On Tue 15-10-13 19:15:56, Ming Lei wrote: > > This won't quite work because if the page is fully mapped > > mpage_process_page_bufs() will immediately submit the page and decrease > > nr_to_write. So now you would end up writing less than you were asked for > > in some cases. > > Yes, your are right, so how about below? > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 32c04ab..3cf7abb 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -2295,6 +2295,7 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd) > struct address_space *mapping = mpd->inode->i_mapping; > struct pagevec pvec; > unsigned int nr_pages; > + int left = mpd->wbc->nr_to_write; 'long' please. Otherwise the patch looks fine. Thanks! Honza > pgoff_t index = mpd->first_page; > pgoff_t end = mpd->last_page; > int tag; > @@ -2330,6 +2331,17 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd) > if (page->index > end) > goto out; > > + /* > + * Accumulated enough dirty pages? This doesn't apply > + * to WB_SYNC_ALL mode. For integrity sync we have to > + * keep going because someone may be concurrently > + * dirtying pages, and we might have synced a lot of > + * newly appeared dirty pages, but have not synced all > + * of the old dirty pages. > + */ > + if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0) > + goto out; > + > /* If we can't merge this page, we are done. */ > if (mpd->map.m_len > 0 && mpd->next_page != page->index) > goto out; > @@ -2364,19 +2376,7 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd) > if (err <= 0) > goto out; > err = 0; > - > - /* > - * Accumulated enough dirty pages? This doesn't apply > - * to WB_SYNC_ALL mode. For integrity sync we have to > - * keep going because someone may be concurrently > - * dirtying pages, and we might have synced a lot of > - * newly appeared dirty pages, but have not synced all > - * of the old dirty pages. > - */ > - if (mpd->wbc->sync_mode == WB_SYNC_NONE && > - mpd->next_page - mpd->first_page >= > - mpd->wbc->nr_to_write) > - goto out; > + left--; > } > pagevec_release(&pvec); > cond_resched(); > > > > Attached patch should do what's needed. Can you try whether > > it fixes the problem for you (it seems to work OK in my testing). > > In fact, I had wrote and tested your attached patch before my last post, > and it may trigger BUG() in mpage_release_unused_pages(), that is because > we touch mpd->next_page without locking current page, so it is better to > not increase mpd->next_page if the current page won't be processed. > > > Thanks, > -- > Ming Lei -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
