示例#1
0
int
msdosfs_mountfs(struct vnode *devvp, struct mount *mp, struct proc *p,
    struct msdosfs_args *argp)
{
	struct msdosfsmount *pmp;
	struct buf *bp;
	dev_t dev = devvp->v_rdev;
	union bootsector *bsp;
	struct byte_bpb33 *b33;
	struct byte_bpb50 *b50;
	struct byte_bpb710 *b710;
	extern struct vnode *rootvp;
	u_int8_t SecPerClust;
	int	ronly, error, bmapsiz;
	uint32_t fat_max_clusters;

	/*
	 * Disallow multiple mounts of the same device.
	 * Disallow mounting of a device that is currently in use
	 * (except for root, which might share swap device for miniroot).
	 * Flush out any old buffers remaining from a previous use.
	 */
	if ((error = vfs_mountedon(devvp)) != 0)
		return (error);
	if (vcount(devvp) > 1 && devvp != rootvp)
		return (EBUSY);
	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, p);
	error = vinvalbuf(devvp, V_SAVE, p->p_ucred, p, 0, 0);
	VOP_UNLOCK(devvp, 0, p);
	if (error)
		return (error);

	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
	error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED, p);
	if (error)
		return (error);

	bp  = NULL; /* both used in error_exit */
	pmp = NULL;

	/*
	 * Read the boot sector of the filesystem, and then check the
	 * boot signature.  If not a dos boot sector then error out.
	 */
	if ((error = bread(devvp, 0, 4096, NOCRED, &bp)) != 0)
		goto error_exit;
	bp->b_flags |= B_AGE;
	bsp = (union bootsector *)bp->b_data;
	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
	b710 = (struct byte_bpb710 *)bsp->bs710.bsPBP;

	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
	pmp->pm_mountp = mp;

	/*
	 * Compute several useful quantities from the bpb in the
	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
	 * the fields that are different between dos 5 and dos 3.3.
	 */
	SecPerClust = b50->bpbSecPerClust;
	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
	pmp->pm_FATs = b50->bpbFATs;
	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
	pmp->pm_Sectors = getushort(b50->bpbSectors);
	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
	pmp->pm_Heads = getushort(b50->bpbHeads);
	pmp->pm_Media = b50->bpbMedia;

	/* Determine the number of DEV_BSIZE blocks in a MSDOSFS sector */
	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;

    	if (!pmp->pm_BytesPerSec || !SecPerClust || pmp->pm_SecPerTrack > 64) {
		error = EFTYPE;
		goto error_exit;
	}

	if (pmp->pm_Sectors == 0) {
		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
	} else {
		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
		pmp->pm_HugeSectors = pmp->pm_Sectors;
	}

	if (pmp->pm_RootDirEnts == 0) {
		if (pmp->pm_Sectors || pmp->pm_FATsecs ||
		    getushort(b710->bpbFSVers)) {
		        error = EINVAL;
			goto error_exit;
		}
		pmp->pm_fatmask = FAT32_MASK;
		pmp->pm_fatmult = 4;
		pmp->pm_fatdiv = 1;
		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
		if (getushort(b710->bpbExtFlags) & FATMIRROR)
		        pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
		else
		        pmp->pm_flags |= MSDOSFS_FATMIRROR;
	} else
	        pmp->pm_flags |= MSDOSFS_FATMIRROR;

	/*
	 * More sanity checks:
	 *	MSDOSFS sectors per cluster: >0 && power of 2
	 *	MSDOSFS sector size: >= DEV_BSIZE && power of 2
	 *	HUGE sector count: >0
	 * 	FAT sectors: >0
	 */
	if ((SecPerClust == 0) || (SecPerClust & (SecPerClust - 1)) ||
	    (pmp->pm_BytesPerSec < DEV_BSIZE) ||
	    (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1)) ||
	    (pmp->pm_HugeSectors == 0) || (pmp->pm_FATsecs == 0)) {
		error = EINVAL;
		goto error_exit;
	}		
	
	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;
	pmp->pm_FATsecs *= pmp->pm_BlkPerSec;
	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
	SecPerClust *= pmp->pm_BlkPerSec;

	if (FAT32(pmp)) {
	        pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
		pmp->pm_firstcluster = pmp->pm_fatblk
		        + (pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
	} else {
	        pmp->pm_rootdirblk = pmp->pm_fatblk +
		        (pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
				       + DEV_BSIZE - 1) / DEV_BSIZE;
		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
	}

	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
	    SecPerClust;
	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;

	if (pmp->pm_fatmask == 0) {
		if (pmp->pm_maxcluster
		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
			/*
			 * This will usually be a floppy disk. This size makes
			 * sure that one fat entry will not be split across
			 * multiple blocks.
			 */
			pmp->pm_fatmask = FAT12_MASK;
			pmp->pm_fatmult = 3;
			pmp->pm_fatdiv = 2;
		} else {
			pmp->pm_fatmask = FAT16_MASK;
			pmp->pm_fatmult = 2;
			pmp->pm_fatdiv = 1;
		}
	}
	if (FAT12(pmp))
		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
	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 / DEV_BSIZE;
	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;

	/*
	 * Compute mask and shift value for isolating cluster relative byte
	 * offsets and cluster numbers from a file offset.
	 */
	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;

	/*
	 * Check for valid cluster size
	 * must be a power of 2
	 */
	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
		error = EFTYPE;
		goto error_exit;
	}

	/*
	 * Release the bootsector buffer.
	 */
	brelse(bp);
	bp = NULL;

