linux-ext4 - [PATCH 2/2] ext4: check free inode count before allocaing an inode

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Message-Id: <1346579109-25016-2-git-send-email-xiaoqiangnk@gmail.com>
Date:	Sun,  2 Sep 2012 17:45:09 +0800
From:	Yongqiang Yang <xiaoqiangnk@...il.com>
To:	linux-ext4@...r.kernel.org
Cc:	tytso@....edu, Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: [PATCH 2/2] ext4: check free inode count before allocaing an inode

Recnetly, I ecountered some corrupted filesystems in which some
groups' free inode counts were negative, it seemed that free inode
count was overflow.  This patch teaches ext4 to check free inode
count before allocaing an inode.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
---
 fs/ext4/ialloc.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 26154b8..fa36372 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -697,6 +697,15 @@ got_group:
 		if (!gdp)
 			goto fail;
 
+		/*
+		 * Check free inodes count before loading bitmap.
+		 */
+		if (ext4_free_inodes_count(sb, gdp) == 0) {
+			if (++group == ngroups)
+				group = 0;
+			continue;
+		}
+
 		brelse(inode_bitmap_bh);
 		inode_bitmap_bh = ext4_read_inode_bitmap(sb, group);
 		if (!inode_bitmap_bh)
-- 
1.7.5.1

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