The "bdev" library provides basic primitives for file systems to talk
to block device drivers, hiding the details of the underlying protocol
and interaction model.
This version of libbdev is rather basic. It is planned to support the
following features in the long run:
- asynchronous requests and replies;
- recovery support for underlying block drivers;
- retrying of failed I/O requests.
The commit also changes our block-based file systems (mfs, ext2, isofs)
to make use of libbdev.
. move cache size heuristic from mfs there
so mfs and ext2 can share it
. add vfs credentials retrieving function, with
backwards compatability from previous struct
format, to be used by both ext2 and mfs
. fix for ext2 - STATICINIT was fed no.
of bytes instead of no. of elements, overallocating
memory by a megabyte or two for the superblock
3 sets of libraries are built now:
. ack: all libraries that ack can compile (/usr/lib/i386/)
. clang+elf: all libraries with minix headers (/usr/lib/)
. clang+elf: all libraries with netbsd headers (/usr/netbsd/)
Once everything can be compiled with netbsd libraries and headers, the
/usr/netbsd hierarchy will be obsolete and its libraries compiled with
netbsd headers will be installed in /usr/lib, and its headers
in /usr/include. (i.e. minix libc and current minix headers set
will be gone.)
To use the NetBSD libc system (libraries + headers) before
it is the default libc, see:
http://wiki.minix3.org/en/DevelopersGuide/UsingNetBSDCode
This wiki page also documents the maintenance of the patch
files of minix-specific changes to imported NetBSD code.
Changes in this commit:
. libsys: Add NBSD compilation and create a safe NBSD-based libc.
. Port rest of libraries (except libddekit) to new header system.
. Enable compilation of libddekit with new headers.
. Enable kernel compilation with new headers.
. Enable drivers compilation with new headers.
. Port legacy commands to new headers and libc.
. Port servers to new headers.
. Add <sys/sigcontext.h> in compat library.
. Remove dependency file in tree.
. Enable compilation of common/lib/libc/atomic in libsys
. Do not generate RCSID strings in libc.
. Temporarily disable zoneinfo as they are incompatible with NetBSD format
. obj-nbsd for .gitignore
. Procfs: use only integer arithmetic. (Antoine Leca)
. Increase ramdisk size to create NBSD-based images.
. Remove INCSYMLINKS handling hack.
. Add nbsd_include/sys/exec_elf.h
. Enable ELF compilation with NBSD libc.
. Add 'make nbsdsrc' in tools to download reference NetBSD sources.
. Automate minix-port.patch creation.
. Avoid using fstavfs() as it is *extremely* slow and unneeded.
. Set err() as PRIVATE to avoid name clash with libc.
. [NBSD] servers/vm: remove compilation warnings.
. u32 is not a long in NBSD headers.
. UPDATING info on netbsd hierarchy
. commands fixes for netbsd libc
A new call to vm lets processes yield a part of their memory to vm,
together with an id, getting newly allocated memory in return. vm is
allowed to forget about it if it runs out of memory. processes can ask
for it back using the same id. (These two operations are normally
combined in a single call.)
It can be used as a as-big-as-memory-will-allow block cache for
filesystems, which is how mfs now uses it.
- Revise VFS-FS protocol and update VFS/MFS/ISOFS accordingly.
- Clean up MFS by removing old, dead code (backwards compatibility is broken by
the new VFS-FS protocol, anyway) and rewrite other parts. Also, make sure all
functions have proper banners and prototypes.
- VFS should always provide a (syntactically) valid path to the FS; no need for
the FS to do sanity checks when leaving/entering mount points.
- Fix several bugs in MFS:
- Several path lookup bugs in MFS.
- A link can be too big for the path buffer.
- A mountpoint can become inaccessible when the creation of a new inode
fails, because the inode already exists and is a mountpoint.
- Introduce support for supplemental groups.
- Add test 46 to test supplemental group functionality (and removed obsolete
suppl. tests from test 2).
- Clean up VFS (not everything is done yet).
- ISOFS now opens device read-only. This makes the -r flag in the mount command
unnecessary (but will still report to be mounted read-write).
- Introduce PipeFS. PipeFS is a new FS that handles all anonymous and
named pipes. However, named pipes still reside on the (M)FS, as they are part
of the file system on disk. To make this work VFS now has a concept of
'mapped' inodes, which causes read, write, truncate and stat requests to be
redirected to the mapped FS, and all other requests to the original FS.
- If allocation of a new buffer fails, use an already-allocated
unused buffer if available (low memory conditions)
- Allocate buffers dynamically, so memory isn't wasted on wrong-sized
buffers.
- No more _MAX_BLOCK_SIZE.
