On 11/23/2010 12:54 PM, Nick Piggin wrote:
> On Tue, Nov 23, 2010 at 12:26:31PM +0200, Boaz Harrosh wrote:
>>> *
>>> * Invoke writeback_inodes_sb if no writeback is currently underway.
>>> * Returns 1 if writeback was started, 0 if not.
>>> + *
>>> + * Even if 1 is returned, writeback may not be started if memory allocation
>>> + * fails. This function makes no guarantees about anything.
>>> */
>>> int writeback_inodes_sb_if_idle(struct super_block *sb)
>>> {
>>> if (!writeback_in_progress(sb->s_bdi)) {
>>> - down_read(&sb->s_umount);
>>> - writeback_inodes_sb(sb);
>>> - up_read(&sb->s_umount);
>>> + bdi_start_writeback(sb->s_bdi, get_nr_dirty_pages());
>>> return 1;
>>> - } else
>>> - return 0;
>>> + }
>>> + return 0;
>>> }
>>> EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
>>>
>>> @@ -1172,17 +1173,18 @@ EXPORT_SYMBOL(writeback_inodes_sb_if_idl
>>> *
>>> * Invoke writeback_inodes_sb if no writeback is currently underway.
>>> * Returns 1 if writeback was started, 0 if not.
>>> + *
>>> + * Even if 1 is returned, writeback may not be started if memory allocation
>>> + * fails. This function makes no guarantees about anything.
>>> */
>>> int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
>>> unsigned long nr)
>>> {
>>> if (!writeback_in_progress(sb->s_bdi)) {
>>> - down_read(&sb->s_umount);
>>> - writeback_inodes_sb_nr(sb, nr);
>>> - up_read(&sb->s_umount);
>>> + bdi_start_writeback(sb->s_bdi, nr);
>>> return 1;
>>> - } else
>>> - return 0;
>>> + }
>>> + return 0;
>>> }
>>> EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle);
>>>
>>
>> static inline int writeback_inodes_sb_if_idle(struct super_block *sb)
>> {
>> return writeback_inodes_sb_nr_if_idle(sb, get_nr_dirty_pages());
>> }
>>
>> In writeback.h, No?
>
> I didn't care enough to move it :P I don't know if it matters.
>
Than please just open code it in ext4 and completely remove it.
One stupid function is enough don't you think?
>
>> But it has a single user so please just kill it.
>>
>> Also writeback_inodes_sb_nr_if_idle() has a single user. Combined with above,
>> two users. Why not open code it in the two sites. It should be much
>> clearer to understand what the magic is all about?
>
> The filesystem shouldn't be aware of the details (the "magic") of how to
> kick writeback, so I think the abstraction is right as is.
>
bdi_start_writeback() looks like a very clear abstraction to me but
if you have plans for it than sure, I'm convinced.
> Thanks,
> Nick
>
Thanks
Boaz
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