1 files changed, 296 insertions, 0 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 7f972e59cc04..baa193423fb8 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -187,6 +187,302 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
         return btrfs_update_inode(trans, root, inode);
 }
 
+static int readahead_cache(struct inode *inode)
+{
+        struct file_ra_state *ra;
+        unsigned long last_index;
+
+        ra = kzalloc(sizeof(*ra), GFP_NOFS);
+        if (!ra)
+                return -ENOMEM;
+
+        file_ra_state_init(ra, inode->i_mapping);
+        last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
+
+        page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
+
+        kfree(ra);
+
+        return 0;
+}
+
+int load_free_space_cache(struct btrfs_fs_info *fs_info,
+                          struct btrfs_block_group_cache *block_group)
+{
+        struct btrfs_root *root = fs_info->tree_root;
+        struct inode *inode;
+        struct btrfs_free_space_header *header;
+        struct extent_buffer *leaf;
+        struct page *page;
+        struct btrfs_path *path;
+        u32 *checksums = NULL, *crc;
+        char *disk_crcs = NULL;
+        struct btrfs_key key;
+        struct list_head bitmaps;
+        u64 num_entries;
+        u64 num_bitmaps;
+        u64 generation;
+        u32 cur_crc = ~(u32)0;
+        pgoff_t index = 0;
+        unsigned long first_page_offset;
+        int num_checksums;
+        int ret = 0;
+
+        /*
+         * If we're unmounting then just return, since this does a search on the
+         * normal root and not the commit root and we could deadlock.
+         */
+        smp_mb();
+        if (fs_info->closing)
+                return 0;
+
+        /*
+         * If this block group has been marked to be cleared for one reason or
+         * another then we can't trust the on disk cache, so just return.
+         */
+        spin_lock(&block_group->lock);
+        if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
+                printk(KERN_ERR "not reading block group %llu, dcs is %d\n", block_group->key.objectid,
+                       block_group->disk_cache_state);
+                spin_unlock(&block_group->lock);
+                return 0;
+        }
+        spin_unlock(&block_group->lock);
+
+        INIT_LIST_HEAD(&bitmaps);
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return 0;
+
+        inode = lookup_free_space_inode(root, block_group, path);
+        if (IS_ERR(inode)) {
+                btrfs_free_path(path);
+                return 0;
+        }
+
+        /* Nothing in the space cache, goodbye */
+        if (!i_size_read(inode)) {
+                btrfs_free_path(path);
+                goto out;
+        }
+
+        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+        key.offset = block_group->key.objectid;
+        key.type = 0;
+
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        if (ret) {
+                btrfs_free_path(path);
+                goto out;
+        }
+
+        leaf = path->nodes[0];
+        header = btrfs_item_ptr(leaf, path->slots[0],
+                                struct btrfs_free_space_header);
+        num_entries = btrfs_free_space_entries(leaf, header);
+        num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
+        generation = btrfs_free_space_generation(leaf, header);
+        btrfs_free_path(path);
+
+        if (BTRFS_I(inode)->generation != generation) {
+                printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
+                       " not match free space cache generation (%llu) for "
+                       "block group %llu\n",
+                       (unsigned long long)BTRFS_I(inode)->generation,
+                       (unsigned long long)generation,
+                       (unsigned long long)block_group->key.objectid);
+                goto out;
+        }
+
+        if (!num_entries)
+                goto out;
+
+        /* Setup everything for doing checksumming */
+        num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
+        checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
+        if (!checksums)
+                goto out;
+        first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
+        disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
+        if (!disk_crcs)
+                goto out;
+
+        ret = readahead_cache(inode);
+        if (ret) {
+                ret = 0;
+                goto out;
+        }
+
+        while (1) {
+                struct btrfs_free_space_entry *entry;
+                struct btrfs_free_space *e;
+                void *addr;
+                unsigned long offset = 0;
+                unsigned long start_offset = 0;
+                int need_loop = 0;
+
+                if (!num_entries && !num_bitmaps)
+                        break;
+
+                if (index == 0) {
+                        start_offset = first_page_offset;
+                        offset = start_offset;
+                }
+
+                page = grab_cache_page(inode->i_mapping, index);
+                if (!page) {
+                        ret = 0;
+                        goto free_cache;
+                }
+
+                if (!PageUptodate(page)) {
+                        btrfs_readpage(NULL, page);
+                        lock_page(page);
+                        if (!PageUptodate(page)) {
+                                unlock_page(page);
+                                page_cache_release(page);
+                                printk(KERN_ERR "btrfs: error reading free "
+                                       "space cache: %llu\n",
+                                       (unsigned long long)
+                                       block_group->key.objectid);
