On Thu, Mar 21, 2013 at 12:12:51PM +0800, Jeff Liu wrote:
> In growfs operation, the unused parts of superblocks in the latest old AG are
> zero filled, hence we can safely read the secondary superblock buffer of it
> rather than getting a new buffer for it again.
>From the code:
oagcount = mp->m_sb.sb_agcount;
And because the AG indexes are zero numbered, the index of the
last original AGs is (oagcount - 1). Hence we shoul donly be reading
from the AG headers if the current AG index is less than oagcount.
> This is a small refinement for commits 1375cb65.
>
> Cc: Dave Chinner <david@xxxxxxxxxxxxx>
> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
> ---
> fs/xfs/xfs_fsops.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index 94eaeed..7d435dd 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -449,7 +449,7 @@ xfs_growfs_data_private(
> * disk as the contents of the new area we are growing into is
> * completely unknown.
> */
> - if (agno < oagcount) {
> + if (agno <= oagcount) {
With this change, when agno == oagcount we are one AG beyond the
original filesystem size and so if we read that space, we are
reading uninitialised data.
AFAICT, the current code is correct...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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