• Christoph Hellwig's avatar
    xfs: merge fsync and O_SYNC handling · 13e6d5cd
    Christoph Hellwig authored
    The guarantees for O_SYNC are exactly the same as the ones we need to
    make for an fsync call (and given that Linux O_SYNC is O_DSYNC the
    equivalent is fdadatasync, but we treat both the same in XFS), except
    with a range data writeout.  Jan Kara has started unifying these two
    path for filesystems using the generic helpers, and I've started to
    look at XFS.
    
    The actual transaction commited by xfs_fsync and xfs_write_sync_logforce
    has a different transaction number, but actually is exactly the same.
    We'll only use the fsync transaction going forward.  One major difference
    is that xfs_write_sync_logforce never issues a cache flush unless we
    commit a transaction causing that as a side-effect, which is an obvious
    bug in the O_SYNC handling.  Second all the locking and i_update_size
    vs i_update_core changes from 978b7237
    never made it to xfs_write_sync_logforce, so we add them back.
    
    To make xfs_fsync easily usable from the O_SYNC path, the filemap_fdatawait
    call is moved up to xfs_file_fsync, so that we don't wait on the whole
    file after we already waited for our portion in xfs_write.
    
    We'll also use a plain call to filemap_write_and_wait_range instead
    of the previous sync_page_rang which did it in two steps including
    an half-hearted inode write out that doesn't help us.
    
    Once we're done with this also remove the now useless i_update_size
    tracking.
    Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    Reviewed-by: default avatarFelix Blyakher <felixb@sgi.com>
    Signed-off-by: default avatarFelix Blyakher <felixb@sgi.com>
    13e6d5cd
xfs_trans.h 34.9 KB