int
osi_UFSTruncate(struct osi_file *afile, afs_int32 asize)
{
afs_ucred_t *oldCred;
struct vattr tvattr;
afs_int32 code;
struct osi_stat tstat;
AFS_STATCNT(osi_Truncate);
/* This routine only shrinks files, and most systems
* have very slow truncates, even when the file is already
* small enough. Check now and save some time.
*/
code = afs_osi_Stat(afile, &tstat);
if (code || tstat.size <= asize)
return code;
ObtainWriteLock(&afs_xosi, 321);
VATTR_NULL(&tvattr);
/* note that this credential swapping stuff is only necessary because
* of ufs's references directly to u.u_cred instead of to
* credentials parameter. Probably should fix ufs some day. */
oldCred = p_cred(u.u_procp);
set_p_cred(u.u_procp, &afs_osi_cred);
tvattr.va_size = asize;
AFS_GUNLOCK();
code = VOP_SETATTR(afile->vnode, &tvattr, &afs_osi_cred, 0);
AFS_GLOCK();
set_p_cred(u.u_procp, oldCred); /* restore */
ReleaseWriteLock(&afs_xosi);
return code;
}
/* return a pointer (sometimes a static copy ) to the cred for a
* given afs_proc_t.
* subsequent calls may overwrite the previously returned value.
*/
const afs_ucred_t *
afs_osi_proc2cred(afs_proc_t * p)
{
if (!p)
return;
/*
* Cannot use afs_warnuser() here, as the code path
* eventually wants to grab sched_lock, which is
* already held here
*/
return p_cred(p);
}
