1. 19 Aug, 2015 5 commits
    • Filipe Manana's avatar
      Btrfs: check if previous transaction aborted to avoid fs corruption · 1f9b8c8f
      Filipe Manana authored
      While we are committing a transaction, it's possible the previous one is
      still finishing its commit and therefore we wait for it to finish first.
      However we were not checking if that previous transaction ended up getting
      aborted after we waited for it to commit, so we ended up committing the
      current transaction which can lead to fs corruption because the new
      superblock can point to trees that have had one or more nodes/leafs that
      were never durably persisted.
      The following sequence diagram exemplifies how this is possible:
      
                CPU 0                                                        CPU 1
      
        transaction N starts
      
        (...)
      
        btrfs_commit_transaction(N)
      
          cur_trans->state = TRANS_STATE_COMMIT_START;
          (...)
          cur_trans->state = TRANS_STATE_COMMIT_DOING;
          (...)
      
          cur_trans->state = TRANS_STATE_UNBLOCKED;
          root->fs_info->running_transaction = NULL;
      
                                                                    btrfs_start_transaction()
                                                                       --> starts transaction N + 1
      
          btrfs_write_and_wait_transaction(trans, root);
            --> starts writing all new or COWed ebs created
                at transaction N
      
                                                                    creates some new ebs, COWs some
                                                                    existing ebs but doesn't COW or
                                                                    deletes eb X
      
                                                                    btrfs_commit_transaction(N + 1)
                                                                      (...)
                                                                      cur_trans->state = TRANS_STATE_COMMIT_START;
                                                                      (...)
                                                                      wait_for_commit(root, prev_trans);
                                                                        --> prev_trans == transaction N
      
          btrfs_write_and_wait_transaction() continues
          writing ebs
             --> fails writing eb X, we abort transaction N
                 and set bit BTRFS_FS_STATE_ERROR on
                 fs_info->fs_state, so no new transactions
                 can start after setting that bit
      
             cleanup_transaction()
               btrfs_cleanup_one_transaction()
                 wakes up task at CPU 1
      
                                                                      continues, doesn't abort because
                                                                      cur_trans->aborted (transaction N + 1)
                                                                      is zero, and no checks for bit
                                                                      BTRFS_FS_STATE_ERROR in fs_info->fs_state
                                                                      are made
      
                                                                      btrfs_write_and_wait_transaction(trans, root);
                                                                        --> succeeds, no errors during writeback
      
                                                                      write_ctree_super(trans, root, 0);
                                                                        --> succeeds
                                                                        --> we have now a superblock that points us
                                                                            to some root that uses eb X, which was
                                                                            never written to disk
      
      In this scenario future attempts to read eb X from disk results in an
      error message like "parent transid verify failed on X wanted Y found Z".
      
      So fix this by aborting the current transaction if after waiting for the
      previous transaction we verify that it was aborted.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
      Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      1f9b8c8f
    • Michal Hocko's avatar
      btrfs: use __GFP_NOFAIL in alloc_btrfs_bio · 277fb5fc
      Michal Hocko authored
      alloc_btrfs_bio relies on GFP_NOFS allocation when committing the
      transaction but this allocation context is rather weak wrt. reclaim
      capabilities. The page allocator currently tries hard to not fail these
      allocations if they are small (<=PAGE_ALLOC_COSTLY_ORDER) but it can
      still fail if the _current_ process is the OOM killer victim. Moreover
      there is an attempt to move away from the default no-fail behavior and
      allow these allocation to fail more eagerly. This would lead to:
      
      [   37.928625] kernel BUG at fs/btrfs/extent_io.c:4045
      
      which is clearly undesirable and the nofail behavior should be explicit
      if the allocation failure cannot be tolerated.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      277fb5fc
    • Michal Hocko's avatar
      btrfs: Prevent from early transaction abort · d1b5c567
      Michal Hocko authored
      Btrfs relies on GFP_NOFS allocation when committing the transaction but
      this allocation context is rather weak wrt. reclaim capabilities. The
      page allocator currently tries hard to not fail these allocations if
      they are small (<=PAGE_ALLOC_COSTLY_ORDER) so this is not a problem
      currently but there is an attempt to move away from the default no-fail
      behavior and allow these allocation to fail more eagerly. And this would
      lead to a pre-mature transaction abort as follows:
      
