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teach sendfile(2) to handle send-to-pipe directly

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no point going through the intermediate pipe

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2021-01-25 22:24:28 -05:00
parent faa97c48c3
commit b964bf53e5
3 changed files with 23 additions and 7 deletions
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19
fs/read_write.c
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@@ -1188,6 +1188,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
{
struct fd in, out;
struct inode *in_inode, *out_inode;
struct pipe_inode_info *opipe;
loff_t pos;
loff_t out_pos;
ssize_t retval;
@@ -1228,9 +1229,6 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
in_inode = file_inode(in.file);
out_inode = file_inode(out.file);
out_pos = out.file->f_pos;
retval = rw_verify_area(WRITE, out.file, &out_pos, count);
if (retval < 0)
goto fput_out;
if (!max)
max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
@@ -1253,9 +1251,18 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
if (in.file->f_flags & O_NONBLOCK)
fl = SPLICE_F_NONBLOCK;
#endif
file_start_write(out.file);
retval = do_splice_direct(in.file, &pos, out.file, &out_pos, count, fl);
file_end_write(out.file);
opipe = get_pipe_info(out.file, true);
if (!opipe) {
retval = rw_verify_area(WRITE, out.file, &out_pos, count);
if (retval < 0)
goto fput_out;
file_start_write(out.file);
retval = do_splice_direct(in.file, &pos, out.file, &out_pos,
count, fl);
file_end_write(out.file);
} else {
retval = splice_file_to_pipe(in.file, opipe, &pos, count, fl);
}
if (retval > 0) {
add_rchar(current, retval);