jing zhang wrote:
> From: Jing Zhang <zj.barak@xxxxxxxxx>
>
> Date: Mon Apr 5 12:10:50 2010
>
> BUG_ON is triggered at [line:1762] in ext4_mb_complex_scan_group(),
Do you have a test case which can trigger this BUG_ON?
-Eric
> and fix is to change the return value of mb_find_extent() if the
> needed extent can not be found. The fix can also be applied to other
> points where mb_find_extent() is called.
>
> Cc: Theodore Ts'o <tytso@xxxxxxx>
> Cc: Andreas Dilger <adilger@xxxxxxx>
> Cc: Dave Kleikamp <shaggy@xxxxxxxxxxxxxxxxxx>
> Cc: "Aneesh Kumar K. V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jing Zhang <zj.barak@xxxxxxxxx>
> ---
> fs/ext4/mballoc.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index bba1282..fbb6899 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -1321,7 +1321,7 @@ static int mb_find_extent(struct ext4_buddy
> *e4b, int order, int block,
> ex->fe_len = 0;
> ex->fe_start = 0;
> ex->fe_group = 0;
> - return 0;
> + return -ENOSPC;
> }
>
> /* FIXME dorp order completely ? */
> @@ -1358,6 +1358,8 @@ static int mb_find_extent(struct ext4_buddy
> *e4b, int order, int block,
> }
>
> BUG_ON(ex->fe_start + ex->fe_len > (1 << (e4b->bd_blkbits + 3)));
> + if (needed > ex->fe_len)
> + return -ENOSPC;
> return ex->fe_len;
> }
>
> @@ -1758,7 +1760,8 @@ void ext4_mb_complex_scan_group(struct
> ext4_allocation_context *ac,
> break;
> }
>
> - mb_find_extent(e4b, 0, i, ac->ac_g_ex.fe_len, &ex);
> + if (0 > mb_find_extent(e4b, 0, i, ac->ac_g_ex.fe_len, &ex))
> + break;
> BUG_ON(ex.fe_len <= 0);
> if (free < ex.fe_len) {
> ext4_grp_locked_error(sb, e4b->bd_group,
> --
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