Re: [PATCH 1/3] fs: fcntl add set_flags wrapper

[Dmitry Monakhov <dmonakhov@openvz.org>]

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Christoph Hellwig <hch@infradead.org> writes:

>> +	else {
>> +		spin_lock(&filp->f_lock);
>> +		filp->f_flags = (arg & SETFL_MASK) |
>> +			(filp->f_flags & ~SETFL_MASK);
>> +		spin_unlock(&filp->f_lock);
>
> Please move this into an exported generic_file_set_flags helper, that
> the filesystems can use in their implementations instead of duplicating
> it.
Ok. Will do
>
> Also a more conceptual question:  Basically any check the filesystems
> may perform needs to be duplicated in open and ->set_flags.  Any chance
> to have the open path call into ->set_flags?
After your point I've checked various ->open callbacks and found
that most filesystem makes important decisions such as:
cifs_open:
        if (file->f_flags & O_DIRECT &&
            cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) {
               if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
                        file->f_op = &cifs_file_direct_nobrl_ops;
                else
                        file->f_op = &cifs_file_direct_ops;
                        }
         }
And I am completely agree that it is reasonable to move such
functionality to ->set_flags and let ->open call ->set_flags internally.
 ->set_flags can determine that it is called from open by condition:
(filp->f_flags & SETFL_MASK) == (arg & SETFL_MASK)
I'll fix setfl to prevent ->set_flags if args are the same

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