	/*
	 * Check FSInfo
	 */
	if (pmp->pm_fsinfo) {
	        struct fsinfo *fp;

		if ((error = bread(devvp, pmp->pm_fsinfo, fsi_size(pmp),
		    NOCRED, &bp)) != 0)
		        goto error_exit;
		fp = (struct fsinfo *)bp->b_data;
		if (!bcmp(fp->fsisig1, "RRaA", 4)
		    && !bcmp(fp->fsisig2, "rrAa", 4)
		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)
		    && !bcmp(fp->fsisig4, "\0\0\125\252", 4))
		        /* Valid FSInfo. */
			;
		else
		        pmp->pm_fsinfo = 0;
		/* XXX make sure this tiny buf doesn't come back in fillinusemap! */
		SET(bp->b_flags, B_INVAL);
		brelse(bp);
		bp = NULL;
	}

	/*
	 * Check and validate (or perhaps invalidate?) the fsinfo structure? XXX
	 */

	/*
	 * Allocate memory for the bitmap of allocated clusters, and then
	 * fill it in.
	 */
	bmapsiz = (pmp->pm_maxcluster + N_INUSEBITS - 1) / N_INUSEBITS;
	if (bmapsiz == 0 || SIZE_MAX / bmapsiz < sizeof(*pmp->pm_inusemap)) {
		/* detect multiplicative integer overflow */
		error = EINVAL;
		goto error_exit;
	}
	pmp->pm_inusemap = malloc(bmapsiz * sizeof(*pmp->pm_inusemap),
	    M_MSDOSFSFAT, M_WAITOK | M_CANFAIL);
	if (pmp->pm_inusemap == NULL) {
		error = EINVAL;
		goto error_exit;
	}

	/*
	 * fillinusemap() needs pm_devvp.
	 */
	pmp->pm_dev = dev;
	pmp->pm_devvp = devvp;

	/*
	 * Have the inuse map filled in.
	 */
	if ((error = fillinusemap(pmp)) != 0)
		goto error_exit;

	/*
	 * If they want fat updates to be synchronous then let them suffer
	 * the performance degradation in exchange for the on disk copy of
	 * the fat being correct just about all the time.  I suppose this
	 * would be a good thing to turn on if the kernel is still flakey.
	 */
	if (mp->mnt_flag & MNT_SYNCHRONOUS)
		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;

	/*
	 * Finish up.
	 */
	if (ronly)
		pmp->pm_flags |= MSDOSFSMNT_RONLY;
	else
		pmp->pm_fmod = 1;
	mp->mnt_data = (qaddr_t)pmp;
        mp->mnt_stat.f_fsid.val[0] = (long)dev;
        mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
#ifdef QUOTA
	/*
	 * If we ever do quotas for DOS filesystems this would be a place
	 * to fill in the info in the msdosfsmount structure. You dolt,
	 * quotas on dos filesystems make no sense because files have no
	 * owners on dos filesystems. of course there is some empty space
	 * in the directory entry where we could put uid's and gid's.
	 */
#endif
	devvp->v_specmountpoint = mp;

	return (0);

error_exit:
	devvp->v_specmountpoint = NULL;
	if (bp)
		brelse(bp);

	vn_lock(devvp, LK_EXCLUSIVE|LK_RETRY, p);
	(void) VOP_CLOSE(devvp, ronly ? FREAD : FREAD|FWRITE, NOCRED, p);
	VOP_UNLOCK(devvp, 0, p);

	if (pmp) {
		if (pmp->pm_inusemap)
			free(pmp->pm_inusemap, M_MSDOSFSFAT);
		free(pmp, M_MSDOSFSMNT);
		mp->mnt_data = (qaddr_t)0;
	}
	return (error);
}
示例#2
0
int
msdosfs_mountfs(struct vnode *devvp, struct mount *mp, struct lwp *l, struct msdosfs_args *argp)
{
	struct msdosfsmount *pmp;
	struct buf *bp;
	dev_t dev = devvp->v_rdev;
	union bootsector *bsp;
	struct byte_bpb33 *b33;
	struct byte_bpb50 *b50;
	struct byte_bpb710 *b710;
	uint8_t SecPerClust;
	int	ronly, error, tmp;
	int	bsize;
	uint64_t psize;
	unsigned secsize;

	/* Flush out any old buffers remaining from a previous use. */
	if ((error = vinvalbuf(devvp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
		return (error);

	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;

	bp  = NULL; /* both used in error_exit */
	pmp = NULL;

	error = fstrans_mount(mp);
	if (error)
		goto error_exit;

	error = getdisksize(devvp, &psize, &secsize);
	if (error) {
		if (argp->flags & MSDOSFSMNT_GEMDOSFS)
			goto error_exit;

		/* ok, so it failed.  we most likely don't need the info */
		secsize = DEV_BSIZE;
		psize = 0;
		error = 0;
	}

	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
		bsize = secsize;
		if (bsize != 512) {
			DPRINTF(("Invalid block bsize %d for GEMDOS\n", bsize));
			error = EINVAL;
			goto error_exit;
		}
	} else
		bsize = 0;

	/*
	 * Read the boot sector of the filesystem, and then check the
	 * boot signature.  If not a dos boot sector then error out.
	 */
	if ((error = bread(devvp, 0, secsize, NOCRED, 0, &bp)) != 0)
		goto error_exit;
	bsp = (union bootsector *)bp->b_data;
	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;

	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
		if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
		    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
			DPRINTF(("bootsig0 %d bootsig1 %d\n", 
			    bsp->bs50.bsBootSectSig0,
			    bsp->bs50.bsBootSectSig1));
			error = EINVAL;
			goto error_exit;
		}
	}

	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK);
	memset(pmp, 0, sizeof *pmp);
	pmp->pm_mountp = mp;

