Btrfs: Support for online FS resize (grow and shrink)

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

1 files changed, 480 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1412d556313f..de0fb0743cf9 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -18,6 +18,7 @@
 
 #include <linux/sched.h>
 #include <linux/crc32c.h>
+#include <linux/pagemap.h>
 #include "hash.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -1622,6 +1623,7 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
         int pending_ret;
         u64 super_used, root_used;
         u64 search_start = 0;
+        u64 new_hint;
         struct btrfs_fs_info *info = root->fs_info;
         struct btrfs_root *extent_root = info->extent_root;
         struct btrfs_extent_item extent_item;
@@ -1629,6 +1631,10 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 
         btrfs_set_stack_extent_refs(&extent_item, 1);
 
+        new_hint = max(hint_byte, 16ULL * 1024 * 1024 * 1024);
+        if (new_hint < btrfs_super_total_bytes(&info->super_copy))
+                hint_byte = new_hint;
+
         WARN_ON(num_bytes < root->sectorsize);
         ret = find_free_extent(trans, root, num_bytes, empty_size,
                                search_start, search_end, hint_byte, ins,
@@ -2100,6 +2106,480 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
         return 0;
 }
 
+static int relocate_inode_pages(struct inode *inode, u64 start, u64 len)
+{
+        u64 page_start;
+        u64 page_end;
+        u64 delalloc_start;
+        u64 existing_delalloc;
+        unsigned long last_index;
+        unsigned long first_index;
+        unsigned long i;
+        struct page *page;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+        struct file_ra_state ra;
+
+        mutex_lock(&inode->i_mutex);
+        first_index = start >> PAGE_CACHE_SHIFT;
+        last_index = (start + len - 1) >> PAGE_CACHE_SHIFT;
+
+        memset(&ra, 0, sizeof(ra));
+        file_ra_state_init(&ra, inode->i_mapping);
+        btrfs_force_ra(inode->i_mapping, &ra, NULL, first_index, last_index);
+
+        for (i = first_index; i <= last_index; i++) {
+                page = grab_cache_page(inode->i_mapping, i);
+                if (!page)
+                        goto out_unlock;
+                if (!PageUptodate(page)) {
+                        btrfs_readpage(NULL, page);
+                        lock_page(page);
+                        if (!PageUptodate(page)) {
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto out_unlock;
+                        }
+                }
+                page_start = (u64)page->index << PAGE_CACHE_SHIFT;
+                page_end = page_start + PAGE_CACHE_SIZE - 1;
+
+                lock_extent(em_tree, page_start, page_end, GFP_NOFS);
+
+                delalloc_start = page_start;
+                existing_delalloc =
+                        count_range_bits(&BTRFS_I(inode)->extent_tree,
+                                         &delalloc_start, page_end,
+                                         PAGE_CACHE_SIZE, EXTENT_DELALLOC);
+
+                set_extent_delalloc(em_tree, page_start,
+                                    page_end, GFP_NOFS);
+
+                spin_lock(&root->fs_info->delalloc_lock);
+                root->fs_info->delalloc_bytes += PAGE_CACHE_SIZE -
+                                                 existing_delalloc;
+                spin_unlock(&root->fs_info->delalloc_lock);
+
+                unlock_extent(em_tree, page_start, page_end, GFP_NOFS);
+                set_page_dirty(page);
+                unlock_page(page);
+                page_cache_release(page);
+        }
+
+out_unlock:
+        mutex_unlock(&inode->i_mutex);
+        return 0;
+}
+
+static int relocate_one_reference(struct btrfs_root *extent_root,
+                                  struct btrfs_path *path,
+                                  struct btrfs_key *extent_key,
+                                  u64 ref_root, u64 ref_gen, u64 ref_objectid,
+                                  u64 ref_offset)
+{
+        struct inode *inode;
+        struct btrfs_root *found_root;
+        struct btrfs_key root_location;
+        int ret;
+
+        root_location.objectid = ref_root;
+        if (ref_gen == 0)
+                root_location.offset = 0;
+        else
+                root_location.offset = (u64)-1;
+        root_location.type = BTRFS_ROOT_ITEM_KEY;
+
+        found_root = btrfs_read_fs_root_no_name(extent_root->fs_info,
+                                                &root_location);
+        BUG_ON(!found_root);
+
+        if (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
+                mutex_unlock(&extent_root->fs_info->fs_mutex);
+                inode = btrfs_iget_locked(extent_root->fs_info->sb,
+                                          ref_objectid, found_root);
+                if (inode->i_state & I_NEW) {
