On Wed, Nov 07, 2018 at 05:31:14PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> The last AG may be very small comapred to all other AGs, and hence
> AG reservations based on the superblock AG size may actually consume
> more space than the AG actually has. This results on assert failures
> like:
>
> XFS: Assertion failed: xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved + xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <= pag->pagf_freeblks + pag->pagf_flcount, file: fs/xfs/libxfs/xfs_ag_resv.c, line: 319
> [ 48.932891] xfs_ag_resv_init+0x1bd/0x1d0
> [ 48.933853] xfs_fs_reserve_ag_blocks+0x37/0xb0
> [ 48.934939] xfs_mountfs+0x5b3/0x920
> [ 48.935804] xfs_fs_fill_super+0x462/0x640
> [ 48.936784] ? xfs_test_remount_options+0x60/0x60
> [ 48.937908] mount_bdev+0x178/0x1b0
> [ 48.938751] mount_fs+0x36/0x170
> [ 48.939533] vfs_kern_mount.part.43+0x54/0x130
> [ 48.940596] do_mount+0x20e/0xcb0
> [ 48.941396] ? memdup_user+0x3e/0x70
> [ 48.942249] ksys_mount+0xba/0xd0
> [ 48.943046] __x64_sys_mount+0x21/0x30
> [ 48.943953] do_syscall_64+0x54/0x170
> [ 48.944835] entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Hence we need to ensure the finobt per-ag space reservations take
> into account the size of the last AG rather than treat it like all
> the other full size AGs.
>
> Note that both refcountbt and rmapbt already take the size of the AG
> into account via reading the AGF length directly.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_ialloc_btree.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
> index 86c50208a143..62014780d5e4 100644
> --- a/fs/xfs/libxfs/xfs_ialloc_btree.c
> +++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
> @@ -538,15 +538,24 @@ xfs_inobt_rec_check_count(
>
> static xfs_extlen_t
> xfs_inobt_max_size(
> - struct xfs_mount *mp)
> + struct xfs_mount *mp,
> + xfs_agnumber_t agno)
> {
> + uint32_t agblocks = mp->m_sb.sb_agblocks;
> +
> /* Bail out if we're uninitialized, which can happen in mkfs. */
> if (mp->m_inobt_mxr[0] == 0)
> return 0;
>
> + /* last AG can be a runt */
> + if (agno == mp->m_sb.sb_agcount - 1) {
> + div_u64_rem(mp->m_sb.sb_dblocks, mp->m_sb.sb_agblocks,
> + &agblocks);
> + }
Why not: agblocks = xfs_ag_block_count(mp, agno); ?
--D
> +
> return xfs_btree_calc_size(mp->m_inobt_mnr,
> - (uint64_t)mp->m_sb.sb_agblocks * mp->m_sb.sb_inopblock /
> - XFS_INODES_PER_CHUNK);
> + (uint64_t)agblocks * mp->m_sb.sb_inopblock /
> + XFS_INODES_PER_CHUNK);
> }
>
> static int
> @@ -594,7 +603,7 @@ xfs_finobt_calc_reserves(
> if (error)
> return error;
>
> - *ask += xfs_inobt_max_size(mp);
> + *ask += xfs_inobt_max_size(mp, agno);
> *used += tree_len;
> return 0;
> }
> --
> 2.19.1
>
