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Message-Id: <1274867803-3050-1-git-send-email-xiaosuo@gmail.com>
Date: Wed, 26 May 2010 17:56:43 +0800
From: Changli Gao <xiaosuo@...il.com>
To: Alexander Viro <viro@...iv.linux.org.uk>
Cc: Matthew Wilcox <matthew@....cx>, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, Changli Gao <xiaosuo@...il.com>
Subject: [PATCH 3/3] sendfile: fix sendfile
fix sendfile
the flags parameter of splice() doesn't mean non-block read of in file, 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.
If output file is in non-block mode, in file should be seekable to avoid data
losing.
do_splice_from() shouldn't use sd->pos, as sd->pos is for file reading,
file->f_pos should be used instead.
Signed-off-by: Changli Gao <xiaosuo@...il.com>
----
fs/read_write.c | 23 ++++++++---------------
fs/splice.c | 22 +++++-----------------
include/linux/fs.h | 2 +-
3 files changed, 14 insertions(+), 33 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 113386d..a844e2c 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..
@@ -808,11 +808,15 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
if (!(in_file->f_mode & FMODE_READ))
goto fput_in;
retval = -ESPIPE;
- if (!ppos)
+ if (!ppos) {
ppos = &in_file->f_pos;
- else
+ if ((out_file->f_flags & O_NONBLOCK) &&
+ !(in_file->f_mode & FMODE_PREAD))
+ goto fput_in;
+ } else {
if (!(in_file->f_mode & FMODE_PREAD))
goto fput_in;
+ }
retval = rw_verify_area(READ, in_file, ppos, count);
if (retval < 0)
goto fput_in;
@@ -846,18 +850,7 @@ 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 8137e23..e921d72 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;
@@ -1232,7 +1221,8 @@ static int direct_splice_actor(struct pipe_inode_info *pipe,
{
struct file *file = sd->u.file;
- return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
+ return do_splice_from(pipe, file, &file->f_pos, sd->total_len,
+ sd->flags);
}
/**
@@ -1241,7 +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
@@ -1251,12 +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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