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mm/page-writeback.c: write_cache_pages(): deduplicate identical checks

PATCH Applied Mauricio Faria de Oliveira 2 participants 2 messages Feb 18, 2020 – Feb 19, 2020

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#0 lore raw

PATCH v2 1/1 mm/page-writeback.c: write_cache_pages(): deduplicate identical checks

There used to be a 'retry' label in between the two (identical) checks when first introduced in commit f446daaea9d4 ("mm: implement writeback livelock avoidance using page tagging"), and later modified/updated in commit 6e6938b6d313 ("writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage").

The label has been removed in commit 64081362e8ff ("mm/page-writeback.c:
fix range_cyclic writeback vs writepages deadlock"), and the (identical) checks are now present / performed immediately one after another.

So, remove/deduplicate the latter check, moving tag_pages_for_writeback() into the former check before the 'tag' variable assignment, so it's clear that it's not used in this (similarly-named) function call but only later in pagevec_lookup_range_tag().

---

v2: add the missing braces to the conditional statement
with more than a single statement.. doh; and to the else branch (w/a single statement, per coding style.)

 mm/page-writeback.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
mm/page-writeback.c +4 -4
index 2caf780a42e7..ab5a3cee8ad3 100644
@@ -2182,12 +2182,12 @@ int write_cache_pages(struct address_space *mapping,
 		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 			range_whole = 1;
 	}
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) {
+		tag_pages_for_writeback(mapping, index, end);
 		tag = PAGECACHE_TAG_TOWRITE;
-	else
+	} else {
 		tag = PAGECACHE_TAG_DIRTY;
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		tag_pages_for_writeback(mapping, index, end);
+	}
 	done_index = index;
 	while (!done && (index <= end)) {
 		int i;
Signature · 1 line
2.20.1
Reviewed-by on v2 1/1
#1 lore raw
Quoted 10 lines · Mauricio Faria de Oliveira

There used to be a 'retry' label in between the two (identical) checks when first introduced in commit f446daaea9d4 ("mm: implement writeback livelock avoidance using page tagging"), and later modified/updated in commit 6e6938b6d313 ("writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage").

The label has been removed in commit 64081362e8ff ("mm/page-writeback.c:
fix range_cyclic writeback vs writepages deadlock"), and the (identical) checks are now present / performed immediately one after another.

Quoted 6 lines

So, remove/deduplicate the latter check, moving tag_pages_for_writeback() into the former check before the 'tag' variable assignment, so it's clear that it's not used in this (similarly-named) function call but only later in pagevec_lookup_range_tag().

Quoted 33 lines

---

v2: add the missing braces to the conditional statement
with more than a single statement.. doh; and to the else branch (w/a single statement, per coding style.)

 mm/page-writeback.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
mm/page-writeback.c +4 -4
index 2caf780a42e7..ab5a3cee8ad3 100644
@@ -2182,12 +2182,12 @@ int write_cache_pages(struct address_space *mapping,
 		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 			range_whole = 1;
 	}
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) {
+		tag_pages_for_writeback(mapping, index, end);
 		tag = PAGECACHE_TAG_TOWRITE;
-	else
+	} else {
 		tag = PAGECACHE_TAG_DIRTY;
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		tag_pages_for_writeback(mapping, index, end);
+	}
 	done_index = index;
 	while (!done && (index <= end)) {
 		int i;
Signature · 1 line
2.20.1