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 mfs-specific struct, constants to mfs/, so
mfs-specific, on-disk format structs and consts are
fully isolated from generic structs and functions
. removes de and readfs utils
- Remove unused includes.
- Add include guards to headers.
- Use unsigned variables in case they're never going to hold a negative
value. This causes GCC's complaints to disappear and should make flexelint
a lot happier, too.
- Make functions private when they're used only within a module.
- Remove unused variables.
- Add casts where appropriate.
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.
- VFS: check for negative sizes in all truncate calls
- VFS: update file size after truncating with fcntl(F_FREESP)
- VFS: move pos/len checks for F_FREESP with l_len!=0 from FS to VFS
- MFS: do not zero data block for small files when fully truncating
- MFS: do not write out freed indirect blocks after freeing space
- MFS: make truncate work correctly with differing zone/block sizes
- tests: add new test50 for truncate call family
- 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.
- Changed VFS-FS protocol to only store OK or negative error code in
m_type field of reply messages.
- Changed VFS to treat nonzero positive replies from FS as requests.
- Added backwards compatibility to VFS and MFS.
No protection of global data structures is provided in VFS, so many
VFS calls cannot be made safely by FS servers during many FS calls.
Use with caution (or, preferably, not at all).
- slight code cleanup
- neater exit procedure: exit when unmount
message received and kill signal (from RS 'down' or
reboot/shutdown) received (speed up unmount, but don't
confuse VFS by exiting before/during unmount msg)
. changed umount() and mount() to call 'service', so that it can include
a custom label, so that umount() works again (RS slot gets freed now).
merged umount() and mount() into one file to encode keep this label
knowledge in one file.
. removed obsolete RS_PID field and RS_RESCUE rescue command
. added label to RS_START struct
. vfs no longer does kill of fs process on unmount (which was failing
due to RS_PID request not working)
. don't assume that if error wasn't one of three errors, that no error
occured in vfs/request.c
mfs changes:
. added checks to copy statements to truncate copies at buffer sizes
(left in debug code for now)
. added checks for null-terminatedness, if less than NAME_MAX was copied
. added checks for copy function success
is changes:
. dump rs label
drivers.conf changes:
. added acl for mfs so that mfs can be started with 'service start',
so that a custom label can be provided
print debug message if copy is truncated
. increased buffer in lookup() to be PATH_MAX instead of NAME_MAX
. sanity check in fetch_name() in vfs to see if name fits, and
is null-terminated
. first check i < NAME_MAX, then string[i] in search_dir, as we're
not supposed to look at string[NAME_MAX]
