• Jan Kara's avatar
    writeback: Fix periodic writeback after fs mount · 9fa65e09
    Jan Kara authored
    commit a5faeaf9109578e65e1a32e2a3e76c8b47e7dcb6 upstream.
    
    Code in blkdev.c moves a device inode to default_backing_dev_info when
    the last reference to the device is put and moves the device inode back
    to its bdi when the first reference is acquired. This includes moving to
    wb.b_dirty list if the device inode is dirty. The code however doesn't
    setup timer to wake corresponding flusher thread and while wb.b_dirty
    list is non-empty __mark_inode_dirty() will not set it up either. Thus
    periodic writeback is effectively disabled until a sync(2) call which can
    lead to unexpected data loss in case of crash or power failure.
    
    Fix the problem by setting up a timer for periodic writeback in case we
    add the first dirty inode to wb.b_dirty list in bdev_inode_switch_bdi().
    Reported-by: 's avatarBert De Jonghe <Bert.DeJonghe@amplidata.com>
    Signed-off-by: 's avatarJan Kara <jack@suse.cz>
    Signed-off-by: 's avatarJens Axboe <axboe@kernel.dk>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    9fa65e09
block_dev.c 42.2 KB