From: Tao Ma Date: Wed, 23 Mar 2011 19:48:11 +0000 (-0400) Subject: ext4: fix a BUG in mb_mark_used during trim. X-Git-Tag: v2.6.39-rc1~73^2 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ba0851714beebb800992e5105a79dc3a4c504b0;p=pandora-kernel.git 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 [] mb_mark_used+0x47/0x26c [ext4] Mar 4 01:21:09 boyu-tm kernel: RSP Mar 4 01:21:09 boyu-tm kernel: ---[ end trace 9f461696f6a9dcf2 ]--- Fix this bug by doing the accounting correctly. Cc: Lukas Czerner Signed-off-by: Tao Ma Signed-off-by: "Theodore Ts'o" --- diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index cdc84953f1d4..a5837a837a8b 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -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,