The patch titled
Subject: writeback: Factor folio_prepare_writeback() out of write_cache_pages()
has been added to the -mm mm-unstable branch. Its filename is
writeback-factor-folio_prepare_writeback-out-of-write_cache_pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/writeback-factor-folio_prepare_writeback-out-of-write_cache_pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: writeback: Factor folio_prepare_writeback() out of write_cache_pages()
Date: Thu, 15 Feb 2024 07:36:42 +0100
Reduce write_cache_pages() by about 30 lines; much of it is commentary,
but it all bundles nicely into an obvious function.
[hch@xxxxxx: rename should_writeback_folio to folio_prepare_writeback per Jan]
Link: https://lkml.kernel.org/r/20240215063649.2164017-8-hch@xxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
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>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 61 +++++++++++++++++++++++-------------------
1 file changed, 34 insertions(+), 27 deletions(-)
--- a/mm/page-writeback.c~writeback-factor-folio_prepare_writeback-out-of-write_cache_pages
+++ a/mm/page-writeback.c
@@ -2360,6 +2360,38 @@ void tag_pages_for_writeback(struct addr
}
EXPORT_SYMBOL(tag_pages_for_writeback);
+static bool folio_prepare_writeback(struct address_space *mapping,
+ struct writeback_control *wbc, struct folio *folio)
+{
+ /*
+ * Folio truncated or invalidated. We can freely skip it then,
+ * even for data integrity operations: the folio has disappeared
+ * concurrently, so there could be no real expectation of this
+ * data integrity operation even if there is now a new, dirty
+ * folio at the same pagecache index.
+ */
+ if (unlikely(folio->mapping != mapping))
+ return false;
+
+ /*
+ * Did somebody else write it for us?
+ */
+ if (!folio_test_dirty(folio))
+ return false;
+
+ if (folio_test_writeback(folio)) {
+ if (wbc->sync_mode == WB_SYNC_NONE)
+ return false;
+ folio_wait_writeback(folio);
+ }
+ BUG_ON(folio_test_writeback(folio));
+
+ if (!folio_clear_dirty_for_io(folio))
+ return false;
+
+ return true;
+}
+
/**
* 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
@@ -2430,38 +2462,13 @@ int write_cache_pages(struct address_spa
for (i = 0; i < nr_folios; i++) {
folio = fbatch.folios[i];
folio_lock(folio);
-
- /*
- * Page truncated or invalidated. We can freely skip it
- * then, even for data integrity operations: the page
- * has disappeared concurrently, so there could be no
- * real expectation of this data integrity operation
- * even if there is now a new, dirty page at the same
- * pagecache address.
- */
- if (unlikely(folio->mapping != mapping)) {
-continue_unlock:
+ if (!folio_prepare_writeback(mapping, wbc, folio)) {
folio_unlock(folio);
continue;
}
- if (!folio_test_dirty(folio)) {
- /* someone wrote it for us */
- goto continue_unlock;
- }
-
- if (folio_test_writeback(folio)) {
- if (wbc->sync_mode != WB_SYNC_NONE)
- folio_wait_writeback(folio);
- else
- goto continue_unlock;
- }
-
- BUG_ON(folio_test_writeback(folio));
- if (!folio_clear_dirty_for_io(folio))
- goto continue_unlock;
-
trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
+
error = writepage(folio, wbc, data);
wbc->nr_to_write -= folio_nr_pages(folio);
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
memcg-convert-mem_cgroup_move_charge_pte_range-to-use-a-folio.patch
memcg-return-the-folio-in-union-mc_target.patch
memcg-use-a-folio-in-get_mctgt_type.patch
memcg-use-a-folio-in-get_mctgt_type_thp.patch
mm-add-pfn_swap_entry_folio.patch
proc-use-pfn_swap_entry_folio-where-obvious.patch
mprotect-use-pfn_swap_entry_folio.patch
highmem-add-kernel-doc-for-memcpy__folio.patch
rmap-replace-two-calls-to-compound_order-with-folio_order.patch
writeback-remove-a-duplicate-prototype-for-tag_pages_for_writeback.patch
writeback-factor-folio_prepare_writeback-out-of-write_cache_pages.patch
writeback-factor-writeback_get_batch-out-of-write_cache_pages.patch
writeback-simplify-the-loops-in-write_cache_pages.patch
pagevec-add-ability-to-iterate-a-queue.patch
writeback-use-the-folio_batch-queue-iterator.patch
writeback-move-the-folio_prepare_writeback-loop-out-of-write_cache_pages.patch
writeback-remove-a-use-of-write_cache_pages-from-do_writepages.patch
bounds-support-non-power-of-two-config_nr_cpus.patch
