linux-kernel - [PATCH 1/1] f2fs: fix to check space of current segment journal

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Date:   Wed, 14 Sep 2022 12:04:23 +0800
From:   Wu Bo <bo.wu@...o.com>
To:     jaegeuk@...nel.org, chao@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Wu Bo <bo.wu@...o.com>,
        Philippe De Muyter <phdm@...q.eu>
Subject: [PATCH 1/1] f2fs: fix to check space of current segment journal

As Philippe De Muyter reported:
https://lore.kernel.org/linux-f2fs-devel/20220913224908.GA25100@172.21.0.10/T/#u

The warning log showed that when finding a new space for nat the journal
space turned out to be full. This because the journal_rwsem is not
locked before the journal space checking. The journal space may become
full just after we check it.

Reported-by: Philippe De Muyter <phdm@...q.eu>
Signed-off-by: Wu Bo <bo.wu@...o.com>
---
 fs/f2fs/node.c    |  6 +++---
 fs/f2fs/segment.c | 10 +++++-----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index e06a0c478b39..971d8b9ccdf1 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -2995,13 +2995,13 @@ static int __flush_nat_entry_set(struct f2fs_sb_info *sbi,
 	 * #1, flush nat entries to journal in current hot data summary block.
 	 * #2, flush nat entries to nat page.
 	 */
+	down_write(&curseg->journal_rwsem);
 	if ((cpc->reason & CP_UMOUNT) ||
 		!__has_cursum_space(journal, set->entry_cnt, NAT_JOURNAL))
 		to_journal = false;
 
-	if (to_journal) {
-		down_write(&curseg->journal_rwsem);
-	} else {
+	if (!to_journal) {
+		up_write(&curseg->journal_rwsem);
 		page = get_next_nat_page(sbi, start_nid);
 		if (IS_ERR(page))
 			return PTR_ERR(page);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 0de21f82d7bc..d545032d2f6f 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3914,13 +3914,13 @@ int f2fs_lookup_journal_in_cursum(struct f2fs_journal *journal, int type,
 			if (le32_to_cpu(nid_in_journal(journal, i)) == val)
 				return i;
 		}
-		if (alloc && __has_cursum_space(journal, 1, NAT_JOURNAL))
+		if (alloc)
 			return update_nats_in_cursum(journal, 1);
 	} else if (type == SIT_JOURNAL) {
 		for (i = 0; i < sits_in_cursum(journal); i++)
 			if (le32_to_cpu(segno_in_journal(journal, i)) == val)
 				return i;
-		if (alloc && __has_cursum_space(journal, 1, SIT_JOURNAL))
+		if (alloc)
 			return update_sits_in_cursum(journal, 1);
 	}
 	return -1;
@@ -4085,13 +4085,13 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 						(unsigned long)MAIN_SEGS(sbi));
 		unsigned int segno = start_segno;
 
+		down_write(&curseg->journal_rwsem);
 		if (to_journal &&
 			!__has_cursum_space(journal, ses->entry_cnt, SIT_JOURNAL))
 			to_journal = false;
 
-		if (to_journal) {
-			down_write(&curseg->journal_rwsem);
-		} else {
+		if (!to_journal) {
+			up_write(&curseg->journal_rwsem);
 			page = get_next_sit_page(sbi, start_segno);
 			raw_sit = page_address(page);
 		}
-- 
2.36.1