Btrfs: early work to file_write in big extents

[linux-2.6-block.git] / fs / btrfs / file-item.c

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index d9fd7f4d379478fc363c4b4c1a7a7d48577e8f64..93d42d650820d6bcfb805c5365db4d9b756130d8 100644 (file)
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -3,6 +3,9 @@
 #include "disk-io.h"
 #include "transaction.h"
 
+#define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
+                                sizeof(struct btrfs_item)) / \
+                               sizeof(struct btrfs_csum_item)) - 1))
 int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
                               struct btrfs_root *root,
                               u64 objectid, u64 offset,
@@ -43,6 +46,54 @@ int btrfs_alloc_file_extent(struct btrfs_trans_handle *trans,
        return 0;
 }
 
+static struct btrfs_csum_item *__lookup_csum_item(struct btrfs_root *root,
+                                                 struct btrfs_path *path,
+                                                 u64 objectid, u64 offset)
+{
+       int ret;
+       struct btrfs_key file_key;
+       struct btrfs_key found_key;
+       struct btrfs_csum_item *item;
+       struct btrfs_leaf *leaf;
+       u64 csum_offset = 0;
+
+       file_key.objectid = objectid;
+       file_key.offset = offset;
+       file_key.flags = 0;
+       btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+       ret = btrfs_search_slot(NULL, root, &file_key, path, 0, 0);
+       if (ret < 0)
+               goto fail;
+       leaf = btrfs_buffer_leaf(path->nodes[0]);
+       if (ret > 0) {
+               ret = 1;
+               if (path->slots[0] == 0)
+                       goto fail;
+               path->slots[0]--;
+               btrfs_disk_key_to_cpu(&found_key,
+                                     &leaf->items[path->slots[0]].key);
+               if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
+                   found_key.objectid != objectid) {
+                       goto fail;
+               }
+               csum_offset = (offset - found_key.offset) >>
+                               root->fs_info->sb->s_blocksize_bits;
+               if (csum_offset >=
+                   btrfs_item_size(leaf->items + path->slots[0]) /
+                   sizeof(struct btrfs_csum_item)) {
+                       goto fail;
+               }
+       }
+       item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
+       item += csum_offset;
+       return item;
+fail:
+       if (ret > 0)
+               ret = -EIO;
+       return ERR_PTR(ret);
+}
+
+
 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root,
                             struct btrfs_path *path, u64 objectid,
@@ -52,11 +103,16 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
        struct btrfs_key file_key;
        int ins_len = mod < 0 ? -1 : 0;
        int cow = mod != 0;
+       struct btrfs_csum_item *csum_item;
 
+       csum_item = __lookup_csum_item(root, path, objectid, offset);
+       if (IS_ERR(csum_item))
+               return PTR_ERR(csum_item);
        file_key.objectid = objectid;
-       file_key.offset = offset;
+       file_key.offset = btrfs_csum_extent_offset(csum_item);
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
+       btrfs_release_path(root, path);
        ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
        return ret;
 }
@@ -64,12 +120,16 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root,
                          u64 objectid, u64 offset,
+                         u64 extent_offset,
                          char *data, size_t len)
 {
        int ret;
        struct btrfs_key file_key;
+       struct btrfs_key found_key;
        struct btrfs_path *path;
        struct btrfs_csum_item *item;
+       struct btrfs_leaf *leaf;
+       u64 csum_offset;
 
        path = btrfs_alloc_path();
        BUG_ON(!path);
@@ -78,14 +138,50 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
        file_key.offset = offset;
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+       ret = btrfs_search_slot(trans, root, &file_key, path,
+                               sizeof(struct btrfs_csum_item), 1);
+       if (ret < 0)
+               goto fail;
+       if (ret == 0) {
+               csum_offset = 0;
+               goto csum;
+       }
+       if (path->slots[0] == 0) {
+               btrfs_release_path(root, path);
+               goto insert;
+       }
+       path->slots[0]--;
+       leaf = btrfs_buffer_leaf(path->nodes[0]);
+       btrfs_disk_key_to_cpu(&found_key, &leaf->items[path->slots[0]].key);
+       csum_offset = (offset - found_key.offset) >>
+                       root->fs_info->sb->s_blocksize_bits;
+       if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
+           found_key.objectid != objectid ||
+           csum_offset >= MAX_CSUM_ITEMS(root)) {
+               btrfs_release_path(root, path);
+               goto insert;
+       }
+       if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
+           sizeof(struct btrfs_csum_item)) {
+               ret = btrfs_extend_item(trans, root, path,
+                                       sizeof(struct btrfs_csum_item));
+               BUG_ON(ret);
+               goto csum;
+       }
+
+insert:
+       csum_offset = 0;
        ret = btrfs_insert_empty_item(trans, root, path, &file_key,
-                                     BTRFS_CSUM_SIZE);
+                                     sizeof(struct btrfs_csum_item));
        if (ret != 0 && ret != -EEXIST)
                goto fail;
+csum:
        item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                              struct btrfs_csum_item);
        ret = 0;
+       item += csum_offset;
        ret = btrfs_csum_data(root, data, len, item->csum);
+       btrfs_set_csum_extent_offset(item, extent_offset);
        btrfs_mark_buffer_dirty(path->nodes[0]);
 fail:
        btrfs_release_path(root, path);
@@ -111,12 +207,13 @@ int btrfs_csum_verify_file_block(struct btrfs_root *root,
        file_key.flags = 0;
        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
        mutex_lock(&root->fs_info->fs_mutex);
-       ret = btrfs_search_slot(NULL, root, &file_key, path, 0, 0);
-       if (ret)
+
+       item = __lookup_csum_item(root, path, objectid, offset);
+       if (IS_ERR(item)) {
+               ret = PTR_ERR(item);
                goto fail;
-       item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
-                             struct btrfs_csum_item);
-       ret = 0;
+       }
+
        ret = btrfs_csum_data(root, data, len, result);
        WARN_ON(ret);
        if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))