fs/msdosfs fatblock: use ulmin() rather than min()

to avoid truncation of pmp->pm_FATsecs.

Submitted by: Robert Morris <rtm@lcs.mit.edu>
PR: 277237
MFC after: 1 week

sys: Remove $FreeBSD$: one-line .c comment pattern

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

fs/msdosfs: Fix potential panic and size calculations

Some combinations of FAT12 file system parameters could cause a kernel
panic due to an unmapped access if the size of the FAT was larger than
the CPU page size. The reason is that FAT12 uses 3 bytes to store
2 FAT pointers, leading to partial FAT pointers at the end of buffers
of a size that is not a multiple of 3.

With a typical page size of 4 KB, this caused the FAT entry at byte
offsets 4095 and 4096 to cross the page boundary, with only the first
page mapped. This was fixed by adjusting the mapping to always cover
both bytes of each FAT entry.

Testing revealed 2 other inconsistencies that are fixed by this commit:

1) The calculation of the size of the data area did not take into
account the fact that the first two data block numbers are reserved
and that the data area starts with block 2. This could cause a
FAT12 file system created with the maximum supported number of
blocks to be incorrectly identified as FAT16.

2) The root directory does not take up space in the data area of a
FAT12 or FAT16 file system, since it is placed into a reserved
area outside of that data area. This commits makes stat() report
the logical size of the root directory, but with 0 blocks allocated
from the data area.

PR: 270587
Reviewed by: mckusick
Differential Revision: https://reviews.freebsd.org/D39386

msdosfs: on integrity error, fire a task to remount filesystem to ro

In collaboration with: pho
Reviewed by: markj, mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D33721

msdosfs: clusterfree() is used only in error handling cases

Change its return type to void, because its result is ignored in both
call sites. Remove oldcnp argument as well, it is NULL always.

Suggested and reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D33721

msdosfs: take inusemap inconsistency as an error, not invariants violation

In other words, stop silently accepting freeing free cluster in
non-debug kernels, but return the error to the caller. Modify callers
to handle errors from usemap_free().

In collaboration with: pho
Reviewed by: markj, mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D33721

fs: clean up empty lines in .c and .h files

Plug the rest of undef behavior places that were missed in r337456.

There are three more places in msdosfs_fat.c which might shift one
into the sign bit. While there, fix formatting of KASSERTs.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

buf: Add B_INVALONERR flag to discard data

Setting the B_INVALONERR flag before a synchronous write causes the buf
cache to forcibly invalidate contents if the write fails (BIO_ERROR).

This is intended to be used to allow layers above the buffer cache to make
more informed decisions about when discarding dirty buffers without
successful write is acceptable.

As a proof of concept, use in msdosfs to handle failures to mark the on-disk
'dirty' bit during rw mount or ro->rw update.

Extending this to other filesystems is left as future work.

PR: 210316
Reviewed by: kib (with objections)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D21539

msdosfs: Remove redundant brelse() after r294954

Same automation.

No functional change.

msdosfs: Drop an unneeded brelse in bread error condition

After r294954, it is an invariant that bread returns non-NULL bp if and only
if the routine succeeded. On error, it handles any buffer cleanup
internally. So the brelse(NULL) here was just redundant.

No functional change.

Discussed with: kib (extracted from a larger differential)

msdosfs_fat: reduce diffs with NetBSD and makefs

Use pointer arithmetic (as now done in makefs, and in NetBSD) instead of
taking the address of array element. No functional change, but this
makes it easier to compare different versions of this file.

Reviewed by: kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21365

Add vn_fsync_buf().

Provide a convenience function to avoid the hack with filling fake
struct vop_fsync_args and then calling vop_stdfsync().

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Fix dirty buf exhaustion easily triggered with msdosfs.

If truncate(2) is performed on msdosfs file, which extends the file by
system-depended large amount, fs creates corresponding amount of dirty
delayed-write buffers, which can consume all buffers. Such buffers
cannot be flushed by the bufdaemon because the ftruncate() thread owns
the vnode lock. So the system runs out of free buffers, and even
truncate() thread starves, which means deadlock because it owns the
vnode lock.

