From: Jan Kara Date: Tue, 11 Jan 2011 20:16:31 +0000 (-0500) Subject: ext4: fix trimming starting with block 0 with small blocksize X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0f0a25b;p=mv-sheeva.git ext4: fix trimming starting with block 0 with small blocksize When s_first_data_block is not zero (which happens e.g. when block size is 1KB) and trim ioctl is called to start trimming from block 0, the math in ext4_get_group_no_and_offset() overflows. The overall result is that ioctl returns EINVAL which is kind of unexpected and we probably don't want userspace tools to bother with internal details of filesystem structure. So just silently increase starting offset (and shorten length) when starting block is below s_first_data_block. CC: Lukas Czerner Signed-off-by: Jan Kara Signed-off-by: "Theodore Ts'o" --- diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index cc1297e15f1..851f49b2f9d 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4808,6 +4808,8 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range) ext4_group_t group, ngroups = ext4_get_groups_count(sb); ext4_grpblk_t cnt = 0, first_block, last_block; uint64_t start, len, minlen, trimmed; + ext4_fsblk_t first_data_blk = + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block); int ret = 0; start = range->start >> sb->s_blocksize_bits; @@ -4817,6 +4819,10 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range) if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb))) return -EINVAL; + if (start < first_data_blk) { + len -= first_data_blk - start; + start = first_data_blk; + } /* Determine first and last group to examine based on start and len */ ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) start,