linux-ext4 - [PATCH 1/6] ext4: Fix error handling in ext4_restore_inline

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Date:   Thu, 13 Jan 2022 08:56:24 +0530
From:   Ritesh Harjani <riteshh@...ux.ibm.com>
To:     linux-ext4@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jan Kara <jack@...e.com>,
        Andreas Dilger <adilger.kernel@...ger.ca>, tytso@....edu,
        Eric Whitney <enwlinux@...il.com>,
        Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: [PATCH 1/6] ext4: Fix error handling in ext4_restore_inline_data()

While running "./check -I 200 generic/475" it sometimes gives below
kernel BUG(). Ideally we should not call ext4_write_inline_data() if
ext4_create_inline_data() has failed.

<log snip>
[73131.453234] kernel BUG at fs/ext4/inline.c:223!

<code snip>
 212 static void ext4_write_inline_data(struct inode *inode, struct ext4_iloc *iloc,
 213                                    void *buffer, loff_t pos, unsigned int len)
 214 {
<...>
 223         BUG_ON(!EXT4_I(inode)->i_inline_off);
 224         BUG_ON(pos + len > EXT4_I(inode)->i_inline_size);

This patch handles the error and prints out a emergency msg saying potential
data loss for the given inode (since we couldn't restore the original
inline_data due to some previous error).

[ 9571.070313] EXT4-fs (dm-0): error restoring inline_data for inode -- potential data loss! (inode 1703982, error -30)

Reported-by: Eric Whitney <enwlinux@...il.com>
Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>
---
 fs/ext4/inline.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 534c0329e110..31741e8a462e 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1135,7 +1135,15 @@ static void ext4_restore_inline_data(handle_t *handle, struct inode *inode,
 				     struct ext4_iloc *iloc,
 				     void *buf, int inline_size)
 {
-	ext4_create_inline_data(handle, inode, inline_size);
+	int ret;
+
+	ret = ext4_create_inline_data(handle, inode, inline_size);
+	if (ret) {
+		ext4_msg(inode->i_sb, KERN_EMERG,
+			"error restoring inline_data for inode -- potential data loss! (inode %lu, error %d)",
+			inode->i_ino, ret);
+		return;
+	}
 	ext4_write_inline_data(inode, iloc, buf, 0, inline_size);
 	ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
 }
-- 
2.31.1