Fix this by doing vnode fsync in extendfile() when low memory or low
buffers condition detected, which flushes all dirty buffers belonging
to the file being extended.

Note that the more usual fallback to bawrite() does not work
acceptable in this situation, because it would only allow one buffer
to be recycled. Other filesystems, most important UFS, do not allow
userspace to create arbitrary amount of dirty delayed-write buffers
without feedback, so bawrite() is good enough for them.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

msdosfs: fixes for Undefined Behavior.

These were found by the Undefined Behaviour GsoC project at NetBSD:

Do not change signedness bit with left shift.
While there avoid signed integer overflow.
Address both issues with using unsigned type.

msdosfs_fat.c:512:42, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:521:44, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:744:14, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:744:24, signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int [20]'
msdosfs_fat.c:840:13, left shift of 1 by 31 places cannot be represented
in type 'int'
msdosfs_fat.c:840:36, signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int [20]'

Detected with micro-UBSan in the user mode.

Hinted from: NetBSD (CVS 1.33)
MFC after: 2 weeks
Differenctial Revision: https://reviews.freebsd.org/D16615

Revert change made in base r171522
(https://svnweb.freebsd.org/base?view=revision&revision=304232)
converting clrbuf() (which clears the entire buffer) to vfs_bio_clrbuf()
(which clears only the new pages that have been added to the buffer).

Failure to properly remove pages from the buffer cache can make
pages that appear not to need clearing to actually have bad random
data in them. See for example base r304232
(https://svnweb.freebsd.org/base?view=revision&revision=304232)
which noted the need to set B_INVAL and B_NOCACHE as well as clear
the B_CACHE flag before calling brelse() to release the buffer.

Rather than trying to find all the incomplete brelse() calls, it
is simpler, though more slightly expensive, to simply clear the
entire buffer when it is newly allocated.

PR: 213507
Submitted by: Damjan Jovanovic
Reviewed by: kib

sys/fs: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Style.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Verify that the BPB media descriptor and FAT ID match.

FAT specification requires that for valid FAT, FAT cluster 0 has a
specific value derived from the BPB media descriptor. The lowest
(little-endian) byte must be equal to bpb.bpbMedia, other bits in the
cluster number must be all 1's. Implement the check to reduce the
chance of the randomly corrupted FAT to pass the mount attempt.

Submitted by: Siva Mahadevan <smahadevan@freebsdfoundation.org>
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D12124

msdosfs: reformat a comment to reduce NetBSD diffs

msdosfs: use mem{cpy,move,set} instead of bcopy,bzero

This somewhat simplifies use of msdosfs code in userland (for makefs),
reduces diffs with NetBSD and is standard C as of C89.

Reviewed by: imp
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D11014

msdosfs: capitalize FAT appropriately

Diff reduction with NetBSD, including some nearby minor whitespace or
style fixes.

Obtained from: NetBSD
Sponsored by: The FreeBSD Foundation

msdosfs: use C99 types

General cleanup, for diff reduction with NetBSD and future use by FAT
support in makefs.

Submitted by: Siva Mahadevan <smahadevan@freebsdfoundation.org>
Obtained from: NetBSD
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D10821

Ensure that cluster allocations never allocate clusters outside the
volume limits. In particular:
- Assert that usemap_alloc() and usemap_free() cluster number argument
is valid.
- In chainlength(), return 0 if cluster start is after the max cluster.
- In chainlength(), cut the calculated cluster chain length at the max
cluster.
- For true paranoia, after the pm_inusemap is calculated in
fillinusemap(), reset all bits in the array for clusters after the
max cluster, as in-use.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

If the fatchain() call in chainalloc() returned an error, revert
marking the cluster run as in-use.

Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Use symbolic name for the value of fully free word in pm_inusemap.
Explicitely mention every bit in the value.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Use symbolic name for the free cluster number.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Fix comment formatting.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

sys/fs: spelling fixes in comments.

No functional change.

fs misc: for pointers replace 0 with NULL.

Mostly cosmetical, no functional change.