      [   55.328093] Call Trace:
      [   55.328890]  [<ffffffff8154e6f0>] dump_stack+0x4f/0x7b
      [   55.330518]  [<ffffffff8108fa28>] ? console_unlock+0x334/0x363
      [   55.332738]  [<ffffffff8110873e>] __alloc_pages_nodemask+0x81d/0x8d4
      [   55.334910]  [<ffffffff81100752>] pagecache_get_page+0x10e/0x20c
      [   55.336844]  [<ffffffffa007d916>] alloc_extent_buffer+0xd0/0x350 [btrfs]
      [   55.338973]  [<ffffffffa0059d8c>] btrfs_find_create_tree_block+0x15/0x17 [btrfs]
      [   55.341329]  [<ffffffffa004f728>] btrfs_alloc_tree_block+0x18c/0x405 [btrfs]
      [   55.343566]  [<ffffffffa003fa34>] split_leaf+0x1e4/0x6a6 [btrfs]
      [   55.345577]  [<ffffffffa0040567>] btrfs_search_slot+0x671/0x831 [btrfs]
      [   55.347679]  [<ffffffff810682d7>] ? get_parent_ip+0xe/0x3e
      [   55.349434]  [<ffffffffa0041cb2>] btrfs_insert_empty_items+0x5d/0xa8 [btrfs]
      [   55.351681]  [<ffffffffa004ecfb>] __btrfs_run_delayed_refs+0x7a6/0xf35 [btrfs]
      [   55.353979]  [<ffffffffa00512ea>] btrfs_run_delayed_refs+0x6e/0x226 [btrfs]
      [   55.356212]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
      [   55.358378]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
      [   55.360626]  [<ffffffffa0060221>] btrfs_commit_transaction+0x4c/0xaba [btrfs]
      [   55.362894]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
      [   55.365221]  [<ffffffffa0073428>] btrfs_sync_file+0x29c/0x310 [btrfs]
      [   55.367273]  [<ffffffff81186808>] vfs_fsync_range+0x8f/0x9e
      [   55.369047]  [<ffffffff81186833>] vfs_fsync+0x1c/0x1e
      [   55.370654]  [<ffffffff81186869>] do_fsync+0x34/0x4e
      [   55.372246]  [<ffffffff81186ab3>] SyS_fsync+0x10/0x14
      [   55.373851]  [<ffffffff81554f97>] system_call_fastpath+0x12/0x6f
      [   55.381070] BTRFS: error (device hdb1) in btrfs_run_delayed_refs:2821: errno=-12 Out of memory
      [   55.382431] BTRFS warning (device hdb1): Skipping commit of aborted transaction.
      [   55.382433] BTRFS warning (device hdb1): cleanup_transaction:1692: Aborting unused transaction(IO failure).
      [   55.384280] ------------[ cut here ]------------
      [   55.384312] WARNING: CPU: 0 PID: 3010 at fs/btrfs/delayed-ref.c:438 btrfs_select_ref_head+0xd9/0xfe [btrfs]()
      [...]
      [   55.384337] Call Trace:
      [   55.384353]  [<ffffffff8154e6f0>] dump_stack+0x4f/0x7b
      [   55.384357]  [<ffffffff8107f717>] ? down_trylock+0x2d/0x37
      [   55.384359]  [<ffffffff81046977>] warn_slowpath_common+0xa1/0xbb
      [   55.384398]  [<ffffffffa00a1d6b>] ? btrfs_select_ref_head+0xd9/0xfe [btrfs]
      [   55.384400]  [<ffffffff81046a34>] warn_slowpath_null+0x1a/0x1c
      [   55.384423]  [<ffffffffa00a1d6b>] btrfs_select_ref_head+0xd9/0xfe [btrfs]
      [   55.384446]  [<ffffffffa004e5f7>] ? __btrfs_run_delayed_refs+0xa2/0xf35 [btrfs]
      [   55.384455]  [<ffffffffa004e600>] __btrfs_run_delayed_refs+0xab/0xf35 [btrfs]
      [   55.384476]  [<ffffffffa00512ea>] btrfs_run_delayed_refs+0x6e/0x226 [btrfs]
      [   55.384499]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
      [   55.384521]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
      [   55.384543]  [<ffffffffa0060221>] btrfs_commit_transaction+0x4c/0xaba [btrfs]
      [   55.384565]  [<ffffffffa0060e21>] ? start_transaction+0x192/0x534 [btrfs]
      [   55.384588]  [<ffffffffa0073428>] btrfs_sync_file+0x29c/0x310 [btrfs]
      [   55.384591]  [<ffffffff81186808>] vfs_fsync_range+0x8f/0x9e
      [   55.384592]  [<ffffffff81186833>] vfs_fsync+0x1c/0x1e
      [   55.384593]  [<ffffffff81186869>] do_fsync+0x34/0x4e
      [   55.384594]  [<ffffffff81186ab3>] SyS_fsync+0x10/0x14
      [   55.384595]  [<ffffffff81554f97>] system_call_fastpath+0x12/0x6f
      [...]
      [   55.384608] ---[ end trace c29799da1d4dd621 ]---
      [   55.437323] BTRFS info (device hdb1): forced readonly
      [   55.438815] BTRFS info (device hdb1): delayed_refs has NO entry
      
      Fix this by being explicit about the no-fail behavior of this allocation
      path and use __GFP_NOFAIL.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      d1b5c567
    • Zhaolei's avatar
      btrfs: Remove unused arguments in tree-log.c · 60d53eb3
      Zhaolei authored
      Following arguments are not used in tree-log.c:
       insert_one_name(): path, type
       wait_log_commit(): trans
       wait_for_writer(): trans
      
      This patch remove them.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      60d53eb3
    • Zhaolei's avatar
      btrfs: Remove useless condition in start_log_trans() · 34eb2a52
      Zhaolei authored
      Dan Carpenter <dan.carpenter@oracle.com> reported a smatch warning
      for start_log_trans():
       fs/btrfs/tree-log.c:178 start_log_trans()
       warn: we tested 'root->log_root' before and it was 'false'
      
       fs/btrfs/tree-log.c
       147          if (root->log_root) {
       We test "root->log_root" here.
       ...
      
      Reason:
       Condition of:
       fs/btrfs/tree-log.c:178: if (!root->log_root) {
       is not necessary after commit: 7237f183
      
       It caused a smatch warning, and no functionally error.
      
      Fix:
       Deleting above condition will make smatch shut up,
       but a better way is to do cleanup for start_log_trans()
       to remove duplicated code and make code more readable.
      Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      34eb2a52
  2. 09 Aug, 2015 35 commits
    • Chris Mason's avatar
      46cd2855
    • Chris Mason's avatar
      Btrfs: add support for blkio controllers · da2f0f74
      Chris Mason authored
      This attaches accounting information to bios as we submit them so the
      new blkio controllers can throttle on btrfs filesystems.
      
      Not much is required, we're just associating bios with blkcgs during clone,
      calling wbc_init_bio()/wbc_account_io() during writepages submission,
      and attaching the bios to the current context during direct IO.
      
      Finally if we are splitting bios during btrfs_map_bio, this attaches
      accounting information to the split.
      
      The end result is able to throttle nicely on single disk filesystems.  A
      little more work is required for multi-device filesystems.
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      da2f0f74
    • Byongho Lee's avatar
      Btrfs: remove unused mutex from struct 'btrfs_fs_info' · a4027a20
      Byongho Lee authored
      The code using 'ordered_extent_flush_mutex' mutex has removed by below
      commit.
       - 8d875f95
         btrfs: disable strict file flushes for renames and truncates
      But the mutex still lives in struct 'btrfs_fs_info'.
      
      So, this patch removes the mutex from struct 'btrfs_fs_info' and its
      initialization code.
      Signed-off-by: default avatarByongho Lee <bhlee.kernel@gmail.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      a4027a20
    • Omar Sandoval's avatar
      Btrfs: fix parity scrub of RAID 5/6 with missing device · 4a770891
      Omar Sandoval authored
      When testing the previous patch, Zhao Lei reported a similar bug when
      attempting to scrub a degraded RAID 5/6 filesystem with a missing
      device, leading to NULL pointer dereferences from the RAID 5/6 parity
      scrubbing code.
      
      The first cause was the same as in the previous patch: attempting to
      call bio_add_page() on a missing block device. To fix this,
      scrub_extent_for_parity() can just mark the sectors on the missing
      device as errors instead of attempting to read from it.
      
