+ writeback-fix-done_index-when-hitting-the-wbc-nr_to_write.patch added to mm-unstable branch

+ writeback-fix-done_index-when-hitting-the-wbc-nr_to_write.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: writeback: fix done_index when hitting the wbc->nr_to_write
has been added to the -mm mm-unstable branch.  Its filename is
     writeback-fix-done_index-when-hitting-the-wbc-nr_to_write.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/writeback-fix-done_index-when-hitting-the-wbc-nr_to_write.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: Christoph Hellwig <hch@lst.de>
Subject: writeback: fix done_index when hitting the wbc->nr_to_write
Date: Thu, 15 Feb 2024 07:36:38 +0100

When write_cache_pages finishes writing out a folio, it fails to update
done_index to account for the number of pages in the folio just written. 
That means when range_cyclic writeback is restarted, it will be restarted
at this folio instead of after it as it should.  Fix that by updating
done_index before breaking out of the loop.

Link: https://lkml.kernel.org/r/20240215063649.2164017-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page-writeback.c |    1 +
 1 file changed, 1 insertion(+)

--- a/mm/page-writeback.c~writeback-fix-done_index-when-hitting-the-wbc-nr_to_write
+++ a/mm/page-writeback.c
@@ -2505,6 +2505,7 @@ continue_unlock:
 			 * keep going until we have written all the pages
 			 * we tagged for writeback prior to entering this loop.
 			 */
+			done_index = folio->index + nr;
 			wbc->nr_to_write -= nr;
 			if (wbc->nr_to_write <= 0 &&
 			    wbc->sync_mode == WB_SYNC_NONE) {
_

Patches currently in -mm which might be from hch@lst.de are

writeback-dont-call-mapping_set_error-on-aop_writepage_activate.patch
writeback-fix-done_index-when-hitting-the-wbc-nr_to_write.patch
writeback-also-update-wbc-nr_to_write-on-writeback-failure.patch
writeback-only-update-writeback_index-for-range_cyclic-writeback.patch
writeback-rework-the-loop-termination-condition-in-write_cache_pages.patch
writeback-add-a-writeback-iterator.patch