Found with devel/coccinelle.

Assert that an msdosfs mount is not read-only when FAT modifications
are requested.

PR: 199152
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

ANSIfy msdosfs

Add a few cases and style(9) fixes missed in r276887

Sponsored by: The FreeBSD Foundation

ANSIfy sys/fs/msdosfs

There are a number of msdosfs improvements in NetBSD that may be worth
bringing over, and this reduces noise in the comparison.

Differential Revision: https://reviews.freebsd.org/D1466
Reviewed by: kib
Sponsored by: The FreeBSD Foundation

Do not update the fsinfo block on each update of any fat block, this
is excessive. Postpone the flush of the fsinfo to VFS_SYNC(),
remembering the need for update with the flag MSDOSFS_FSIMOD, stored
in pm_flags.

FAT32 specification describes both FSI_Free_Count and FSI_Nxt_Free as
the advisory hints, not requiring them to be correct.

Based on the patch from bde, modified by me.

Reviewed by: bde
MFC after: 2 weeks

The MSDOSFSMNT_WAITONFAT flag is bogus and broken. It does less than
track the MNT_SYNCHRONOUS flag. It is set to the latter at mount time
but not updated by MNT_UPDATE.

Use MNT_SYNCHRONOUS to decide to write the FAT updates syncrhonously.

Submitted by: bde
MFC after: 1 week

Backup FATs were sometimes marked dirty by copying their first block
from the primary FAT, and then they were not marked clean on unmount.
Force marking them clean when appropriate.

Submitted by: bde
MFC after: 1 week

Fix a backwards comment in markvoldirty().

Submitted by: bde
MFC after: 1 week

Put all the messages from msdosfs under the MSDOSFS_DEBUG ifdef.
They are confusing to user, and not informative for general consumption.

MFC after: 1 week

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

MFC r204472:
Add assertions for FAT bitmap state.

MFC r204471:
Use pm_fatlock to protect fat bitmap.

MFC r204466:
Assert that the msdosfs vnode is (e)locked in several places.
Change the check and return on impossible condition into KASSERT().

MFC r204465:
Remove unused global statistic about fat cache usage.

Add assertions for FAT bitmap state.

Tested by: pho
MFC after: 3 weeks

Use pm_fatlock to protect fat bitmap.

Tested by: pho
MFC after: 3 weeks

Assert that the msdosfs vnode is (e)locked in several places.
The plan is to use vnode lock to protect denode and fat cache,
and having separate lock for block use map.

Change the check and return on impossible condition into KASSERT().

Tested by: pho
MFC after: 3 weeks

Remove unused global statistic about fat cache usage.

Tested by: pho
MFC after: 3 weeks

MFC r203866:
Invalid filesystem might cause the bp to be never read.

Invalid filesystem might cause the bp to be never read.

Noted by: Pedro F. Giffuni <giffunip tutopia com>
Obtanined from: NetBSD
MFC after: 1 week

- Import the HEAD csup code which is the basis for the cvsmode work.

In rev. 1.17 (r33548) of msdosfs_fat.c, relative cluster numbers were
replaced by file relative sector numbers as the buffer block number when
zero-padding a file during extension. Revert the change, it causes wrong
blocks filled with zeroes on seeking beyond end of file.

PR: kern/47628
Submitted by: tegge
MFC after: 3 days

Remove some debugging code that, while useful, doesn't belong in the committed
version. While here, expand a macro only used once.

Discussed with/oked by: bde

Remove some of the pessimizations involving writing the fsi sector.
All active fields in fsi are advisory/optional, so we shouldn't do
extra work to make them valid at all times, but instead we write to
the fsi too often (we still do), and we searched for a free cluster
for fsinxtfree too often.

