From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tao Ma Subject: [PATCH] ext3: fix trim length underflow with small trim length. Date: Wed, 19 Jan 2011 17:49:10 +0800 Message-ID: <1295430550-8978-1-git-send-email-tm@tao.ma> Cc: Jan Kara , Lukas Czerner To: linux-ext4@vger.kernel.org Return-path: Received: from cpoproxy1-pub.bluehost.com ([69.89.21.11]:38465 "HELO cpoproxy1-pub.bluehost.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753644Ab1ASJtx (ORCPT ); Wed, 19 Jan 2011 04:49:53 -0500 Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Tao Ma We adjust 'len' with s_first_data_block - start in case of start is less than s_first_data_block, but it could underflow in case blocksize=1K, while fstrim_range.len=512 and fstrim_range.start = 0. In this case len happens to be underflow and in the end, although we are safe that last_group check will limit the trim to the whole volume, I am afraid that isn't what the user really want. So this patch fix it. It also adds a new variable s_first_data_block so that the 4 le32_to_cpu can be replaced with 1. Cc: Jan Kara Cc: Lukas Czerner Signed-off-by: Tao Ma --- fs/ext3/balloc.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c index 045995c..ee7e0f3 100644 --- a/fs/ext3/balloc.c +++ b/fs/ext3/balloc.c @@ -2088,6 +2088,7 @@ int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range) struct ext3_super_block *es = EXT3_SB(sb)->s_es; uint64_t start, len, minlen, trimmed; ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count); + ext3_fsblk_t first_data_block = le32_to_cpu(es->s_first_data_block); int ret = 0; start = range->start >> sb->s_blocksize_bits; @@ -2097,11 +2098,11 @@ int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range) if (unlikely(minlen > EXT3_BLOCKS_PER_GROUP(sb))) return -EINVAL; - if (start >= max_blks) + if (start >= max_blks || start + len <= first_data_block) goto out; - if (start < le32_to_cpu(es->s_first_data_block)) { - len -= le32_to_cpu(es->s_first_data_block) - start; - start = le32_to_cpu(es->s_first_data_block); + if (start < first_data_block) { + len -= first_data_block - start; + start = first_data_block; } if (start + len > max_blks) len = max_blks - start; -- 1.6.3.GIT