Btrfs: Add writepages support

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

3 files changed, 124 insertions, 25 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index ff8881fb56d6..b0677c84bb75 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -10,6 +10,7 @@
 #include <linux/blkdev.h>
 #include <linux/swap.h>
 #include <linux/version.h>
+#include <linux/writeback.h>
 #include "extent_map.h"
 
 /* temporary define until extent_map moves out of btrfs */
@@ -35,6 +36,12 @@ struct tree_entry {
         struct rb_node rb_node;
 };
 
+struct extent_page_data {
+        struct bio *bio;
+        struct extent_map_tree *tree;
+        get_extent_t *get_extent;
+};
+
 void __init extent_map_init(void)
 {
         extent_map_cache = btrfs_cache_create("extent_map",
@@ -1460,40 +1467,76 @@ static int end_bio_extent_preparewrite(struct bio *bio,
 #endif
 }
 
-static int submit_extent_page(int rw, struct extent_map_tree *tree,
-                              struct page *page, sector_t sector,
-                              size_t size, unsigned long offset,
-                              struct block_device *bdev,
-                              bio_end_io_t end_io_func)
+static struct bio *
+extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
+                 gfp_t gfp_flags)
 {
         struct bio *bio;
-        int ret = 0;
 
-        bio = bio_alloc(GFP_NOIO, 1);
+        bio = bio_alloc(gfp_flags, nr_vecs);
 
-        bio->bi_sector = sector;
-        bio->bi_bdev = bdev;
-        bio->bi_io_vec[0].bv_page = page;
-        bio->bi_io_vec[0].bv_len = size;
-        bio->bi_io_vec[0].bv_offset = offset;
-
-        bio->bi_vcnt = 1;
-        bio->bi_idx = 0;
-        bio->bi_size = size;
+        if (bio == NULL && (current->flags & PF_MEMALLOC)) {
+                while (!bio && (nr_vecs /= 2))
+                        bio = bio_alloc(gfp_flags, nr_vecs);
+        }
 
-        bio->bi_end_io = end_io_func;
-        bio->bi_private = tree;
+        if (bio) {
+                bio->bi_bdev = bdev;
+                bio->bi_sector = first_sector;
+        }
+        return bio;
+}
 
+static int submit_one_bio(int rw, struct bio *bio)
+{
+        int ret = 0;
         bio_get(bio);
         submit_bio(rw, bio);
-
         if (bio_flagged(bio, BIO_EOPNOTSUPP))
                 ret = -EOPNOTSUPP;
-
         bio_put(bio);
         return ret;
 }
 
