Attachment 7679 Details for Bug 9017 – patch -- when server doesn't set CAP_LARGE_READ_X, cap default rsize at MaxBufferSize

[patch] patch -- when server doesn't set CAP_LARGE_READ_X, cap default rsize at MaxBufferSize

0001-cifs-when-server-doesn-t-set-CAP_LARGE_READ_X-cap-de.patch (text/plain), 2.18 KB, created by Jeff Layton on 2012-06-30 11:37:16 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Jeff Layton

Created: 2012-06-30 11:37:16 UTC

Size: 2.18 KB

patch

obsolete

>From 74f7777ccf593550f7417a582b742b5d1a92eb2d Mon Sep 17 00:00:00 2001
>From: Jeff Layton <jlayton@redhat.com>
>Date: Sat, 30 Jun 2012 07:33:37 -0400
>Subject: [PATCH] cifs: when server doesn't set CAP_LARGE_READ_X, cap default
> rsize at MaxBufferSize
>
>When the server doesn't advertise CAP_LARGE_READ_X, then MS-CIFS states
>that you must cap the size of the read at the client's MaxBufferSize.
>Unfortunately, testing with many older servers shows that they further
>cap the size of a READ_ANDX response at the size of the server's
>MaxBufferSize.
>
>Since we can't clearly tell what the server will do, we must be
>conservative here for the default. When the server can't do large reads,
>then assume that it can't satisfy any read larger than its MaxBufferSize
>either. This just governs the default however. The admin can always
>override this on his own.
>
>Cc: <stable@vger.kernel.org> # 3.2
>Reported-by: David H. Durgee <dhdurgee@acm.org>
>Signed-off-by: Jeff Layton <jlayton@redhat.com>
>---
> fs/cifs/connect.c |    9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
>
>diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
>index 402fe08..f0a1a24 100644
>--- a/fs/cifs/connect.c
>+++ b/fs/cifs/connect.c
>@@ -3508,18 +3508,15 @@ cifs_negotiate_rsize(struct cifs_tcon *tcon, struct smb_vol *pvolume_info)
> 	 * MS-CIFS indicates that servers are only limited by the client's
> 	 * bufsize for reads, testing against win98se shows that it throws
> 	 * INVALID_PARAMETER errors if you try to request too large a read.
>+	 * OS/2 just sends back short reads.
> 	 *
>-	 * If the server advertises a MaxBufferSize of less than one page,
>-	 * assume that it also can't satisfy reads larger than that either.
>-	 *
>-	 * FIXME: Is there a better heuristic for this?
>+	 * If the server doesn't advertise CAP_LARGE_READ_X, then assume that
>+	 * it can't handle a read request larger than its MaxBufferSize either.
> 	 */
> 	if (tcon->unix_ext && (unix_cap & CIFS_UNIX_LARGE_READ_CAP))
> 		defsize = CIFS_DEFAULT_IOSIZE;
> 	else if (server->capabilities & CAP_LARGE_READ_X)
> 		defsize = CIFS_DEFAULT_NON_POSIX_RSIZE;
>-	else if (server->maxBuf >= PAGE_CACHE_SIZE)
>-		defsize = CIFSMaxBufSize;
> 	else
> 		defsize = server->maxBuf - sizeof(READ_RSP);
> 
>-- 
>1.7.7.6
>

Actions: View

Attachments on bug 9017: 7677 | 7678 | 7679 | 7684