Its purpose was to translate the values for msdosfs inode numbers,
which is calculated from the msdosfs structures describing the file,
into the range representable by 32bit ino_t. The translation acted
for filesystems larger than 128Gb, it reserved the range 0xf0000000
(FILENO_FIRST_DYN) to UINT32_MAX and remembered some arbitrary
translation of ino >= FILENO_FIRST_DYN into this range. It consumed
memory that could be only freed by unmount, and the translation was
not stable across remounts.
With ino_t type extended to 64 bit, there is no such issue and values
can be returned without compaction to 32bit. That is, for the native
environments, the translation layer is not necessary and adds
significant undeserved code complexity. For compat ABIs which use
32bit ino_t, the vfs.ino64_trunc_error sysctl provides some measures
to soften the failure mode when inode numbers truncation is not safe.
Discussed with: bde
Sponsored by: The FreeBSD Foundation
This should fix the run time bustage observed on recent -CURRENT whilst
mounting a MSDOS filesystem with non-default locale/code page:
link_elf: symbol msdosfs_fileno_free undefined
KLD msdosfs_iconv.ko: depends on msdosfs - not available
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.
it with vfsload("msdos").
(The proper fix would be to rename the `msdos' file system to
`msdosfs' in VFS_SET(), and mount_msdos(8) to mount_msdosfs(8).
But that would break too many existing fstab(5) setups, and
would require a lot of unnecessary documentation and code
msdos -> msdosfs changes.)
Noticed by: markm
This means that the kernel can be totally self contained now and is not
dependent on the last buildworld to update /usr/share/mk. This might
also make it easier to build 5.x kernels on 4.0 boxes etc, assuming
gensetdefs and config(8) are updated.
needed for ages, but keeps getting cut/pasted into new Makefiles.
(Once apon a time it was used to activate mount arguments in
<sys/mount.h>, but that was killed with extreme prejudice long ago)
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.
