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authorDavid Howells <dhowells@redhat.com>2020-01-14 17:07:11 +0000
committerDavid Howells <dhowells@redhat.com>2020-05-19 15:38:18 +0100
commit8cfba76383e902acbed95092163052b1572f17a8 (patch)
treef454a431df62749357767cf70feba3c2022b5cb0 /fs
parentf5b5a164f9a11aab5b225f082b33a8f03c07516c (diff)
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')
-rw-r--r--fs/pipe.c8
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) {