Attachment 315202 Details for Bug 460063 – upstream proposed patch

[patch] upstream proposed patch

0001-cifs-fix-O_APPEND-on-directio-mounts.patch (text/plain), 2.09 KB, created by Jeff Layton on 2008-08-28 12:14:47 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Jeff Layton

Created: 2008-08-28 12:14:47 UTC

Size: 2.09 KB

patch

obsolete

>From eecea50662aaaa33b7a9aa7767aa80d722ab7190 Mon Sep 17 00:00:00 2001
>From: Jeff Layton <jlayton@redhat.com>
>Date: Thu, 28 Aug 2008 07:54:59 -0400
>Subject: [PATCH] cifs: fix O_APPEND on directio mounts
>
>The direct I/O write codepath for CIFS is done through
>cifs_user_write(). That function does not currently call
>generic_write_checks() so the file position isn't being properly set
>when the file is opened with O_APPEND.  It's also not doing the other
>"normal" checks that should be done for a write call.
>
>The problem is currently that when you open a file with O_APPEND on a
>mount with the directio mount option, the file position is set to the
>beginning of the file. This makes any subsequent writes clobber the data
>in the file starting at the beginning.
>
>This seems to fix the problem in cursory testing. It is, however
>important to note that NFS disallows the combination of
>(O_DIRECT|O_APPEND). If my understanding is correct, the concern is
>races with multiple clients appending to a file clobbering each others'
>data. Since the write model for CIFS and NFS is pretty similar in this
>regard, CIFS is probably subject to the same sort of races. What's
>unclear to me is why this is a particular problem with O_DIRECT and not
>with buffered writes...
>
>Regardless, disallowing O_APPEND on an entire mount is probably not
>reasonable, so we'll probably just have to deal with it and reevaluate
>this flag combination when we get proper support for O_DIRECT. In the
>meantime this patch at least fixes the existing problem.
>
>Signed-off-by: Jeff Layton <jlayton@redhat.com>
>Cc: stable@kernel.org
>---
> fs/cifs/file.c |    4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
>diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>index ff14d14..cbefe1f 100644
>--- a/fs/cifs/file.c
>+++ b/fs/cifs/file.c
>@@ -833,6 +833,10 @@ ssize_t cifs_user_write(struct file *file, const char __user *write_data,
> 		return -EBADF;
> 	open_file = (struct cifsFileInfo *) file->private_data;
> 
>+	rc = generic_write_checks(file, poffset, &write_size, 0);
>+	if (rc)
>+		return rc;
>+
> 	xid = GetXid();
> 
> 	if (*poffset > file->f_path.dentry->d_inode->i_size)
>-- 
>1.5.5.1
>

Actions: View | Diff

Attachments on bug 460063: 314991 | 314992 | 315202