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Message-Id: <E1OHw3d-0001yr-Ag@pomaz-ex.szeredi.hu>
Date: Fri, 28 May 2010 11:40:49 +0200
From: Miklos Szeredi <miklos@...redi.hu>
To: Changli Gao <xiaosuo@...il.com>
CC: axboe@...nel.dk, viro@...iv.linux.org.uk, matthew@....cx,
mszeredi@...e.cz, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, xiaosuo@...il.com
Subject: Re: [PATCH v2 3/4]: sendfile: remove flags paramter of do_splice_direct()
On Wed, 26 May 2010, Changli Gao wrote:
> remove flags paramter of do_splice_direct().
>
> the flags parameter of do_splice_direct() doesn't mean non-block read of
> in file,
Actually, it does. Look at the SPLICE_F_NONBLOCK usage in
__generic_splice_file_read().
> but non-block read/write of pipe. As the reader and writer of process
> internal pipe is the process itself, we don't need this flags.
>
> Signed-off-by: Changli Gao <xiaosuo@...il.com>
> ----
> fs/read_write.c | 15 ++-------------
> fs/splice.c | 19 +++----------------
> include/linux/fs.h | 2 +-
> 3 files changed, 6 insertions(+), 30 deletions(-)
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 113386d..0688e05 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -796,7 +796,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> struct inode * in_inode, * out_inode;
> loff_t pos;
> ssize_t retval;
> - int fput_needed_in, fput_needed_out, fl;
> + int fput_needed_in, fput_needed_out;
>
> /*
> * Get input file, and verify that it is ok..
> @@ -846,18 +846,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> count = max - pos;
> }
>
> - fl = 0;
> -#if 0
> - /*
> - * We need to debate whether we can enable this or not. The
> - * man page documents EAGAIN return for the output at least,
> - * and the application is arguably buggy if it doesn't expect
> - * EAGAIN on a non-blocking file descriptor.
> - */
> - if (in_file->f_flags & O_NONBLOCK)
> - fl = SPLICE_F_NONBLOCK;
> -#endif
> - retval = do_splice_direct(in_file, ppos, out_file, count, fl);
> + retval = do_splice_direct(in_file, ppos, out_file, count);
>
> if (retval > 0) {
> add_rchar(current, retval);
> diff --git a/fs/splice.c b/fs/splice.c
> index eb602cb..57172ca 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -1125,7 +1125,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
> long ret, bytes;
> umode_t i_mode;
> size_t len;
> - int i, flags;
> + int i;
>
> /*
> * We require the input being a regular file, as we don't want to
> @@ -1162,29 +1162,18 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
> ret = 0;
> bytes = 0;
> len = sd->total_len;
> - flags = sd->flags;
> -
> - /*
> - * Don't block on output, we have to drain the direct pipe.
> - */
> - sd->flags &= ~SPLICE_F_NONBLOCK;
>
> while (len) {
> size_t read_len;
> loff_t pos = sd->pos, prev_pos = pos;
>
> - ret = do_splice_to(in, &pos, pipe, len, flags);
> + ret = do_splice_to(in, &pos, pipe, len, 0);
> if (unlikely(ret <= 0))
> goto out_release;
>
> read_len = ret;
> sd->total_len = read_len;
>
> - /*
> - * NOTE: nonblocking mode only applies to the input. We
> - * must not do the output in nonblocking mode as then we
> - * could get stuck data in the internal pipe:
> - */
> ret = actor(pipe, sd);
> if (unlikely(ret <= 0)) {
> sd->pos = prev_pos;
> @@ -1242,7 +1231,6 @@ static int direct_splice_actor(struct pipe_inode_info *pipe,
> * @ppos: input file offset
> * @out: file to splice to
> * @len: number of bytes to splice
> - * @flags: splice modifier flags
> *
> * Description:
> * For use by do_sendfile(). splice can easily emulate sendfile, but
> @@ -1252,12 +1240,11 @@ static int direct_splice_actor(struct pipe_inode_info *pipe,
> *
> */
> long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
> - size_t len, unsigned int flags)
> + size_t len)
> {
> struct splice_desc sd = {
> .len = len,
> .total_len = len,
> - .flags = flags,
> .pos = *ppos,
> .u.file = out,
> };
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 4079ef9..eb86433 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2224,7 +2224,7 @@ extern ssize_t generic_file_splice_write(struct pipe_inode_info *,
> extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
> struct file *out, loff_t *, size_t len, unsigned int flags);
> extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
> - size_t len, unsigned int flags);
> + size_t len);
>
> extern void
> file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
> --
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