	/*
	 * Compute several useful quantities from the bpb in the
	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
	 * the fields that are different between dos 5 and dos 3.3.
	 */
	SecPerClust = b50->bpbSecPerClust;
	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
	pmp->pm_FATs = b50->bpbFATs;
	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
	pmp->pm_Sectors = getushort(b50->bpbSectors);
	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
	pmp->pm_Heads = getushort(b50->bpbHeads);
	pmp->pm_Media = b50->bpbMedia;

	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
		/* XXX - We should probably check more values here */
    		if (!pmp->pm_BytesPerSec || !SecPerClust
	    		|| pmp->pm_SecPerTrack > 63) {
			DPRINTF(("bytespersec %d secperclust %d "
			    "secpertrack %d\n", 
			    pmp->pm_BytesPerSec, SecPerClust,
			    pmp->pm_SecPerTrack));
			error = EINVAL;
			goto error_exit;
		}
	}

	if (pmp->pm_Sectors == 0) {
		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
	} else {
		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
		pmp->pm_HugeSectors = pmp->pm_Sectors;
	}

	if (pmp->pm_RootDirEnts == 0) {
		unsigned short vers = getushort(b710->bpbFSVers);
		/*
		 * Some say that bsBootSectSig[23] must be zero, but
		 * Windows does not require this and some digital cameras
		 * do not set these to zero.  Therefore, do not insist.
		 */
		if (pmp->pm_Sectors || pmp->pm_FATsecs || vers) {
			DPRINTF(("sectors %d fatsecs %lu vers %d\n",
			    pmp->pm_Sectors, pmp->pm_FATsecs, vers));
			error = EINVAL;
			goto error_exit;
		}
		pmp->pm_fatmask = FAT32_MASK;
		pmp->pm_fatmult = 4;
		pmp->pm_fatdiv = 1;
		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);

		/* mirrorring is enabled if the FATMIRROR bit is not set */
		if ((getushort(b710->bpbExtFlags) & FATMIRROR) == 0)
			pmp->pm_flags |= MSDOSFS_FATMIRROR;
		else
			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
	} else
		pmp->pm_flags |= MSDOSFS_FATMIRROR;

	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
		if (FAT32(pmp)) {
			DPRINTF(("FAT32 for GEMDOS\n"));
			/*
			 * GEMDOS doesn't know FAT32.
			 */
			error = EINVAL;
			goto error_exit;
		}

		/*
		 * Check a few values (could do some more):
		 * - logical sector size: power of 2, >= block size
		 * - sectors per cluster: power of 2, >= 1
		 * - number of sectors:   >= 1, <= size of partition
		 */
		if ( (SecPerClust == 0)
		  || (SecPerClust & (SecPerClust - 1))
		  || (pmp->pm_BytesPerSec < bsize)
		  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
		  || (pmp->pm_HugeSectors == 0)
		  || (pmp->pm_HugeSectors * (pmp->pm_BytesPerSec / bsize)
		      > psize)) {
			DPRINTF(("consistency checks for GEMDOS\n"));
			error = EINVAL;
			goto error_exit;
		}
		/*
		 * XXX - Many parts of the msdosfs driver seem to assume that
		 * the number of bytes per logical sector (BytesPerSec) will
		 * always be the same as the number of bytes per disk block
		 * Let's pretend it is.
		 */
		tmp = pmp->pm_BytesPerSec / bsize;
		pmp->pm_BytesPerSec  = bsize;
		pmp->pm_HugeSectors *= tmp;
		pmp->pm_HiddenSects *= tmp;
		pmp->pm_ResSectors  *= tmp;
		pmp->pm_Sectors     *= tmp;
		pmp->pm_FATsecs     *= tmp;
		SecPerClust         *= tmp;
	}

	/* Check that fs has nonzero FAT size */
	if (pmp->pm_FATsecs == 0) {
		DPRINTF(("FATsecs is 0\n"));
		error = EINVAL;
		goto error_exit;
	}

	pmp->pm_fatblk = pmp->pm_ResSectors;
	if (FAT32(pmp)) {
		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
		pmp->pm_firstcluster = pmp->pm_fatblk
			+ (pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_fsinfo = getushort(b710->bpbFSInfo);
	} else {
		pmp->pm_rootdirblk = pmp->pm_fatblk +
			(pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
				       + pmp->pm_BytesPerSec - 1)
			/ pmp->pm_BytesPerSec;/* in sectors */
		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
	}

	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
	    SecPerClust;
	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
	pmp->pm_fatsize = pmp->pm_FATsecs * pmp->pm_BytesPerSec;

	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
		if (pmp->pm_nmbrofclusters <= (0xff0 - 2)) {
			pmp->pm_fatmask = FAT12_MASK;
			pmp->pm_fatmult = 3;
			pmp->pm_fatdiv = 2;
		} else {
			pmp->pm_fatmask = FAT16_MASK;
			pmp->pm_fatmult = 2;
			pmp->pm_fatdiv = 1;
		}
	} else if (pmp->pm_fatmask == 0) {
		if (pmp->pm_maxcluster
		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
			/*
			 * This will usually be a floppy disk. This size makes
			 * sure that one FAT entry will not be split across
			 * multiple blocks.
			 */
			pmp->pm_fatmask = FAT12_MASK;
			pmp->pm_fatmult = 3;
			pmp->pm_fatdiv = 2;
		} else {
			pmp->pm_fatmask = FAT16_MASK;
			pmp->pm_fatmult = 2;
			pmp->pm_fatdiv = 1;
		}
	}
	if (FAT12(pmp))
		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
	else
		pmp->pm_fatblocksize = MAXBSIZE;

	pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;
	pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1;

