From: Zach Brown <z...@redhat.com>
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 <z...@redhat.com>
Signed-off-by: Kent Overstreet <koverstr...@google.com>
Cc: Felipe Balbi <ba...@ti.com>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Mark Fasheh <mfas...@suse.com>
Cc: Joel Becker <jl...@evilplan.org>
Cc: Rusty Russell <ru...@rustcorp.com.au>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: Asai Thambi S P <asamymuth...@micron.com>
Cc: Selvan Mani <sm...@micron.com>
Cc: Sam Bradshaw <sbrads...@micron.com>
Cc: Jeff Moyer <jmo...@redhat.com>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <b...@kvack.org>
Cc: Theodore Ts'o <ty...@mit.edu>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---
drivers/char/mem.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 2c644af..e49265f 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -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,
};
--
1.8.1.3
--
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