Re: [linux-cifs-client] [PATCH 04/13] cifs: clean up set_cifs_acl interfaces

[Shirish Pargaonkar <shirishpargaonkar@gmail.com>]

On Thu, May 14, 2009 at 7:21 AM, Jeff Layton <jlayton@redhat.com> wrote:
> On Wed, 13 May 2009 21:53:13 -0500
> Shirish Pargaonkar <shirishpargaonkar@gmail.com> wrote:
>
>> On Wed, May 13, 2009 at 3:04 PM, Jeff Layton <jlayton@redhat.com> wrote:
>> > From: Christoph Hellwig <hch@infradead.org>
>> >
>> > Signed-off-by: Christoph Hellwig <hch@lst.de>
>> > Signed-off-by: Jeff Layton <jlayton@redhat.com>
>> > ---
>> >  fs/cifs/cifsacl.c |   78 ++++++++++++++++++++++++++++-------------------------
>> >  1 files changed, 41 insertions(+), 37 deletions(-)
>> >
>> > diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
>> > index 7f8e6c4..1403b5d 100644
>> > --- a/fs/cifs/cifsacl.c
>> > +++ b/fs/cifs/cifsacl.c
>> > @@ -612,57 +612,61 @@ static struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
>> >        return pntsd;
>> >  }
>> >
>> > -/* Set an ACL on the server */
>> > -static int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
>> > -                               struct inode *inode, const char *path)
>> > +static int set_cifs_acl_by_fid(struct cifs_sb_info *cifs_sb, __u16 fid,
>> > +               struct cifs_ntsd *pnntsd, u32 acllen)
>> >  {
>> > -       struct cifsFileInfo *open_file;
>> > -       bool unlock_file = false;
>> > -       int xid;
>> > -       int rc = -EIO;
>> > -       __u16 fid;
>> > -       struct super_block *sb;
>> > -       struct cifs_sb_info *cifs_sb;
>> > +       int xid, rc;
>> >
>> > -       cFYI(DBG2, ("set ACL for %s from mode 0x%x", path, inode->i_mode));
>> > +       xid = GetXid();
>> > +       rc = CIFSSMBSetCIFSACL(xid, cifs_sb->tcon, fid, pnntsd, acllen);
>> > +       FreeXid(xid);
>> >
>> > -       if (!inode)
>> > -               return rc;
>> > +       cFYI(DBG2, ("SetCIFSACL rc = %d", rc));
>> > +       return rc;
>> > +}
>> >
>> > -       sb = inode->i_sb;
>> > -       if (sb == NULL)
>> > -               return rc;
>> > +static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
>> > +               struct cifs_ntsd *pnntsd, u32 acllen)
>> > +{
>> > +       int oplock = 0;
>> > +       int xid, rc;
>> > +       __u16 fid;
>> >
>> > -       cifs_sb = CIFS_SB(sb);
>> >        xid = GetXid();
>> >
>> > -       open_file = find_readable_file(CIFS_I(inode));
>> > -       if (open_file) {
>> > -               unlock_file = true;
>> > -               fid = open_file->netfid;
>> > -       } else {
>> > -               int oplock = 0;
>> > -               /* open file */
>> > -               rc = CIFSSMBOpen(xid, cifs_sb->tcon, path, FILE_OPEN,
>> > -                               WRITE_DAC, 0, &fid, &oplock, NULL,
>> > -                               cifs_sb->local_nls, cifs_sb->mnt_cifs_flags &
>> > -                                       CIFS_MOUNT_MAP_SPECIAL_CHR);
>> > -               if (rc != 0) {
>> > -                       cERROR(1, ("Unable to open file to set ACL"));
>> > -                       FreeXid(xid);
>> > -                       return rc;
>> > -               }
>> > +       rc = CIFSSMBOpen(xid, cifs_sb->tcon, path, FILE_OPEN, WRITE_DAC, 0,
>> > +                        &fid, &oplock, NULL, cifs_sb->local_nls,
>> > +                        cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
>> > +       if (rc) {
>> > +               cERROR(1, ("Unable to open file to set ACL"));
>> > +               goto out;
>> >        }
>> >
>> >        rc = CIFSSMBSetCIFSACL(xid, cifs_sb->tcon, fid, pnntsd, acllen);
>> >        cFYI(DBG2, ("SetCIFSACL rc = %d", rc));
>> > -       if (unlock_file)
>> > -               atomic_dec(&open_file->wrtPending);
>> > -       else
>> > -               CIFSSMBClose(xid, cifs_sb->tcon, fid);
>> >
>> > +       CIFSSMBClose(xid, cifs_sb->tcon, fid);
>> > + out:
>> >        FreeXid(xid);
>> > +       return rc;
>> > +}
>> >
>> > +/* Set an ACL on the server */
>> > +static int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
>> > +                               struct inode *inode, const char *path)
>> > +{
>> > +       struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
>> > +       struct cifsFileInfo *open_file;
>> > +       int rc;
>> > +
>> > +       cFYI(DBG2, ("set ACL for %s from mode 0x%x", path, inode->i_mode));
>> > +
>> > +       open_file = find_readable_file(CIFS_I(inode));
>>
>> We do not know how the file was opened or whether one can set the
>> attributes just
>> because we have a file handle.
>> So there is a possibility that set_cifs_acl_by_fid can fail but
>> set_cifs_acl_by_path
>> will succeed by virtue of opening file with attribute FILE_OPEN, WRITE_DAC?
>>
>
> You're correct that that does seem wrong, but I don't think this patch
> makes that any worse than it already is. The current set_cifs_acl code
> does a find_readable_file, and uses that fid to try and set the ACL.
>

Jeff, you are right.

> On a side note, this whole find_readable_file/find_writeable_file
> interface is a real mess. What we really need I think is a new
> find_open_file function that takes a set of open flags as an arg. When
> it finds an open fh with flags that match the ones you've requested, it
> can return that with the refcount bumped.
>
> In fact, it would be even better if all of the "fallback to doing a new
> open" stuff was hidden in an interface too so that callers didn't have
> to worry about it.
>
>> > +       if (!open_file)
>> > +               return set_cifs_acl_by_path(cifs_sb, path, pnntsd, acllen);
>> > +
>> > +       rc = set_cifs_acl_by_fid(cifs_sb, open_file->netfid, pnntsd, acllen);
>> > +       atomic_dec(&open_file->wrtPending);
>> >        return rc;
>> >  }
>> >
>> > --
>> > 1.6.2.2
>> >
>
>
> --
> Jeff Layton <jlayton@redhat.com>
>