On 4/22/19 10:45 AM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> When we fix the freelist at the end of build_agf_agfl in phase 5 of
> repair, we need to create incore rmap records for the blocks that get
> added to the AGFL. We can't let the regular freelist fixing code use
> the regular on-disk rmapbt update code because the rmapbt isn't fully
> set up yet.
>
> Unfortunately, the original code fails to account for the fact that the
> free space btrees can shrink when we allocate blocks to fix the
> freelist; those blocks are also put on the freelist, but there are
> already incore rmaps for all the free space btree blocks. We must not
> create (redundant) incore rmaps for those blocks. If we do, repair
> fails with a complaint that rebuilding the rmapbt failed during phase 5.
> xfs/137 on a 1k block size occasionally triggers this bug.
>
> To fix the problem, construct a bitmap of all OWN_AG blocks that we know
> about before traversing the AGFL, and only create new incore rmaps for
> those AGFL blocks that are not already tracked in the bitmap.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
> repair/rmap.c | 54 ++++++++++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 44 insertions(+), 10 deletions(-)
>
>
> diff --git a/repair/rmap.c b/repair/rmap.c
> index d0156f9d..19cceca3 100644
> --- a/repair/rmap.c
> +++ b/repair/rmap.c
> @@ -12,6 +12,7 @@
> #include "dinode.h"
> #include "slab.h"
> #include "rmap.h"
> +#include "bitmap.h"
>
> #undef RMAP_DEBUG
>
> @@ -450,15 +451,16 @@ rmap_store_ag_btree_rec(
> struct xfs_buf *agflbp = NULL;
> struct xfs_trans *tp;
> __be32 *agfl_bno, *b;
> + struct xfs_ag_rmap *ag_rmap = &ag_rmaps[agno];
> + struct bitmap *own_ag_bitmap = NULL;
> int error = 0;
>
> if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> return 0;
>
> /* Release the ar_rmaps; they were put into the rmapbt during p5. */
> - free_slab(&ag_rmaps[agno].ar_rmaps);
> - error = init_slab(&ag_rmaps[agno].ar_rmaps,
> - sizeof(struct xfs_rmap_irec));
> + free_slab(&ag_rmap->ar_rmaps);
> + error = init_slab(&ag_rmap->ar_rmaps, sizeof(struct xfs_rmap_irec));
> if (error)
> goto err;
>
> @@ -478,19 +480,50 @@ rmap_store_ag_btree_rec(
> * rmap, we only need to add rmap records for AGFL blocks past
> * that point in the AGFL because those blocks are a result of a
> * no-rmap no-shrink freelist fixup that we did earlier.
> + *
> + * However, some blocks end up on the AGFL because the free space
> + * btrees shed blocks as a result of allocating space to fix the
> + * freelist. We already created in-core rmap records for the free
> + * space btree blocks, so we must be careful not to create those
> + * records again. Create a bitmap of already-recorded OWN_AG rmaps.
> */
> + error = init_slab_cursor(ag_rmap->ar_raw_rmaps, rmap_compare, &rm_cur);
> + if (error)
> + goto err;
> + if (!bitmap_init(&own_ag_bitmap)) {
> + error = -ENOMEM;
> + goto err_slab;
> + }
> + while ((rm_rec = pop_slab_cursor(rm_cur)) != NULL) {
> + if (rm_rec->rm_owner != XFS_RMAP_OWN_AG)
> + continue;
> + if (!bitmap_set(own_ag_bitmap, rm_rec->rm_startblock,
> + rm_rec->rm_blockcount)) {
> + error = EFSCORRUPTED;
> + goto err_slab;
> + }
> + }
> + free_slab_cursor(&rm_cur);
> +
> + /* Create rmaps for any AGFL blocks that aren't already rmapped. */
> agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agflbp);
> - b = agfl_bno + ag_rmaps[agno].ar_flcount;
> + b = agfl_bno + ag_rmap->ar_flcount;
> while (*b != cpu_to_be32(NULLAGBLOCK) &&
> b - agfl_bno < libxfs_agfl_size(mp)) {
> - error = rmap_add_ag_rec(mp, agno, be32_to_cpu(*b), 1,
> - XFS_RMAP_OWN_AG);
> - if (error)
> - goto err;
> + xfs_agblock_t agbno;
> +
> + agbno = be32_to_cpu(*b);
> + if (!bitmap_test(own_ag_bitmap, agbno, 1)) {
> + error = rmap_add_ag_rec(mp, agno, agbno, 1,
> + XFS_RMAP_OWN_AG);
> + if (error)
> + goto err;
> + }
> b++;
> }
> libxfs_putbuf(agflbp);
> agflbp = NULL;
> + bitmap_free(&own_ag_bitmap);
>
> /* Merge all the raw rmaps into the main list */
> error = rmap_fold_raw_recs(mp, agno);
> @@ -498,8 +531,7 @@ rmap_store_ag_btree_rec(
> goto err;
>
> /* Create cursors to refcount structures */
> - error = init_slab_cursor(ag_rmaps[agno].ar_rmaps, rmap_compare,
> - &rm_cur);
> + error = init_slab_cursor(ag_rmap->ar_rmaps, rmap_compare, &rm_cur);
> if (error)
> goto err;
>
> @@ -542,6 +574,8 @@ rmap_store_ag_btree_rec(
> err:
> if (agflbp)
> libxfs_putbuf(agflbp);
> + if (own_ag_bitmap)
> + bitmap_free(&own_ag_bitmap);
> return error;
> }
>
>