	/*
	 * Compute mask and shift value for isolating cluster relative byte
	 * offsets and cluster numbers from a file offset.
	 */
	pmp->pm_bpcluster = SecPerClust * pmp->pm_BytesPerSec;
	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;

	/*
	 * Check for valid cluster size
	 * must be a power of 2
	 */
	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
		DPRINTF(("bpcluster %lu cnshift %lu\n", 
		    pmp->pm_bpcluster, pmp->pm_cnshift));
		error = EINVAL;
		goto error_exit;
	}

	/*
	 * Cluster size must be within limit of MAXBSIZE.
	 * Many FAT filesystems will not have clusters larger than
	 * 32KiB due to limits in Windows versions before Vista.
	 */
	if (pmp->pm_bpcluster > MAXBSIZE) {
		DPRINTF(("bpcluster %lu > MAXBSIZE %d\n",
		    pmp->pm_bpcluster, MAXBSIZE));
		error = EINVAL;
		goto error_exit;
	}

	/*
	 * Release the bootsector buffer.
	 */
	brelse(bp, BC_AGE);
	bp = NULL;

	/*
	 * Check FSInfo.
	 */
	if (pmp->pm_fsinfo) {
		struct fsinfo *fp;

		/*
		 * XXX	If the fsinfo block is stored on media with
		 *	2KB or larger sectors, is the fsinfo structure
		 *	padded at the end or in the middle?
		 */
		if ((error = bread(devvp, de_bn2kb(pmp, pmp->pm_fsinfo),
		    pmp->pm_BytesPerSec, NOCRED, 0, &bp)) != 0)
			goto error_exit;
		fp = (struct fsinfo *)bp->b_data;
		if (!memcmp(fp->fsisig1, "RRaA", 4)
		    && !memcmp(fp->fsisig2, "rrAa", 4)
		    && !memcmp(fp->fsisig3, "\0\0\125\252", 4)
		    && !memcmp(fp->fsisig4, "\0\0\125\252", 4))
			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
		else
			pmp->pm_fsinfo = 0;
		brelse(bp, 0);
		bp = NULL;
	}

	/*
	 * Check and validate (or perhaps invalidate?) the fsinfo structure?
	 * XXX
	 */
	if (pmp->pm_fsinfo) {
		if ((pmp->pm_nxtfree == 0xffffffffUL) ||
		    (pmp->pm_nxtfree > pmp->pm_maxcluster))
			pmp->pm_fsinfo = 0;
	}

	/*
	 * Allocate memory for the bitmap of allocated clusters, and then
	 * fill it in.
	 */
	pmp->pm_inusemap = malloc(((pmp->pm_maxcluster + N_INUSEBITS)
				   / N_INUSEBITS)
				  * sizeof(*pmp->pm_inusemap),
				  M_MSDOSFSFAT, M_WAITOK);

	/*
	 * fillinusemap() needs pm_devvp.
	 */
	pmp->pm_dev = dev;
	pmp->pm_devvp = devvp;

	/*
	 * Have the inuse map filled in.
	 */
	if ((error = fillinusemap(pmp)) != 0) {
		DPRINTF(("fillinusemap %d\n", error));
		goto error_exit;
	}

	/*
	 * If they want FAT updates to be synchronous then let them suffer
	 * the performance degradation in exchange for the on disk copy of
	 * the FAT being correct just about all the time.  I suppose this
	 * would be a good thing to turn on if the kernel is still flakey.
	 */
	if (mp->mnt_flag & MNT_SYNCHRONOUS)
		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;

	/*
	 * Finish up.
	 */
	if (ronly)
		pmp->pm_flags |= MSDOSFSMNT_RONLY;
	else
		pmp->pm_fmod = 1;
	mp->mnt_data = pmp;
	mp->mnt_stat.f_fsidx.__fsid_val[0] = (long)dev;
	mp->mnt_stat.f_fsidx.__fsid_val[1] = makefstype(MOUNT_MSDOS);
	mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
	mp->mnt_stat.f_namemax = MSDOSFS_NAMEMAX(pmp);
	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_dev_bshift = pmp->pm_bnshift;
	mp->mnt_fs_bshift = pmp->pm_cnshift;

	/*
	 * If we ever do quotas for DOS filesystems this would be a place
	 * to fill in the info in the msdosfsmount structure. You dolt,
	 * quotas on dos filesystems make no sense because files have no
	 * owners on dos filesystems. of course there is some empty space
	 * in the directory entry where we could put uid's and gid's.
	 */

	spec_node_setmountedfs(devvp, mp);

	return (0);

error_exit:
	fstrans_unmount(mp);
	if (bp)
		brelse(bp, BC_AGE);
	if (pmp) {
		if (pmp->pm_inusemap)
			free(pmp->pm_inusemap, M_MSDOSFSFAT);
		free(pmp, M_MSDOSFSMNT);
		mp->mnt_data = NULL;
	}
	return (error);
}
示例#3
0
static int
mountmsdosfs(struct vnode *devvp, struct mount *mp)
{
	struct msdosfsmount *pmp;
	struct buf *bp;
	struct cdev *dev;
	union bootsector *bsp;
	struct byte_bpb33 *b33;
	struct byte_bpb50 *b50;
	struct byte_bpb710 *b710;
	u_int8_t SecPerClust;
	u_long clusters;
	int ronly, error;
	struct g_consumer *cp;
	struct bufobj *bo;

	bp = NULL;		/* This and pmp both used in error_exit. */
	pmp = NULL;
	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;

	dev = devvp->v_rdev;
	dev_ref(dev);
	DROP_GIANT();
	g_topology_lock();
	error = g_vfs_open(devvp, &cp, "msdosfs", ronly ? 0 : 1);
	g_topology_unlock();
	PICKUP_GIANT();
	VOP_UNLOCK(devvp, 0);
	if (error)
		goto error_exit;

	bo = &devvp->v_bufobj;

