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splice: stop abusing iov_iter_advance() to flush a pipe 

Use pipe_discard_from() explicitly in generic_file_read_iter(); don't bother
with rather non-obvious use of iov_iter_advance() in there.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-06-12 16:07:49 -04:00
parent 3e20a751af
commit 0d96493413
1 changed files with 2 additions and 5 deletions
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7
fs/splice.c
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@ -301,11 +301,9 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
{
struct iov_iter to;
struct kiocb kiocb;
unsigned int i_head;
int ret;
iov_iter_pipe(&to, READ, pipe, len);
i_head = to.head;
init_sync_kiocb(&kiocb, in);
kiocb.ki_pos = *ppos;
ret = call_read_iter(in, &kiocb, &to);
@ -313,9 +311,8 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
*ppos = kiocb.ki_pos;
file_accessed(in);
} else if (ret < 0) {
to.head = i_head;
to.iov_offset = 0;
iov_iter_advance(&to, 0); /* to free what was emitted */
/* free what was emitted */
pipe_discard_from(pipe, to.start_head);
/*
* callers of ->splice_read() expect -EAGAIN on
* "can't put anything in there", rather than -EFAULT.