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    Subject[RFC 10/15] PM / Hibernate: user, implement user_ops reader
    Date
    Switch /dev/snapshot reader to sws_module_ops approach so that we
    can transparently rewrite the rest of the snapshot from pages pulling
    to their pushing through layers.

    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    Cc: Nigel Cunningham <ncunningham@crca.org.au>
    Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
    ---
    kernel/power/user.c | 73 +++++++++++++++++++++++++++++++++++++++++++++-----
    1 files changed, 65 insertions(+), 8 deletions(-)

    diff --git a/kernel/power/user.c b/kernel/power/user.c
    index 748567d..1b5d2e1 100644
    --- a/kernel/power/user.c
    +++ b/kernel/power/user.c
    @@ -76,6 +76,7 @@ static DECLARE_BITMAP(to_do_flags, 10);
    #define TODO_FINISH 2
    #define TODO_CLOSED 3
    #define TODO_ERROR 4
    +#define TODO_RD_RUNNING 5

    static unsigned long user_storage_available(void)
    {
    @@ -123,12 +124,41 @@ static int put_user_writer(unsigned int flags, int error)
    return error;
    }

    +static int get_user_reader(unsigned int *flags_p)
    +{
    + return 0;
    +}
    +
    +static int user_read_page(void *addr, struct bio **bio_chain)
    +{
    + int err = 0;
    +
    + to_do_buf = addr;
    + wmb();
    + set_bit(TODO_WORK, to_do_flags);
    + wake_up_interruptible(&to_do_wait);
    +
    + wait_event(to_do_done, !test_bit(TODO_WORK, to_do_flags) ||
    + (err = test_bit(TODO_CLOSED, to_do_flags)));
    +
    + return err ? -EIO : 0;
    +}
    +
    +static int put_user_reader(void)
    +{
    + return 0;
    +}
    +
    struct sws_module_ops user_ops = {
    .storage_available = user_storage_available,

    .get_writer = get_user_writer,
    .put_writer = put_user_writer,
    .write_page = user_write_page,
    +
    + .get_reader = get_user_reader,
    + .put_reader = put_user_reader,
    + .read_page = user_read_page,
    };

    static void snapshot_writer(struct work_struct *work)
    @@ -142,6 +172,22 @@ static void snapshot_writer(struct work_struct *work)

    static DECLARE_WORK(snapshot_writer_w, snapshot_writer);

    +static void snapshot_reader(struct work_struct *work)
    +{
    + int ret;
    +
    + set_bit(TODO_RD_RUNNING, to_do_flags);
    + ret = swsusp_read(NULL);
    + if (ret) {
    + printk(KERN_ERR "PM: read failed with %d\n", ret);
    + set_bit(TODO_ERROR, to_do_flags);
    + }
    + clear_bit(TODO_RD_RUNNING, to_do_flags);
    + wake_up_interruptible(&to_do_wait);
    +}
    +
    +static DECLARE_WORK(snapshot_reader_w, snapshot_reader);
    +
    static int snapshot_open(struct inode *inode, struct file *filp)
    {
    struct snapshot_data *data;
    @@ -287,19 +333,27 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,

    mutex_lock(&pm_mutex);

    + if (!test_bit(TODO_RD_RUNNING, to_do_flags))
    + queue_work(suspend_worker, &snapshot_reader_w);
    +
    data = filp->private_data;

    if (!pg_offp) {
    - res = snapshot_write_next(&data->handle);
    - if (res <= 0)
    + res = wait_event_interruptible(to_do_wait,
    + test_bit(TODO_WORK, to_do_flags));
    + if (res)
    goto unlock;
    - } else
    - res = PAGE_SIZE - pg_offp;
    + }
    + res = PAGE_SIZE - pg_offp;

    - res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
    - buf, count);
    + res = simple_write_to_buffer(to_do_buf, res, &pg_offp, buf, count);
    if (res > 0)
    *offp += res;
    +
    + if (!(pg_offp & ~PAGE_MASK)) {
    + clear_bit(TODO_WORK, to_do_flags);
    + wake_up(&to_do_done);
    + }
    unlock:
    mutex_unlock(&pm_mutex);

    @@ -384,9 +438,12 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
    break;

    case SNAPSHOT_ATOMIC_RESTORE:
    - snapshot_write_finalize(&data->handle);
    + error = wait_event_interruptible(to_do_wait,
    + !test_bit(TODO_RD_RUNNING, to_do_flags));
    + if (error)
    + break;
    if (data->mode != O_WRONLY || !data->frozen ||
    - !snapshot_image_loaded(&data->handle)) {
    + test_bit(TODO_ERROR, to_do_flags)) {
    error = -EPERM;
    break;
    }
    --
    1.7.0.2



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