linux-kernel - [PATCH] fs: btrfs: Add an assertion to warn incorrct case in insert_inline

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Date:   Sat, 27 Jul 2019 16:51:13 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     clm@...com, josef@...icpanda.com, dsterba@...e.cz,
        quwenruo.btrfs@....com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] fs: btrfs: Add an assertion to warn incorrct case in insert_inline_extent()

In insert_inline_extent(), the case that compressed_size > 0 
and compressed_pages = NULL cannot occur, otherwise a null-pointer
dereference may occur on line 215:
     cpage = compressed_pages[i];

To warn this incorrect case, an assertion is added.
Thank Qu Wenruo and David Sterba for good advice.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 fs/btrfs/inode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1af069a9a0c7..21d6e2dcc25f 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -178,6 +178,9 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
 	size_t cur_size = size;
 	unsigned long offset;
 
+	ASSERT((compressed_size > 0 && compressed_pages) ||
+			(compressed_size == 0 && !compressed_pages))
+
 	if (compressed_size && compressed_pages)
 		cur_size = compressed_size;
 
-- 
2.17.0