• J
    Btrfs: account merges/splits properly · ba117213
    Josef Bacik 提交于
    My fix
    
    Btrfs: fix merge delalloc logic
    
    only fixed half of the problems, it didn't fix the case where we have two large
    extents on either side and then join them together with a new small extent.  We
    need to instead keep track of how many extents we have accounted for with each
    side of the new extent, and then see how many extents we need for the new large
    extent.  If they match then we know we need to keep our reservation, otherwise
    we need to drop our reservation.  This shows up with a case like this
    
    [BTRFS_MAX_EXTENT_SIZE+4K][4K HOLE][BTRFS_MAX_EXTENT_SIZE+4K]
    
    Previously the logic would have said that the number extents required for the
    new size (3) is larger than the number of extents required for the largest side
    (2) therefore we need to keep our reservation.  But this isn't the case, since
    both sides require a reservation of 2 which leads to 4 for the whole range
    currently reserved, but we only need 3, so we need to drop one of the
    reservations.  The same problem existed for splits, we'd think we only need 3
    extents when creating the hole but in reality we need 4.  Thanks,
    Signed-off-by: NJosef Bacik <jbacik@fb.com>
    ba117213
inode.c 254.7 KB