The patch titled
Subject: writeback: factor writeback_get_batch() out of write_cache_pages()
has been added to the -mm mm-unstable branch. Its filename is
writeback-factor-writeback_get_batch-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-writeback_get_batch-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 writeback_get_batch() out of write_cache_pages()
Date: Thu, 15 Feb 2024 07:36:43 +0100
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@xxxxxx: 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@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>
---
include/linux/writeback.h | 6 +++
mm/page-writeback.c | 60 ++++++++++++++++++++++--------------
2 files changed, 44 insertions(+), 22 deletions(-)
--- a/include/linux/writeback.h~writeback-factor-writeback_get_batch-out-of-write_cache_pages
+++ a/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 */
--- a/mm/page-writeback.c~writeback-factor-writeback_get_batch-out-of-write_cache_pages
+++ a/mm/page-writeback.c
@@ -2392,6 +2392,29 @@ static bool folio_prepare_writeback(stru
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_spa
{
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_spa
goto done;
}
}
- folio_batch_release(&fbatch);
- cond_resched();
}
/*
@@ -2512,6 +2527,7 @@ int write_cache_pages(struct address_spa
* 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_spa
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);
_
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
