• Chris Mason's avatar
    btrfs: disable strict file flushes for renames and truncates · 8d875f95
    Chris Mason authored
    Truncates and renames are often used to replace old versions of a file
    with new versions.  Applications often expect this to be an atomic
    replacement, even if they haven't done anything to make sure the new
    version is fully on disk.
    
    Btrfs has strict flushing in place to make sure that renaming over an
    old file with a new file will fully flush out the new file before
    allowing the transaction commit with the rename to complete.
    
    This ordering means the commit code needs to be able to lock file pages,
    and there are a few paths in the filesystem where we will try to end a
    transaction with the page lock held.  It's rare, but these things can
    deadlock.
    
    This patch removes the ordered flushes and switches to a best effort
    filemap_flush like ext4 uses. It's not perfect, but it should fix the
    deadlocks.
    Signed-off-by: default avatarChris Mason <clm@fb.com>
    8d875f95
ordered-data.h 6.52 KB