Conrad Meyer <ceme...@uw.edu> writes: Hi,
> When possible, infer DOS 2.x BIOS Parameter Block from block device > geometry (for floppies and floppy images). Update in-memory only. We > only perform this update when the entire BPB region is zeroed, like > produced by DOS 1.x-era FORMAT (and other OEM variations on DOS). > > Fixes kernel.org bug #42617. > > BPB default values are inferred from media size and a table.[0] Media > size is assumed to be static for archaic FAT volumes. See also [1]. > > [0]: https://en.wikipedia.org/wiki/File_Allocation_Table#Exceptions > [1]: http://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html [...] > +static void fat_update_archaic_boot_sector(struct super_block *sb, > + struct fat_boot_sector *b) > +{ > + sector_t bd_sects; > + > + if (get_unaligned_le16(&b->sector_size) != 0 || b->sec_per_clus != 0 || > + b->reserved != 0 || b->fats != 0 || > + get_unaligned_le16(&b->dir_entries) != 0 || > + get_unaligned_le16(&b->sectors) != 0 || b->media != 0 || > + b->fat_length != 0 || b->secs_track != 0 || b->heads != 0 || > + b->secs_track != 0 || b->heads != 0) > + return; > + > + bd_sects = part_nr_sects_read(sb->s_bdev->bd_part); > + switch (bd_sects) { > + case 160 * KB_IN_SECTORS: > + b->sec_per_clus = 1; > + put_unaligned_le16(64, &b->dir_entries); > + b->media = 0xFE; > + b->fat_length = cpu_to_le16(1); > + break; [...] Hm, this looks like check the volume size. But if there is newer fat format on same volume size, how to detect it? Or, it is conflicting? [BTW, we should avoid to mount if it doesn't seem fatfs, to prevent mis-mount as fatfs (auto mount is depending on this detection).] Thanks. -- OGAWA Hirofumi <hirof...@mail.parknet.co.jp> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
