From: Evan Green evgreen@chromium.org
[ Upstream commit 88a5045f176b78c33a269a30a7b146e99c550bd9 ]
snapshot_write() is inappropriately limiting the amount of data that can be written in cases where a partial page has already been written. For example, one would expect to be able to write 1 byte, then 4095 bytes to the snapshot device, and have both of those complete fully (since now we're aligned to a page again). But what ends up happening is we write 1 byte, then 4094/4095 bytes complete successfully.
The reason is that simple_write_to_buffer()'s second argument is the total size of the buffer, not the size of the buffer minus the offset. Since simple_write_to_buffer() accounts for the offset in its implementation, snapshot_write() can just pass the full page size directly down.
Signed-off-by: Evan Green evgreen@chromium.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/power/user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/power/user.c b/kernel/power/user.c index 77438954cc2b0..8f678cd567a62 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -180,7 +180,7 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf, if (res <= 0) goto unlock; } else { - res = PAGE_SIZE - pg_offp; + res = PAGE_SIZE; }
if (!data_of(data->handle)) {