Btrfs: use a btree inode instead of sb_getblk

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

1 files changed, 161 insertions, 13 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 758a62aba063..970103f2cacd 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1,14 +1,17 @@
 #include <linux/module.h>
 #include <linux/fs.h>
+#include <linux/blkdev.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
 
+
 static int check_tree_block(struct btrfs_root *root, struct buffer_head *buf)
 {
         struct btrfs_node *node = btrfs_buffer_node(buf);
-        if (buf->b_blocknr != btrfs_header_blocknr(&node->header))
+        if (buf->b_blocknr != btrfs_header_blocknr(&node->header)) {
                 BUG();
+        }
         if (root->node && btrfs_header_parentid(&node->header) !=
             btrfs_header_parentid(btrfs_buffer_header(root->node))) {
                 BUG();
@@ -16,25 +19,154 @@ static int check_tree_block(struct btrfs_root *root, struct buffer_head *buf)
         return 0;
 }
 
-struct buffer_head *alloc_tree_block(struct btrfs_root *root, u64 blocknr)
+struct buffer_head *btrfs_find_tree_block(struct btrfs_root *root, u64 blocknr)
+{
+        struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
+        int blockbits = root->fs_info->sb->s_blocksize_bits;
+        unsigned long index = blocknr >> (PAGE_CACHE_SHIFT - blockbits);
+        struct page *page;
+        struct buffer_head *bh;
+        struct buffer_head *head;
+        struct buffer_head *ret = NULL;
+
+        page = find_lock_page(mapping, index);
+        if (!page)
+                return NULL;
+
+        if (!page_has_buffers(page))
+                goto out_unlock;
+
+        head = page_buffers(page);
+        bh = head;
+        do {
+                if (buffer_mapped(bh) && bh->b_blocknr == blocknr) {
+                        ret = bh;
+                        get_bh(bh);
+                        goto out_unlock;
+                }
+                bh = bh->b_this_page;
+        } while (bh != head);
+out_unlock:
+        unlock_page(page);
+        page_cache_release(page);
+        return ret;
+}
+
+struct buffer_head *btrfs_find_create_tree_block(struct btrfs_root *root,
+                                                 u64 blocknr)
+{
+        struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
+        int blockbits = root->fs_info->sb->s_blocksize_bits;
+        unsigned long index = blocknr >> (PAGE_CACHE_SHIFT - blockbits);
+        struct page *page;
+        struct buffer_head *bh;
+        struct buffer_head *head;
+        struct buffer_head *ret = NULL;
+        u64 first_block = index << (PAGE_CACHE_SHIFT - blockbits);
+        page = grab_cache_page(mapping, index);
+        if (!page)
+                return NULL;
+
+        wait_on_page_writeback(page);
+        if (!page_has_buffers(page))
+                create_empty_buffers(page, root->fs_info->sb->s_blocksize, 0);
+        head = page_buffers(page);
+        bh = head;
+        do {
+                if (!buffer_mapped(bh)) {
+                        bh->b_bdev = root->fs_info->sb->s_bdev;
+                        bh->b_blocknr = first_block;
+                        set_buffer_mapped(bh);
+                }
+                if (bh->b_blocknr == blocknr) {
+                        ret = bh;
+                        get_bh(bh);
+                        goto out_unlock;
+                }
+                bh = bh->b_this_page;
+                first_block++;
+        } while (bh != head);
+out_unlock:
+        unlock_page(page);
+        page_cache_release(page);
+        return ret;
+}
+
+static sector_t max_block(struct block_device *bdev)
+{
+        sector_t retval = ~((sector_t)0);
+        loff_t sz = i_size_read(bdev->bd_inode);
+
+        if (sz) {
+                unsigned int size = block_size(bdev);
+                unsigned int sizebits = blksize_bits(size);
+                retval = (sz >> sizebits);
+        }
+        return retval;
+}
+
+static int btree_get_block(struct inode *inode, sector_t iblock,
+                           struct buffer_head *bh, int create)
+{
+        if (iblock >= max_block(inode->i_sb->s_bdev)) {
+                if (create)
+                        return -EIO;
+
+                /*
+                 * for reads, we're just trying to fill a partial page.
+                 * return a hole, they will have to call get_block again
+                 * before they can fill it, and they will get -EIO at that
+                 * time
+                 */
+                return 0;
+        }
+        bh->b_bdev = inode->i_sb->s_bdev;
+        bh->b_blocknr = iblock;
+        set_buffer_mapped(bh);
+        return 0;
+}
+
+static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
-        return sb_getblk(root->fs_info->sb, blocknr);
+        return block_write_full_page(page, btree_get_block, wbc);
 }
 