	/*
	 * Read the boot sector of the filesystem, and then check the
	 * boot signature.  If not a dos boot sector then error out.
	 *
	 * NOTE: 8192 is a magic size that works for ffs.
	 */
	error = bread(devvp, 0, 8192, NOCRED, &bp);
	if (error)
		goto error_exit;
	bp->b_flags |= B_AGE;
	bsp = (union bootsector *)bp->b_data;
	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;

#ifndef MSDOSFS_NOCHECKSIG
	if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
	    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
		error = EINVAL;
		goto error_exit;
	}
#endif

	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
	pmp->pm_mountp = mp;
	pmp->pm_cp = cp;
	pmp->pm_bo = bo;

	lockinit(&pmp->pm_fatlock, 0, msdosfs_lock_msg, 0, 0);

	/*
	 * Initialize ownerships and permissions, since nothing else will
	 * initialize them iff we are mounting root.
	 */
	pmp->pm_uid = UID_ROOT;
	pmp->pm_gid = GID_WHEEL;
	pmp->pm_mask = pmp->pm_dirmask = S_IXUSR | S_IXGRP | S_IXOTH |
	    S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR;

	/*
	 * Experimental support for large MS-DOS filesystems.
	 * WARNING: This uses at least 32 bytes of kernel memory (which is not
	 * reclaimed until the FS is unmounted) for each file on disk to map
	 * between the 32-bit inode numbers used by VFS and the 64-bit
	 * pseudo-inode numbers used internally by msdosfs. This is only
	 * safe to use in certain controlled situations (e.g. read-only FS
	 * with less than 1 million files).
	 * Since the mappings do not persist across unmounts (or reboots), these
	 * filesystems are not suitable for exporting through NFS, or any other
	 * application that requires fixed inode numbers.
	 */
	vfs_flagopt(mp->mnt_optnew, "large", &pmp->pm_flags, MSDOSFS_LARGEFS);

	/*
	 * Compute several useful quantities from the bpb in the
	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
	 * the fields that are different between dos 5 and dos 3.3.
	 */
	SecPerClust = b50->bpbSecPerClust;
	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
	if (pmp->pm_BytesPerSec < DEV_BSIZE) {
		error = EINVAL;
		goto error_exit;
	}
	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
	pmp->pm_FATs = b50->bpbFATs;
	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
	pmp->pm_Sectors = getushort(b50->bpbSectors);
	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
	pmp->pm_Heads = getushort(b50->bpbHeads);
	pmp->pm_Media = b50->bpbMedia;

	/* calculate the ratio of sector size to DEV_BSIZE */
	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;

	/*
	 * We don't check pm_Heads nor pm_SecPerTrack, because
	 * these may not be set for EFI file systems. We don't
	 * use these anyway, so we're unaffected if they are
	 * invalid.
	 */
	if (!pmp->pm_BytesPerSec || !SecPerClust) {
		error = EINVAL;
		goto error_exit;
	}

	if (pmp->pm_Sectors == 0) {
		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
	} else {
		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
		pmp->pm_HugeSectors = pmp->pm_Sectors;
	}
	if (!(pmp->pm_flags & MSDOSFS_LARGEFS)) {
		if (pmp->pm_HugeSectors > 0xffffffff /
		    (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1) {
			/*
			 * We cannot deal currently with this size of disk
			 * due to fileid limitations (see msdosfs_getattr and
			 * msdosfs_readdir)
			 */
			error = EINVAL;
			vfs_mount_error(mp,
			    "Disk too big, try '-o large' mount option");
			goto error_exit;
		}
	}

	if (pmp->pm_RootDirEnts == 0) {
		if (pmp->pm_FATsecs
		    || getushort(b710->bpbFSVers)) {
			error = EINVAL;
#ifdef MSDOSFS_DEBUG
			printf("mountmsdosfs(): bad FAT32 filesystem\n");
#endif
			goto error_exit;
		}
		pmp->pm_fatmask = FAT32_MASK;
		pmp->pm_fatmult = 4;
		pmp->pm_fatdiv = 1;
		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
		if (getushort(b710->bpbExtFlags) & FATMIRROR)
			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
		else
			pmp->pm_flags |= MSDOSFS_FATMIRROR;
	} else
		pmp->pm_flags |= MSDOSFS_FATMIRROR;

	/*
	 * Check a few values (could do some more):
	 * - logical sector size: power of 2, >= block size
	 * - sectors per cluster: power of 2, >= 1
	 * - number of sectors:   >= 1, <= size of partition
	 * - number of FAT sectors: >= 1
	 */
	if ( (SecPerClust == 0)
	  || (SecPerClust & (SecPerClust - 1))
	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
	  || (pmp->pm_HugeSectors == 0)
	  || (pmp->pm_FATsecs == 0)
	  || (SecPerClust * pmp->pm_BlkPerSec > MAXBSIZE / DEV_BSIZE)
	) {
		error = EINVAL;
		goto error_exit;
	}

	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;	/* XXX not used? */
	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
	SecPerClust         *= pmp->pm_BlkPerSec;

	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;

	if (FAT32(pmp)) {
		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
		pmp->pm_firstcluster = pmp->pm_fatblk
			+ (pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
	} else {
		pmp->pm_rootdirblk = pmp->pm_fatblk +
			(pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_rootdirsize = howmany(pmp->pm_RootDirEnts *
			sizeof(struct direntry), DEV_BSIZE); /* in blocks */
		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
	}

