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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Chao Yu <yuchao0@huawei.com>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.9 056/391] f2fs: compress: fix to disallow enabling compress on non-empty file
Date:   Tue,  3 Nov 2020 21:31:47 +0100
Message-Id: <20201103203351.210726314@linuxfoundation.org>
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From: Chao Yu <yuchao0@huawei.com>

[ Upstream commit 519a5a2f37b850f4eb86674a10d143088670a390 ]

Compressed inode and normal inode has different layout, so we should
disallow enabling compress on non-empty file to avoid race condition
during inode .i_addr array parsing and updating.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: Fix missing condition]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/f2fs/file.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 8a422400e824d..4ec10256dc67f 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1836,6 +1836,8 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
 		if (iflags & F2FS_COMPR_FL) {
 			if (!f2fs_may_compress(inode))
 				return -EINVAL;
+			if (S_ISREG(inode->i_mode) && inode->i_size)
+				return -EINVAL;
 
 			set_compress_context(inode);
 		}
-- 
2.27.0