mount.h
View File

@ -182,6 +182,7 @@ struct mount {
int mnt_secondary_accwrites;/* (i) secondary wr. starts */
#define mnt_endzero mnt_gjprovider
char *mnt_gjprovider; /* gjournal provider name */
struct lock mnt_explock; /* vfs_export walkers lock */
};
struct vnode *__mnt_vnode_next(struct vnode **mvp, struct mount *mp);