• Jaegeuk Kim's avatar
    f2fs: support atomic writes · 88b88a66
    Jaegeuk Kim authored
    This patch introduces a very limited functionality for atomic write support.
    In order to support atomic write, this patch adds two ioctls:
     o F2FS_IOC_START_ATOMIC_WRITE
     o F2FS_IOC_COMMIT_ATOMIC_WRITE
    
    The database engine should be aware of the following sequence.
    1. open
     -> ioctl(F2FS_IOC_START_ATOMIC_WRITE);
    2. writes
      : all the written data will be treated as atomic pages.
    3. commit
     -> ioctl(F2FS_IOC_COMMIT_ATOMIC_WRITE);
      : this flushes all the data blocks to the disk, which will be shown all or
      nothing by f2fs recovery procedure.
    4. repeat to #2
    
    .
    
    The IO pattens should be:
    
      ,- START_ATOMIC_WRITE                  ,- COMMIT_ATOMIC_WRITE
     CP | D D D D D D | FSYNC | D D D D | FSYNC ...
                          `- COMMIT_ATOMIC_WRITE
    Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
    88b88a66
file.c 22.6 KB