+static int submit_extent_page(int rw, struct extent_map_tree *tree,
+                              struct page *page, sector_t sector,
+                              size_t size, unsigned long offset,
+                              struct block_device *bdev,
+                              struct bio **bio_ret,
+                              int max_pages,
+                              bio_end_io_t end_io_func)
+{
+        int ret = 0;
+        struct bio *bio;
+        int nr;
+
+        if (bio_ret && *bio_ret) {
+                bio = *bio_ret;
+                if (bio->bi_sector + (bio->bi_size >> 9) != sector ||
+                    bio_add_page(bio, page, size, offset) < size) {
+                        ret = submit_one_bio(rw, bio);
+                        bio = NULL;
+                } else {
+                        return 0;
+                }
+        }
+        nr = min(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);
+        }
+        bio_add_page(bio, page, size, offset);
+        bio->bi_end_io = end_io_func;
+        bio->bi_private = tree;
+        if (bio_ret) {
+                *bio_ret = bio;
+        } else {
+                ret = submit_one_bio(rw, bio);
+        }
+
+        return ret;
+}
+
 void set_page_extent_mapped(struct page *page)
 {
         if (!PagePrivate(page)) {
@@ -1590,7 +1633,8 @@ int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
                 if (!ret) {
                         ret = submit_extent_page(READ, tree, page,
                                                  sector, iosize, page_offset,
-                                                 bdev, end_bio_extent_readpage);
+                                                 bdev, NULL, 1,
+                                                 end_bio_extent_readpage);
                 }
                 if (ret)
                         SetPageError(page);
@@ -1613,11 +1657,12 @@ EXPORT_SYMBOL(extent_read_full_page);
  * are found, they are marked writeback.  Then the lock bits are removed
  * and the end_io handler clears the writeback ranges
  */
-int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
-                          get_extent_t *get_extent,
-                          struct writeback_control *wbc)
+static int __extent_writepage(struct page *page, struct writeback_control *wbc,
+                              void *data)
 {
         struct inode *inode = page->mapping->host;
+        struct extent_page_data *epd = data;
+        struct extent_map_tree *tree = epd->tree;
         u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
         u64 page_end = start + PAGE_CACHE_SIZE - 1;
         u64 end;
@@ -1691,7 +1736,7 @@ int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
                         clear_extent_dirty(tree, cur, page_end, GFP_NOFS);
                         break;
                 }
-                em = get_extent(inode, page, page_offset, cur, end, 1);
+                em = epd->get_extent(inode, page, page_offset, cur, end, 1);
                 if (IS_ERR(em) || !em) {
                         SetPageError(page);
                         break;
@@ -1734,9 +1779,12 @@ int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
                 if (ret)
                         SetPageError(page);
                 else {
+                        unsigned long nr = end_index + 1;
                         set_range_writeback(tree, cur, cur + iosize - 1);
+
                         ret = submit_extent_page(WRITE, tree, page, sector,
                                                  iosize, page_offset, bdev,
+                                                 &epd->bio, nr,
                                                  end_bio_extent_writepage);
                         if (ret)
                                 SetPageError(page);
@@ -1750,8 +1798,44 @@ done:
         unlock_page(page);
         return 0;
 }
+
+int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
+                          get_extent_t *get_extent,
+                          struct writeback_control *wbc)
+{
+        int ret;
+        struct extent_page_data epd = {
+                .bio = NULL,
+                .tree = tree,
+                .get_extent = get_extent,
+        };
+
+        ret = __extent_writepage(page, wbc, &epd);
+        if (epd.bio)
+                submit_one_bio(WRITE, epd.bio);
+        return ret;
+}
 EXPORT_SYMBOL(extent_write_full_page);
 
+int extent_writepages(struct extent_map_tree *tree,
+                      struct address_space *mapping,
+                      get_extent_t *get_extent,
+                      struct writeback_control *wbc)
+{
+        int ret;
+        struct extent_page_data epd = {
+                .bio = NULL,
+                .tree = tree,
+                .get_extent = get_extent,
+        };
+
+        ret = write_cache_pages(mapping, wbc, __extent_writepage, &epd);
+        if (epd.bio)
+                submit_one_bio(WRITE, epd.bio);
+        return ret;
+}
+EXPORT_SYMBOL(extent_writepages);
+
 /*
  * basic invalidatepage code, this waits on any locked or writeback
  * ranges corresponding to the page, and then deletes any extent state
@@ -1869,6 +1953,7 @@ int extent_prepare_write(struct extent_map_tree *tree,
                                        EXTENT_LOCKED, 0, NULL, GFP_NOFS);
                         ret = submit_extent_page(READ, tree, page,
                                          sector, iosize, page_offset, em->bdev,
+                                         NULL, 1,
                                          end_bio_extent_preparewrite);
                         iocount++;
                         block_start = block_start + iosize;
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index b6f6519f9ba3..0b0dcf19fe45 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -136,6 +136,10 @@ int extent_invalidatepage(struct extent_map_tree *tree,
 int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
                           get_extent_t *get_extent,
                           struct writeback_control *wbc);
+int extent_writepages(struct extent_map_tree *tree,
+                      struct address_space *mapping,
+                      get_extent_t *get_extent,
+                      struct writeback_control *wbc);
 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 0c65141b9993..25f32d7c7ee8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1747,6 +1747,15 @@ 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)
+{
+        struct extent_map_tree *tree;
+        tree = &BTRFS_I(mapping->host)->extent_tree;
+        return extent_writepages(tree, mapping, btrfs_get_extent, wbc);
+}
+
 static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 {
         struct extent_map_tree *tree;
@@ -2526,6 +2535,7 @@ static struct extent_map_ops btrfs_extent_map_ops = {
 static struct address_space_operations btrfs_aops = {
         .readpage       = btrfs_readpage,
         .writepage      = btrfs_writepage,
+        .writepages     = btrfs_writepages,
         .sync_page      = block_sync_page,
         .prepare_write  = btrfs_prepare_write,
         .commit_write   = btrfs_commit_write,