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ext4: fix a BUG in mb_mark_used during trim. 

In a bs=4096 volume, if we call FITRIM with the following parameter as
fstrim_range(start = 102400, len = 134144000, minlen = 10240),
we will trigger this BUG_ON:

	BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3));

Mar  4 00:55:52 boyu-tm kernel: ------------[ cut here ]------------
Mar  4 00:55:52 boyu-tm kernel: kernel BUG at fs/ext4/mballoc.c:1506!
Mar  4 01:21:09 boyu-tm kernel: Code: d4 00 00 00 00 49 89 fe 8b 56 0c 44 8b 7e 04 89 55 c4 48 8b 4f 28 89 d6 44 01 fe 48 63 d6 48 8b 41 18 48 c1 e0 03 48 39 c2 76 04 <0f> 0b eb fe 48 8b 55 b0 8b 47 34 3b 42 08 74 04 0f 0b eb fe 48
Mar  4 01:21:09 boyu-tm kernel: RIP  [<ffffffffa053eb42>] mb_mark_used+0x47/0x26c [ext4]
Mar  4 01:21:09 boyu-tm kernel:  RSP <ffff880121e45c38>
Mar  4 01:21:09 boyu-tm kernel: ---[ end trace 9f461696f6a9dcf2 ]---

Fix this bug by doing the accounting correctly.

Cc: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Tao Ma 2011-03-23 15:48:11 -04:00 committed by Theodore Ts'o
parent 65922cb5ce
commit 0ba0851714
1 changed files with 8 additions and 3 deletions
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11
fs/ext4/mballoc.c
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@ -4870,10 +4870,15 @@ int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
break;
}
if (len >= EXT4_BLOCKS_PER_GROUP(sb))
len -= (EXT4_BLOCKS_PER_GROUP(sb) - first_block);
else
/*
* For all the groups except the last one, last block will
* always be EXT4_BLOCKS_PER_GROUP(sb), so we only need to
* change it for the last group in which case start +
* len < EXT4_BLOCKS_PER_GROUP(sb).
*/
if (first_block + len < EXT4_BLOCKS_PER_GROUP(sb))
last_block = first_block + len;
len -= last_block - first_block;
if (e4b.bd_info->bb_free >= minlen) {
cnt = ext4_trim_all_free(sb, &e4b, first_block,