linux-toradex.git/fs/read_write.c, branch tegra-11.2.10

fsnotify: pass a file instead of an inode to open, read, and write

2010-07-28T13:58:32+00:00

fanotify, the upcoming notification system actually needs a struct path so it can
do opens in the context of listeners, and it needs a file so it can get f_flags
from the original process.  Close was the only operation that already was passing
a struct file to the notification hook.  This patch passes a file for access,
modify, and open as well as they are easily available to these hooks.

Signed-off-by: Eric Paris

vfs: introduce noop_llseek()

2010-05-27T16:12:56+00:00

This is an implementation of ->llseek useable for the rare special case
when userspace expects the seek to succeed but the (device) file is
actually not able to perform the seek.  In this case you use noop_llseek()
instead of falling back to the default implementation of ->llseek.

Signed-off-by: Jan Blunck 
Cc: Frederic Weisbecker 
Cc: Christoph Hellwig 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

do_sync_read/write() should set kiocb.ki_nbytes to be consistent

2010-03-24T23:43:29+00:00

do_sync_read/write() should set kiocb.ki_nbytes to be consistent with
do_sync_readv_writev().

Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

sendfile(): check f_op.splice_write() rather than f_op.sendpage()

2009-11-04T08:09:52+00:00

sendfile(2) was reworked with the splice infrastructure, but it still
checks f_op.sendpage() instead of f_op.splice_write() wrongly.  Although
if f_op.sendpage() exists, f_op.splice_write() always exists at the same
time currently, the assumption will be broken in future silently.  This
patch also brings a side effect: sendfile(2) can work with any output
file.  Some security checks related to f_op are added too.

Signed-off-by: Changli Gao 
Signed-off-by: Jens Axboe

vfs: remove redundant position check in do_sendfile

2009-09-24T11:47:34+00:00

As Johannes Weiner pointed out, one of the range checks in do_sendfile
is redundant and is already checked in rw_verify_area.

Signed-off-by: Jeff Layton 
Reviewed-by: Johannes Weiner 
Cc: Christoph Hellwig 
Cc: Al Viro 
Cc: Robert Love 
Cc: Mandeep Singh Baines 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro

splice: implement default splice_read method

2009-05-11T12:13:10+00:00

If f_op->splice_read() is not implemented, fall back to a plain read.
Use vfs_readv() to read into previously allocated pages.

This will allow splice and functions using splice, such as the loop
device, to work on all filesystems.  This includes "direct_io" files
in fuse which bypass the page cache.

Signed-off-by: Miklos Szeredi 
Signed-off-by: Jens Axboe

Make non-compat preadv/pwritev use native register size

2009-04-04T21:20:34+00:00

Instead of always splitting the file offset into 32-bit 'high' and 'low'
parts, just split them into the largest natural word-size - which in C
terms is 'unsigned long'.

This allows 64-bit architectures to avoid the unnecessary 32-bit
shifting and masking for native format (while the compat interfaces will
obviously always have to do it).

This also changes the order of 'high' and 'low' to be "low first".  Why?
Because when we have it like this, the 64-bit system calls now don't use
the "pos_high" argument at all, and it makes more sense for the native
system call to simply match the user-mode prototype.

This results in a much more natural calling convention, and allows the
compiler to generate much more straightforward code.  On x86-64, we now
generate

        testq   %rcx, %rcx      # pos_l
        js      .L122   #,
        movq    %rcx, -48(%rbp) # pos_l, pos

from the C source

        loff_t pos = pos_from_hilo(pos_h, pos_l);
	...
        if (pos < 0)
                return -EINVAL;

and the 'pos_h' register isn't even touched.  It used to generate code
like

        mov     %r8d, %r8d      # pos_low, pos_low
        salq    $32, %rcx       #, tmp71
        movq    %r8, %rax       # pos_low, pos.386
        orq     %rcx, %rax      # tmp71, pos.386
        js      .L122   #,
        movq    %rax, -48(%rbp) # pos.386, pos

which isn't _that_ horrible, but it does show how the natural word size
is just a more sensible interface (same arguments will hold in the user
level glibc wrapper function, of course, so the kernel side is just half
of the equation!)

Note: in all cases the user code wrapper can again be the same. You can
just do

	#define HALF_BITS (sizeof(unsigned long)*4)
	__syscall(PWRITEV, fd, iov, count, offset, (offset >> HALF_BITS) >> HALF_BITS);

or something like that.  That way the user mode wrapper will also be
nicely passing in a zero (it won't actually have to do the shifts, the
compiler will understand what is going on) for the last argument.

And that is a good idea, even if nobody will necessarily ever care: if
we ever do move to a 128-bit lloff_t, this particular system call might
be left alone.  Of course, that will be the least of our worries if we
really ever need to care, so this may not be worth really caring about.

[ Fixed for lost 'loff_t' cast noticed by Andrew Morton ]

Acked-by: Gerd Hoffmann 
Cc: H. Peter Anvin 
Cc: Andrew Morton 
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: Ingo Molnar 
Cc: Ralf Baechle >
Cc: Al Viro 
Signed-off-by: Linus Torvalds

preadv/pwritev: Add preadv and pwritev system calls.

2009-04-03T02:05:08+00:00

This patch adds preadv and pwritev system calls.  These syscalls are a
pretty straightforward combination of pread and readv (same for write).
They are quite useful for doing vectored I/O in threaded applications.
Using lseek+readv instead opens race windows you'll have to plug with
locking.

Other systems have such system calls too, for example NetBSD, check
here: http://www.daemon-systems.org/man/preadv.2.html

The application-visible interface provided by glibc should look like
this to be compatible to the existing implementations in the *BSD family:

  ssize_t preadv(int d, const struct iovec *iov, int iovcnt, off_t offset);
  ssize_t pwritev(int d, const struct iovec *iov, int iovcnt, off_t offset);

This prototype has one problem though: On 32bit archs is the (64bit)
offset argument unaligned, which the syscall ABI of several archs doesn't
allow to do.  At least s390 needs a wrapper in glibc to handle this.  As
we'll need a wrappers in glibc anyway I've decided to push problem to
glibc entriely and use a syscall prototype which works without
arch-specific wrappers inside the kernel: The offset argument is
explicitly splitted into two 32bit values.

The patch sports the actual system call implementation and the windup in
the x86 system call tables.  Other archs follow as separate patches.

Signed-off-by: Gerd Hoffmann 
Cc: Arnd Bergmann 
Cc: Al Viro 
Cc: 
Cc: 
Cc: Ralf Baechle 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[CVE-2009-0029] System call wrappers part 20

2009-01-14T13:15:26+00:00

Signed-off-by: Heiko Carstens

[CVE-2009-0029] System call wrappers part 19

2009-01-14T13:15:26+00:00

Signed-off-by: Heiko Carstens