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))
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)
FAT32 filesystems to be mounted, subject to some fairly serious limitations.
This works by extending the internal pseudo-inode-numbers generated from
the file's starting cluster number to 64-bits, then creating a table
mapping these into arbitrary 32-bit inode numbers, which can fit in
struct dirent's d_fileno and struct vattr's va_fileid fields. The mappings
do not persist across unmounts or reboots, so it's not possible to export
these filesystems through NFS. The mapping table may grow to be rather
large, and may grow large enough to exhaust kernel memory on filesystems
with millions of files.
Don't enable this option unless you understand the consequences.
masks for files and directories. This should make some
of the Midnight Commander users happy.
Remove an extra ')' in the manual page.
PR: 35699
Submitted by: Eugene Grosbein <eugen@grosbein.pp.ru> (original version)
Tested by: simon
to struct mount.
This makes the "struct netexport *" paramter to the vfs_export
and vfs_checkexport interface unneeded.
Consequently that all non-stacking filesystems can use
vfs_stdcheckexp().
At the same time, make it a pointer to a struct netexport
in struct mount, so that we can remove the bogus AF_MAX
and #include <net/radix.h> from <sys/mount.h>
longs larger than 32 bits or strict alignment requirements.
pm_fatmask had type u_long, but it must have a type that has precisely
32 bits and this type must be no smaller than int, so that ~pmp->pm_fatmask
has no bits above the 31st set. Otherwise, comparisons between (cn
| ~pmp->pm_fatmask) and magic 32-bit "cluster" numbers always fail.
The correct fix is to use the C99 type uint_least32_t and mask with
0xffffffff. The quick fix is to use u_int32_t and assume that ints
have
msdosfs metadata is riddled with unaligned fields, and on alphas,
unaligned_fixup() apparently has problems fixing up the unaligned
accesses caused by this. The quick fix is to not comment out the
NetBSD code that sort of handles this, and define UNALIGNED_ACCESS on
i386's so that the code doesn't change on i386's. The correct fix
would define UNALIGNED_ACCESS in a central machine-dependent header
and maybe add some extra cases to unaligned_fixup(). UNALIGNED_ACCESS
is also tested in isofs.
Submitted by: parts by Mark Abene <phiber@radicalmedia.com>
PR: 19086
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.
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
Distribute all but the most fundamental malloc types. This time I also
remembered the trick to making things static: Put "static" in front of
them.
A couple of finer points by: bde
- *fs_init routines now take a "struct vfsconf * vfsp" pointer
as an argument.
- Use the correct type for cookies.
- Update function prototypes.
Submitted by: bde
changes, so don't expect to be able to run the kernel as-is (very well)
without the appropriate Lite/2 userland changes.
The system boots and can mount UFS filesystems.
Untested: ext2fs, msdosfs, NFS
Known problems: Incorrect Berkeley ID strings in some files.
Mount_std mounts will not work until the getfsent
library routine is changed.
Reviewed by: various people
Submitted by: Jeffery Hsu <hsu@freebsd.org>
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.
