[PATCH] Swapless page migration: add R/W migration entries

[linux-2.6-block.git] / mm / swapfile.c

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 47a6812f5f8cf5dcd6e0afc1894f9911e3ecfbd7..e3b1362372c2ff8054c664113c39174687348b6a 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -395,6 +395,9 @@ void free_swap_and_cache(swp_entry_t entry)
        struct swap_info_struct * p;
        struct page *page = NULL;
 
+       if (is_migration_entry(entry))
+               return;
+
        p = swap_info_get(entry);
        if (p) {
                if (swap_entry_free(p, swp_offset(entry)) == 1) {
@@ -1400,19 +1403,7 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
                if (!(p->flags & SWP_USED))
                        break;
        error = -EPERM;
-       /*
-        * Test if adding another swap device is possible. There are
-        * two limiting factors: 1) the number of bits for the swap
-        * type swp_entry_t definition and 2) the number of bits for
-        * the swap type in the swap ptes as defined by the different
-        * architectures. To honor both limitations a swap entry
-        * with swap offset 0 and swap type ~0UL is created, encoded
-        * to a swap pte, decoded to a swp_entry_t again and finally
-        * the swap type part is extracted. This will mask all bits
-        * from the initial ~0UL that can't be encoded in either the
-        * swp_entry_t or the architecture definition of a swap pte.
-        */
-       if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
+       if (type >= MAX_SWAPFILES) {
                spin_unlock(&swap_lock);
                goto out;
        }
@@ -1702,6 +1693,9 @@ int swap_duplicate(swp_entry_t entry)
        unsigned long offset, type;
        int result = 0;
 
+       if (is_migration_entry(entry))
+               return 1;
+
        type = swp_type(entry);
        if (type >= nr_swapfiles)
                goto bad_file;