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- Fix interlock handling in vn_lock(). Previously, vn_lock() could return

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with interlock held in error conditions when the caller did not specify
   LK_INTERLOCK.
 - Add several comments to vn_lock() describing the rational behind the code
   flow since it was not immediately obvious.
This commit is contained in:
Jeff Roberson 2002-08-22 06:51:06 +00:00
parent c4f6a2a9e1
commit 183158485a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=102251
1 changed files with 9 additions and 17 deletions
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26
sys/kern/vfs_subr.c
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@ -931,17 +931,6 @@ getnewvnode(tag, mp, vops, vpp)
splx(s);
#if 0
mp_fixme("This code does not lock access to numvnodes && freevnodes.");
vnodeallocs++;
if (vnodeallocs % vnoderecycleperiod == 0 &&
freevnodes < vnoderecycleminfreevn &&
vnoderecyclemintotalvn < numvnodes) {
/* Recycle vnodes. */
cache_purgeleafdirs(vnoderecyclenumber);
}
#endif
return (0);
}
@ -2183,12 +2172,12 @@ vflush(mp, rootrefs, flags)
nvp = TAILQ_NEXT(vp, v_nmntvnodes);
mtx_unlock(&mntvnode_mtx);
VI_LOCK(vp);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
/*
* Skip over a vnodes marked VV_SYSTEM.
*/
if ((flags & SKIPSYSTEM) && (vp->v_vflag & VV_SYSTEM)) {
VI_UNLOCK(vp);
VOP_UNLOCK(vp, 0, td);
mtx_lock(&mntvnode_mtx);
continue;
}
@ -2197,17 +2186,20 @@ vflush(mp, rootrefs, flags)
* files (even if open only for reading) and regular file
* vnodes open for writing.
*/
mp_fixme("Getattr called with interlock held!");
error = VOP_GETATTR(vp, &vattr, td->td_ucred, td);
VI_LOCK(vp);
if ((flags & WRITECLOSE) &&
(vp->v_type == VNON ||
(VOP_GETATTR(vp, &vattr, td->td_ucred, td) == 0 &&
vattr.va_nlink > 0)) &&
(error == 0 && vattr.va_nlink > 0)) &&
(vp->v_writecount == 0 || vp->v_type != VREG)) {
mtx_unlock(&vp->v_interlock);
VOP_UNLOCK(vp, LK_INTERLOCK, td);
mtx_lock(&mntvnode_mtx);
continue;
}
VOP_UNLOCK(vp, 0, td);
/*
* With v_usecount == 0, all we need to do is clear out the
* vnode data structures and we are done.