This commit just removes the whole search and its results, so that we
write out our in-core copy of fsinxtfree instead of writing a "fixed"
copy and clobbering our in-core copy. This saves fixing 3 bugs:
- off-by-1 error for the end of the search, resulting in fsinxtfree
not actually being adjusted iff only the last cluster is free.
- missing adjustment when no clusters are free.
- off-by-many error for the start of the search. Starting the search
at 0 instead of at (the in-core copy of) fsinxtfree did more than
defeat the reasons for existence of fsinxtfree. fsinxtfree exists
mainly to avoid having to start at 0 for just the first search per
mount, but has the side effect of reducing bias towards allocating
near cluster 0. The bias would normally only be generated by the
first search per mount (if fsinxtfree is not supported), but since
we also adjusted the in-core copy of fsinxtfree here, we were doing
extra work to maximize the bias.

Approved by: re (kensmith)

Fix some style bugs (some whitespace errors only).

Approved by: re (kensmith) (blanket)

Sort includes.

Remove banal comments before includes. Remove rotted banal comments attached
to includes.

Approved by: re (kensmith) (blanket)

Remove unused include(s).

Approved by: re (kensmith) (blanket)

Oops, fix the fix for the i/o size of the fsinfo block. Its log
message explained why the size is 1 sector, but the code used a
size of 1 cluster.

I/o sizes larger than necessary may cause serious coherency problems
in the buffer cache. Here I think there were only minor efficiency
problems, since a too-large fsinfo buffer could only get far enough
to overlap buffers for the same vnode (the device vnode), so mappings
are coherent at the page level although not at the buffer level, and
the former is probably enough due to our limited use of the fsinfo
buffer.

Approved by: re (kensmith)

Clean up before implementing vfs clustering for msdosfs:

In msdosfs_read(), mainly reorder the main loop to the same order as in
ffs_read().

In msdosfs_write() and extendfile(), use vfs_bio_clrbuf() instead of
clrbuf(). I think this just just a bogus optimization, but ffs always
does it and msdosfs already did it in one place, and it is what I've
tested.

In msdosfs_write(), merge good bits from a comment in ffs_write(), and
fix 1 style bug.

In the main comment for msdosfs_pcbmap(), improve wording and catch
up with 13 years of changes in the function. This comment belongs in
VOP_BMAP.9 but that doesn't exist.

In msdosfs_bmap(), return EFBIG if the requested cluster number is out
of bounds instead of blindly truncating it, and fix many style bugs.

Approved by: re (hrs)

Fix some bugs involving the fsinfo block (many remain unfixed). This is
part of fixing msdosfs for large sector sizes. One of the fixed bugs
was fatal for large sector sizes.

1. The fsinfo block has size 512, but it was misunderstood and declared
as having size 1024, with nothing in the second 512 bytes except a
signature at the end. The second 512 bytes actually normally (if
the file system was created by Windows) consist of a second boot
sector which is normally (in WinXP) empty except for a signature --
the normal layout is one boot sector, one fsinfo sector, another
boot sector, then these 3 sectors duplicated. However, other
layouts are valid. newfs_msdos produces a valid layout with one
boot sector, one fsinfo sector, then these 2 sectors duplicated.
The signature check for the extra part of the fsinfo was thus
normally checking the signature in either the second boot sector
or the first boot sector in the copy, and thus accidentally
succeeding. The extra signature check would just fail for weirder
layouts with 512-byte sectors, and for normal layouts with any other
sector size.

Remove the extra bytes and the extra signature check.

2. Old versions did i/o to the fsinfo block using size 1024, with the
second half only used for the extra signature check on read. This
was harmless for sector size 512, and worked accidentally for sector
size 1024. The i/o just failed for larger sector sizes.

The version being fixed did i/o to the fsinfo block using size
fsi_size(pmp) = (1024 << ((pmp)->pm_BlkPerSec >> 2)). This
expression makes no sense. It happens to work for sector small
sector sizes, but for sector size 32K it gives the preposterous
value of 64M and thus causes panics. A sector size of 32768 is
necessary for at least some DVD-RW's (where the minimum write size
is 32768 although the minimum read size is 2048).

Now that the size of the fsinfo block is 512, it always fits in
one sector so there is no need for a macro to express it. Just
use the sector size where the old code uses 1024.

