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    block: allow migration to work with image files (v3) · 0f15423c
    Anthony Liguori 提交于
    Image files have two types of data: immutable data that describes things like
    image size, backing files, etc. and mutable data that includes offset and
    reference count tables.
    
    Today, image formats aggressively cache mutable data to improve performance.  In
    some cases, this happens before a guest even starts.  When dealing with live
    migration, since a file is open on two machines, the caching of meta data can
    lead to data corruption.
    
    This patch addresses this by introducing a mechanism to invalidate any cached
    mutable data a block driver may have which is then used by the live migration
    code.
    
    NB, this still requires coherent shared storage.  Addressing migration without
    coherent shared storage (i.e. NFS) requires additional work.
    Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
    0f15423c
migration.c 12.1 KB