MFS: do not crash when reading superblock fails

While MFS failing to do I/O on a block is generally fatal, reading
the superblock at mount time is an exception: this case may occur
when the given pa

MFS: do not crash when reading superblock fails

While MFS failing to do I/O on a block is generally fatal, reading
the superblock at mount time is an exception: this case may occur
when the given partition is too small to contain the superblock.
Therefore, MFS should not crash or even report anything in this
case, but rather refuse to mount cleanly.

This fixes #121.

Change-Id: I11326b48922a0e0ebefecbb8eec7c428f985f2b3

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NetBSD re-synchronization of the source tree

This brings our tree to NetBSD 7.0, as found on -current on the
10-10-2015.

This updates:
- LLVM to 3.6.1
- GCC to GCC 5.1
- Replace minix/commands/z

NetBSD re-synchronization of the source tree

This brings our tree to NetBSD 7.0, as found on -current on the
10-10-2015.

This updates:
- LLVM to 3.6.1
- GCC to GCC 5.1
- Replace minix/commands/zdump with usr.bin/zdump
- external/bsd/libelf has moved to /external/bsd/elftoolchain/
- Import ctwm
- Drop sprintf from libminc

Change-Id: I149836ac18e9326be9353958bab9b266efb056f0

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Fix noassert builds

Change-Id: I5626950ffa29afe7a0fb9e9144839b311824da92

Resolve more warnings

Change-Id: Ibc1b7f7cd45ad7295285e59c6ce55888266fece8

Annotations and tweaks for live update

This change is necessary for instrumentation-aided state transfer.

Change-Id: I24be938009f02e302a15083f9a7a11824975e42b

libminixfs: rework prefetch API

This patch changes the prefetch API so that file systems must now
provide a set of block numbers, rather than a set of buffers. The
result is a leaner and more well-

libminixfs: rework prefetch API

This patch changes the prefetch API so that file systems must now
provide a set of block numbers, rather than a set of buffers. The
result is a leaner and more well-defined API; linear computation of
the range of blocks to prefetch; duplicates no longer interfering
with the prefetch process; guaranteed inclusion of the block needed
next into the prefetch range; and, limits and policy decisions better
established by libminixfs now actually being moved into libminixfs.

Change-Id: I7e44daf2d2d164bc5e2f1473ad717f3ff0f0a77f

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libminixfs: better support for read errors and EOF

- The lmfs_get_block*(3) API calls may now return an error. The idea
is to encourage a next generation of file system services to do a
better

libminixfs: better support for read errors and EOF

- The lmfs_get_block*(3) API calls may now return an error. The idea
is to encourage a next generation of file system services to do a
better job at dealing with block read errors than the MFS-derived
implementations do. These existing file systems have been changed
to panic immediately upon getting a block read error, in order to
let unchecked errors cause corruption. Note that libbdev already
retries failing I/O operations a few times first.

- The libminixfs block device I/O module (bio.c) now deals properly
with end-of-file conditions on block devices. Since a device or
partition size may not be a multiple of the root file system's block
size, support for partial block retrival has been added, with a new
internal lmfs_get_partial_block(3) call. A new test program,
test85, tests the new handling of EOF conditions when reading,
writing, and memory-mapping a block device.

Change-Id: I05e35b6b8851488328a2679da635ebba0c6d08ce

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libminixfs: keep track of block usage

This patch changes the libminixfs API and implementation such that the
library is at all times aware of how many total and used blocks there
are in the file sys

libminixfs: keep track of block usage

This patch changes the libminixfs API and implementation such that the
library is at all times aware of how many total and used blocks there
are in the file system. This removes the last upcall of libminixfs
into file systems (fs_blockstats). In the process, make this part of
the libminixfs API a little prettier and more robust. Change file
systems accordingly. Since this change only adds to MFS being unable
to deal with zones and blocks having different sizes, fail to mount
such file systems immediately rather than triggering an assert later.

Change-Id: I078e589c7e1be1fa691cf391bf5dfddd1baf2c86

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libminixfs: miscellaneous API cleanup

Mostly removal of unused parameters from calls.

Change-Id: I0eb7b568265d1669492d958e78b9e69d7cf6fc05

libminixfs: do not flush blocks that are in use

This removes an implicit requirement for the way the libminixfs API is
to be used, namely that a block is to be marked as dirty only once its
contents

libminixfs: do not flush blocks that are in use

This removes an implicit requirement for the way the libminixfs API is
to be used, namely that a block is to be marked as dirty only once its
contents have been fully updated, within a single get_block/put_block
window. The requirement may not be appropriate for all file systems.

Change-Id: I6a129d51b1a5e9aec1572039dc7c1c82dd795db5

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libminixfs: add support for peeking blocks

With this change, the lmfs_get_block*(3) functions allow the caller to
specify that it only wants the block if it is in the cache or the
secondary VM cache

libminixfs: add support for peeking blocks

With this change, the lmfs_get_block*(3) functions allow the caller to
specify that it only wants the block if it is in the cache or the
secondary VM cache. If the block is not found there, the functions
return NULL. Previously, the PREFETCH method would be used to this
end instead, which was both abuse in name and less efficient.

Change-Id: Ieb5a15b67fa25d2008a8eeef9d126ac908fc2395

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libminixfs: add support for memory-mapped holes

When VM asks a file system to provide a block to satisfy a page fault
on a file memory mapping, the file system previously had no way to
inform VM tha

libminixfs: add support for memory-mapped holes

When VM asks a file system to provide a block to satisfy a page fault
on a file memory mapping, the file system previously had no way to
inform VM that the block is a hole, since there is no corresponding
block on the underlying device. To work around this, MFS and ext2
would actually allocate a block for the hole when asked by VM, which
not only defeats the point of holes in the first place, but also does
not work on read-only file systems. With this patch, a new libminixfs
call allows the file system to inform VM about holes. This issue does
raise the question as to whether the VM cache is using the right data
structures, since there are now two places where we have to fake a
device offset. This will have to be revisited in the future.