      Additionally, the code uses scrub_remap_extent() to map the extent of
      the corresponding data stripe, but the extent wasn't already mapped. If
      scrub_remap_extent() finds a missing block device, it doesn't initialize
      extent_dev, so we're left with a NULL struct btrfs_device. The solution
      is to use btrfs_map_block() directly.
      Reported-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      4a770891
    • Omar Sandoval's avatar
      Btrfs: fix device replace of a missing RAID 5/6 device · 73ff61db
      Omar Sandoval authored
      The original implementation of device replace on RAID 5/6 seems to have
      missed support for replacing a missing device. When this is attempted,
      we end up calling bio_add_page() on a bio with a NULL ->bi_bdev, which
      crashes when we try to dereference it. This happens because
      btrfs_map_block() has no choice but to return us the missing device
      because RAID 5/6 don't have any alternate mirrors to read from, and a
      missing device has a NULL bdev.
      
      The idea implemented here is to handle the missing device case
      separately, which better only happen when we're replacing a missing RAID
      5/6 device. We use the new BTRFS_RBIO_REBUILD_MISSING operation to
      reconstruct the data from parity, check it with
      scrub_recheck_block_checksum(), and write it out with
      scrub_write_block_to_dev_replace().
      Reported-by: default avatarPhilip <bugzilla@philip-seeger.de>
      Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96141Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      73ff61db
    • Omar Sandoval's avatar
      Btrfs: add RAID 5/6 BTRFS_RBIO_REBUILD_MISSING operation · b4ee1782
      Omar Sandoval authored
      The current RAID 5/6 recovery code isn't quite prepared to handle
      missing devices. In particular, it expects a bio that we previously
      attempted to use in the read path, meaning that it has valid pages
      allocated. However, missing devices have a NULL blkdev, and we can't
      call bio_add_page() on a bio with a NULL blkdev. We could do manual
      manipulation of bio->bi_io_vec, but that's pretty gross. So instead, add
      a separate path that allows us to manually add pages to the rbio.
      Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      b4ee1782
    • Omar Sandoval's avatar
      Btrfs: count devices correctly in readahead during RAID 5/6 replace · 7cb2c420
      Omar Sandoval authored
      Commit 5fbc7c59 ("Btrfs: fix unfinished readahead thread for raid5/6
      degraded mounting") fixed a problem where we would skip a missing device
      when we shouldn't have because there are no other mirrors to read from
      in RAID 5/6. After commit 2c8cdd6e ("Btrfs, replace: write dirty
      pages into the replace target device"), the fix doesn't work when we're
      doing a missing device replace on RAID 5/6 because the replace device is
      counted as a mirror so we're tricked into thinking we can safely skip
      the missing device. The fix is to count only the real stripes and decide
      based on that.
      Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      7cb2c420
    • Omar Sandoval's avatar
      Btrfs: remove misleading handling of missing device scrub · 03679ade
      Omar Sandoval authored
      scrub_submit() claims that it can handle a bio with a NULL block device,
      but this is misleading, as calling bio_add_page() on a bio with a NULL
      ->bi_bdev would've already crashed. Delete this, as we're about to
      properly handle a missing block device.
      Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      03679ade
    • Mark Fasheh's avatar
      btrfs: fix clone / extent-same deadlocks · 293a8489
      Mark Fasheh authored
      Clone and extent same lock their source and target inodes in opposite order.
      In addition to this, the range locking in clone doesn't take ordering into
      account. Fix this by having clone use the same locking helpers as
      btrfs-extent-same.
      
      In addition, I do a small cleanup of the locking helpers, removing a case
      (both inodes being the same) which was poorly accounted for and never
      actually used by the callers.
      Signed-off-by: default avatarMark Fasheh <mfasheh@suse.de>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      293a8489
    • Liu Bo's avatar
      Btrfs: fix defrag to merge tail file extent · 4a3560c4
      Liu Bo authored
      The file layout is
      
      [extent 1]...[extent n][4k extent][HOLE][extent x]
      
      extent 1~n and 4k extent can be merged during defrag, and the whole
      defrag bytes is larger than our defrag thresh(256k), 4k extent as a
      tail is left unmerged since we check if its next extent can be merged
      (the next one is a hole, so the check will fail), the layout thus can
      be
      
      [new extent][4k extent][HOLE][extent x]
       (1~n)
      
      To fix it, beside looking at the next one, this also looks at the
      previous one by checking @defrag_end, which is set to 0 when we
      decide to stop merging contiguous extents, otherwise, we can merge
      the previous one with our extent.
      
      Also, this makes btrfs behave consistent with how xfs and ext4 do.
      Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      4a3560c4
    • Liu Bo's avatar
      Btrfs: fix warning in backref walking · acdf898d
      Liu Bo authored
      When we do backref walking, we search firstly in queued delayed refs
      and then the on-disk backrefs, but we parse differently for shared
      references, for delayed refs we also add 'ref->root' while for on-disk
      backrefs we don't, this can prevent us from merging refs indexed
      by the same bytenr and cause find_parent_nodes() to throw a warning at
      'WARN_ON(ref->count < 0)', for example, when we have a shared data extent
      with 'ref_cnt=1' and a delayed shared data with a BTRFS_DROP_DELAYED_REF,
      that happens.
      
      For shared references, no matter if it's delayed or on-disk, ref->root is
      not at all used, instead it's ref->parent that really matters, so this has
      delayed refs handled as the same way as on-disk refs.
      Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      acdf898d
    • Zhaolei's avatar
      btrfs: Add WARN_ON() for double lock in btrfs_tree_lock() · 166f66d0
      Zhaolei authored
      When a task trying to double lock a extent buffer, there are no
      lockdep warning about it because this lock may be in "blocking_lock"
      state, and make us hard to debug.
      
      This patch add a WARN_ON() for above condition, it can not report
      all deadlock cases(as lock between tasks), but at least helps us
      some.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      166f66d0
    • Zhaolei's avatar
      btrfs: Remove root argument in extent_data_ref_count() · 9ed0dea0
      Zhaolei authored
      Because it is never used.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      9ed0dea0
    • Zhaolei's avatar
      btrfs: Fix wrong comment of btrfs_alloc_tree_block() · d0220751
      Zhaolei authored
      These wrong comment was copyed from another function(expired) from
      init, this patch fixed them.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      d0220751
    • Zhaolei's avatar
      btrfs: abort transaction on btrfs_reloc_cow_block() · 93314e3b
      Zhaolei authored
      When btrfs_reloc_cow_block() failed in __btrfs_cow_block(), current
      code just return a err-value to caller, but leave new_created extent
      buffer exist and locked.
      
