From 751e0d559c62a87dc828af22c3c58dc078c734e3 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 15 Feb 2024 07:36:43 +0100 Subject: [PATCH] writeback: factor writeback_get_batch() out of write_cache_pages() 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. [hch@lst.de: heavily rebased, add helpers to get the tag and end index, don't keep the end index in struct writeback_control] Link: https://lkml.kernel.org/r/20240215063649.2164017-9-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Christoph Hellwig Reviewed-by: Brian Foster Reviewed-by: Jan Kara Acked-by: Dave Chinner Cc: Christian Brauner Cc: David Howells Signed-off-by: Andrew Morton --- 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 4b8cf9e4810b..f67b3ea866a0 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -11,6 +11,7 @@ #include #include #include +#include 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 4bc55ce9597d..5b8dbbef7137 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(); } /* @@ -2512,6 +2527,7 @@ 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; @@ -2519,7 +2535,7 @@ int write_cache_pages(struct address_space *mapping, done: if (wbc->range_cyclic) mapping->writeback_index = folio->index + folio_nr_pages(folio); - folio_batch_release(&fbatch); + folio_batch_release(&wbc->fbatch); return error; } EXPORT_SYMBOL(write_cache_pages);