	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
	    SecPerClust + 1;
	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;	/* XXX not used? */

	if (pmp->pm_fatmask == 0) {
		if (pmp->pm_maxcluster
		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
			/*
			 * This will usually be a floppy disk. This size makes
			 * sure that one fat entry will not be split across
			 * multiple blocks.
			 */
			pmp->pm_fatmask = FAT12_MASK;
			pmp->pm_fatmult = 3;
			pmp->pm_fatdiv = 2;
		} else {
			pmp->pm_fatmask = FAT16_MASK;
			pmp->pm_fatmult = 2;
			pmp->pm_fatdiv = 1;
		}
	}

	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
	if (pmp->pm_maxcluster >= clusters) {
#ifdef MSDOSFS_DEBUG
		printf("Warning: number of clusters (%ld) exceeds FAT "
		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
#endif
		pmp->pm_maxcluster = clusters - 1;
	}

	if (FAT12(pmp))
		pmp->pm_fatblocksize = 3 * 512;
	else
		pmp->pm_fatblocksize = PAGE_SIZE;
	pmp->pm_fatblocksize = roundup(pmp->pm_fatblocksize,
	    pmp->pm_BytesPerSec);
	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;

	/*
	 * Compute mask and shift value for isolating cluster relative byte
	 * offsets and cluster numbers from a file offset.
	 */
	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;

	/*
	 * Check for valid cluster size
	 * must be a power of 2
	 */
	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
		error = EINVAL;
		goto error_exit;
	}

	/*
	 * Release the bootsector buffer.
	 */
	brelse(bp);
	bp = NULL;

	/*
	 * Check the fsinfo sector if we have one.  Silently fix up our
	 * in-core copy of fp->fsinxtfree if it is unknown (0xffffffff)
	 * or too large.  Ignore fp->fsinfree for now, since we need to
	 * read the entire FAT anyway to fill the inuse map.
	 */
	if (pmp->pm_fsinfo) {
		struct fsinfo *fp;

		if ((error = bread(devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
		    NOCRED, &bp)) != 0)
			goto error_exit;
		fp = (struct fsinfo *)bp->b_data;
		if (!bcmp(fp->fsisig1, "RRaA", 4)
		    && !bcmp(fp->fsisig2, "rrAa", 4)
		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)) {
			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
			if (pmp->pm_nxtfree > pmp->pm_maxcluster)
				pmp->pm_nxtfree = CLUST_FIRST;
		} else
			pmp->pm_fsinfo = 0;
		brelse(bp);
		bp = NULL;
	}

	/*
	 * Finish initializing pmp->pm_nxtfree (just in case the first few
	 * sectors aren't properly reserved in the FAT).  This completes
	 * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
	 * value if there is no fsinfo.  We will use pmp->pm_nxtfree
	 * internally even if there is no fsinfo.
	 */
	if (pmp->pm_nxtfree < CLUST_FIRST)
		pmp->pm_nxtfree = CLUST_FIRST;

	/*
	 * Allocate memory for the bitmap of allocated clusters, and then
	 * fill it in.
	 */
	pmp->pm_inusemap = malloc(howmany(pmp->pm_maxcluster + 1, N_INUSEBITS)
				  * sizeof(*pmp->pm_inusemap),
				  M_MSDOSFSFAT, M_WAITOK);

	/*
	 * fillinusemap() needs pm_devvp.
	 */
	pmp->pm_devvp = devvp;
	pmp->pm_dev = dev;

	/*
	 * Have the inuse map filled in.
	 */
	MSDOSFS_LOCK_MP(pmp);
	error = fillinusemap(pmp);
	MSDOSFS_UNLOCK_MP(pmp);
	if (error != 0)
		goto error_exit;

	/*
	 * If they want fat updates to be synchronous then let them suffer
	 * the performance degradation in exchange for the on disk copy of
	 * the fat being correct just about all the time.  I suppose this
	 * would be a good thing to turn on if the kernel is still flakey.
	 */
	if (mp->mnt_flag & MNT_SYNCHRONOUS)
		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;

	/*
	 * Finish up.
	 */
	if (ronly)
		pmp->pm_flags |= MSDOSFSMNT_RONLY;
	else {
		if ((error = markvoldirty(pmp, 1)) != 0) {
			(void)markvoldirty(pmp, 0);
			goto error_exit;
		}
		pmp->pm_fmod = 1;
	}
	mp->mnt_data =  pmp;
	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
	MNT_IUNLOCK(mp);

	if (pmp->pm_flags & MSDOSFS_LARGEFS)
		msdosfs_fileno_init(mp);

	return 0;

error_exit:
	if (bp)
		brelse(bp);
	if (cp != NULL) {
		DROP_GIANT();
		g_topology_lock();
		g_vfs_close(cp);
		g_topology_unlock();
		PICKUP_GIANT();
	}
	if (pmp) {
		lockdestroy(&pmp->pm_fatlock);
		if (pmp->pm_inusemap)
			free(pmp->pm_inusemap, M_MSDOSFSFAT);
		free(pmp, M_MSDOSFSMNT);
		mp->mnt_data = NULL;
	}
	dev_rel(dev);
	return (error);
}
示例#4
0
struct msdosfsmount *
msdosfs_mount(struct vnode *devvp, int flags)
{
	struct msdosfsmount *pmp = NULL;
	struct buf *bp;
	union bootsector *bsp;
	struct byte_bpb33 *b33;
	struct byte_bpb50 *b50;
	struct byte_bpb710 *b710;
	uint8_t SecPerClust;
	int	ronly = 0, error, tmp;
	int	bsize;
	struct msdos_options *m = devvp->fs->fs_specific;
	uint64_t psize = m->create_size;
	unsigned secsize = 512;