      Then subsequent code (in relocate) try to lock above eb again,
      and caused deadlock without any dmesg.
      (eb lock use wait_event(), so no lockdep message)
      
      It is hard to do recover work in __btrfs_cow_block() at this error
      point, but we can abort transaction to avoid deadlock and operate on
      unstable state.a
      
      It also helps developer to find wrong place quickly.
      (better than a frozen fs without any dmesg before patch)
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      93314e3b
    • Zhaolei's avatar
      btrfs: Remove unnecessary variants in relocation.c · 147d256e
      Zhaolei authored
      These arguments are not used in functions, remove them for cleanup
      and make kernel stack happy.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      147d256e
    • Zhaolei's avatar
      btrfs: Cleanup: Remove chunk_objectid argument from btrfs_relocate_chunk() · dc2ee4e2
      Zhaolei authored
      Remove chunk_objectid argument from btrfs_relocate_chunk() because
      it is not necessary, it can also cleanup some code in caller for
      prepare its value.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      dc2ee4e2
    • Zhaolei's avatar
      btrfs: Cleanup: Remove objectid's init-value in create_reloc_inode() · 4624900d
      Zhaolei authored
      objectid's init-value is not used in any case, remove it.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      4624900d
    • Zhaolei's avatar
      btrfs: Error handle for get_ref_objectid_v0() in relocate_block_group() · 4b3576e4
      Zhaolei authored
      We need error checking code for get_ref_objectid_v0() in
      relocate_block_group(), to avoid unpredictable result, especially
      for accessing uninitialized value(when function failed) after
      this line.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      4b3576e4
    • Zhaolei's avatar
      btrfs: Fix data checksum error cause by replace with io-load. · 55e3a601
      Zhaolei authored
      xfstests btrfs/070 sometimes failed.
      In my test machine, its fail rate is about 30%.
      In another vm(vmware), its fail rate is about 50%.
      
      Reason:
        btrfs/070 do replace and defrag with fsstress simultaneously,
        after above operation, checksum error is found by scrub.
      
        Actually, it have no relationship with defrag operation, only
        replace with fsstress can trigger this bug.
      
        New data writen to target device have possibility rewrited by
        old data from source device by replace code in debug, to avoid
        above problem, we can set target block group to readonly in
        replace period, so new data requested by other operation will
        not write to same place with replace code.
      
        Before patch(4.1-rc3):
          30% failed in 100 xfstests.
        After patch:
          0% failed in 300 xfstests.
      
      It also happened in btrfs/071 as it's another scrub with IO load tests.
      Reported-by: default avatarQu Wenruo <quwenruo@cn.fujitsu.com>
      Signed-off-by: default avatarQu Wenruo <quwenruo@cn.fujitsu.com>
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      55e3a601
    • Zhaolei's avatar
      btrfs: use scrub_pause_on/off() to reduce code in scrub_enumerate_chunks() · b708ce96
      Zhaolei authored
      Use new intruduced scrub_pause_on/off() can make this code block
      clean and more readable.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      b708ce96
    • Zhaolei's avatar
      btrfs: Separate scrub_blocked_if_needed() to scrub_pause_on/off() · 0e22be89
      Zhaolei authored
      It can reduce current duplicated code which is similar to
      scrub_blocked_if_needed() but can not call it because little
      different.
      It also used by my next patch which is in same case.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      0e22be89
    • Zhaolei's avatar
      btrfs: Use ref_cnt for set_block_group_ro() · 868f401a
      Zhaolei authored
      More than one code call set_block_group_ro() and restore rw in fail.
      
      Old code use bool bit to save blockgroup's ro state, it can not
      support parallel case(it is confirmd exist in my debug log).
      
      This patch use ref count to store ro state, and rename
      set_block_group_ro/set_block_group_rw
      to
      inc_block_group_ro/dec_block_group_ro.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      868f401a
    • Zhao Lei's avatar
      btrfs: Bypass unrelated items before accessing its contents in scrub · d7cad238
      Zhao Lei authored
      When we access extent_root in scrub_stripe() and
      scrub_raid56_parity(), we need bypass unrelated tree item firstly
      before using its contents to do other condition.
      
      It is not a bug fix, only making code sequence in logic.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      d7cad238
    • Zhao Lei's avatar
      btrfs: Load only necessary csums into list in scrub · fe8cf654
      Zhao Lei authored
      We need not load csum of whole strip in scrub because strip is trimed
      before use, it is to say, what we really need to calculate csum is
      data between [extent_logical, extent_len).
      
      This patch changed to use above segment for btrfs_lookup_csums_range()
      in scrub_stripe()
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      fe8cf654
    • Zhao Lei's avatar
      btrfs: Fix calculate typo caused by ambiguous meaning of logic_end · a0dd59de
      Zhao Lei authored
      For example, in scrub_raid56_parity(), following lines are used
      to judge is all data processed:
       place1: if (key.objectid > logic_end) ...
       place2: if (logic_start >= logic_end) ...
       ...
       (place2 is typo, is should be ">", it is copied from other
        place, where logic_end's meaning is different, long story...)
      
      We can fix above typo directly, but the root reason is ambiguous
      meaning of logic_end in scrub raid56 parity.
      
      In other place, XXX_end is pointed to data which is not included,
      and we need to process segment of [XXX_start, XXX_end).
      
      But for scrub raid56 parity, logic_end is pointed to lattest data
      need to process, and introduced many "+ 1" and "- 1" in code as
      below:
       length = sparity->logic_end - sparity->logic_start + 1
       logic_end - logic_start + 1
       stripe_logical + increment - 1
      
      This patch changed logic_end's meaning to make it in normal understanding
      in raid56 parity functions and data struct alone with above bugfix.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      a0dd59de
    • Zhao Lei's avatar
      btrfs: Free checksum list on scrub_extent() fail · 6fa96d72
      Zhao Lei authored
      When scrub_extent() failed, we need to free previois created
      checksum list.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      6fa96d72
    • Zhao Lei's avatar
      btrfs: Check cancel and pause in interval of scrub operation · f2f66a2f
      Zhao Lei authored
      Old code checking cancel and pause request inside scrub stripe
      operation, like:
        loop() {
          if (parity) {
            scrub_parity_stripe();
            continue;
          }
      
          check_cancel_and_pause()
      
          scrub_normal_stripe();
        }
      
      Reason is when introduce raid56 stripe scrub, new code is inserted
      simplely to front of loop.
      
