Re: CIFS: reset ATTR_READONLY on Windows
- From: Steve French <smfrench@xxxxxxxxxxxxx>
- Date: Thu, 22 Mar 2007 22:35:36 -0500
When all write permission bits are removed from a file onchmod ugo+w filename). The read-only
the Windows share (e.g. using chmod ugo-w filename), the
read-only bit is set in the file (as seen in the Windows Explorer).
Now it is not possible to get the write permissions back (e.g. using
bit has to be removed in the Windows Explorer. When this is done,
the file is still displayed to be read-only (ls -l filename),
but it can be made writeable (chmod ugo+w filename). When the
patch from the message mentioned above is applied (discovered
by Alan Tyson of HP, reported by Jeff Layton), the writeable bits
are displayed correctly as soon as the read-only bit is
removed in the Windows Explorer. The main problem,
however, still exists as it is not possible to make the
file writeable from the Linux CIFS client.
Investigating the problem further, I found out that the problem occurs
only if no other attribute is set on the file. If I set the archived or
hidden bit in the Windows Explorer or unmark the "for fast searching,
allow Indexing Service to index this file" checkbox (which sets the
ATTR_NOT_CONTENT_INDEXED bit), the read-only bit can be cleared from the
Linux client. Looking into the function cifs_setattr() in fs/cifs/inode.c
and adding some debug output, it can be seen that time_buf.Attributes is
zero in the problem case and the attribute will not be set. Sending the
attributes with a zero value does not help as this seems to mean that no
attributes have to be changed. So I added the ATTR_NORMAL bit in the case
where ATTR_READONLY has to be cleared and no other attribute is set.
Urs,
Yes - you were correct. Good catch. Thanks. The patch I put in the cifs
tree was implemented slightly differently (I did not read the 2nd half of
your email until too late) but is a similar idea. Would you take a look
at it?
http://master.kernel.org/git/?p=linux/kernel/git/sfrench/cifs-2.6.git;a=commitdiff;h=066fcb06d3e27c258bc229bb688ced2b16daa6c2
I made another small change: The ATTR_READONLY is only cleared if all
writeable bits are set in the Linux permissions (the file is writeable for
user, group and others). This is caused by the check ((mode & S_IWUGO) ==
S_IWUGO). I think that this does not make sense, as soon as any write flag
is set, the file is no longer read-only.
I agree that the 2nd change is intuitive, but it changes behavior slightly
more - and this close to the next point release coming out I would
rather fix the bug the least risky way.
Fortunately this compensation won't matter as much when the code is finished
to store the mode in the CIFS ACL for those type of servers. I am tempted
to just save the mode in an xattr (actually OS/2 EA which NTFS still supports)
for these cases.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
- Follow-Ups:
- Re: CIFS: reset ATTR_READONLY on Windows
- From: Urs Fleisch
- Re: CIFS: reset ATTR_READONLY on Windows
- Prev by Date: Re: [patch] 2.6.21-rc4 nicksched v32
- Next by Date: Re: RSDL 0.31 causes slowdown
- Previous by thread: [PATCH 000 of 3] md: bug fixes for md for 2.6.21
- Next by thread: Re: CIFS: reset ATTR_READONLY on Windows
- Index(es):
Relevant Pages
|