	DPRINTF(("%s(bread 0)\n", __func__));
	if ((error = bread(devvp, 0, secsize, NULL, 0, &bp)) != 0)
		goto error_exit;

	bsp = (union bootsector *)bp->b_data;
	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;

	if (!(flags & MSDOSFSMNT_GEMDOSFS)) {
		if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
		    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
			DPRINTF(("bootsig0 %d bootsig1 %d\n", 
			    bsp->bs50.bsBootSectSig0,
			    bsp->bs50.bsBootSectSig1));
			error = EINVAL;
			goto error_exit;
		}
		bsize = 0;
	} else
		bsize = 512;

	pmp = ecalloc(1, sizeof *pmp);
	/*
	 * Compute several useful quantities from the bpb in the
	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
	 * the fields that are different between dos 5 and dos 3.3.
	 */
	SecPerClust = b50->bpbSecPerClust;
	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
	pmp->pm_FATs = b50->bpbFATs;
	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
	pmp->pm_Sectors = getushort(b50->bpbSectors);
	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
	pmp->pm_Heads = getushort(b50->bpbHeads);
	pmp->pm_Media = b50->bpbMedia;

	DPRINTF(("%s(BytesPerSec=%u, ResSectors=%u, FATs=%d, RootDirEnts=%u, "
	    "Sectors=%u, FATsecs=%lu, SecPerTrack=%u, Heads=%u, Media=%u)\n",
	    __func__, pmp->pm_BytesPerSec, pmp->pm_ResSectors, pmp->pm_FATs,
	    pmp->pm_RootDirEnts, pmp->pm_Sectors, pmp->pm_FATsecs,
	    pmp->pm_SecPerTrack, pmp->pm_Heads, pmp->pm_Media));
	if (!(flags & MSDOSFSMNT_GEMDOSFS)) {
		/* XXX - We should probably check more values here */
    		if (!pmp->pm_BytesPerSec || !SecPerClust
	    		|| pmp->pm_SecPerTrack > 63) {
			DPRINTF(("bytespersec %d secperclust %d "
			    "secpertrack %d\n", 
			    pmp->pm_BytesPerSec, SecPerClust,
			    pmp->pm_SecPerTrack));
			error = EINVAL;
			goto error_exit;
		}
	}

	if (pmp->pm_Sectors == 0) {
		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
	} else {
		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
		pmp->pm_HugeSectors = pmp->pm_Sectors;
	}

	if (pmp->pm_RootDirEnts == 0) {
		unsigned short vers = getushort(b710->bpbFSVers);
		/*
		 * Some say that bsBootSectSig[23] must be zero, but
		 * Windows does not require this and some digital cameras
		 * do not set these to zero.  Therefore, do not insist.
		 */
		if (pmp->pm_Sectors || pmp->pm_FATsecs || vers) {
			DPRINTF(("sectors %d fatsecs %lu vers %d\n",
			    pmp->pm_Sectors, pmp->pm_FATsecs, vers));
			error = EINVAL;
			goto error_exit;
		}
		pmp->pm_fatmask = FAT32_MASK;
		pmp->pm_fatmult = 4;
		pmp->pm_fatdiv = 1;
		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);

		/* mirrorring is enabled if the FATMIRROR bit is not set */
		if ((getushort(b710->bpbExtFlags) & FATMIRROR) == 0)
			pmp->pm_flags |= MSDOSFS_FATMIRROR;
		else
			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
	} else
		pmp->pm_flags |= MSDOSFS_FATMIRROR;

	if (flags & MSDOSFSMNT_GEMDOSFS) {
		if (FAT32(pmp)) {
			DPRINTF(("FAT32 for GEMDOS\n"));
			/*
			 * GEMDOS doesn't know FAT32.
			 */
			error = EINVAL;
			goto error_exit;
		}

		/*
		 * Check a few values (could do some more):
		 * - logical sector size: power of 2, >= block size
		 * - sectors per cluster: power of 2, >= 1
		 * - number of sectors:   >= 1, <= size of partition
		 */
		if ( (SecPerClust == 0)
		  || (SecPerClust & (SecPerClust - 1))
		  || (pmp->pm_BytesPerSec < bsize)
		  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
		  || (pmp->pm_HugeSectors == 0)
		  || (pmp->pm_HugeSectors * (pmp->pm_BytesPerSec / bsize)
		      > psize)) {
			DPRINTF(("consistency checks for GEMDOS\n"));
			error = EINVAL;
			goto error_exit;
		}
		/*
		 * XXX - Many parts of the msdosfs driver seem to assume that
		 * the number of bytes per logical sector (BytesPerSec) will
		 * always be the same as the number of bytes per disk block
		 * Let's pretend it is.
		 */
		tmp = pmp->pm_BytesPerSec / bsize;
		pmp->pm_BytesPerSec  = bsize;
		pmp->pm_HugeSectors *= tmp;
		pmp->pm_HiddenSects *= tmp;
		pmp->pm_ResSectors  *= tmp;
		pmp->pm_Sectors     *= tmp;
		pmp->pm_FATsecs     *= tmp;
		SecPerClust         *= tmp;
	}

	/* Check that fs has nonzero FAT size */
	if (pmp->pm_FATsecs == 0) {
		DPRINTF(("FATsecs is 0\n"));
		error = EINVAL;
		goto error_exit;
	}

	pmp->pm_fatblk = pmp->pm_ResSectors;
	if (FAT32(pmp)) {
		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
		pmp->pm_firstcluster = pmp->pm_fatblk
			+ (pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_fsinfo = getushort(b710->bpbFSInfo);
	} else {
		pmp->pm_rootdirblk = pmp->pm_fatblk +
			(pmp->pm_FATs * pmp->pm_FATsecs);
		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
				       + pmp->pm_BytesPerSec - 1)
			/ pmp->pm_BytesPerSec;/* in sectors */
		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
	}

