• Josef Bacik's avatar
    Btrfs: add basic DIO read/write support · 4b46fce2
    Josef Bacik authored
    This provides basic DIO support for reading and writing.  It does not do the
    work to recover from mismatching checksums, that will come later.  A few design
    changes have been made from Jim's code (sorry Jim!)
    
    1) Use the generic direct-io code.  Jim originally re-wrote all the generic DIO
    code in order to account for all of BTRFS's oddities, but thanks to that work it
    seems like the best bet is to just ignore compression and such and just opt to
    fallback on buffered IO.
    
    2) Fallback on buffered IO for compressed or inline extents.  Jim's code did
    it's own buffering to make dio with compressed extents work.  Now we just
    fallback onto normal buffered IO.
    
    3) Use ordered extents for the writes so that all of the
    
    lock_extent()
    lookup_ordered()
    
    type checks continue to work.
    
    4) Do the lock_extent() lookup_ordered() loop in readpage so we don't race with
    DIO writes.
    
    I've tested this with fsx and everything works great.  This patch depends on my
    dio and filemap.c patches to work.  Thanks,
    Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
    Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
    4b46fce2
ordered-data.h 5.22 KB