mm: split swap_type_of
swap_type_of is used for two entirely different purposes:
(1) check what swap type a given device/offset corresponds to
(2) find the first available swap device that can be written to
Mixing both in a single function creates an unreadable mess. Create two
separate functions instead, and switch both to pass a dev_t instead of
a struct block_device to further simplify the code.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 7438c4a..b90f869 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1801,13 +1801,12 @@ int free_swap_and_cache(swp_entry_t entry)
*
* This is needed for the suspend to disk (aka swsusp).
*/
-int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
+int swap_type_of(dev_t device, sector_t offset)
{
- struct block_device *bdev = NULL;
int type;
- if (device)
- bdev = bdget(device);
+ if (!device)
+ return -1;
spin_lock(&swap_lock);
for (type = 0; type < nr_swapfiles; type++) {
@@ -1816,30 +1815,34 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
if (!(sis->flags & SWP_WRITEOK))
continue;
- if (!bdev) {
- if (bdev_p)
- *bdev_p = bdgrab(sis->bdev);
-
- spin_unlock(&swap_lock);
- return type;
- }
- if (bdev == sis->bdev) {
+ if (device == sis->bdev->bd_dev) {
struct swap_extent *se = first_se(sis);
if (se->start_block == offset) {
- if (bdev_p)
- *bdev_p = bdgrab(sis->bdev);
-
spin_unlock(&swap_lock);
- bdput(bdev);
return type;
}
}
}
spin_unlock(&swap_lock);
- if (bdev)
- bdput(bdev);
+ return -ENODEV;
+}
+int find_first_swap(dev_t *device)
+{
+ int type;
+
+ spin_lock(&swap_lock);
+ for (type = 0; type < nr_swapfiles; type++) {
+ struct swap_info_struct *sis = swap_info[type];
+
+ if (!(sis->flags & SWP_WRITEOK))
+ continue;
+ *device = sis->bdev->bd_dev;
+ spin_unlock(&swap_lock);
+ return type;
+ }
+ spin_unlock(&swap_lock);
return -ENODEV;
}