+                                goto free_cache;
+                        }
+                }
+                addr = kmap(page);
+
+                if (index == 0) {
+                        u64 *gen;
+
+                        memcpy(disk_crcs, addr, first_page_offset);
+                        gen = addr + (sizeof(u32) * num_checksums);
+                        if (*gen != BTRFS_I(inode)->generation) {
+                                printk(KERN_ERR "btrfs: space cache generation"
+                                       " (%llu) does not match inode (%llu) "
+                                       "for block group %llu\n",
+                                       (unsigned long long)*gen,
+                                       (unsigned long long)
+                                       BTRFS_I(inode)->generation,
+                                       (unsigned long long)
+                                       block_group->key.objectid);
+                                kunmap(page);
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto free_cache;
+                        }
+                        crc = (u32 *)disk_crcs;
+                }
+                entry = addr + start_offset;
+
+                /* First lets check our crc before we do anything fun */
+                cur_crc = ~(u32)0;
+                cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
+                                          PAGE_CACHE_SIZE - start_offset);
+                btrfs_csum_final(cur_crc, (char *)&cur_crc);
+                if (cur_crc != *crc) {
+                        printk(KERN_ERR "btrfs: crc mismatch for page %lu in "
+                               "block group %llu\n", index,
+                               (unsigned long long)block_group->key.objectid);
+                        kunmap(page);
+                        unlock_page(page);
+                        page_cache_release(page);
+                        goto free_cache;
+                }
+                crc++;
+
+                while (1) {
+                        if (!num_entries)
+                                break;
+
+                        need_loop = 1;
+                        e = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
+                        if (!e) {
+                                kunmap(page);
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto free_cache;
+                        }
+
+                        e->offset = le64_to_cpu(entry->offset);
+                        e->bytes = le64_to_cpu(entry->bytes);
+                        if (!e->bytes) {
+                                kunmap(page);
+                                kfree(e);
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto free_cache;
+                        }
+
+                        if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
+                                spin_lock(&block_group->tree_lock);
+                                ret = link_free_space(block_group, e);
+                                spin_unlock(&block_group->tree_lock);
+                                BUG_ON(ret);
+                        } else {
+                                e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
+                                if (!e->bitmap) {
+                                        kunmap(page);
+                                        kfree(e);
+                                        unlock_page(page);
+                                        page_cache_release(page);
+                                        goto free_cache;
+                                }
+                                spin_lock(&block_group->tree_lock);
+                                ret = link_free_space(block_group, e);
+                                block_group->total_bitmaps++;
+                                recalculate_thresholds(block_group);
+                                spin_unlock(&block_group->tree_lock);
+                                list_add_tail(&e->list, &bitmaps);
+                        }
+
+                        num_entries--;
+                        offset += sizeof(struct btrfs_free_space_entry);
+                        if (offset + sizeof(struct btrfs_free_space_entry) >=
+                            PAGE_CACHE_SIZE)
+                                break;
+                        entry++;
+                }
+
+                /*
+                 * We read an entry out of this page, we need to move on to the
+                 * next page.
+                 */
+                if (need_loop) {
+                        kunmap(page);
+                        goto next;
+                }
+
+                /*
+                 * We add the bitmaps at the end of the entries in order that
+                 * the bitmap entries are added to the cache.
+                 */
+                e = list_entry(bitmaps.next, struct btrfs_free_space, list);
+                list_del_init(&e->list);
+                memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
+                kunmap(page);
+                num_bitmaps--;
+next:
+                unlock_page(page);
+                page_cache_release(page);
+                index++;
+        }
+
+        ret = 1;
+out:
+        kfree(checksums);
+        kfree(disk_crcs);
+        iput(inode);
+        return ret;
+
+free_cache:
+        /* This cache is bogus, make sure it gets cleared */
+        spin_lock(&block_group->lock);
+        block_group->disk_cache_state = BTRFS_DC_CLEAR;
+        spin_unlock(&block_group->lock);
+        btrfs_remove_free_space_cache(block_group);
+        goto out;
+}
+
 int btrfs_write_out_cache(struct btrfs_root *root,
                           struct btrfs_trans_handle *trans,
                           struct btrfs_block_group_cache *block_group,