Removed unused `dirlookup` argument in `create`

The `off` argument to `dirlookup` is optional. It
was not being used in the `dirlookup` call in `create`,
so pass NULL instead and delete the unused

Removed unused `dirlookup` argument in `create`

The `off` argument to `dirlookup` is optional. It
was not being used in the `dirlookup` call in `create`,
so pass NULL instead and delete the unused local.

Signed-off-by: Dan Cross <cross@gajendra.net>

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Read curproc from cpu structure, but be careful because after a schedule event
myproc() points to a different thread.

myproc();
sched();
myproc(); // this proc maybe different than the one

Read curproc from cpu structure, but be careful because after a schedule event
myproc() points to a different thread.

myproc();
sched();
myproc(); // this proc maybe different than the one before sched

Thus, in a function that operates on one thread better to retrieve the
current process once at the start of the function.

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Start of an experiment to remove the use of gs for cpu local variables.

Replace I_BUSY with sleep locks

Remove unused variable, nits.

a start at concurrent FS system calls

every iput() and namei() must be inside a transaction

Make fetchint and fetchstr use proc instead of taking a struct proc

Previously, these were inconsistent: they used their struct proc
argument for bounds checking, but always copied the argument from

Make fetchint and fetchstr use proc instead of taking a struct proc

Previously, these were inconsistent: they used their struct proc
argument for bounds checking, but always copied the argument from the
current address space (and hence the current process). Drop the
struct proc argument and always use the current proc.

Suggested by Carmi Merimovich.

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don't let dirty blocks be evicted from cache!

Shorten sys_unlink a little; create now fits in column

Revert "Introduce and use sleeplocks instead of BUSY flags"
My changes have a race with re-used bufs and the code doesn't seem to get shorter
Keep the changes that fixed ip->off race

This reverts co

Revert "Introduce and use sleeplocks instead of BUSY flags"
My changes have a race with re-used bufs and the code doesn't seem to get shorter
Keep the changes that fixed ip->off race

This reverts commit 3a5fa7ed9020eaf8ab843a16d26db7393b2ec072.

Conflicts:

defs.h
file.c
file.h

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Introduce and use sleeplocks instead of BUSY flags
Remove I_BUSY, B_BUSY, and intrans defs and usages
One spinlock per buf to avoid ugly loop in bget
fix race in filewrite (don't update f->off after

Introduce and use sleeplocks instead of BUSY flags
Remove I_BUSY, B_BUSY, and intrans defs and usages
One spinlock per buf to avoid ugly loop in bget
fix race in filewrite (don't update f->off after releasing lock)

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avoid deadlock by calling begin_trans() before locking any inodes

log write() data
usertest for big write()s
push begin_trans/commit_trans down into syscalls

make new code like old code

Variable declarations at top of function,
separate from initialization.

Use == 0 instead of ! for checking pointers.

Consistent spacing around {, *, casts.

Declare 0-p

make new code like old code

Variable declarations at top of function,
separate from initialization.

Use == 0 instead of ! for checking pointers.

Consistent spacing around {, *, casts.

Declare 0-parameter functions as (void) not ().

Integer valued functions return -1 on failure, 0 on success.

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copyout() copies data to a va in a pagetable, for exec() &c
usertest that passes too many arguments, break exec

Initial version of single-cpu xv6 with page tables

assorted fixes:
* rename c/cp to cpu/proc
* rename cpu.context to cpu.scheduler
* fix some comments
* formatting for printout

shuffle and tweak for formatting.
pdf has very good page breaks now.
would be a good copy for fall 2009.

rearrangements and cleanup for text

simplify

try harder to get directory refcounts right

make mkdir crash-safer, as noticed by many students on midterm

believe it or not, this was working

the macro expansion of "char *cp;" turned into
char *(curproc[cpu()]); which declares a dynamically
sized array of char* called curproc.

so then &cp == &(curpro

believe it or not, this was working

the macro expansion of "char *cp;" turned into
char *(curproc[cpu()]); which declares a dynamically
sized array of char* called curproc.

so then &cp == &(curproc[cpu()]) was actually a
stack variable as "expected". it was one past the
end of the array, but the implicit alloca allocated
more than was necessary.

do not tell me that making cp a #define was a bad idea.
there are worse problems to fix. more on that later.

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spaces around else for rtm