linux-ext4 - [RFC 13/20] ext4: mballoc: Don't BUG if kmalloc or read blk bitmap fail for DOUBLE

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Date:   Fri,  1 May 2020 11:59:55 +0530
From:   Ritesh Harjani <riteshh@...ux.ibm.com>
To:     linux-ext4@...r.kernel.org
Cc:     "Paul E . McKenney" <paulmck@...nel.org>,
        linux-fsdevel@...r.kernel.org, Jan Kara <jack@...e.com>,
        tytso@....edu, "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: [RFC 13/20] ext4: mballoc: Don't BUG if kmalloc or read blk bitmap fail for DOUBLE_CHECK

Remove the BUG_ON() logic if kmalloc() or ext4_read_block_bitmap() fails.
We should simply mark grp->bb_bitmap as NULL if above happens.
In fact ext4_read_block_bitmap() may even return an error in case of resize
ioctl. Hence remove this BUG_ON logic (fstests ext4/032 may trigger
this).

---
Should we add a ext4_msg() if any of above fails?

Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>
---
 fs/ext4/mballoc.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e32f3675f962..aa22ecf3f827 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -548,13 +548,20 @@ static void mb_group_bb_bitmap_alloc(struct super_block *sb,
 	struct buffer_head *bh;
 
 	grp->bb_bitmap = kmalloc(sb->s_blocksize, GFP_NOFS);
-	BUG_ON(grp->bb_bitmap == NULL);
+	if (!grp->bb_bitmap)
+		goto out;
 
 	bh = ext4_read_block_bitmap(sb, group);
-	BUG_ON(IS_ERR_OR_NULL(bh));
+	if (IS_ERR_OR_NULL(bh)) {
+		kfree(grp->bb_bitmap);
+		grp->bb_bitmap = NULL;
+		goto out;
+	}
 
 	memcpy(grp->bb_bitmap, bh->b_data, sb->s_blocksize);
 	put_bh(bh);
+out:
+	return;
 }
 
 static void mb_group_bb_bitmap_free(struct ext4_group_info *grp)
-- 
2.21.0