      Better to:
        loop() {
          check_cancel_and_pause()
      
          if (parity)
            scrub_parity_stripe();
          else
            scrub_normal_stripe();
        }
      
      This patch adjusted code place to realize above sequence.
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      f2f66a2f
    • Zhao Lei's avatar
      btrfs: Show detail information when mount failed on missing devices · 78fa1770
      Zhao Lei authored
      When mount failed because missing device, we can see following
      dmesg:
       [ 1060.267743] BTRFS: too many missing devices, writeable mount is not allowed
       [ 1060.273158] BTRFS: open_ctree failed
      
      This patch add missing_device_number and tolerated_missing_device_number
      to above output, to let user know what really happened, and helps
      bug-report and debug.
      
      dmesg after patch:
       [  127.050367] BTRFS: missing devices(1) exceeds the limit(0), writeable mount is not allowed
       [  127.056099] BTRFS: open_ctree failed
      
      Changelog v1->v2:
      1: Changed to more clear description, suggested-by:
         Anand Jain <anand.jain@oracle.com>
      Suggested-by: default avatarAnand Jain <anand.jain@oracle.com>
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      78fa1770
    • Zhao Lei's avatar
      btrfs: Fix scrub panic when leaf crosses stripes · a323e813
      Zhao Lei authored
      Scrub panic in following operation:
        mkfs.ext4 /dev/vdh
        btrfs-convert /dev/vdh
        mount /dev/vdh /mnt/tmp1
        btrfs scrub start -B /dev/vdh
        (panic)
      
      Reason:
        1: In some case, leaf created by btrfs-convert was splited into 2
           strips.
        2: Scrub bypassed part of above wrong leaf data, but remain data
           caused panic in scrub_checksum_tree_block().
      
      For reason 1:
        we can get following information after some simple operation.
        a. mkfs.ext4 /dev/vdh
           btrfs-convert /dev/vdh
        b. btrfs-debug-tree /dev/vdh
           we can see following item in extent tree:
           item 25 key (27054080 METADATA_ITEM 0) itemoff 15083 itemsize 33
           Its logical address is [27054080, 27070464)
           and acrossed 2 strips:
           [27000832, 27066368)
           [27066368, 27131904)
        Will be fixed in btrfs-progs(btrfs-convert, btrfsck, ...)
      
      For reason 2:
        Scrub is trying to do a "bypass" in this case, but the result is
        "panic", because current code lacks of some condition in bypass,
        and let some wrong leaf data escaped.
      
      This patch fixed above scrub code.
      
      Before patch:
        # btrfs scrub start -B /dev/vdh
        (panic)
      
      After patch:
        # btrfs scrub start -B /dev/vdh
        scrub done for 353cec8f-da31-4a94-aa35-be72d997b06e
        ...
        # dmesg
        ...
        [   59.088697] BTRFS error (device vdh): scrub: tree block 27054080 spanning stripes, ignored. logical=27000832
        [   59.089929] BTRFS error (device vdh): scrub: tree block 27054080 spanning stripes, ignored. logical=27066368
        #
      Reported-by: default avatarChris Murphy <lists@colorremedies.com>
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      a323e813
    • Filipe Manana's avatar
      Btrfs: fix stale dir entries after removing a link and fsync · 18aa0922
      Filipe Manana authored
      We have one more case where after a log tree is replayed we get
      inconsistent metadata leading to stale directory entries, due to
      some directories having entries pointing to some inode while the
      inode does not have a matching BTRFS_INODE_[REF|EXTREF]_KEY item.
      
      To trigger the problem we need to have a file with multiple hard links
      belonging to different parent directories. Then if one of those hard
      links is removed and we fsync the file using one of its other links
      that belongs to a different parent directory, we end up not logging
      the fact that the removed hard link doesn't exists anymore in the
      parent directory.
      
      Simple reproducer:
      
        seq=`basename $0`
        seqres=$RESULT_DIR/$seq
        echo "QA output created by $seq"
        tmp=/tmp/$$
        status=1	# failure is the default!
        trap "_cleanup; exit \$status" 0 1 2 3 15
      
        _cleanup()
        {
            _cleanup_flakey
            rm -f $tmp.*
        }
      
        # get standard environment, filters and checks
        . ./common/rc
        . ./common/filter
        . ./common/dmflakey
      
        # real QA test starts here
        _need_to_be_root
        _supported_fs generic
        _supported_os Linux
        _require_scratch
        _require_dm_flakey
        _require_metadata_journaling $SCRATCH_DEV
      
        rm -f $seqres.full
      
        _scratch_mkfs >>$seqres.full 2>&1
        _init_flakey
        _mount_flakey
      
        # Create our test directory and file.
        mkdir $SCRATCH_MNT/testdir
        touch $SCRATCH_MNT/foo
        ln $SCRATCH_MNT/foo $SCRATCH_MNT/testdir/foo2
        ln $SCRATCH_MNT/foo $SCRATCH_MNT/testdir/foo3
      
        # Make sure everything done so far is durably persisted.
        sync
      
        # Now we remove one of our file's hardlinks in the directory testdir.
        unlink $SCRATCH_MNT/testdir/foo3
      
        # We now fsync our file using the "foo" link, which has a parent that
        # is not the directory "testdir".
        $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
      
        # Silently drop all writes and unmount to simulate a crash/power
        # failure.
        _load_flakey_table $FLAKEY_DROP_WRITES
        _unmount_flakey
      
        # Allow writes again, mount to trigger journal/log replay.
        _load_flakey_table $FLAKEY_ALLOW_WRITES
        _mount_flakey
      
        # After the journal/log is replayed we expect to not see the "foo3"
        # link anymore and we should be able to remove all names in the
        # directory "testdir" and then remove it (no stale directory entries
        # left after the journal/log replay).
        echo "Entries in testdir:"
        ls -1 $SCRATCH_MNT/testdir
      
        rm -f $SCRATCH_MNT/testdir/*
        rmdir $SCRATCH_MNT/testdir
      
        _unmount_flakey
      
        status=0
        exit
      
      The test fails with:
      
        $ ./check generic/107
        FSTYP         -- btrfs
        PLATFORM      -- Linux/x86_64 debian3 4.1.0-rc6-btrfs-next-11+
        MKFS_OPTIONS  -- /dev/sdc
        MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1
      
        generic/107 3s ... - output mismatch (see .../results/generic/107.out.bad)
          --- tests/generic/107.out	2015-08-01 01:39:45.807462161 +0100
          +++ /home/fdmanana/git/hub/xfstests/results//generic/107.out.bad
          @@ -1,3 +1,5 @@
           QA output created by 107
           Entries in testdir:
           foo2
          +foo3
          +rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/testdir': Directory not empty
          ...
          _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent \
            (see /home/fdmanana/git/hub/xfstests/results//generic/107.full)
          _check_dmesg: something found in dmesg (see .../results/generic/107.dmesg)
        Ran: generic/107
        Failures: generic/107
        Failed 1 of 1 tests
      
        $ cat /home/fdmanana/git/hub/xfstests/results//generic/107.full
        (...)
        checking fs roots
        root 5 inode 257 errors 200, dir isize wrong
      	unresolved ref dir 257 index 3 namelen 4 name foo3 filetype 1 errors 5, no dir item, no inode ref
        (...)
      
