lkml.org 
[lkml]   [2006]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH 03/20] mm: add support for non block device backed swap files
    Date
    From
    A new addres_space_operations method is added:
    int swapfile(struct address_space *, int)

    When during sys_swapon() this method is found and returns no error the
    swapper_space.a_ops will proxy to sis->swap_file->f_mapping->a_ops.

    The swapfile method will be used to communicate to the address_space that the
    VM relies on it, and the address_space should take adequate measures (like
    reserving memory for mempools or the like).

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    CC: Trond Myklebust <trond.myklebust@fys.uio.no>
    ---
    fs/buffer.c | 2 -
    include/linux/fs.h | 1
    include/linux/swap.h | 4 +++
    init/Kconfig | 5 ++++
    mm/page_io.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++
    mm/swap_state.c | 6 +++++
    mm/swapfile.c | 27 ++++++++++++++++++++++
    7 files changed, 103 insertions(+), 2 deletions(-)

    Index: linux-2.6/include/linux/swap.h
    ===================================================================
    --- linux-2.6.orig/include/linux/swap.h
    +++ linux-2.6/include/linux/swap.h
    @@ -115,6 +115,7 @@ enum {
    SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
    SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
    SWP_ACTIVE = (SWP_USED | SWP_WRITEOK),
    + SWP_FILE = (1 << 2), /* file swap area */
    /* add others here before... */
    SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */
    };
    @@ -212,6 +213,9 @@ extern void swap_unplug_io_fn(struct bac
    /* linux/mm/page_io.c */
    extern int swap_readpage(struct file *, struct page *);
    extern int swap_writepage(struct page *page, struct writeback_control *wbc);
    +extern void swap_sync_page(struct page *page);
    +extern int swap_set_page_dirty(struct page *page);
    +extern int swap_releasepage(struct page *page, gfp_t gfp_mask);
    extern int rw_swap_page_sync(int, swp_entry_t, struct page *);

    /* linux/mm/swap_state.c */
    Index: linux-2.6/init/Kconfig
    ===================================================================
    --- linux-2.6.orig/init/Kconfig
    +++ linux-2.6/init/Kconfig
    @@ -100,6 +100,11 @@ config SWAP
    used to provide more virtual memory than the actual RAM present
    in your computer. If unsure say Y.

    +config SWAP_FILE
    + bool "Support for paging to/from non block device files"
    + depends on SWAP
    + default n
    +
    config SYSVIPC
    bool "System V IPC"
    ---help---
    Index: linux-2.6/mm/page_io.c
    ===================================================================
    --- linux-2.6.orig/mm/page_io.c
    +++ linux-2.6/mm/page_io.c
    @@ -17,6 +17,7 @@
    #include <linux/bio.h>
    #include <linux/swapops.h>
    #include <linux/writeback.h>
    +#include <linux/buffer_head.h>
    #include <asm/pgtable.h>

    static struct bio *get_swap_bio(gfp_t gfp_flags, pgoff_t index,
    @@ -91,6 +92,14 @@ int swap_writepage(struct page *page, st
    unlock_page(page);
    goto out;
    }
    +#ifdef CONFIG_SWAP_FILE
    + {
    + struct swap_info_struct *sis = page_swap_info(page);
    + if (sis->flags & SWP_FILE)
    + return sis->swap_file->f_mapping->
    + a_ops->writepage(page, wbc);
    + }
    +#endif
    bio = get_swap_bio(GFP_NOIO, page_private(page), page,
    end_swap_bio_write);
    if (bio == NULL) {
    @@ -116,6 +125,14 @@ int swap_readpage(struct file *file, str

    BUG_ON(!PageLocked(page));
    ClearPageUptodate(page);
    +#ifdef CONFIG_SWAP_FILE
    + {
    + struct swap_info_struct *sis = page_swap_info(page);
    + if (sis->flags & SWP_FILE)
    + return sis->swap_file->f_mapping->
    + a_ops->readpage(sis->swap_file, page);
    + }
    +#endif
    bio = get_swap_bio(GFP_KERNEL, page_private(page), page,
    end_swap_bio_read);
    if (bio == NULL) {
    @@ -129,6 +146,49 @@ out:
    return ret;
    }

    +#ifdef CONFIG_SWAP_FILE
    +void swap_sync_page(struct page *page)
    +{
    + struct swap_info_struct *sis = page_swap_info(page);
    +
    + if (sis->flags & SWP_FILE) {
    + const struct address_space_operations * a_ops =
    + sis->swap_file->f_mapping->a_ops;
    + if (a_ops->sync_page)
    + a_ops->sync_page(page);
    + } else
    + block_sync_page(page);
    +}
    +
    +int swap_set_page_dirty(struct page *page)
    +{
    + struct swap_info_struct *sis = page_swap_info(page);
    +
    + if (sis->flags & SWP_FILE) {
    + const struct address_space_operations * a_ops =
    + sis->swap_file->f_mapping->a_ops;
    + if (a_ops->set_page_dirty)
    + return a_ops->set_page_dirty(page);
    + return __set_page_dirty_buffers(page);
    + }
    +
    + return __set_page_dirty_nobuffers(page);
    +}
    +
    +int swap_releasepage(struct page *page, gfp_t gfp_mask)
    +{
    + struct swap_info_struct *sis = page_swap_info(page);
    + const struct address_space_operations * a_ops =
    + sis->swap_file->f_mapping->a_ops;
    +
    + if ((sis->flags & SWP_FILE) && a_ops->releasepage)
    + return a_ops->releasepage(page, gfp_mask);
    +
    + BUG();
    + return 0;
    +}
    +#endif
    +
    #ifdef CONFIG_SOFTWARE_SUSPEND
    /*
    * A scruffy utility function to read or write an arbitrary swap page
    Index: linux-2.6/mm/swap_state.c
    ===================================================================
    --- linux-2.6.orig/mm/swap_state.c
    +++ linux-2.6/mm/swap_state.c
    @@ -26,8 +26,14 @@
    */
    static const struct address_space_operations swap_aops = {
    .writepage = swap_writepage,
    +#ifdef CONFIG_SWAP_FILE
    + .sync_page = swap_sync_page,
    + .set_page_dirty = swap_set_page_dirty,
    + .releasepage = swap_releasepage,
    +#else
    .sync_page = block_sync_page,
    .set_page_dirty = __set_page_dirty_nobuffers,
    +#endif
    .migratepage = migrate_page,
    };

    Index: linux-2.6/mm/swapfile.c
    ===================================================================
    --- linux-2.6.orig/mm/swapfile.c
    +++ linux-2.6/mm/swapfile.c
    @@ -411,7 +411,12 @@ void free_swap_and_cache(swp_entry_t ent
    if (page) {
    int one_user;

    +#ifdef CONFIG_SWAP_FILE
    + if (PagePrivate(page))
    + page_mapping(page)->a_ops->releasepage(page, 0);
    +#else
    BUG_ON(PagePrivate(page));
    +#endif
    one_user = (page_count(page) == 2);
    /* Only cache user (+us), or swap space full? Free it! */
    /* Also recheck PageSwapCache after page is locked (above) */
    @@ -944,6 +949,13 @@ static void destroy_swap_extents(struct
    list_del(&se->list);
    kfree(se);
    }
    +#ifdef CONFIG_SWAP_FILE
    + if (sis->flags & SWP_FILE) {
    + sis->flags &= ~SWP_FILE;
    + sis->swap_file->f_mapping->a_ops->
    + swapfile(sis->swap_file->f_mapping, 0);
    + }
    +#endif
    }

    /*
    @@ -1036,6 +1048,19 @@ static int setup_swap_extents(struct swa
    goto done;
    }

    +#ifdef CONFIG_SWAP_FILE
    + if (sis->swap_file->f_mapping->a_ops->swapfile) {
    + ret = sis->swap_file->f_mapping->a_ops->
    + swapfile(sis->swap_file->f_mapping, 1);
    + if (!ret) {
    + sis->flags |= SWP_FILE;
    + ret = add_swap_extent(sis, 0, sis->max, 0);
    + *span = sis->pages;
    + }
    + goto done;
    + }
    +#endif
    +
    blkbits = inode->i_blkbits;
    blocks_per_page = PAGE_SIZE >> blkbits;

    @@ -1592,7 +1617,7 @@ asmlinkage long sys_swapon(const char __

    mutex_lock(&swapon_mutex);
    spin_lock(&swap_lock);
    - p->flags = SWP_ACTIVE;
    + p->flags |= SWP_WRITEOK;
    nr_swap_pages += nr_good_pages;
    total_swap_pages += nr_good_pages;

    Index: linux-2.6/include/linux/fs.h
    ===================================================================
    --- linux-2.6.orig/include/linux/fs.h
    +++ linux-2.6/include/linux/fs.h
    @@ -382,6 +382,7 @@ struct address_space_operations {
    /* migrate the contents of a page to the specified target */
    int (*migratepage) (struct address_space *,
    struct page *, struct page *);
    + int (*swapfile)(struct address_space *, int);
    };

    struct backing_dev_info;
    Index: linux-2.6/fs/buffer.c
    ===================================================================
    --- linux-2.6.orig/fs/buffer.c
    +++ linux-2.6/fs/buffer.c
    @@ -1567,7 +1567,7 @@ static void discard_buffer(struct buffer
    */
    int try_to_release_page(struct page *page, gfp_t gfp_mask)
    {
    - struct address_space * const mapping = page->mapping;
    + struct address_space * const mapping = page_mapping(page);

    BUG_ON(!PageLocked(page));
    if (PageWriteback(page))
    --

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-09-12 19:17    [W:0.060 / U:30.296 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site