1. 29 1月, 2014 3 次提交
  2. 12 12月, 2013 1 次提交
    • F
      Btrfs: don't miss skinny extent items on delayed ref head contention · 639eefc8
      Filipe David Borba Manana 提交于
      Currently extent-tree.c:btrfs_lookup_extent_info() can miss the lookup
      of skinny extent items. This can happen when the execution flow is the
      following:
      
      * We do an extent tree lookup and fail to find a skinny extent item;
      
      * As a result, we attempt to see if a non-skinny extent item exists,
        either by looking at previous item in the leaf or by doing another
        full extent tree search;
      
      * We have a transaction and then we check for a matching delayed ref
        head in the transaction's delayed refs rbtree;
      
      * We find such delayed ref head and then we try to lock it with a
        call to mutex_trylock();
      
      * The lock was contended so we jump to the label "again", which repeats
        the extent tree search but for a non-skinny extent item, because we set
        previously metadata variable to 0 and the search key to look for a
        non-skinny extent-item;
      
      * After the jump (and after releasing the transaction's delayed refs
        lock), a skinny extent item might have been added to the extent tree
        but we will miss it because metadata is set to 0 and the search key
        is set for a non-skinny extent-item.
      
      The fix here is to not reset metadata to 0 and to jump to the initial search
      key setup if the delayed ref head is contended, instead of jumping directly
      to the extent tree search label ("again").
      
      This issue was found while investigating the issue reported at Bugzilla 64961.
      
      David Sterba suspected this function was missing extent items, and that
      this could be caused by the last change to this function, which was made
      in the following patch:
      
          [PATCH] Btrfs: optimize btrfs_lookup_extent_info()
          (commit 74be9510)
      
      But in fact this issue already existed before, because after failing to find
      a skinny extent item, the code set the search key for a non-skinny extent
      item, and on contention of a matching delayed ref head it would not search
      the extent tree for a skinny extent item anymore.
      Signed-off-by: NFilipe David Borba Manana <fdmanana@gmail.com>
      Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
      Signed-off-by: NChris Mason <clm@fb.com>
      639eefc8
  3. 12 11月, 2013 18 次提交
  4. 21 9月, 2013 4 次提交
  5. 01 9月, 2013 13 次提交
  6. 20 7月, 2013 1 次提交