+ writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: writeback: fix build problems of "writeback: support retrieving per group debug writeback stats of bdi"
has been added to the -mm mm-unstable branch.  Its filename is
     writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix.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: Kemeng Shi <shikemeng@huaweicloud.com>
Subject: writeback: fix build problems of "writeback: support retrieving per group debug writeback stats of bdi"
Date: Tue, 23 Apr 2024 11:46:41 +0800

Fix two build problems:
1. implicit declaration of function 'cgroup_ino'.
2. unused variable 'stats'.

After this fix, No build problem is found when CGROUPS is disabled.
The wb_stats could be successfully retrieved when CGROUP_WRITEBACK is
disabled:
cat wb_stats
WbCgIno:                    1
WbWriteback:                0 kB
WbReclaimable:         685440 kB
WbDirtyThresh:      195530960 kB
WbDirtied:             691488 kB
WbWritten:               6048 kB
WbWriteBandwidth:      102400 kBps
b_dirty:                    2
b_io:                       0
b_more_io:                  0
b_dirty_time:               0
state:                      5

cat wb_stats
WbCgIno:                    1
WbWriteback:                0 kB
WbReclaimable:         818944 kB
WbDirtyThresh:      195527484 kB
WbDirtied:             824992 kB
WbWritten:               6048 kB
WbWriteBandwidth:      102400 kBps
b_dirty:                    2
b_io:                       0
b_more_io:                  0
b_dirty_time:               0
state:                      5

Link: https://lkml.kernel.org/r/20240423034643.141219-4-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reported-by: SeongJae Park <sj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> 
Cc: Brian Foster <bfoster@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/backing-dev.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/backing-dev.c~writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix
+++ a/mm/backing-dev.c
@@ -172,7 +172,11 @@ static void wb_stats_show(struct seq_fil
 		   "b_more_io:         %10lu\n"
 		   "b_dirty_time:      %10lu\n"
 		   "state:             %10lx\n\n",
+#ifdef CONFIG_CGROUP_WRITEBACK
 		   cgroup_ino(wb->memcg_css->cgroup),
+#else
+		   1ul,
+#endif
 		   K(stats->nr_writeback),
 		   K(stats->nr_reclaimable),
 		   K(stats->wb_thresh),
@@ -192,7 +196,6 @@ static int cgwb_debug_stats_show(struct
 	unsigned long background_thresh;
 	unsigned long dirty_thresh;
 	struct bdi_writeback *wb;
-	struct wb_stats stats;
 
 	global_dirty_limits(&background_thresh, &dirty_thresh);
 
_

Patches currently in -mm which might be from shikemeng@huaweicloud.com are

writeback-collect-stats-of-all-wb-of-bdi-in-bdi_debug_stats_show.patch
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi.patch
writeback-support-retrieving-per-group-debug-writeback-stats-of-bdi-fix.patch
writeback-add-wb_monitorpy-script-to-monitor-writeback-info-on-bdi.patch
writeback-rename-nr_reclaimable-to-nr_dirty-in-balance_dirty_pages.patch