Btrfs: Add readpages support

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 754bc42..0077c6c 100644 (file)
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -11,6 +11,7 @@
 #include <linux/swap.h>
 #include <linux/version.h>
 #include <linux/writeback.h>
+#include <linux/pagevec.h>
 #include "extent_map.h"
 
 /* temporary define until extent_map moves out of btrfs */
@@ -1503,7 +1504,7 @@ static int submit_extent_page(int rw, struct extent_map_tree *tree,
                              size_t size, unsigned long offset,
                              struct block_device *bdev,
                              struct bio **bio_ret,
-                             int max_pages,
+                             unsigned long max_pages,
                              bio_end_io_t end_io_func)
 {
        int ret = 0;
@@ -1520,7 +1521,7 @@ static int submit_extent_page(int rw, struct extent_map_tree *tree,
                        return 0;
                }
        }
-       nr = min(max_pages, bio_get_nr_vecs(bdev));
+       nr = min_t(int, max_pages, bio_get_nr_vecs(bdev));
        bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
        if (!bio) {
                printk("failed to allocate bio nr %d\n", nr);
@@ -1552,8 +1553,10 @@ void set_page_extent_mapped(struct page *page)
  * into the tree that are removed when the IO is done (by the end_io
  * handlers)
  */
-int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
-                         get_extent_t *get_extent)
+static int __extent_read_full_page(struct extent_map_tree *tree,
+                                  struct page *page,
+                                  get_extent_t *get_extent,
+                                  struct bio **bio)
 {
        struct inode *inode = page->mapping->host;
        u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
@@ -1631,10 +1634,12 @@ int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
                                                          cur + iosize - 1);
                }
                if (!ret) {
+                       unsigned long nr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
+                       nr -= page->index;
                        ret = submit_extent_page(READ, tree, page,
-                                                sector, iosize, page_offset,
-                                                bdev, NULL, 1,
-                                                end_bio_extent_readpage);
+                                        sector, iosize, page_offset,
+                                        bdev, bio, nr,
+                                        end_bio_extent_readpage);
                }
                if (ret)
                        SetPageError(page);
@@ -1649,6 +1654,18 @@ int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
        }
        return 0;
 }
+
+int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
+                           get_extent_t *get_extent)
+{
+       struct bio *bio = NULL;
+       int ret;
+
+       ret = __extent_read_full_page(tree, page, get_extent, &bio);
+       if (bio)
+               submit_one_bio(READ, bio);
+       return ret;
+}
 EXPORT_SYMBOL(extent_read_full_page);
 
 /*
@@ -1836,6 +1853,45 @@ int extent_writepages(struct extent_map_tree *tree,
 }
 EXPORT_SYMBOL(extent_writepages);
 
+int extent_readpages(struct extent_map_tree *tree,
+                    struct address_space *mapping,
+                    struct list_head *pages, unsigned nr_pages,
+                    get_extent_t get_extent)
+{
+       struct bio *bio = NULL;
+       unsigned page_idx;
+       struct pagevec pvec;
+
+       pagevec_init(&pvec, 0);
+       for (page_idx = 0; page_idx < nr_pages; page_idx++) {
+               struct page *page = list_entry(pages->prev, struct page, lru);
+
+               prefetchw(&page->flags);
+               list_del(&page->lru);
+               /*
+                * what we want to do here is call add_to_page_cache_lru,
+                * but that isn't exported, so we reproduce it here
+                */
+               if (!add_to_page_cache(page, mapping,
+                                       page->index, GFP_KERNEL)) {
+
+                       /* open coding of lru_cache_add, also not exported */
+                       page_cache_get(page);
+                       if (!pagevec_add(&pvec, page))
+                               __pagevec_lru_add(&pvec);
+                       __extent_read_full_page(tree, page, get_extent, &bio);
+               }
+               page_cache_release(page);
+       }
+       if (pagevec_count(&pvec))
+               __pagevec_lru_add(&pvec);
+       BUG_ON(!list_empty(pages));
+       if (bio)
+               submit_one_bio(READ, bio);
+       return 0;
+}
+EXPORT_SYMBOL(extent_readpages);
+
 /*
  * basic invalidatepage code, this waits on any locked or writeback
  * ranges corresponding to the page, and then deletes any extent state

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 0b0dcf1..fbd23a7 100644 (file)
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -140,6 +140,10 @@ int extent_writepages(struct extent_map_tree *tree,
                      struct address_space *mapping,
                      get_extent_t *get_extent,
                      struct writeback_control *wbc);
+int extent_readpages(struct extent_map_tree *tree,
+                    struct address_space *mapping,
+                    struct list_head *pages, unsigned nr_pages,
+                    get_extent_t get_extent);
 int extent_prepare_write(struct extent_map_tree *tree,
                         struct inode *inode, struct page *page,
                         unsigned from, unsigned to, get_extent_t *get_extent);

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 90cb71d..d6d3246 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1748,7 +1748,6 @@ static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
        return extent_write_full_page(tree, page, btrfs_get_extent, wbc);
 }
 
-
 static int btrfs_writepages(struct address_space *mapping,
                            struct writeback_control *wbc)
 {
@@ -1757,6 +1756,16 @@ static int btrfs_writepages(struct address_space *mapping,
        return extent_writepages(tree, mapping, btrfs_get_extent, wbc);
 }
 
+static int
+btrfs_readpages(struct file *file, struct address_space *mapping,
+               struct list_head *pages, unsigned nr_pages)
+{
+       struct extent_map_tree *tree;
+       tree = &BTRFS_I(mapping->host)->extent_tree;
+       return extent_readpages(tree, mapping, pages, nr_pages,
+                               btrfs_get_extent);
+}
+
 static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 {
        struct extent_map_tree *tree;
@@ -2537,6 +2546,7 @@ static struct address_space_operations btrfs_aops = {
        .readpage       = btrfs_readpage,
        .writepage      = btrfs_writepage,
        .writepages     = btrfs_writepages,
+       .readpages      = btrfs_readpages,
        .sync_page      = block_sync_page,
        .prepare_write  = btrfs_prepare_write,
        .commit_write   = btrfs_commit_write,