shmem: eliminate struct page from shmem_swapin_folio()

Convert shmem_swapin() to return a folio and use swap_cache_get_folio(),
removing all uses of struct page in this function.

Link: https://lkml.kernel.org/r/20220902194653.1739778-21-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 2bb6f5cfdc111e57b84539c4fb7bd3168d7a5786..b685acd9f1495d1db07d1bb2bf67e609df65e904 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1486,7 +1486,7 @@ static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
        mpol_cond_put(vma->vm_policy);
 }
 
-static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
+static struct folio *shmem_swapin(swp_entry_t swap, gfp_t gfp,
                        struct shmem_inode_info *info, pgoff_t index)
 {
        struct vm_area_struct pvma;
@@ -1499,7 +1499,9 @@ static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
        page = swap_cluster_readahead(swap, gfp, &vmf);
        shmem_pseudo_vma_destroy(&pvma);
 
-       return page;
+       if (!page)
+               return NULL;
+       return page_folio(page);
 }
 
 /*
@@ -1721,7 +1723,6 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
        struct address_space *mapping = inode->i_mapping;
        struct shmem_inode_info *info = SHMEM_I(inode);
        struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
-       struct page *page;
        struct folio *folio = NULL;
        swp_entry_t swap;
        int error;
@@ -1734,8 +1735,8 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
                return -EIO;
 
        /* Look it up and read it in.. */
-       page = lookup_swap_cache(swap, NULL, 0);
-       if (!page) {
+       folio = swap_cache_get_folio(swap, NULL, 0);
+       if (!folio) {
                /* Or update major stats only when swapin succeeds?? */
                if (fault_type) {
                        *fault_type |= VM_FAULT_MAJOR;
@@ -1743,13 +1744,12 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
                        count_memcg_event_mm(charge_mm, PGMAJFAULT);
                }
                /* Here we actually start the io */
-               page = shmem_swapin(swap, gfp, info, index);
-               if (!page) {
+               folio = shmem_swapin(swap, gfp, info, index);
+               if (!folio) {
                        error = -ENOMEM;
                        goto failed;
                }
        }
-       folio = page_folio(page);
 
        /* We have to do this with folio locked to prevent races */
        folio_lock(folio);