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File handling changes
I have some changes to file descriptor handling:
- A few stylistic changes: KNF, remove unused casts now that caddr_t is
gone. Replace dumb gotos with loop control in a few places.
- Don't do redundant pointer passing (struct proc, lwp, filedesc *)
unless the routine is likely to be inlined. 99% of the time it's about
the current process.
- Redo reference counting to be sane. Right now it looks like the product of
~30 years worth of incremental changes. With the patch, LWPs accessing
files take a short term reference on the local file descriptor. This is
the most common case. While a file is in a process descriptor table, a
reference is held to the file. The file reference count only changes
during control operations like open() or close(). Code that comes at files
from an unusual direction (i.e. foreign to the process) like procfs or
sysctl takes a reference on the file (f_count), and not on a descriptor.
- Remove knowledge of refrence counting and locking from most code that
deals with files. With the changes most file users look something like
if ((fp = fd_getfile(fd)) == NULL)
There are still problems with the patched code, which I am working on it at
the moment. Comments?
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