run through copy-on-write. Call fscow_run() with valid data where possible.
The LP_UFSCOW hack is no longer needed to protect ffs_copyonwrite() against
endless recursion.
- Add a flag B_MODIFY to bread(), breada() and breadn(). If set the caller
intends to modify the buffer returned.
- Always run copy-on-write on buffers returned from ffs_balloc().
- Add new function ffs_getblk() that gets a buffer, assigns a new blkno,
may clear the buffer and runs copy-on-write. Process possible errors
from getblk() or fscow_run(). Part of PR kern/38664.
Welcome to 4.99.63
Reviewed by: YAMAMOTO Takashi <yamt@netbsd.org>
error-out the master buffer.
The old setup was undeterministic since a later sheduled nested buffer
could clear the error again since there is no B_ERROR flag anymore. It also
would discard the error the nested buffer returned.
buf_memcalc is used by bootstrap as well. fix NULL dereference for them.
- limit kva usage for each cache to 20% of vm_map. XXX a bit arbitrary.
- add a comment.
- Lock processes, credentials, filehead etc correctly.
- Acquire a read hold on sysctl_treelock if only doing a query.
- Don't wire down the output buffer. It doesn't work correctly and the code
regularly does long term sleeps with it held - it's not worth it.
- Don't hold locks other than sysctl_lock while doing copyout().
- Drop sysctl_lock while doing copyout / allocating memory in a few places.
- Don't take kernel_lock for sysctl.
- Fix a number of bugs spotted along the way
Buffers run through copy-on-write are marked B_COWDONE. This condition
is valid until the buffer has run through bwrite() and gets cleared from
biodone().
Welcome to 4.99.39.
Reviewed by: YAMAMOTO Takashi <yamt@netbsd.org>
need to understand the locking around that field. Instead of setting
B_ERROR, set b_error instead. b_error is 'owned' by whoever completes
the I/O request.
from doc/BRANCHES:
idle lwp, and some changes depending on it.
1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.
systems will never, ever need this -- because they use 8k/1k or even,
these days, 16k/2k or 32k/4k filesystems. On the other hand, when you
do need this, you *really* need it: on anoncvs.netbsd.org, for instance,
where /tmp is 4k/512 and the filesystem contains tens or even hundreds
of thousands of single-frag directories, this essentially doubles the
efficiency of the allocator. Since the overhead of keeping one extra
pool around is minimal, just add it by default.
buffer when the passed nested buffer has no B_ERROR flag set but not all
was transfered for the nested iobuf extent.
Discussed on tech-kern and ok'd by Takashi
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