+                        /* the inode and parent dir are two different roots */
+                        BTRFS_I(inode)->root = found_root;
+                        BTRFS_I(inode)->location.objectid = ref_objectid;
+                        BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY;
+                        BTRFS_I(inode)->location.offset = 0;
+                        btrfs_read_locked_inode(inode);
+                        unlock_new_inode(inode);
+
+                }
+                /* this can happen if the reference is not against
+                 * the latest version of the tree root
+                 */
+                if (is_bad_inode(inode)) {
+                        mutex_lock(&extent_root->fs_info->fs_mutex);
+                        goto out;
+                }
+                relocate_inode_pages(inode, ref_offset, extent_key->offset);
+                /* FIXME, data=ordered will help get rid of this */
+                filemap_fdatawrite(inode->i_mapping);
+                iput(inode);
+                mutex_lock(&extent_root->fs_info->fs_mutex);
+        } else {
+                struct btrfs_trans_handle *trans;
+                struct btrfs_key found_key;
+                struct extent_buffer *eb;
+                int level;
+                int i;
+
+                trans = btrfs_start_transaction(found_root, 1);
+                eb = read_tree_block(found_root, extent_key->objectid,
+                                     extent_key->offset);
+                level = btrfs_header_level(eb);
+
+                if (level == 0)
+                        btrfs_item_key_to_cpu(eb, &found_key, 0);
+                else
+                        btrfs_node_key_to_cpu(eb, &found_key, 0);
+
+                free_extent_buffer(eb);
+
+                path->lowest_level = level;
+                path->reada = 0;
+                ret = btrfs_search_slot(trans, found_root, &found_key, path,
+                                        0, 1);
+                path->lowest_level = 0;
+                for (i = level; i < BTRFS_MAX_LEVEL; i++) {
+                        if (!path->nodes[i])
+                                break;
+                        free_extent_buffer(path->nodes[i]);
+                        path->nodes[i] = NULL;
+                }
+                btrfs_release_path(found_root, path);
+                btrfs_end_transaction(trans, found_root);
+        }
+
+out:
+        return 0;
+}
+
+static int relocate_one_extent(struct btrfs_root *extent_root,
+                               struct btrfs_path *path,
+                               struct btrfs_key *extent_key)
+{
+        struct btrfs_key key;
+        struct btrfs_key found_key;
+        struct btrfs_extent_ref *ref;
+        struct extent_buffer *leaf;
+        u64 ref_root;
+        u64 ref_gen;
+        u64 ref_objectid;
+        u64 ref_offset;
+        u32 nritems;
+        u32 item_size;
+        int ret = 0;
+
+        key.objectid = extent_key->objectid;
+        key.type = BTRFS_EXTENT_REF_KEY;
+        key.offset = 0;
+
+        while(1) {
+                ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
+
+                BUG_ON(ret == 0);
+
+                if (ret < 0)
+                        goto out;
+
+                ret = 0;
+                leaf = path->nodes[0];
+                nritems = btrfs_header_nritems(leaf);
+                if (path->slots[0] == nritems)
+                        goto out;
+
+                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+                if (found_key.objectid != extent_key->objectid)
+                        break;
+
+                if (found_key.type != BTRFS_EXTENT_REF_KEY)
+                        break;
+
+                key.offset = found_key.offset + 1;
+                item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+
+                ref = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_extent_ref);
+                ref_root = btrfs_ref_root(leaf, ref);
+                ref_gen = btrfs_ref_generation(leaf, ref);
+                ref_objectid = btrfs_ref_objectid(leaf, ref);
+                ref_offset = btrfs_ref_offset(leaf, ref);
+                btrfs_release_path(extent_root, path);
+
+                ret = relocate_one_reference(extent_root, path,
+                                             extent_key, ref_root, ref_gen,
+                                             ref_objectid, ref_offset);
+                if (ret)
+                        goto out;
+        }
+        ret = 0;
+out:
+        btrfs_release_path(extent_root, path);
+        return ret;
+}
+
+static int find_overlapping_extent(struct btrfs_root *root,
+                                   struct btrfs_path *path, u64 new_size)
+{
+        struct btrfs_key found_key;
+        struct extent_buffer *leaf;
+        int ret;
+
+        while(1) {
+                if (path->slots[0] == 0) {
