linux.git/fs/read_write.c, branch v2.6.24

mark sys_open/sys_read exports unused

2007-11-15T02:45:42+00:00

sys_open / sys_read were used in the early 1.2 days to load firmware from
disk inside drivers.  Since 2.0 or so this was deprecated behavior, but
several drivers still were using this.  Since a few years we have a
request_firmware() API that implements this in a nice, consistent way.
Only some old ISA sound drivers (pre-ALSA) still straggled along for some
time....  however with commit c2b1239a9f22f19c53543b460b24507d0e21ea0c the
last user is now gone.

This is a good thing, since using sys_open / sys_read etc for firmware is a
very buggy to dangerous thing to do; these operations put an fd in the
process file descriptor table....  which then can be tampered with from
other threads for example.  For those who don't want the firmware loader,
filp_open()/vfs_read are the better APIs to use, without this security
issue.

The patch below marks sys_open and sys_read unused now that they're
really not used anymore, and for deletion in the 2.6.25 timeframe.

Signed-off-by: Arjan van de Ven 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Cleanup macros for distinguishing mandatory locks

2007-10-09T22:32:46+00:00

The combination of S_ISGID bit set and S_IXGRP bit unset is used to mark the
inode as "mandatory lockable" and there's a macro for this check called
MANDATORY_LOCK(inode).  However, fs/locks.c and some filesystems still perform
the explicit i_mode checking.  Besides, Andrew pointed out, that this macro is
buggy itself, as it dereferences the inode arg twice.

Convert this macro into static inline function and switch its users to it,
making the code shorter and more readable.

The __mandatory_lock() helper is to be used in places where the IS_MANDLOCK()
for superblock is already known to be true.

Signed-off-by: Pavel Emelyanov 
Cc: Trond Myklebust 
Cc: "J. Bruce Fields" 
Cc: David Howells 
Cc: Eric Van Hensbergen 
Cc: Ron Minnich 
Cc: Latchesar Ionkov 
Cc: Steven Whitehouse 
Signed-off-by: Andrew Morton

Remove remnants of sendfile()

2007-07-10T06:04:15+00:00

There are now zero users of .sendfile() in the kernel, so kill
it from the file_operations structure and in do_sendfile().

Signed-off-by: Jens Axboe

splice: divorce the splice structure/function definitions from the pipe header

2007-07-10T06:04:14+00:00

We need to move even more stuff into the header so that folks can use
the splice_to_pipe() implementation instead of open-coding a lot of
pipe knowledge (see relay implementation), so move to our own header
file finally.

Signed-off-by: Jens Axboe

sys_sendfile: switch to using ->splice_read, if available

2007-07-10T06:04:12+00:00

This patch makes sendfile prefer to use ->splice_read(), if it's
available in the file_operations structure.

Signed-off-by: Jens Axboe

use use SEEK_MAX to validate user lseek arguments

2007-05-08T18:14:59+00:00

Add SEEK_MAX and use it to validate lseek arguments from userspace.

Signed-off-by: Chris Snook 
Acked-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

use symbolic constants in generic lseek code

2007-05-08T18:14:59+00:00

Convert magic numbers to SEEK_* values from fs.h

Signed-off-by: Chris Snook 
Acked-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] FS: speed up rw_verify_area()

2007-02-12T17:48:29+00:00

oprofile hunting showed a stall in rw_verify_area(), because of triple
indirection and potential cache misses.
(file->f_path.dentry->d_inode->i_flock)

By moving initialization of 'struct inode' pointer before the pos/count
sanity tests, we allow the compiler and processor to perform two loads by
anticipation, reducing stall, without prefetch() hints.  Even x86 arch has
enough registers to not use temporary variables and not increase text size.

I validated this patch running a bench and studied oprofile changes, and
absolute perf of the test program.

Results of my epoll_pipe_bench (source available on request) on a Pentium-M
1.6 GHz machine

Before :
# ./epoll_pipe_bench -l 30 -t 20
Avg: 436089 evts/sec read_count=8843037 write_count=8843040 21.218390 samples
per call
(best value out of 10 runs)

After :
# ./epoll_pipe_bench -l 30 -t 20
Avg: 470980 evts/sec read_count=9549871 write_count=9549894 21.216694 samples
per call
(best value out of 10 runs)

oprofile CPU_CLK_UNHALTED events gave a reduction from 5.3401 % to 2.5851 %
for the rw_verify_area() function.

Signed-off-by: Eric Dumazet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] ifdef ->rchar, ->wchar, ->syscr, ->syscw from task_struct

2007-02-11T19:18:07+00:00

They are fat: 4x8 bytes in task_struct.
They are uncoditionally updated in every fork, read, write and sendfile.
They are used only if you have some "extended acct fields feature".

And please, please, please, read(2) knows about bytes, not characters,
why it is called "rchar"?

Signed-off-by: Alexey Dobriyan 
Cc: Jay Lan 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] one more EXPORT_UNUSED_SYMBOL removal

2006-12-13T17:05:53+00:00

Signed-off-by: Adrian Bunk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds