1 files changed, 145 insertions, 0 deletions

diff --git a/mm/page_io.c b/mm/page_io.c
index 34f02923744..78eee32ee48 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -17,6 +17,7 @@
 #include <linux/swap.h>
 #include <linux/bio.h>
 #include <linux/swapops.h>
+#include <linux/buffer_head.h>
 #include <linux/writeback.h>
 #include <linux/frontswap.h>
 #include <asm/pgtable.h>
@@ -86,6 +87,98 @@ void end_swap_bio_read(struct bio *bio, int err)
         bio_put(bio);
 }
 
+int generic_swapfile_activate(struct swap_info_struct *sis,
+                                struct file *swap_file,
+                                sector_t *span)
+{
+        struct address_space *mapping = swap_file->f_mapping;
+        struct inode *inode = mapping->host;
+        unsigned blocks_per_page;
+        unsigned long page_no;
+        unsigned blkbits;
+        sector_t probe_block;
+        sector_t last_block;
+        sector_t lowest_block = -1;
+        sector_t highest_block = 0;
+        int nr_extents = 0;
+        int ret;
+
+        blkbits = inode->i_blkbits;
+        blocks_per_page = PAGE_SIZE >> blkbits;
+
+        /*
+         * Map all the blocks into the extent list.  This code doesn't try
+         * to be very smart.
+         */
+        probe_block = 0;
+        page_no = 0;
+        last_block = i_size_read(inode) >> blkbits;
+        while ((probe_block + blocks_per_page) <= last_block &&
+                        page_no < sis->max) {
+                unsigned block_in_page;
+                sector_t first_block;
+
+                first_block = bmap(inode, probe_block);
+                if (first_block == 0)
+                        goto bad_bmap;
+
+                /*
+                 * It must be PAGE_SIZE aligned on-disk
+                 */
+                if (first_block & (blocks_per_page - 1)) {
+                        probe_block++;
+                        goto reprobe;
+                }
+
+                for (block_in_page = 1; block_in_page < blocks_per_page;
+                                        block_in_page++) {
+                        sector_t block;
+
+                        block = bmap(inode, probe_block + block_in_page);
+                        if (block == 0)
+                                goto bad_bmap;
+                        if (block != first_block + block_in_page) {
+                                /* Discontiguity */
+                                probe_block++;
+                                goto reprobe;
+                        }
+                }
+
+                first_block >>= (PAGE_SHIFT - blkbits);
+                if (page_no) {  /* exclude the header page */
+                        if (first_block < lowest_block)
+                                lowest_block = first_block;
+                        if (first_block > highest_block)
+                                highest_block = first_block;
+                }
+
+                /*
+                 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
+                 */
+                ret = add_swap_extent(sis, page_no, 1, first_block);
+                if (ret < 0)
+                        goto out;
+                nr_extents += ret;
+                page_no++;
+                probe_block += blocks_per_page;
+reprobe:
+                continue;
+        }
+        ret = nr_extents;
+        *span = 1 + highest_block - lowest_block;
+        if (page_no == 0)
+                page_no = 1;    /* force Empty message */
+        sis->max = page_no;
+        sis->pages = page_no - 1;
+        sis->highest_bit = page_no - 1;
+out:
+        return ret;
+bad_bmap:
+        printk(KERN_ERR "swapon: swapfile has holes\n");
+        ret = -EINVAL;
+        goto out;
+}
+
 /*
  * We may have stale swap cache pages in memory: notice
  * them here and get rid of the unnecessary final write.
@@ -94,6 +187,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
 {
         struct bio *bio;
         int ret = 0, rw = WRITE;
+        struct swap_info_struct *sis = page_swap_info(page);
 
         if (try_to_free_swap(page)) {
                 unlock_page(page);
@@ -105,6 +199,33 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
                 end_page_writeback(page);
                 goto out;
         }
+
+        if (sis->flags & SWP_FILE) {
+                struct kiocb kiocb;
+                struct file *swap_file = sis->swap_file;
+                struct address_space *mapping = swap_file->f_mapping;
+                struct iovec iov = {
+                        .iov_base = kmap(page),
+                        .iov_len  = PAGE_SIZE,
+                };
+
+                init_sync_kiocb(&kiocb, swap_file);
+                kiocb.ki_pos = page_file_offset(page);
+                kiocb.ki_left = PAGE_SIZE;
+                kiocb.ki_nbytes = PAGE_SIZE;
+
+                unlock_page(page);
+                ret = mapping->a_ops->direct_IO(KERNEL_WRITE,
+                                                &kiocb, &iov,
+                                                kiocb.ki_pos, 1);
+                kunmap(page);
+                if (ret == PAGE_SIZE) {
+                        count_vm_event(PSWPOUT);
+                        ret = 0;
+                }
+                return ret;
+        }
+
         bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write);
         if (bio == NULL) {
                 set_page_dirty(page);
@@ -126,6 +247,7 @@ int swap_readpage(struct page *page)
 {
         struct bio *bio;
         int ret = 0;
+        struct swap_info_struct *sis = page_swap_info(page);
 
         VM_BUG_ON(!PageLocked(page));
         VM_BUG_ON(PageUptodate(page));
@@ -134,6 +256,17 @@ int swap_readpage(struct page *page)
                 unlock_page(page);
                 goto out;
         }
+
+        if (sis->flags & SWP_FILE) {
+                struct file *swap_file = sis->swap_file;
+                struct address_space *mapping = swap_file->f_mapping;
+
+                ret = mapping->a_ops->readpage(swap_file, page);
+                if (!ret)
+                        count_vm_event(PSWPIN);
+                return ret;
+        }
+
         bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
         if (bio == NULL) {
                 unlock_page(page);
@@ -145,3 +278,15 @@ int swap_readpage(struct page *page)
 out:
         return ret;
 }
+
+int swap_set_page_dirty(struct page *page)
+{
+        struct swap_info_struct *sis = page_swap_info(page);
+
+        if (sis->flags & SWP_FILE) {
+                struct address_space *mapping = sis->swap_file->f_mapping;
+                return mapping->a_ops->set_page_dirty(page);
+        } else {
+                return __set_page_dirty_no_writeback(page);
+        }
+}