+                        ret = btrfs_prev_leaf(root, path);
+                        if (ret == 1) {
+                                return 1;
+                        }
+                        if (ret < 0)
+                                return ret;
+                } else {
+                        path->slots[0]--;
+                }
+                leaf = path->nodes[0];
+                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+                if (found_key.type == BTRFS_EXTENT_ITEM_KEY) {
+                        if (found_key.objectid + found_key.offset > new_size)
+                                return 0;
+                        else
+                                return 1;
+                }
+        }
+        return 1;
+}
+
+int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
+{
+        struct btrfs_trans_handle *trans;
+        struct btrfs_root *tree_root = root->fs_info->tree_root;
+        struct btrfs_path *path;
+        u64 cur_byte;
+        u64 total_found;
+        u64 ptr;
+        struct btrfs_fs_info *info = root->fs_info;
+        struct extent_map_tree *block_group_cache;
+        struct btrfs_key key;
+        struct btrfs_key found_key = { 0, 0, 0 };
+        struct extent_buffer *leaf;
+        u32 nritems;
+        int ret;
+        int slot;
+
+        btrfs_set_super_total_bytes(&info->super_copy, new_size);
+        block_group_cache = &info->block_group_cache;
+        path = btrfs_alloc_path();
+        root = root->fs_info->extent_root;
+
+again:
+        total_found = 0;
+        key.objectid = new_size;
+        cur_byte = key.objectid;
+        key.offset = 0;
+        key.type = 0;
+        while(1) {
+                ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+                if (ret < 0)
+                        goto out;
+next:
+                leaf = path->nodes[0];
+                if (key.objectid == new_size - 1) {
+                        ret = find_overlapping_extent(root, path, new_size);
+                        if (ret != 0) {
+                                btrfs_release_path(root, path);
+                                ret = btrfs_search_slot(NULL, root, &key,
+                                                        path, 0, 0);
+                                if (ret < 0)
+                                        goto out;
+                        }
+                }
+                nritems = btrfs_header_nritems(leaf);
+                ret = 0;
+                slot = path->slots[0];
+                if (slot < nritems)
+                        btrfs_item_key_to_cpu(leaf, &found_key, slot);
+                if (slot == nritems ||
+                    btrfs_key_type(&found_key) != BTRFS_EXTENT_ITEM_KEY) {
+                        path->slots[0]++;
+                        if (path->slots[0] >= nritems) {
+                                ret = btrfs_next_leaf(root, path);
+                                if (ret < 0)
+                                        goto out;
+                                if (ret == 1) {
+                                        ret = 0;
+                                        break;
+                                }
+                        }
+                        goto next;
+                }
+                btrfs_item_key_to_cpu(leaf, &found_key, slot);
+                if (found_key.objectid + found_key.offset <= cur_byte)
+                        continue;
+                total_found++;
+                cur_byte = found_key.objectid + found_key.offset;
+                key.objectid = cur_byte;
+                btrfs_release_path(root, path);
+                ret = relocate_one_extent(root, path, &found_key);
+        }
+
+        btrfs_release_path(root, path);
+
+        if (total_found > 0) {
+                trans = btrfs_start_transaction(tree_root, 1);
+                btrfs_commit_transaction(trans, tree_root);
+
+                mutex_unlock(&root->fs_info->fs_mutex);
+                btrfs_clean_old_snapshots(tree_root);
+                mutex_lock(&root->fs_info->fs_mutex);
+
+                trans = btrfs_start_transaction(tree_root, 1);
+                btrfs_commit_transaction(trans, tree_root);
+                goto again;
+        }
+
+        trans = btrfs_start_transaction(root, 1);
+        key.objectid = new_size;
+        key.offset = 0;
+        key.type = 0;
+        while(1) {
+                ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+                if (ret < 0)
+                        goto out;
+bg_next:
+                leaf = path->nodes[0];
+                nritems = btrfs_header_nritems(leaf);
+                ret = 0;
+                slot = path->slots[0];
+                if (slot < nritems)
+                        btrfs_item_key_to_cpu(leaf, &found_key, slot);
+                if (slot == nritems ||
+                    btrfs_key_type(&found_key) != BTRFS_BLOCK_GROUP_ITEM_KEY) {