Approved by: re (kensmith)
Approved by: nyan (several years ago for a different version of (2))

Don't use almost perfectly pessimal cluster allocation. Allocation
of the the first cluster in a file (and, if the allocation cannot be
continued contiguously, for subsequent clusters in a file) was randomized
in an attempt to leave space for contiguous allocation of subsequent
clusters in each file when there are multiple writers. This reduced
internal fragmentation by a few percent, but it increased external
fragmentation by up to a few thousand percent.

Use simple sequential allocation instead. Actually maintain the fsinfo
sequence index for this. The read and write of this index from/to
disk still have many non-critical bugs, but we now write an index that
has something to do with our allocations instead of being modified
garbage. If there is no fsinfo on the disk, then we maintain the index
internally and don't go near the bugs for writing it.

Allocating the first free cluster gives a layout that is almost as good
(better in some cases), but takes too much CPU if the FAT is large and
the first free cluster is not near the beginning.

The effect of this change for untar and tar of a slightly reduced copy
of /usr/src on a new file system was:

Before (msdosfs 4K-clusters):
untar: 459.57 real untar from cached file (actually a pipe)
tar: 342.50 real tar from uncached tree to /dev/zero
Before (ffs2 soft updates 4K-blocks 4K-frags)
untar: 39.18 real
tar: 29.94 real
Before (ffs2 soft updates 16K-blocks 2K-frags)
untar: 31.35 real
tar: 18.30 real

After (msdosfs 4K-clusters):
untar 54.83 real
tar 16.18 real

All of these times can be improved further.

With multiple concurrent writers or readers (especially readers), the
improvement is smaller, but I couldn't find any case where it is
negative. 342 seconds for tarring up about 342 MB on a ~47MB/S partition
is just hard to unimprove on. (This operation would take about 7.3
seconds with reasonably localized allocation and perfect read-ahead.)
However, for active file systems, 342 seconds is closer to normal than
the 16+ seconds above or the 11 seconds with other changes (best I've
measured -- won easily by msdosfs!). E.g., my active /usr/src on ffs1
is quite old and fragmented, so reading to prepare for the above
benchmark takes about 6 times longer than reading back the fresh copies
of it.

Approved by: re (kensmith)

Fix spacing from my previous commit to this file:

Noticed by: fjoe

Add a 3rd entry in the cache, which keeps the end position
from just before extending a file. This has the desired effect
of keeping the write speed constant. And yes, that helps a lot
copying large files always at full speed now, and I have seen
improvements using benchmarks/bonnie.

Stolen from: NetBSD
Reviewed by: bde

/* -> /*- for copyright notices, minor format tweaks as necessary

Merge from NetBSD:
Fix a panic that occurred when trying to traverse a corrupt msdosfs
filesystem. With this particular corruption, the code in pcbmap()
would compute an offset into an array that was way out of bounds,
so check the bounds before trying to access and return an error if
the offset would be out of bounds.

Submitted by: Xin LI

Fixed some (most) style bugs in rev.1.33. Mainly 4-char indentation
(msdosfs uses normal 8-char indentation almost everywhere else),
too-long lines, and minor English usage errors. The verbose formal
comment before the new function is still abnormal.

Make msdosfs support the dirty flag in FAT16 and FAT32.
Enable lockf support.

PR: 55861
Submitted by: Jun Su <junsu@m-net.arbornet.org> (original version)
Reviewed by: make universe

- Add a new 'flags' parameter to getblk().
- Define one flag GB_LOCK_NOWAIT that tells getblk() to pass the LK_NOWAIT
flag to the initial BUF_LOCK(). This will eventually be used in cases
were we want to use a buffer only if it is not currently in use.
- Convert all consumers of the getblk() api to use this extra parameter.

Reviwed by: arch
Not objected to by: mckusick

More s/file system/filesystem/g

Fixed some style bugs in the removal of __P(()). Continuation lines
were not outdented to preserve non-KNF lining up of code with parentheses.
Switch to KNF formatting.

Remove __P.

