From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> This simple helper will be the basis of the writeback iterator. To make this work, we need to remember the current index and end positions in writeback_control. Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> [hch: heavily rebased, add helpers to get the tag and end index, don't keep the end index in struct writeback_control] Signed-off-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Acked-by: Dave Chinner <dchinner@xxxxxxxxxx> --- include/linux/writeback.h | 6 ++++ mm/page-writeback.c | 60 +++++++++++++++++++++++++-------------- 2 files changed, 44 insertions(+), 22 deletions(-) diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 4b8cf9e4810bad..f67b3ea866a0fb 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -11,6 +11,7 @@ #include <linux/flex_proportions.h> #include <linux/backing-dev-defs.h> #include <linux/blk_types.h> +#include <linux/pagevec.h> struct bio; @@ -40,6 +41,7 @@ enum writeback_sync_modes { * in a manner such that unspecified fields are set to zero. */ struct writeback_control { + /* public fields that can be set and/or consumed by the caller: */ long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */ @@ -77,6 +79,10 @@ struct writeback_control { */ struct swap_iocb **swap_plug; + /* internal fields used by the ->writepages implementation: */ + struct folio_batch fbatch; + pgoff_t index; + #ifdef CONFIG_CGROUP_WRITEBACK struct bdi_writeback *wb; /* wb this writeback is issued under */ struct inode *inode; /* inode being written out */ diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 949193624baa38..23363ed712f646 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2392,6 +2392,29 @@ static bool folio_prepare_writeback(struct address_space *mapping, return true; } +static xa_mark_t wbc_to_tag(struct writeback_control *wbc) +{ + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + return PAGECACHE_TAG_TOWRITE; + return PAGECACHE_TAG_DIRTY; +} + +static pgoff_t wbc_end(struct writeback_control *wbc) +{ + if (wbc->range_cyclic) + return -1; + return wbc->range_end >> PAGE_SHIFT; +} + +static void writeback_get_batch(struct address_space *mapping, + struct writeback_control *wbc) +{ + folio_batch_release(&wbc->fbatch); + cond_resched(); + filemap_get_folios_tag(mapping, &wbc->index, wbc_end(wbc), + wbc_to_tag(wbc), &wbc->fbatch); +} + /** * write_cache_pages - walk the list of dirty pages of the given address space and write all of them. * @mapping: address space structure to write @@ -2429,38 +2452,32 @@ int write_cache_pages(struct address_space *mapping, { int ret = 0; int error; - struct folio_batch fbatch; struct folio *folio; - int nr_folios; - pgoff_t index; pgoff_t end; /* Inclusive */ - xa_mark_t tag; - folio_batch_init(&fbatch); if (wbc->range_cyclic) { - index = mapping->writeback_index; /* prev offset */ + wbc->index = mapping->writeback_index; /* prev offset */ end = -1; } else { - index = wbc->range_start >> PAGE_SHIFT; + wbc->index = wbc->range_start >> PAGE_SHIFT; end = wbc->range_end >> PAGE_SHIFT; } - if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) { - tag_pages_for_writeback(mapping, index, end); - tag = PAGECACHE_TAG_TOWRITE; - } else { - tag = PAGECACHE_TAG_DIRTY; - } - while (index <= end) { + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + tag_pages_for_writeback(mapping, wbc->index, end); + + folio_batch_init(&wbc->fbatch); + + while (wbc->index <= end) { int i; - nr_folios = filemap_get_folios_tag(mapping, &index, end, - tag, &fbatch); + writeback_get_batch(mapping, wbc); - if (nr_folios == 0) + if (wbc->fbatch.nr == 0) break; - for (i = 0; i < nr_folios; i++) { - folio = fbatch.folios[i]; + for (i = 0; i < wbc->fbatch.nr; i++) { + folio = wbc->fbatch.folios[i]; + folio_lock(folio); if (!folio_prepare_writeback(mapping, wbc, folio)) { folio_unlock(folio); @@ -2498,8 +2515,6 @@ int write_cache_pages(struct address_space *mapping, goto done; } } - folio_batch_release(&fbatch); - cond_resched(); } /* @@ -2512,12 +2527,13 @@ int write_cache_pages(struct address_space *mapping, * of the file if we are called again, which can only happen due to * -ENOMEM from the file system. */ + folio_batch_release(&wbc->fbatch); if (wbc->range_cyclic) mapping->writeback_index = 0; return ret; done: - folio_batch_release(&fbatch); + folio_batch_release(&wbc->fbatch); if (wbc->range_cyclic) mapping->writeback_index = folio->index + folio_nr_pages(folio); return error; -- 2.39.2