diff options
Diffstat (limited to 'sys/msdosfs')
| -rw-r--r-- | sys/msdosfs/msdosfs_vfsops.c | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/sys/msdosfs/msdosfs_vfsops.c b/sys/msdosfs/msdosfs_vfsops.c index 114644f0e9f..a0de9923ad1 100644 --- a/sys/msdosfs/msdosfs_vfsops.c +++ b/sys/msdosfs/msdosfs_vfsops.c @@ -1,4 +1,4 @@ -/* $OpenBSD: msdosfs_vfsops.c,v 1.42 2006/11/29 13:35:07 deraadt Exp $ */ +/* $OpenBSD: msdosfs_vfsops.c,v 1.43 2006/12/14 07:37:24 tom Exp $ */ /* $NetBSD: msdosfs_vfsops.c,v 1.48 1997/10/18 02:54:57 briggs Exp $ */ /*- @@ -273,6 +273,7 @@ msdosfs_mountfs(devvp, mp, p, argp) int ronly, error, bmapsiz; int bsize = 0, dtype = 0, tmp; uint32_t dirsperblk; + uint32_t fat_max_clusters; /* * Disallow multiple mounts of the same device. @@ -485,6 +486,29 @@ msdosfs_mountfs(devvp, mp, p, argp) else pmp->pm_fatblocksize = MAXBSIZE; + /* + * We now have the number of sectors in each FAT, so can work + * out how many clusters can be represented in a FAT. Let's + * make sure the file system doesn't claim to have more clusters + * than this. + * + * We perform the calculation like we do to avoid integer overflow. + * + * This will give us a count of clusters. They are numbered + * from 0, so the max cluster value is one less than the value + * we end up with. + */ + fat_max_clusters = pmp->pm_fatsize / pmp->pm_fatmult; + fat_max_clusters *= pmp->pm_fatdiv; + if (pmp->pm_maxcluster >= fat_max_clusters) { +#ifndef SMALL_KERNEL + printf("msdosfs: reducing max cluster to %d from %d " + "due to FAT size\n", fat_max_clusters - 1, + pmp->pm_maxcluster); +#endif + pmp->pm_maxcluster = fat_max_clusters - 1; + } + pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec; pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1; |