linux-ext4 - [PATCH] ext2: fix missing percpu_counter

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Date:   Tue, 9 Jun 2020 13:14:18 -0400 (EDT)
From:   Mikulas Patocka <mpatocka@...hat.com>
To:     "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.com>
cc:     linux-ext4@...r.kernel.org
Subject: [PATCH] ext2: fix missing percpu_counter_inc (fwd)

I'm resending this because I didn't get any response.

Mikulas



---------- Forwarded message ----------
Date: Mon, 20 Apr 2020 16:02:21 -0400 (EDT)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Jan Kara <jack@...e.com>
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH] ext2: fix missing percpu_counter_inc

sbi->s_freeinodes_counter is only decreased by the ext2 code, it is never
increased. This patch fixes it.

Note that sbi->s_freeinodes_counter is only used in the algorithm that
tries to find the group for new allocations, so this bug is not easily
visible (the only visibility is that the group finding algorithm selects
inoptinal result).

Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Cc: stable@...r.kernel.org

---
 fs/ext2/ialloc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6/fs/ext2/ialloc.c
===================================================================
--- linux-2.6.orig/fs/ext2/ialloc.c	2019-09-20 14:39:07.951999000 +0200
+++ linux-2.6/fs/ext2/ialloc.c	2020-04-20 21:33:26.389999000 +0200
@@ -80,6 +80,7 @@ static void ext2_release_inode(struct su
 	if (dir)
 		le16_add_cpu(&desc->bg_used_dirs_count, -1);
 	spin_unlock(sb_bgl_lock(EXT2_SB(sb), group));
+	percpu_counter_inc(&EXT2_SB(sb)->s_freeinodes_counter);
 	if (dir)
 		percpu_counter_dec(&EXT2_SB(sb)->s_dirs_counter);
 	mark_buffer_dirty(bh);
@@ -528,7 +529,7 @@ got:
 		goto fail;
 	}
 
-	percpu_counter_add(&sbi->s_freeinodes_counter, -1);
+	percpu_counter_dec(&sbi->s_freeinodes_counter);
 	if (S_ISDIR(mode))
 		percpu_counter_inc(&sbi->s_dirs_counter);