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| author | Conrad Meyer <cse.cem@gmail.com> | 2014-06-07 01:36:37 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-07 03:08:10 +0400 |
| commit | 190a8843ded231638d0e7ae7d8ca6a712472d114 (patch) | |
| tree | 30e99192bc39f30584197eab47b119478d8dfe37 /Documentation/filesystems/vfat.txt | |
| parent | a19189e5535ed8fd191d8989fc39da1637cfa224 (diff) | |
| download | linux-190a8843ded231638d0e7ae7d8ca6a712472d114.tar.xz | |
fs/fat/: add support for DOS 1.x formatted volumes
Add structure for parsed BPB information, struct fat_bios_param_block,
and move all of the deserialization and validation logic from
fat_fill_super() into fat_read_bpb().
Add a 'dos1xfloppy' mount option to infer DOS 2.x BIOS Parameter Block
defaults from block device geometry for ancient floppies and floppy
images, as a fall-back from the default BPB parsing logic.
When fat_read_bpb() finds an invalid FAT filesystem and dos1xfloppy is
set, fall back to fat_read_static_bpb(). fat_read_static_bpb()
validates that the entire BPB is zero, and that the floppy has a
DOS-style 8086 code bootstrapping header. Then it fills in default BPB
values from media size and a table.[0]
Media size is assumed to be static for archaic FAT volumes. See also:
[1].
Fixes kernel.org bug #42617.
[0]: https://en.wikipedia.org/wiki/File_Allocation_Table#Exceptions
[1]: http://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html
[hirofumi@mail.parknet.co.jp: fix missed error code]
Signed-off-by: Conrad Meyer <cse.cem@gmail.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Tested-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems/vfat.txt')
| -rw-r--r-- | Documentation/filesystems/vfat.txt | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt index 4a93e98b290a..ce1126aceed8 100644 --- a/Documentation/filesystems/vfat.txt +++ b/Documentation/filesystems/vfat.txt @@ -172,6 +172,11 @@ nfs=stale_rw|nostale_ro To maintain backward compatibility, '-o nfs' is also accepted, defaulting to stale_rw +dos1xfloppy -- If set, use a fallback default BIOS Parameter Block + configuration, determined by backing device size. These static + parameters match defaults assumed by DOS 1.x for 160 kiB, + 180 kiB, 320 kiB, and 360 kiB floppies and floppy images. + <bool>: 0,1,yes,no,true,false |