      And produces the following warning in dmesg:
      
        [127298.759064] BTRFS info (device dm-0): failed to delete reference to foo3, inode 258 parent 257
        [127298.762081] ------------[ cut here ]------------
        [127298.763311] WARNING: CPU: 10 PID: 7891 at fs/btrfs/inode.c:3956 __btrfs_unlink_inode+0x182/0x35a [btrfs]()
        [127298.767327] BTRFS: Transaction aborted (error -2)
        (...)
        [127298.788611] Call Trace:
        [127298.789137]  [<ffffffff8145f077>] dump_stack+0x4f/0x7b
        [127298.790090]  [<ffffffff81095de5>] ? console_unlock+0x356/0x3a2
        [127298.791157]  [<ffffffff8104b3b0>] warn_slowpath_common+0xa1/0xbb
        [127298.792323]  [<ffffffffa065ad09>] ? __btrfs_unlink_inode+0x182/0x35a [btrfs]
        [127298.793633]  [<ffffffff8104b410>] warn_slowpath_fmt+0x46/0x48
        [127298.794699]  [<ffffffffa065ad09>] __btrfs_unlink_inode+0x182/0x35a [btrfs]
        [127298.797640]  [<ffffffffa065be8f>] btrfs_unlink_inode+0x1e/0x40 [btrfs]
        [127298.798876]  [<ffffffffa065bf11>] btrfs_unlink+0x60/0x9b [btrfs]
        [127298.800154]  [<ffffffff8116fb48>] vfs_unlink+0x9c/0xed
        [127298.801303]  [<ffffffff81173481>] do_unlinkat+0x12b/0x1fb
        [127298.802450]  [<ffffffff81253855>] ? lockdep_sys_exit_thunk+0x12/0x14
        [127298.803797]  [<ffffffff81174056>] SyS_unlinkat+0x29/0x2b
        [127298.805017]  [<ffffffff81465197>] system_call_fastpath+0x12/0x6f
        [127298.806310] ---[ end trace bbfddacb7aaada7b ]---
        [127298.807325] BTRFS warning (device dm-0): __btrfs_unlink_inode:3956: Aborting unused transaction(No such entry).
      
      So fix this by logging all parent inodes, current and old ones, to make
      sure we do not get stale entries after log replay. This is not a simple
      solution such as triggering a full transaction commit because it would
      imply full transaction commit when an inode is fsynced in the same
      transaction that modified it and reloaded it after eviction (because its
      last_unlink_trans is set to the same value as its last_trans as of the
      commit with the title "Btrfs: fix stale dir entries after unlink, inode
      eviction and fsync"), and it would also make fstest generic/066 fail
      since one of the fsyncs triggers a full commit and the next fsync will
      not find the inode in the log anymore (therefore not removing the xattr).
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      18aa0922
    • Naohiro Aota's avatar
      btrfs: fix search key advancing condition · dd81d459
      Naohiro Aota authored
      The search key advancing condition used in copy_to_sk() is loose. It can
      advance the key even if it reaches sk->max_*: e.g. when the max key = (512,
      1024, -1) and the current key = (512, 1025, 10), it increments the
      offset by 1, continues hopeless search from (512, 1025, 11). This issue
      make ioctl() to take unexpectedly long time scanning all the leaf a blocks
      one by one.
      
      This commit fix the problem using standard way of key comparison:
      btrfs_comp_cpu_keys()
      Signed-off-by: default avatarNaohiro Aota <naota@elisp.net>
      Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      dd81d459
    • Filipe Manana's avatar
      Btrfs: teach backref walking about backrefs with underflowed offset values · d6589101
      Filipe Manana authored
      When cloning/deduplicating file extents (through the clone and extent_same
      ioctls) we can get data back references with offset values that are a
      result of an unsigned integer arithmetic underflow, that is, values that
      are much larger then they could be otherwise.
      
      This is not a problem when decrementing or dropping the back references
      (happens when we overwrite the extents or punch a hole for example, through
      __btrfs_drop_extents()), since we compute the same too large offset value,
      but it is a problem for the backref walking code, used by an incremental
      send and the ioctls that are used by the btrfs tool "inspect-internal"
      commands, as it makes it miss the corresponding file extent items because
      the search key is set for an extent item that starts at an offset matching
      the exceptionally large offset value of the data back reference. For an
      incremental send this causes the send ioctl to fail with -EIO.
      
      So teach the backref walking code to deal with these cases by setting the
      search key's offset to 0 if the backref's offset value is larger than
      LLONG_MAX (the largest possible file offset). This makes sure the backref
      walking code finds the corresponding file extent items at the expense of
      scanning more items and leafs in the btree.
      
      Fixing the clone/dedup ioctls to not produce such underflowed results would
      require major changes breaking backward compatibility, updating user space
      tools, etc.
      
