msdosfs: fixes for Undefined Behavior

[Stefan Fritsch]

>From FreeBSD commits
    
      commit c0db7289c3de290d821311942d5533f2284af77f
      Author: pfg <p...@freebsd.org>
      Date:   Wed Aug 8 15:08:22 2018 +0000
    
      msdosfs: fixes for Undefined Behavior.
    
and
    
      commit 852150953b828e4e8c32789637061001158a8cf4
      Author: kib <k...@freebsd.org>
      Date:   Fri Oct 11 18:37:02 2019 +0000
    
      Plug the rest of undef behavior places that were missed in r337456.


ok ?

diff --git a/sys/msdosfs/msdosfs_fat.c b/sys/msdosfs/msdosfs_fat.c
index d31abf7d11d..be23e161e29 100644
--- a/sys/msdosfs/msdosfs_fat.c
+++ b/sys/msdosfs/msdosfs_fat.c
@@ -411,7 +411,7 @@ usemap_alloc(struct msdosfsmount *pmp, uint32_t cn)
 {
        KASSERT(cn <= pmp->pm_maxcluster);
 
-       pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
+       pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
        pmp->pm_freeclustercount--;
 }
 
@@ -421,7 +421,7 @@ usemap_free(struct msdosfsmount *pmp, uint32_t cn)
        KASSERT(cn <= pmp->pm_maxcluster);
 
        pmp->pm_freeclustercount++;
-       pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
+       pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS));
 }
 
 int
@@ -652,7 +652,7 @@ chainlength(struct msdosfsmount *pmp, uint32_t start, 
uint32_t count)
        idx = start / N_INUSEBITS;
        start %= N_INUSEBITS;
        map = pmp->pm_inusemap[idx];
-       map &= ~((1 << start) - 1);
+       map &= ~((1U << start) - 1);
        if (map) {
                len = ffs(map) - 1 - start;
                len = MIN(len, count);
@@ -759,7 +759,7 @@ clusteralloc(struct msdosfsmount *pmp, uint32_t start, 
uint32_t count,
        for (cn = newst; cn <= pmp->pm_maxcluster;) {
                idx = cn / N_INUSEBITS;
                map = pmp->pm_inusemap[idx];
-               map |= (1 << (cn % N_INUSEBITS)) - 1;
+               map |= (1U << (cn % N_INUSEBITS)) - 1;
                if (map != (u_int)-1) {
                        cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
                        if ((l = chainlength(pmp, cn, count)) >= count)
@@ -776,7 +776,7 @@ clusteralloc(struct msdosfsmount *pmp, uint32_t start, 
uint32_t count,
        for (cn = 0; cn < newst;) {
                idx = cn / N_INUSEBITS;
                map = pmp->pm_inusemap[idx];
-               map |= (1 << (cn % N_INUSEBITS)) - 1;
+               map |= (1U << (cn % N_INUSEBITS)) - 1;
                if (map != (u_int)-1) {
                        cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
                        if ((l = chainlength(pmp, cn, count)) >= count)