ublk: fix ublk_ch_mmap() for 64K page size

In ublk_ch_mmap(), queue id is calculated in the following way:

	(vma->vm_pgoff << PAGE_SHIFT) / `max_cmd_buf_size`

'max_cmd_buf_size' is equal to

	`UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc)`

and UBLK_MAX_QUEUE_DEPTH is 4096 and part of UAPI, so 'max_cmd_buf_size'
is always page aligned in 4K page size kernel. However, it isn't true in
64K page size kernel.

Fixes the issue by always rounding up 'max_cmd_buf_size' with PAGE_SIZE.

Cc: stable@vger.kernel.org
Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241111110718.1394001-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 59951e7c25939f471a777956916fa768d8c46e18..4ae4fdb8bb7fe0dcca0cfe035d06219ca7a58c51 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -669,12 +669,21 @@ static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
        return ublk_get_queue(ub, q_id)->io_cmd_buf;
 }
 
+static inline int __ublk_queue_cmd_buf_size(int depth)
+{
+       return round_up(depth * sizeof(struct ublksrv_io_desc), PAGE_SIZE);
+}
+
 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 {
        struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 
-       return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
-                       PAGE_SIZE);
+       return __ublk_queue_cmd_buf_size(ubq->q_depth);
+}
+
+static int ublk_max_cmd_buf_size(void)
+{
+       return __ublk_queue_cmd_buf_size(UBLK_MAX_QUEUE_DEPTH);
 }
 
 /*
@@ -1358,7 +1367,7 @@ static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 {
        struct ublk_device *ub = filp->private_data;
        size_t sz = vma->vm_end - vma->vm_start;
-       unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
+       unsigned max_sz = ublk_max_cmd_buf_size();
        unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
        int q_id, ret = 0;