	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
	    SecPerClust;
	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
	pmp->pm_fatsize = pmp->pm_FATsecs * pmp->pm_BytesPerSec;

	if (flags & MSDOSFSMNT_GEMDOSFS) {
		if (pmp->pm_nmbrofclusters <= (0xff0 - 2)) {
			pmp->pm_fatmask = FAT12_MASK;
			pmp->pm_fatmult = 3;
			pmp->pm_fatdiv = 2;
		} else {
			pmp->pm_fatmask = FAT16_MASK;
			pmp->pm_fatmult = 2;
			pmp->pm_fatdiv = 1;
		}
	} else if (pmp->pm_fatmask == 0) {
		if (pmp->pm_maxcluster
		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
			/*
			 * This will usually be a floppy disk. This size makes
			 * sure that one FAT entry will not be split across
			 * multiple blocks.
			 */
			pmp->pm_fatmask = FAT12_MASK;
			pmp->pm_fatmult = 3;
			pmp->pm_fatdiv = 2;
		} else {
			pmp->pm_fatmask = FAT16_MASK;
			pmp->pm_fatmult = 2;
			pmp->pm_fatdiv = 1;
		}
	}
	if (FAT12(pmp))
		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
	else
		pmp->pm_fatblocksize = MAXBSIZE;

	pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;
	pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1;

	/*
	 * Compute mask and shift value for isolating cluster relative byte
	 * offsets and cluster numbers from a file offset.
	 */
	pmp->pm_bpcluster = SecPerClust * pmp->pm_BytesPerSec;
	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;

	DPRINTF(("%s(fatmask=%lu, fatmult=%u, fatdiv=%u, fatblocksize=%lu, "
	    "fatblocksec=%lu, bnshift=%lu, pbcluster=%lu, crbomask=%lu, "
	    "cnshift=%lu)\n",
	    __func__, pmp->pm_fatmask, pmp->pm_fatmult, pmp->pm_fatdiv,
	    pmp->pm_fatblocksize, pmp->pm_fatblocksec, pmp->pm_bnshift,
	    pmp->pm_bpcluster, pmp->pm_crbomask, pmp->pm_cnshift));
	/*
	 * Check for valid cluster size
	 * must be a power of 2
	 */
	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
		DPRINTF(("bpcluster %lu cnshift %lu\n", 
		    pmp->pm_bpcluster, pmp->pm_cnshift));
		error = EINVAL;
		goto error_exit;
	}

	/*
	 * Release the bootsector buffer.
	 */
	brelse(bp, BC_AGE);
	bp = NULL;

	/*
	 * Check FSInfo.
	 */
	if (pmp->pm_fsinfo) {
		struct fsinfo *fp;

		/*
		 * XXX	If the fsinfo block is stored on media with
		 *	2KB or larger sectors, is the fsinfo structure
		 *	padded at the end or in the middle?
		 */
		DPRINTF(("%s(bread %lu)\n", __func__,
		    (unsigned long)de_bn2kb(pmp, pmp->pm_fsinfo)));
		if ((error = bread(devvp, de_bn2kb(pmp, pmp->pm_fsinfo),
		    pmp->pm_BytesPerSec, NULL, 0, &bp)) != 0)
			goto error_exit;
		fp = (struct fsinfo *)bp->b_data;
		if (!memcmp(fp->fsisig1, "RRaA", 4)
		    && !memcmp(fp->fsisig2, "rrAa", 4)
		    && !memcmp(fp->fsisig3, "\0\0\125\252", 4)
		    && !memcmp(fp->fsisig4, "\0\0\125\252", 4))
			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
		else
			pmp->pm_fsinfo = 0;
		brelse(bp, 0);
		bp = NULL;
	}

	/*
	 * Check and validate (or perhaps invalidate?) the fsinfo structure?
	 * XXX
	 */
	if (pmp->pm_fsinfo) {
		if ((pmp->pm_nxtfree == 0xffffffffUL) ||
		    (pmp->pm_nxtfree > pmp->pm_maxcluster))
			pmp->pm_fsinfo = 0;
	}

	/*
	 * Allocate memory for the bitmap of allocated clusters, and then
	 * fill it in.
	 */
	pmp->pm_inusemap = ecalloc(sizeof(*pmp->pm_inusemap),
	    ((pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS));
	/*
	 * fillinusemap() needs pm_devvp.
	 */
	pmp->pm_dev = 0;
	pmp->pm_devvp = devvp;

	/*
	 * Have the inuse map filled in.
	 */
	if ((error = fillinusemap(pmp)) != 0) {
		DPRINTF(("fillinusemap %d\n", error));
		goto error_exit;
	}

	/*
	 * Finish up.
	 */
	if (ronly)
		pmp->pm_flags |= MSDOSFSMNT_RONLY;
	else
		pmp->pm_fmod = 1;

	/*
	 * If we ever do quotas for DOS filesystems this would be a place
	 * to fill in the info in the msdosfsmount structure. You dolt,
	 * quotas on dos filesystems make no sense because files have no
	 * owners on dos filesystems. of course there is some empty space
	 * in the directory entry where we could put uid's and gid's.
	 */

	return pmp;

error_exit:
	if (bp)
		brelse(bp, BC_AGE);
	if (pmp) {
		if (pmp->pm_inusemap)
			free(pmp->pm_inusemap);
		free(pmp);
	}
	errno = error;
	return pmp;
}