From 4ae4dde6f34a4124c65468ae4fa1f915fb40f900 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 3 Dec 2025 21:55:27 +0000 Subject: [PATCH] cifs: Fix handling of a beyond-EOF DIO/unbuffered read over SMB2 If a DIO read or an unbuffered read request extends beyond the EOF, the server will return a short read and a status code indicating that EOF was hit, which gets translated to -ENODATA. Note that the client does not cap the request at i_size, but asks for the amount requested in case there's a race on the server with a third party. Now, on the client side, the request will get split into multiple subrequests if rsize is smaller than the full request size. A subrequest that starts before or at the EOF and returns short data up to the EOF will be correctly handled, with the NETFS_SREQ_HIT_EOF flag being set, indicating to netfslib that we can't read more. If a subrequest, however, starts after the EOF and not at it, HIT_EOF will not be flagged, its error will be set to -ENODATA and it will be abandoned. This will cause the request as a whole to fail with -ENODATA. Fix this by setting NETFS_SREQ_HIT_EOF on any subrequest that lies beyond the EOF marker. Fixes: 1da29f2c39b6 ("netfs, cifs: Fix handling of short DIO read") Signed-off-by: David Howells Reviewed-by: Paulo Alcantara (Red Hat) cc: Shyam Prasad N cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French --- fs/smb/client/smb2pdu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index e8b423a28e18c..dec9968ffb488 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -4695,7 +4695,7 @@ do_retry: } else { size_t trans = rdata->subreq.transferred + rdata->got_bytes; if (trans < rdata->subreq.len && - rdata->subreq.start + trans == ictx->remote_i_size) { + rdata->subreq.start + trans >= ictx->remote_i_size) { __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags); rdata->result = 0; } -- 2.47.3