mm, swap: don't use VMA based swap readahead if HDD is used as swap

[sfrench/cifs-2.6.git] / include / linux / swap.h

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 76f1632eea5a43ace67d77fc7cb15f4b676942e4..9c4ae6f14eeaee14eac1951f772414a6696bba0d 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -251,6 +251,25 @@ struct swap_info_struct {
        struct swap_cluster_list discard_clusters; /* discard clusters list */
 };
 
+#ifdef CONFIG_64BIT
+#define SWAP_RA_ORDER_CEILING  5
+#else
+/* Avoid stack overflow, because we need to save part of page table */
+#define SWAP_RA_ORDER_CEILING  3
+#define SWAP_RA_PTE_CACHE_SIZE (1 << SWAP_RA_ORDER_CEILING)
+#endif
+
+struct vma_swap_readahead {
+       unsigned short win;
+       unsigned short offset;
+       unsigned short nr_pte;
+#ifdef CONFIG_64BIT
+       pte_t *ptes;
+#else
+       pte_t ptes[SWAP_RA_PTE_CACHE_SIZE];
+#endif
+};
+
 /* linux/mm/workingset.c */
 void *workingset_eviction(struct address_space *mapping, struct page *page);
 bool workingset_refault(void *shadow);
@@ -350,6 +369,7 @@ int generic_swapfile_activate(struct swap_info_struct *, struct file *,
 #define SWAP_ADDRESS_SPACE_SHIFT       14
 #define SWAP_ADDRESS_SPACE_PAGES       (1 << SWAP_ADDRESS_SPACE_SHIFT)
 extern struct address_space *swapper_spaces[];
+extern bool swap_vma_readahead;
 #define swap_address_space(entry)                          \
        (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
                >> SWAP_ADDRESS_SPACE_SHIFT])
@@ -362,7 +382,9 @@ extern void __delete_from_swap_cache(struct page *);
 extern void delete_from_swap_cache(struct page *);
 extern void free_page_and_swap_cache(struct page *);
 extern void free_pages_and_swap_cache(struct page **, int);
-extern struct page *lookup_swap_cache(swp_entry_t);
+extern struct page *lookup_swap_cache(swp_entry_t entry,
+                                     struct vm_area_struct *vma,
+                                     unsigned long addr);
 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
                        struct vm_area_struct *vma, unsigned long addr,
                        bool do_poll);
@@ -372,11 +394,23 @@ extern struct page *__read_swap_cache_async(swp_entry_t, gfp_t,
 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
                        struct vm_area_struct *vma, unsigned long addr);
 
+extern struct page *swap_readahead_detect(struct vm_fault *vmf,
+                                         struct vma_swap_readahead *swap_ra);
+extern struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
+                                          struct vm_fault *vmf,
+                                          struct vma_swap_readahead *swap_ra);
+
 /* linux/mm/swapfile.c */
 extern atomic_long_t nr_swap_pages;
 extern long total_swap_pages;
+extern atomic_t nr_rotate_swap;
 extern bool has_usable_swap(void);
 
+static inline bool swap_use_vma_readahead(void)
+{
+       return READ_ONCE(swap_vma_readahead) && !atomic_read(&nr_rotate_swap);
+}
+
 /* Swap 50% full? Release swapcache more aggressively.. */
 static inline bool vm_swap_full(void)
 {
@@ -466,12 +500,32 @@ static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
        return NULL;
 }
 
+static inline bool swap_use_vma_readahead(void)
+{
+       return false;
+}
+
+static inline struct page *swap_readahead_detect(
+       struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
+{
+       return NULL;
+}
+
+static inline struct page *do_swap_page_readahead(
+       swp_entry_t fentry, gfp_t gfp_mask,
+       struct vm_fault *vmf, struct vma_swap_readahead *swap_ra)
+{
+       return NULL;
+}
+
 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 {
        return 0;
 }
 
-static inline struct page *lookup_swap_cache(swp_entry_t swp)
+static inline struct page *lookup_swap_cache(swp_entry_t swp,
+                                            struct vm_area_struct *vma,
+                                            unsigned long addr)
 {
        return NULL;
 }