-struct buffer_head *find_tree_block(struct btrfs_root *root, u64 blocknr)
+static int btree_readpage(struct file * file, struct page * page)
 {
-        return sb_getblk(root->fs_info->sb, blocknr);
+        return block_read_full_page(page, btree_get_block);
 }
 
+static struct address_space_operations btree_aops = {
+        .readpage       = btree_readpage,
+        .writepage      = btree_writepage,
+        .sync_page      = block_sync_page,
+};
+
 struct buffer_head *read_tree_block(struct btrfs_root *root, u64 blocknr)
 {
-        struct buffer_head *buf = sb_bread(root->fs_info->sb, blocknr);
+        struct buffer_head *bh = NULL;
 
-        if (!buf)
-                return buf;
-        if (check_tree_block(root, buf))
+        bh = btrfs_find_create_tree_block(root, blocknr);
+        if (!bh)
+                return bh;
+        lock_buffer(bh);
+        if (!buffer_uptodate(bh)) {
+                get_bh(bh);
+                bh->b_end_io = end_buffer_read_sync;
+                submit_bh(READ, bh);
+                wait_on_buffer(bh);
+                if (!buffer_uptodate(bh))
+                        goto fail;
+        } else {
+                unlock_buffer(bh);
+        }
+        if (check_tree_block(root, bh))
                 BUG();
-        return buf;
+        return bh;
+fail:
+        brelse(bh);
+        return NULL;
+
 }
 
 int dirty_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
@@ -101,11 +233,11 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                                                 GFP_NOFS);
         int ret;
 
-        /* FIXME: don't be stupid */
         if (!btrfs_super_root(disk_super))
                 return NULL;
         init_bit_radix(&fs_info->pinned_radix);
         init_bit_radix(&fs_info->pending_del_radix);
+        sb_set_blocksize(sb, sb_buffer->b_size);
         fs_info->running_transaction = NULL;
         fs_info->fs_root = root;
         fs_info->tree_root = tree_root;
@@ -114,14 +246,30 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         fs_info->last_inode_alloc = 0;
         fs_info->last_inode_alloc_dirid = 0;
         fs_info->disk_super = disk_super;
-        fs_info->sb_buffer = sb_buffer;
         fs_info->sb = sb;
+        fs_info->btree_inode = new_inode(sb);
+        fs_info->btree_inode->i_ino = 1;
+        fs_info->btree_inode->i_size = sb->s_bdev->bd_inode->i_size;
+        fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
+        mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
+
         mutex_init(&fs_info->trans_mutex);
         mutex_init(&fs_info->fs_mutex);
         memset(&fs_info->current_insert, 0, sizeof(fs_info->current_insert));
         memset(&fs_info->last_insert, 0, sizeof(fs_info->last_insert));
 
         __setup_root(disk_super, tree_root, fs_info, BTRFS_ROOT_TREE_OBJECTID);
+
+        fs_info->sb_buffer = read_tree_block(tree_root, sb_buffer->b_blocknr);
+
+        if (!fs_info->sb_buffer)
+                return NULL;
+
+        brelse(sb_buffer);
+        sb_buffer = NULL;
+        disk_super = (struct btrfs_super_block *)fs_info->sb_buffer->b_data;
+        fs_info->disk_super = disk_super;
+
         tree_root->node = read_tree_block(tree_root,
                                           btrfs_super_root(disk_super));
         BUG_ON(!tree_root->node);
@@ -137,7 +285,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         ret = find_and_setup_root(disk_super, tree_root, fs_info,
                                   BTRFS_FS_TREE_OBJECTID, root);
         BUG_ON(ret);
-
         root->commit_root = root->node;
         get_bh(root->node);
         root->ref_cows = 1;
@@ -191,6 +338,7 @@ int close_ctree(struct btrfs_root *root)
                                     root->fs_info->tree_root->node);
         btrfs_block_release(root, root->commit_root);
         btrfs_block_release(root, root->fs_info->sb_buffer);
+        iput(root->fs_info->btree_inode);
         kfree(root->fs_info->extent_root);
         kfree(root->fs_info->inode_root);
         kfree(root->fs_info->tree_root);