      Simple reproducer case for fstests:
      
        seq=`basename $0`
        seqres=$RESULT_DIR/$seq
        echo "QA output created by $seq"
      
        tmp=/tmp/$$
        status=1	# failure is the default!
        trap "_cleanup; exit \$status" 0 1 2 3 15
      
        _cleanup()
        {
            rm -fr $send_files_dir
            rm -f $tmp.*
        }
      
        # get standard environment, filters and checks
        . ./common/rc
        . ./common/filter
      
        # real QA test starts here
        _supported_fs btrfs
        _supported_os Linux
        _require_scratch
        _require_cloner
        _need_to_be_root
      
        send_files_dir=$TEST_DIR/btrfs-test-$seq
      
        rm -f $seqres.full
        rm -fr $send_files_dir
        mkdir $send_files_dir
      
        _scratch_mkfs >>$seqres.full 2>&1
        _scratch_mount
      
        # Create our test file with a single extent of 64K starting at file
        # offset 128K.
        $XFS_IO_PROG -f -c "pwrite -S 0xaa 128K 64K" $SCRATCH_MNT/foo \
            | _filter_xfs_io
      
        _run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT \
            $SCRATCH_MNT/mysnap1
      
        # Now clone parts of the original extent into lower offsets of the file.
        #
        # The first clone operation adds a file extent item to file offset 0
        # that points to our initial extent with a data offset of 16K. The
        # corresponding data back reference in the extent tree has an offset of
        # 18446744073709535232, which is the result of file_offset - data_offset
        # = 0 - 16K.
        #
        # The second clone operation adds a file extent item to file offset 16K
        # that points to our initial extent with a data offset of 48K. The
        # corresponding data back reference in the extent tree has an offset of
        # 18446744073709518848, which is the result of file_offset - data_offset
        # = 16K - 48K.
        #
        # Those large back reference offsets (result of unsigned arithmetic
        # underflow) confused the back reference walking code (used by an
        # incremental send and the multiple inspect-internal ioctls) and made it
        # miss the back references, which for the case of an incremental send it
        # made it fail with -EIO and print a message like the following to
        # dmesg:
        #
        # "BTRFS error (device sdc): did not find backref in send_root. \
        #  inode=257, offset=0, disk_byte=12845056 found extent=12845056"
        #
        $CLONER_PROG -s $(((128 + 16) * 1024)) -d 0 -l $((16 * 1024)) \
            $SCRATCH_MNT/foo $SCRATCH_MNT/foo
        $CLONER_PROG -s $(((128 + 48) * 1024)) -d $((16 * 1024)) \
            -l $((16 * 1024)) $SCRATCH_MNT/foo $SCRATCH_MNT/foo
      
        _run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT \
            $SCRATCH_MNT/mysnap2
      
        _run_btrfs_util_prog send $SCRATCH_MNT/mysnap1 -f $send_files_dir/1.snap
        _run_btrfs_util_prog send -p $SCRATCH_MNT/mysnap1 $SCRATCH_MNT/mysnap2 \
            -f $send_files_dir/2.snap
      
        echo "File digest in the original filesystem:"
        md5sum $SCRATCH_MNT/mysnap2/foo | _filter_scratch
      
        # Now recreate the filesystem by receiving both send streams and verify
        # we get the same file contents that the original filesystem had.
        _scratch_unmount
        _scratch_mkfs >>$seqres.full 2>&1
        _scratch_mount
      
        _run_btrfs_util_prog receive $SCRATCH_MNT -f $send_files_dir/1.snap
        _run_btrfs_util_prog receive $SCRATCH_MNT -f $send_files_dir/2.snap
      
        echo "File digest in the new filesystem:"
        md5sum $SCRATCH_MNT/mysnap2/foo | _filter_scratch
      
        status=0
        exit
      
      The test's expected golden output is:
      
        wrote 65536/65536 bytes at offset 131072
        XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
        File digest in the original filesystem:
        6c6079335cff141b8a31233ead04cbff  SCRATCH_MNT/mysnap2/foo
        File digest in the new filesystem:
        6c6079335cff141b8a31233ead04cbff  SCRATCH_MNT/mysnap2/foo
      
      But it failed with:
      
          (...)
          @@ -1,7 +1,5 @@
           QA output created by 097
           wrote 65536/65536 bytes at offset 131072
           XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
          -File digest in the original filesystem:
          -6c6079335cff141b8a31233ead04cbff  SCRATCH_MNT/mysnap2/foo
          -File digest in the new filesystem:
          -6c6079335cff141b8a31233ead04cbff  SCRATCH_MNT/mysnap2/foo
          ...
      
        $ cat /home/fdmanana/git/hub/xfstests/results//btrfs/097.full
        (...)
        ERROR: send ioctl failed with -5: Input/output error
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      d6589101
    • Filipe Manana's avatar
      Btrfs: fix stale dir entries after unlink, inode eviction and fsync · bde6c242
      Filipe Manana authored
      If we remove a hard link from an inode, the inode gets evicted, then
      we fsync the inode and then power fail/crash, when the log tree is
      replayed, the parent directory inode still has entries pointing to
      the name that no longer exists, while our inode no longer has the
      BTRFS_INODE_REF_KEY item matching the deleted hard link (as expected),
      leaving the filesystem in an inconsistent state. The stale directory
      entries can not be deleted (an attempt to delete them causes -ESTALE
      errors), which makes it impossible to delete the parent directory.
      
      This happens because we track the id of the transaction where the last
      unlink operation for the inode happened (last_unlink_trans) in an
      in-memory only field of the inode, that is, a value that is never
      persisted in the inode item stored on the fs/subvol btree. So if an
      inode is evicted and loaded again, the value for last_unlink_trans is
      set to 0, which prevents the fsync from logging the parent directory
      at btrfs_log_inode_parent(). So fix this by setting last_unlink_trans
      to the id of the transaction that last modified the inode when we
      load the inode. This is a pessimistic approach but it always ensures
      correctness with the trade off of ocassional full transaction commits
      when an fsync is done against the inode in the same transaction where
      it was evicted and reloaded when our inode is a directory and often
      logging its parent unnecessarily when our inode is not a directory.
      
      The following test case for fstests triggers the problem:
      
        seq=`basename $0`
        seqres=$RESULT_DIR/$seq
        echo "QA output created by $seq"
        tmp=/tmp/$$
        status=1	# failure is the default!
        trap "_cleanup; exit \$status" 0 1 2 3 15
      
        _cleanup()
        {
            _cleanup_flakey
            rm -f $tmp.*
        }
      
        # get standard environment, filters and checks
        . ./common/rc
        . ./common/filter
        . ./common/dmflakey
      
        # real QA test starts here
        _need_to_be_root
        _supported_fs generic
        _supported_os Linux
        _require_scratch
        _require_dm_flakey
        _require_metadata_journaling $SCRATCH_DEV
      
        rm -f $seqres.full
      
        _scratch_mkfs >>$seqres.full 2>&1
        _init_flakey
        _mount_flakey
      
        # Create our test file with 2 hard links.
        mkdir $SCRATCH_MNT/testdir
        touch $SCRATCH_MNT/testdir/foo
        ln $SCRATCH_MNT/testdir/foo $SCRATCH_MNT/testdir/bar
      
