linux-kernel - [PATCH 5.10 106/306] f2fs: should put a page beyond EOF when preparing a write

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Message-Id: <20210916155757.688000875@linuxfoundation.org>
Date:   Thu, 16 Sep 2021 17:57:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chao Yu <chao@...nel.org>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 106/306] f2fs: should put a page beyond EOF when preparing a write

From: Jaegeuk Kim <jaegeuk@...nel.org>

[ Upstream commit 9605f75cf36e0bcc0f4ada07b5be712d30107607 ]

The prepare_compress_overwrite() gets/locks a page to prepare a read, and calls
f2fs_read_multi_pages() which checks EOF first. If there's any page beyond EOF,
we unlock the page and set cc->rpages[i] = NULL, which we can't put the page
anymore. This makes page leak, so let's fix by putting that page.

Fixes: a949dc5f2c5c ("f2fs: compress: fix race condition of overwrite vs truncate")
Reviewed-by: Chao Yu <chao@...nel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/f2fs/data.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 70a91c47f72f..1b11a42847c4 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2219,6 +2219,8 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
 			continue;
 		}
 		unlock_page(page);
+		if (for_write)
+			put_page(page);
 		cc->rpages[i] = NULL;
 		cc->nr_rpages--;
 	}
-- 
2.30.2