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| author | David Howells <dhowells@redhat.com> | 2020-01-14 18:07:11 +0100 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2020-05-19 16:38:18 +0200 |
| commit | 8cfba76383e902acbed95092163052b1572f17a8 (patch) | |
| tree | f454a431df62749357767cf70feba3c2022b5cb0 /fs/pipe.c | |
| parent | Add sample notification program (diff) | |
| download | linux-8cfba76383e902acbed95092163052b1572f17a8.tar.xz linux-8cfba76383e902acbed95092163052b1572f17a8.zip | |
pipe: Allow buffers to be marked read-whole-or-error for notifications
Allow a buffer to be marked such that read() must return the entire buffer
in one go or return ENOBUFS. Multiple buffers can be amalgamated into a
single read, but a short read will occur if the next "whole" buffer won't
fit.
This is useful for watch queue notifications to make sure we don't split a
notification across multiple reads, especially given that we need to
fabricate an overrun record under some circumstances - and that isn't in
the buffers.
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/pipe.c')
| -rw-r--r-- | fs/pipe.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index da9bc1f21fd1..0f9fd897ceb5 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -320,8 +320,14 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) size_t written; int error; - if (chars > total_len) + if (chars > total_len) { + if (buf->flags & PIPE_BUF_FLAG_WHOLE) { + if (ret == 0) + ret = -ENOBUFS; + break; + } chars = total_len; + } error = pipe_buf_confirm(pipe, buf); if (error) { |