        # Make sure everything done so far is durably persisted.
        sync
      
        # Now remove one of the links, trigger inode eviction and then fsync
        # our inode.
        unlink $SCRATCH_MNT/testdir/bar
        echo 2 > /proc/sys/vm/drop_caches
        $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/testdir/foo
      
        # Silently drop all writes on our scratch device to simulate a power failure.
        _load_flakey_table $FLAKEY_DROP_WRITES
        _unmount_flakey
      
        # Allow writes again and mount the fs to trigger log/journal replay.
        _load_flakey_table $FLAKEY_ALLOW_WRITES
        _mount_flakey
      
        # Now verify our directory entries.
        echo "Entries in testdir:"
        ls -1 $SCRATCH_MNT/testdir
      
        # If we remove our inode, its parent should become empty and therefore we should
        # be able to remove the parent.
        rm -f $SCRATCH_MNT/testdir/*
        rmdir $SCRATCH_MNT/testdir
      
        _unmount_flakey
      
        # The fstests framework will call fsck against our filesystem which will verify
        # that all metadata is in a consistent state.
      
        status=0
        exit
      
      The test failed on btrfs with:
      
        generic/098 4s ... - output mismatch (see /home/fdmanana/git/hub/xfstests/results//generic/098.out.bad)
          --- tests/generic/098.out	2015-07-23 18:01:12.616175932 +0100
          +++ /home/fdmanana/git/hub/xfstests/results//generic/098.out.bad	2015-07-23 18:04:58.924138308 +0100
          @@ -1,3 +1,6 @@
           QA output created by 098
           Entries in testdir:
          +bar
           foo
          +rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/testdir/foo': Stale file handle
          +rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/testdir': Directory not empty
          ...
          (Run 'diff -u tests/generic/098.out /home/fdmanana/git/hub/xfstests/results//generic/098.out.bad'  to see the entire diff)
        _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent (see /home/fdmanana/git/hub/xfstests/results//generic/098.full)
      
        $ cat /home/fdmanana/git/hub/xfstests/results//generic/098.full
        (...)
        checking fs roots
        root 5 inode 258 errors 2001, no inode item, link count wrong
           unresolved ref dir 257 index 0 namelen 3 name foo filetype 1 errors 6, no dir index, no inode ref
           unresolved ref dir 257 index 3 namelen 3 name bar filetype 1 errors 5, no dir item, no inode ref
        Checking filesystem on /dev/sdc
        (...)
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      bde6c242
    • Filipe Manana's avatar
      Btrfs: fix stale directory entries after fsync log replay · bb53eda9
      Filipe Manana authored
      We have another case where after an fsync log replay we get an inode with
      a wrong link count (smaller than it should be) and a number of directory
      entries greater than its link count. This happens when we add a new link
      hard link to our inode A and then we fsync some other inode B that has
      the side effect of logging the parent directory inode too. In this case
      at log replay time we add the new hard link to our inode (the item with
      key BTRFS_INODE_REF_KEY) when processing the parent directory but we
      never adjust the link count of our inode A. As a result we get stale dir
      entries for our inode A that can never be deleted and therefore it makes
      it impossible to remove the parent directory (as its i_size can never
      decrease back to 0).
      
      A simple reproducer for fstests that triggers this issue:
      
        seq=`basename $0`
        seqres=$RESULT_DIR/$seq
        echo "QA output created by $seq"
        tmp=/tmp/$$
        status=1	# failure is the default!
        trap "_cleanup; exit \$status" 0 1 2 3 15
      
        _cleanup()
        {
            _cleanup_flakey
            rm -f $tmp.*
        }
      
        # get standard environment, filters and checks
        . ./common/rc
        . ./common/filter
        . ./common/dmflakey
      
        # real QA test starts here
        _need_to_be_root
        _supported_fs generic
        _supported_os Linux
        _require_scratch
        _require_dm_flakey
        _require_metadata_journaling $SCRATCH_DEV
      
        rm -f $seqres.full
      
        _scratch_mkfs >>$seqres.full 2>&1
        _init_flakey
        _mount_flakey
      
        # Create our test directory and files.
        mkdir $SCRATCH_MNT/testdir
        touch $SCRATCH_MNT/testdir/foo
        touch $SCRATCH_MNT/testdir/bar
      
        # Make sure everything done so far is durably persisted.
        sync
      
        # Create one hard link for file foo and another one for file bar. After
        # that fsync only the file bar.
        ln $SCRATCH_MNT/testdir/bar $SCRATCH_MNT/testdir/bar_link
        ln $SCRATCH_MNT/testdir/foo $SCRATCH_MNT/testdir/foo_link
        $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/testdir/bar
      
        # Silently drop all writes on scratch device to simulate power failure.
        _load_flakey_table $FLAKEY_DROP_WRITES
        _unmount_flakey
      
        # Allow writes again and mount the fs to trigger log/journal replay.
        _load_flakey_table $FLAKEY_ALLOW_WRITES
        _mount_flakey
      
        # Now verify both our files have a link count of 2.
        echo "Link count for file foo: $(stat --format=%h $SCRATCH_MNT/testdir/foo)"
        echo "Link count for file bar: $(stat --format=%h $SCRATCH_MNT/testdir/bar)"
      
        # We should be able to remove all the links of our files in testdir, and
        # after that the parent directory should become empty and therefore
        # possible to remove it.
        rm -f $SCRATCH_MNT/testdir/*
        rmdir $SCRATCH_MNT/testdir
      
        _unmount_flakey
      
        # The fstests framework will call fsck against our filesystem which will verify
        # that all metadata is in a consistent state.
      
        status=0
        exit
      
      The test fails with:
      
       -Link count for file foo: 2
       +Link count for file foo: 1
        Link count for file bar: 2
       +rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/testdir/foo_link': Stale file handle
       +rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/testdir': Directory not empty
       (...)
       _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent
      
      And fsck's output:
      
        (...)
        checking fs roots
        root 5 inode 258 errors 2001, no inode item, link count wrong
            unresolved ref dir 257 index 5 namelen 8 name foo_link filetype 1 errors 4, no inode ref
        Checking filesystem on /dev/sdc
        (...)
      
      So fix this by marking inodes for link count fixup at log replay time
      whenever a directory entry is replayed if the entry was created in the
      transaction where the fsync was made and if it points to a non-directory
      inode.
      
      This isn't a new problem/regression, the issue exists for a long time,
      possibly since the log tree feature was added (2008).
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      bb53eda9