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char: add aio_{read,write} to /dev/{null,zero}

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These are handy for measuring the cost of the aio infrastructure with
operations that do very little and complete immediately.

Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Zach Brown 2013-05-07 16:18:27 -07:00 committed by Linus Torvalds
parent 41003a7bcf
commit 162934de51
1 changed files with 35 additions and 0 deletions
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35
drivers/char/mem.c
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@ -627,6 +627,18 @@ static ssize_t write_null(struct file *file, const char __user *buf,
return count;
}
static ssize_t aio_read_null(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
return 0;
}
static ssize_t aio_write_null(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
return iov_length(iov, nr_segs);
}
static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
struct splice_desc *sd)
{
@ -670,6 +682,24 @@ static ssize_t read_zero(struct file *file, char __user *buf,
return written ? written : -EFAULT;
}
static ssize_t aio_read_zero(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
size_t written = 0;
unsigned long i;
ssize_t ret;
for (i = 0; i < nr_segs; i++) {
ret = read_zero(iocb->ki_filp, iov[i].iov_base, iov[i].iov_len,
&pos);
if (ret < 0)
break;
written += ret;
}
return written ? written : -EFAULT;
}
static int mmap_zero(struct file *file, struct vm_area_struct *vma)
{
#ifndef CONFIG_MMU
@ -738,6 +768,7 @@ static int open_port(struct inode *inode, struct file *filp)
#define full_lseek null_lseek
#define write_zero write_null
#define read_full read_zero
#define aio_write_zero aio_write_null
#define open_mem open_port
#define open_kmem open_mem
#define open_oldmem open_mem
@ -766,6 +797,8 @@ static const struct file_operations null_fops = {
.llseek = null_lseek,
.read = read_null,
.write = write_null,
.aio_read = aio_read_null,
.aio_write = aio_write_null,
.splice_write = splice_write_null,
};
@ -782,6 +815,8 @@ static const struct file_operations zero_fops = {
.llseek = zero_lseek,
.read = read_zero,
.write = write_zero,
.aio_read = aio_read_zero,
.aio_write = aio_write_zero,
.mmap = mmap_zero,
};