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[PATCH] pipe: introduce ->pin() buffer operation

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The ->map() function is really expensive on highmem machines right now,
since it has to use the slower kmap() instead of kmap_atomic(). Splice
rarely needs to access the virtual address of a page, so it's a waste
of time doing it.

Introduce ->pin() to take over the responsibility of making sure the
page data is valid. ->map() is then reduced to just kmap(). That way we
can also share a most of the pipe buffer ops between pipe.c and splice.c

Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe
2006-05-01 19:59:03 +02:00
parent 0568b409c7
commit f84d751994
3 changed files with 73 additions and 78 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
fs/pipe.c
View File

@ -110,14 +110,14 @@ static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
page_cache_release(page);
}
static void * anon_pipe_buf_map(struct file *file, struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
return kmap(buf->page);
}
static void anon_pipe_buf_unmap(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
kunmap(buf->page);
}
@ -135,19 +135,24 @@ static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
return 1;
}
static void anon_pipe_buf_get(struct pipe_inode_info *info,
struct pipe_buffer *buf)
void generic_pipe_buf_get(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
page_cache_get(buf->page);
}
int generic_pipe_buf_pin(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
return 0;
}
static struct pipe_buf_operations anon_pipe_buf_ops = {
.can_merge = 1,
.map = anon_pipe_buf_map,
.unmap = anon_pipe_buf_unmap,
.map = generic_pipe_buf_map,
.unmap = generic_pipe_buf_unmap,
.pin = generic_pipe_buf_pin,
.release = anon_pipe_buf_release,
.steal = anon_pipe_buf_steal,
.get = anon_pipe_buf_get,
.get = generic_pipe_buf_get,
};
static ssize_t
@ -183,12 +188,14 @@ pipe_readv(struct file *filp, const struct iovec *_iov,
if (chars > total_len)
chars = total_len;
addr = ops->map(filp, pipe, buf);
if (IS_ERR(addr)) {
error = ops->pin(pipe, buf);
if (error) {
if (!ret)
ret = PTR_ERR(addr);
error = ret;
break;
}
addr = ops->map(pipe, buf);
error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars);
ops->unmap(pipe, buf);
if (unlikely(error)) {
@ -300,11 +307,11 @@ pipe_writev(struct file *filp, const struct iovec *_iov,
void *addr;
int error;
addr = ops->map(filp, pipe, buf);
if (IS_ERR(addr)) {
error = PTR_ERR(addr);
error = ops->pin(pipe, buf);
if (error)
goto out;
}
addr = ops->map(pipe, buf);
error = pipe_iov_copy_from_user(offset + addr, iov,
chars);
ops->unmap(pipe, buf);