The patch changes file systems accordingly, and adds a test to test74.

Change-Id: Ib537d56b3f30a8eb05bc1f63c92b5c7428d18f4c

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libminixfs/VM: fix memory-mapped file corruption

This patch employs one solution to resolve two independent but related
issues. Both issues are the result of one fundamental aspect of the
way VM's

libminixfs/VM: fix memory-mapped file corruption

This patch employs one solution to resolve two independent but related
issues. Both issues are the result of one fundamental aspect of the
way VM's memory mapping works: VM uses its cache to map in blocks for
memory-mapped file regions, and for blocks already in the VM cache, VM
does not go to the file system before mapping them in. To preserve
consistency between the FS and VM caches, VM relies on being informed
about all updates to file contents through the block cache. The two
issues are both the result of VM not being properly informed about
such updates:

1. Once a file system provides libminixfs with an inode association
(inode number + inode offset) for a disk block, this association
is not broken until a new inode association is provided for it.
If a block is freed and reallocated as a metadata (non-inode)
block, its old association is maintained, and may be supplied to
VM's secondary cache. Due to reuse of inodes, it is possible
that the same inode association becomes valid for an actual file
block again. In that case, when that new file is memory-mapped,
under certain circumstances, VM may end up using the metadata
block to satisfy a page fault on the file, due to the stale inode
association. The result is a corrupted memory mapping, with the
application seeing data other than the current file contents
mapped in at the file block.

2. When a hole is created in a file, the underlying block is freed
from the device, but VM is not informed of this update, and thus,
if VM's cache contains the block with its previous inode
association, this block will remain there. As a result, if an
application subsequently memory-maps the file, VM will map in the
old block at the position of the hole, rather than an all-zeroes
block. Thus, again, the result is a corrupted memory mapping.

This patch resolves both issues by making the file system inform the
minixfs library about blocks being freed, so that libminixfs can
break the inode association for that block, both in its own cache and
in the VM cache. Since libminixfs does not know whether VM has the
block in its cache or not, it makes a call to VM for each block being
freed. Thus, this change introduces more calls to VM, but it solves
the correctness issues at hand; optimizations may be introduced
later. On the upside, all freed blocks are now marked as clean,
which should result in fewer blocks being written back to the device,
and the blocks are removed from the caches entirely, which should
result in slightly better cache usage.

This patch is necessary but not sufficient to resolve the situation
with respect to memory mapping of file holes in general. Therefore,
this patch extends test 74 with a (rather particular but effective)
test for the first issue, but not yet with a test for the second one.

This fixes #90.

Change-Id: Iad8b134d2f88a884f15d3fc303e463280749c467

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libminixfs: add support for 64-bit block numbers

There are currently no devices out there that require this change.
The change is merely needed to support subsequent changes.

Change-Id: I64214c5f46

libminixfs: add support for 64-bit block numbers

There are currently no devices out there that require this change.
The change is merely needed to support subsequent changes.

Change-Id: I64214c5f46ff4a2260815d15c15e4a17709b9036

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libfsdriver: support mmap on FSes with no device

This patch adds (very limited) support for memory-mapping pages on
file systems that are mounted on the special "none" device and that
do not impleme

libfsdriver: support mmap on FSes with no device

This patch adds (very limited) support for memory-mapping pages on
file systems that are mounted on the special "none" device and that
do not implement PEEK support by themselves. This includes hgfs,
vbfs, and procfs.

The solution is implemented in libvtreefs, and consists of allocating
pages, filling them with content by calling the file system's READ
functionality, passing the pages to VM, and freeing them again. A new
VM flag is used to indicate that these pages should be mapped in only
once, and thus not cached beyond their single use. This prevents
stale data from getting mapped in without the involvement of the file
system, which would be problematic on file systems where file contents
may become outdated at any time. No VM caching means no sharing and
poor performance, but mmap no longer fails on these file systems.

Compared to a libc-based approach, this patch retains the on-demand
nature of mmap. Especially tail(1) is known to map in a large file
area only to use a small portion of it.

All file systems now need to be given permission for the SETCACHEPAGE
and CLEARCACHE calls to VM.

A very basic regression test is added to test74.

Change-Id: I17afc4cb97315b515cad1542521b98f293b6b559

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minix libraries: resolve clang warnings

Change-Id: I0f3425fb8838708c9848a006f1eee5ab1bad71d2

Clean up obsolete FS support routines

Change-Id: I56d0ab51f32064bb964051732de7e2465dc22b75

libminixfs: add block I/O routines

The new functionality aims to save each file system server from having
to implement its own block I/O routines just so that it can serve as a
root file system. Th

libminixfs: add block I/O routines

The new functionality aims to save each file system server from having
to implement its own block I/O routines just so that it can serve as a
root file system. The new source file (bio.c) lists the requirements
that file system servers have to fulfill in order to use the routines.

Change-Id: Ia0190fd5c30e8c2097ed8f4b0e3ccde1827e0b92

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libminixfs: do not make fs_sync upcalls

The file system may not be expecting these upcalls at arbitrary
moments, while they serve only as a performance optimization anyway.

Change-Id: I0748fd1f6c26

libminixfs: do not make fs_sync upcalls

The file system may not be expecting these upcalls at arbitrary
moments, while they serve only as a performance optimization anyway.

Change-Id: I0748fd1f6c2645ddbb64466093ee36025aac45e0

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New sources layout

Change-Id: Ic716f336b7071063997cf5b4dae6d50e0b4631e9