On Wed, Jul 15, 2020 at 03:33:10PM -0400, Brian Foster wrote:
> The block reservation calculation for inode allocation is supposed
> to consist of the blocks required for the inode chunk plus
> (maxlevels-1) of the inode btree multiplied by the number of inode
> btrees in the fs (2 when finobt is enabled, 1 otherwise).
>
> Instead, the macro returns (ialloc_blocks + 2) due to a precedence
> error in the calculation logic. This leads to block reservation
> overruns via generic/531 on small block filesystems with finobt
> enabled. Add braces to fix the calculation and reserve the
> appropriate number of blocks.
>
> Fixes: 9d43b180af67 ("xfs: update inode allocation/free transaction reservations for finobt")
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_trans_space.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_trans_space.h b/fs/xfs/libxfs/xfs_trans_space.h
> index 88221c7a04cc..c6df01a2a158 100644
> --- a/fs/xfs/libxfs/xfs_trans_space.h
> +++ b/fs/xfs/libxfs/xfs_trans_space.h
> @@ -57,7 +57,7 @@
> XFS_DAREMOVE_SPACE_RES(mp, XFS_DATA_FORK)
> #define XFS_IALLOC_SPACE_RES(mp) \
> (M_IGEO(mp)->ialloc_blks + \
> - (xfs_sb_version_hasfinobt(&mp->m_sb) ? 2 : 1 * \
> + ((xfs_sb_version_hasfinobt(&mp->m_sb) ? 2 : 1) * \
> (M_IGEO(mp)->inobt_maxlevels - 1)))
Ugh. THese macros really need rewriting as static inline functions.
This would not have happened if it were written as:
static inline int
xfs_ialloc_space_res(struct xfs_mount *mp)
{
int res = M_IGEO(mp)->ialloc_blks;
res += M_IGEO(mp)->inobt_maxlevels - 1;
if (xfs_sb_version_hasfinobt(&mp->m_sb))
res += M_IGEO(mp)->inobt_maxlevels - 1;
return res;
}
Next question: why is this even a macro that is calculated on demand
instead of a read-only constant held in inode geometry calculated
at mount time? Then it doesn't even need to be an inline function
and can just be rolled into xfs_ialloc_setup_geometry()....
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
