@@ -33,6 +33,22 @@ static void netfs_clear_unread(struct netfs_io_subrequest *subreq)
__set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
}
+static void netfs_clear_unread_dio(struct netfs_io_subrequest *subreq)
+{
+ uoff_t pos = subreq->start + subreq->transferred;
+ struct netfs_io_request *rreq = subreq->rreq;
+ size_t fill;
+
+ if (pos >= rreq->i_size)
+ return;
+
+ fill = min_t(uoff_t, rreq->i_size - pos,
+ subreq->len - subreq->transferred);
+
+ netfs_reset_iter(subreq);
+ subreq->transferred += iov_iter_zero(fill, &subreq->io_iter);
+}
+
/*
* Cancel the copy-to-cache mark on a folio.
*/
@@ -311,6 +327,14 @@ static void netfs_collect_read_results(struct netfs_io_request *rreq)
test_bit(NETFS_SREQ_HIT_EOF, &front->flags))
netfs_read_unlock_folios(rreq, ¬es);
} else {
+ if (!(notes & HIT_PENDING) &&
+ front->error == 0 &&
+ transferred < front->len &&
+ test_bit(NETFS_SREQ_CLEAR_TAIL, &front->flags)) {
+ netfs_clear_unread_dio(front);
+ transferred = front->transferred;
+ trace_netfs_sreq(front, netfs_sreq_trace_clear);
+ }
stream->collected_to = front->start + transferred;
rreq->collected_to = stream->collected_to;
}
The buffered read collector zero-fills the tail of a short read that stops below the inode's i_size (netfs_clear_unread()), so a read that races an extending write still returns the expected number of bytes. The non-buffered collector path does no such thing: it just records how much was transferred. Add the same zero-fill for the non-buffered case, gated on NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short result from it is known to be safe to treat as a hole, as opposed to NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of the file and should be reported short as-is. Only CLEAR_TAIL should zero-fill here; a real EOF must stay a real short read. No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest, so this is inert on its own -- a following change teaches cifs to set it in the one case that needs it. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Reviewed-by: David Howells <dhowells@redhat.com> Reviewed-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Paulo Alcantara <pc@manguebit.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Namjae Jeon <linkinjeon@kernel.org> Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com> Cc: Shyam Prasad N <sprasad@microsoft.com> Cc: Tom Talpey <tom@talpey.com> Cc: Bharath SM <bharathsm@microsoft.com> Cc: stable@vger.kernel.org --- fs/netfs/read_collect.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)