linux-ext4 - [PATCH] ext4: fix marking group trimmed if all blocks not trimmed

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Message-Id: <1596471464-198715-1-git-send-email-lazar.beloica@nutanix.com>
Date:   Mon,  3 Aug 2020 16:17:44 +0000
From:   Lazar Beloica <lazarbeloica@...il.com>
To:     linux-ext4@...r.kernel.org
Cc:     stable@...r.kernel.org, lazarbeloica@...il.com,
        lazar.beloica@...anix.com, boyu.mt@...bao.com,
        adilger.kernel@...ger.ca, linux-kernel@...r.kernel.org
Subject: [PATCH] ext4: fix marking group trimmed if all blocks not trimmed

When FTRIM is issued on a group, ext4 marks it as trimmed so another FTRIM
on the same group has no effect. Ext4 marks group as trimmed if at least
one block is trimmed, therefore it is possible that a group is marked as
trimmed even if there are blocks in that group left untrimmed.

This patch marks group as trimmed only if there are no more blocks
in that group to be trimmed.

Fixes: 3d56b8d2c74cc3f375ce332b3ac3519e009d79ee
Tested-by: Lazar Beloica <lazar.beloica@...anix.com>
Signed-off-by: Lazar Beloica <lazar.beloica@...anix.com>
---
 fs/ext4/mballoc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index c0a331e..130936b 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5346,6 +5346,7 @@ static int ext4_trim_extent(struct super_block *sb, int start, int count,
 {
 	void *bitmap;
 	ext4_grpblk_t next, count = 0, free_count = 0;
+	ext4_fsblk_t max_blks = ext4_blocks_count(EXT4_SB(sb)->s_es);
 	struct ext4_buddy e4b;
 	int ret = 0;
 
@@ -5401,7 +5402,9 @@ static int ext4_trim_extent(struct super_block *sb, int start, int count,
 
 	if (!ret) {
 		ret = count;
-		EXT4_MB_GRP_SET_TRIMMED(e4b.bd_info);
+		next = mb_find_next_bit(bitmap, max_blks, max + 1);
+		if (next == max_blks)
+			EXT4_MB_GRP_SET_TRIMMED(e4b.bd_info);
 	}
 out:
 	ext4_unlock_group(sb, group);
-- 
1.8.3.1