+                        if (slot < nritems) {
+                                printk("shrinker found key %Lu %u %Lu\n",
+                                       found_key.objectid, found_key.type,
+                                       found_key.offset);
+                                path->slots[0]++;
+                        }
+                        if (path->slots[0] >= nritems) {
+                                ret = btrfs_next_leaf(root, path);
+                                if (ret < 0)
+                                        break;
+                                if (ret == 1) {
+                                        ret = 0;
+                                        break;
+                                }
+                        }
+                        goto bg_next;
+                }
+                btrfs_item_key_to_cpu(leaf, &found_key, slot);
+                ret = get_state_private(&info->block_group_cache,
+                                        found_key.objectid, &ptr);
+                if (!ret)
+                        kfree((void *)(unsigned long)ptr);
+
+                clear_extent_bits(&info->block_group_cache, found_key.objectid,
+                                  found_key.objectid + found_key.offset - 1,
+                                  (unsigned int)-1, GFP_NOFS);
+
+                key.objectid = found_key.objectid + 1;
+                btrfs_del_item(trans, root, path);
+                btrfs_release_path(root, path);
+        }
+        clear_extent_dirty(&info->free_space_cache, new_size, (u64)-1,
+                           GFP_NOFS);
+        btrfs_commit_transaction(trans, root);
+out:
+        btrfs_free_path(path);
+        return ret;
+}
+
+int btrfs_grow_extent_tree(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root, u64 new_size)
+{
+        struct btrfs_path *path;
+        u64 nr = 0;
+        u64 cur_byte;
+        u64 old_size;
+        struct btrfs_block_group_cache *cache;
+        struct btrfs_block_group_item *item;
+        struct btrfs_fs_info *info = root->fs_info;
+        struct extent_map_tree *block_group_cache;
+        struct btrfs_key key;
+        struct extent_buffer *leaf;
+        int ret;
+        int bit;
+
+        old_size = btrfs_super_total_bytes(&info->super_copy);
+        block_group_cache = &info->block_group_cache;
+
+        root = info->extent_root;
+
+        cache = btrfs_lookup_block_group(root->fs_info, old_size - 1);
+
+        cur_byte = cache->key.objectid + cache->key.offset;
+        if (cur_byte >= new_size)
+                goto set_size;
+
+        key.offset = BTRFS_BLOCK_GROUP_SIZE;
+        btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return -ENOMEM;
+
+        while(cur_byte < new_size) {
+                key.objectid = cur_byte;
+                ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                        sizeof(struct btrfs_block_group_item));
+                BUG_ON(ret);
+                leaf = path->nodes[0];
+                item = btrfs_item_ptr(leaf, path->slots[0],
+                                      struct btrfs_block_group_item);
+
+                btrfs_set_disk_block_group_used(leaf, item, 0);
+                if (nr % 3) {
+                        btrfs_set_disk_block_group_flags(leaf, item,
+                                                 BTRFS_BLOCK_GROUP_DATA);
+                } else {
+                        btrfs_set_disk_block_group_flags(leaf, item, 0);
+                }
+                nr++;
+
+                cache = kmalloc(sizeof(*cache), GFP_NOFS);
+                BUG_ON(!cache);
+
+                read_extent_buffer(leaf, &cache->item, (unsigned long)item,
+                                   sizeof(cache->item));
+
+                memcpy(&cache->key, &key, sizeof(key));
+                cache->cached = 0;
+                cache->pinned = 0;
+                cur_byte = key.objectid + key.offset;
+                btrfs_release_path(root, path);
+
+                if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
+                        bit = BLOCK_GROUP_DATA;
+                        cache->data = BTRFS_BLOCK_GROUP_DATA;
+                } else {
+                        bit = BLOCK_GROUP_METADATA;
+                        cache->data = 0;
+                }
+
+                /* use EXTENT_LOCKED to prevent merging */
+                set_extent_bits(block_group_cache, key.objectid,
+                                key.objectid + key.offset - 1,
+                                bit | EXTENT_LOCKED, GFP_NOFS);
+                set_state_private(block_group_cache, key.objectid,
+                                  (unsigned long)cache);
+        }
+        btrfs_free_path(path);
+set_size:
+        btrfs_set_super_total_bytes(&info->super_copy, new_size);
+        return 0;
+}
+
 int btrfs_read_block_groups(struct btrfs_root *root)
 {
         struct btrfs_path *path;