zfs-patches/0022-Fix-zdb-c-traverse-stop-on-damaged-objset-root.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Chunwei Chen <david.chen@nutanix.com>
   3 Date: Tue, 30 Jan 2018 13:39:11 -0800
   4 Subject: [PATCH] Fix zdb -c traverse stop on damaged objset root
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   8
   9 If a corruption happens to be on a root block of an objset, zdb -c will
  10 not correctly report the error, and it will not traverse the datasets
  11 that come after. This is because traverse_visitbp, which does the
  12 callback and reset error for TRAVERSE_HARD, is skipped when traversing
  13 zil is failed in traverse_impl.
  14
  15 Here's example of what 'zdb -eLcc' command looks like on a pool with
  16 damaged objset root:
  17
  18 == before patch:
  19
  20 Traversing all blocks to verify checksums ...
  21
  22 Error counts:
  23
  24         errno  count
  25 block traversal size 379392 != alloc 33987072 (unreachable 33607680)
  26
  27         bp count:             172
  28         ganged count:           0
  29         bp logical:       1678336      avg:   9757
  30         bp physical:       130560      avg:    759     compression:  12.85
  31         bp allocated:      379392      avg:   2205     compression:   4.42
  32         bp deduped:             0    ref>1:      0   deduplication:   1.00
  33         SPA allocated:   33987072     used:  0.80%
  34
  35         additional, non-pointer bps of type 0:         71
  36         Dittoed blocks on same vdev: 101
  37
  38 == after patch:
  39
  40 Traversing all blocks to verify checksums ...
  41
  42 zdb_blkptr_cb: Got error 52 reading <54, 0, -1, 0>  -- skipping
  43
  44 Error counts:
  45
  46         errno  count
  47            52  1
  48 block traversal size 33963520 != alloc 33987072 (unreachable 23552)
  49
  50         bp count:             447
  51         ganged count:           0
  52         bp logical:      36093440      avg:  80745
  53         bp physical:     33699840      avg:  75391     compression:   1.07
  54         bp allocated:    33963520      avg:  75981     compression:   1.06
  55         bp deduped:             0    ref>1:      0   deduplication:   1.00
  56         SPA allocated:   33987072     used:  0.80%
  57
  58         additional, non-pointer bps of type 0:         76
  59         Dittoed blocks on same vdev: 115
  60
  61 ==
  62
  63 Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
  64 Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
  65 Signed-off-by: Chunwei Chen <david.chen@nutanix.com>
  66 Closes #7099
  67 (cherry picked from commit 23227313a2016449176cbfcbae2d4fc463a2bc09)
  68 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  69 ---
  70  module/zfs/dmu_traverse.c | 26 +++++++++++++++++---------
  71  1 file changed, 17 insertions(+), 9 deletions(-)
  72
  73 diff --git a/module/zfs/dmu_traverse.c b/module/zfs/dmu_traverse.c
  74 index c78228d74..b494bef35 100644
  75 --- a/module/zfs/dmu_traverse.c
  76 +++ b/module/zfs/dmu_traverse.c
  77 @@ -599,19 +599,27 @@ traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
  78
  79         /* See comment on ZIL traversal in dsl_scan_visitds. */
  80         if (ds != NULL && !ds->ds_is_snapshot && !BP_IS_HOLE(rootbp)) {
  81 +               enum zio_flag zio_flags = ZIO_FLAG_CANFAIL;
  82                 uint32_t flags = ARC_FLAG_WAIT;
  83                 objset_phys_t *osp;
  84                 arc_buf_t *buf;
  85
  86 -               err = arc_read(NULL, td->td_spa, rootbp,
  87 -                   arc_getbuf_func, &buf,
  88 -                   ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, czb);
  89 -               if (err != 0)
  90 -                       return (err);
  91 -
  92 -               osp = buf->b_data;
  93 -               traverse_zil(td, &osp->os_zil_header);
  94 -               arc_buf_destroy(buf, &buf);
  95 +               err = arc_read(NULL, td->td_spa, rootbp, arc_getbuf_func,
  96 +                   &buf, ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, czb);
  97 +               if (err != 0) {
  98 +                       /*
  99 +                        * If both TRAVERSE_HARD and TRAVERSE_PRE are set,
 100 +                        * continue to visitbp so that td_func can be called
 101 +                        * in pre stage, and err will reset to zero.
 102 +                        */
 103 +                       if (!(td->td_flags & TRAVERSE_HARD) ||
 104 +                           !(td->td_flags & TRAVERSE_PRE))
 105 +                               return (err);
 106 +               } else {
 107 +                       osp = buf->b_data;
 108 +                       traverse_zil(td, &osp->os_zil_header);
 109 +                       arc_buf_destroy(buf, &buf);
 110 +               }
 111         }
 112
 113         if (!(flags & TRAVERSE_PREFETCH_DATA) ||
 114 --
 115 2.14.2
 116