Introduce the new 64-bit size disk block, daddr64_t. Change
the bio and buffer structures to have daddr64_t bio_pblkno,
b_blkno, and b_lblkno fields which allows access to disks
larger than a Terabyte in size. This change also requires
that the VOP_BMAP vnode operation accept and return daddr64_t
blocks. This delta should not affect system operation in
any way. It merely sets up the necessary interfaces to allow
the development of disk drivers that work with these larger
disk block addresses. It also allows for the development of
UFS2 which will use 64-bit block addresses.

- sys/msdosfs moved to sys/fs/msdosfs
- msdos.ko renamed to msdosfs.ko
- /usr/include/msdosfs moved to /usr/include/fs/msdosfs

Revert consequences of changes to mount.h, part 2.

Requested by: bde

Correct #includes to work with fixed sys/mount.h.

Separate the struct bio related stuff out of <sys/buf.h> into
<sys/bio.h>.

<sys/bio.h> is now a prerequisite for <sys/buf.h> but it shall
not be made a nested include according to bdes teachings on the
subject of nested includes.

Diskdrivers and similar stuff below specfs::strategy() should no
longer need to include <sys/buf.> unless they need caching of data.

Still a few bogus uses of struct buf to track down.

Repocopy by: peter

Supported non-512 bytes/sector format.

PR: misc/12992
Submitted by: chi@bd.mbn.or.jp (Chiharu Shibata) and
Dmitrij Tejblum <tejblum@arc.hq.cti.ru>
Reviewed by: Dmitrij Tejblum <tejblum@arc.hq.cti.ru>

$Id$ -> $FreeBSD$

Support compiling with `gcc -ansi'.

Use random() rather then than homegrown stuff.

Fix dead hang writing to FAT
Submitted by: Dmitrij Tejblum <dima@tejblum.dnttm.rssi.ru>

Removed unused #includes.

Update MSDOSFS code using NetBSD's msdosfs as a guide to support
FAT32 partitions. Unfortunately, we looked around here at
Walnut Creek CDROM for any newer FAT32-supporting versions
of Win95 and we were unsuccessful; only the older stuff here.
So this is untested beyond simply making sure it compiles and
someone with access to an actual FAT32 fs will have
to let us know how well it actually works.
Submitted by: Dmitrij Tejblum <dima@tejblum.dnttm.rssi.ru>
Obtained from: NetBSD

Staticize.

Back out DIAGNOSTIC changes.

Turn DIAGNOSTIC into a new-style option.

Removed unused #includes.

Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Added prototypes.

staticize private parts.

Second batch of cleanup changes.
This time mostly making a lot of things static and some unused
variables here and there.

Remove trailing whitespace.

Submitted by: Wolfgang Solfrank <ws@tools.de>

Fix off-by-1-sector error in the range checking for the end of the root
directory. It was possible for the root directory to overwrite the FAT.

Use the correct block number for updating the backup copy of the FAT when
deleting a file. Deleting a large file used to scramble the backup copy.

Fix numerous timestamp bugs.

DE_UPDATE was confused with DE_MODIFIED in some places (they do have
confusing names). Handle them exactly the same as IN_UPDATE and
IN_MODIFIED. This fixes chmod() and chown() clobbering the mtime
and other bugs.

DE_MODIFIED was set but not used.

Parenthesize macro args.

DE_TIMES() now takes a timeval arg instead of a timespec arg. It was
stupid to use a macro for speed and do unused conversions to prepare
for the macro.

Restore the left shifting of the DOS seconds count by 1. It got
lost among the shifts for the bitfields, so DOS seconds counts
appeared to range from 0 to 29 seconds (step 1) instead of 0 to 58
seconds (step 2).

Actually use the passed-in mtime in deupdat() as documented so that
utimes() works.

Change `extern __inline's to `static inline's so that msdosfs_fat.o
can be linked when it is compiled without -O.

Remove faking of directory mtimes to always be the current time. It's
more surprising for directory mtimes to change when you read the
directories than for them not to change when you write the directories.
This should be controlled by a mount-time option if at all.

Cosmetics. Silence gcc -Wall

Added declarations, fixed bugs due to missing decls. At least one of them
could panic a system. (I know, it paniced mine!).

Added msdosfs.

Obtained from: NetBSD