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Subject[PATCH 4/9] PM / Hibernate: user, implement user_ops reader
Date
Switch /dev/snapshot writer to hibernate_io_ops approach so that we
can do whatever we want with snapshot processing code. All the later
code changes will be transparent and needn't care about different
readers/writers.

In this patch only reader is implemented, writer was done previously.

It works similarly to writer, CONSUMER here is snapshot layer,
PRODUCER is fops->write.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
---
kernel/power/user.c | 76 +++++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 68 insertions(+), 8 deletions(-)
diff --git a/kernel/power/user.c b/kernel/power/user.c
index b4610c3..fb9e5c8 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -79,6 +79,7 @@ static struct {
#define TODO_FINISH 2
#define TODO_CLOSED 3
#define TODO_ERROR 4
+#define TODO_RD_RUNNING 5
DECLARE_BITMAP(flags, 10); /* TODO_* flags defined above */
} to_do;

@@ -131,12 +132,43 @@ static int user_writer_finish(struct hibernate_io_handle *io_handle,
return error;
}

+static struct hibernate_io_handle *user_reader_start(unsigned int *flags_p)
+{
+ return hib_io_handle_alloc(0) ? : ERR_PTR(-ENOMEM);
+}
+
+static int user_read_page(struct hibernate_io_handle *io_handle, void *addr,
+ struct bio **bio_chain)
+{
+ int err = 0;
+
+ mutex_lock(&to_do.lock);
+ to_do.buffer = addr;
+ mutex_unlock(&to_do.lock);
+ 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 user_reader_finish(struct hibernate_io_handle *io_handle)
+{
+ return 0;
+}
+
struct hibernate_io_ops user_ops = {
.free_space = user_free_space,

.writer_start = user_writer_start,
.writer_finish = user_writer_finish,
.write_page = user_write_page,
+
+ .reader_start = user_reader_start,
+ .reader_finish = user_reader_finish,
+ .read_page = user_read_page,
};

static void snapshot_writer(struct work_struct *work)
@@ -150,6 +182,22 @@ 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;
@@ -300,20 +348,29 @@ 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(to_do.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);
+ mutex_lock(&to_do.lock);
+ res = simple_write_to_buffer(to_do.buffer, res, &pg_offp, buf, count);
+ mutex_unlock(&to_do.lock);
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);

@@ -398,9 +455,12 @@ 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;
}
--
1.7.1



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