9 files changed, 236 insertions, 19 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index c96a4e4c5566..b20082e27a9f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -105,6 +105,12 @@ struct btrfs_ordered_sum;
 /* For storing free space cache */
 #define BTRFS_FREE_SPACE_OBJECTID -11ULL
 
+/*
+ * The inode number assigned to the special inode for sotring
+ * free ino cache
+ */
+#define BTRFS_FREE_INO_OBJECTID -12ULL
+
 /* dummy objectid represents multiple objectids */
 #define BTRFS_MULTIPLE_OBJECTIDS -255ULL
 
@@ -1110,6 +1116,7 @@ struct btrfs_root {
         wait_queue_head_t cache_wait;
         struct btrfs_free_space_ctl *free_ino_pinned;
         u64 cache_progress;
+        struct inode *cache_inode;
 
         struct mutex log_mutex;
         wait_queue_head_t log_writer_wait;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d02683b1ee16..4f12c30a5470 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2505,6 +2505,7 @@ int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
 
 static void free_fs_root(struct btrfs_root *root)
 {
+        iput(root->cache_inode);
         WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
         if (root->anon_super.s_dev) {
                 down_write(&root->anon_super.s_umount);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a0e818cb0401..95ce8da63b28 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3145,7 +3145,8 @@ int btrfs_check_data_free_space(struct inode *inode, u64 bytes)
         /* make sure bytes are sectorsize aligned */
         bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 
-        if (root == root->fs_info->tree_root) {
+        if (root == root->fs_info->tree_root ||
+            BTRFS_I(inode)->location.objectid == BTRFS_FREE_INO_OBJECTID) {
                 alloc_chunk = 0;
                 committed = 1;
         }
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index fcbdcef6ca28..7d8b6b643403 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -209,7 +209,8 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
                 return ret;
         }
 
-        return btrfs_update_inode(trans, root, inode);
+        ret = btrfs_update_inode(trans, root, inode);
+        return ret;
 }
 
 static int readahead_cache(struct inode *inode)
@@ -525,6 +526,7 @@ out:
                 spin_lock(&block_group->lock);
                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
                 spin_unlock(&block_group->lock);
+                ret = 0;
 
                 printk(KERN_ERR "btrfs: failed to load free space cache "
                        "for block group %llu\n", block_group->key.objectid);
@@ -893,6 +895,7 @@ int btrfs_write_out_cache(struct btrfs_root *root,
                 spin_lock(&block_group->lock);
                 block_group->disk_cache_state = BTRFS_DC_ERROR;
                 spin_unlock(&block_group->lock);
+                ret = 0;
 
                 printk(KERN_ERR "btrfs: failed to write free space cace "
                        "for block group %llu\n", block_group->key.objectid);
@@ -2458,3 +2461,95 @@ out:
 
         return ino;
 }
+
+struct inode *lookup_free_ino_inode(struct btrfs_root *root,
+                                    struct btrfs_path *path)
+{
+        struct inode *inode = NULL;
+
+        spin_lock(&root->cache_lock);
+        if (root->cache_inode)
+                inode = igrab(root->cache_inode);
+        spin_unlock(&root->cache_lock);
+        if (inode)
+                return inode;
+
+        inode = __lookup_free_space_inode(root, path, 0);
+        if (IS_ERR(inode))
+                return inode;
+
+        spin_lock(&root->cache_lock);
+        if (!root->fs_info->closing)
+                root->cache_inode = igrab(inode);
+        spin_unlock(&root->cache_lock);
+
+        return inode;
+}
+
+int create_free_ino_inode(struct btrfs_root *root,
+                          struct btrfs_trans_handle *trans,
+                          struct btrfs_path *path)
+{
+        return __create_free_space_inode(root, trans, path,
+                                         BTRFS_FREE_INO_OBJECTID, 0);
+}
+
+int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
+{
+        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+        struct btrfs_path *path;
+        struct inode *inode;
+        int ret = 0;
+        u64 root_gen = btrfs_root_generation(&root->root_item);
+
+        /*
+         * 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;
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return 0;
+
+        inode = lookup_free_ino_inode(root, path);
+        if (IS_ERR(inode))
+                goto out;
+
+        if (root_gen != BTRFS_I(inode)->generation)
+                goto out_put;
+
+        ret = __load_free_space_cache(root, inode, ctl, path, 0);
+
+        if (ret < 0)
+                printk(KERN_ERR "btrfs: failed to load free ino cache for "
+                       "root %llu\n", root->root_key.objectid);
+out_put:
+        iput(inode);
+out:
+        btrfs_free_path(path);
+        return ret;
+}
+
+int btrfs_write_out_ino_cache(struct btrfs_root *root,
+                              struct btrfs_trans_handle *trans,
+                              struct btrfs_path *path)
+{
+        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+        struct inode *inode;
+        int ret;
+
+        inode = lookup_free_ino_inode(root, path);
+        if (IS_ERR(inode))
+                return 0;
+
+        ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
+        if (ret < 0)
+                printk(KERN_ERR "btrfs: failed to write free ino cache "
+                       "for root %llu\n", root->root_key.objectid);
+
+        iput(inode);
+        return ret;
+}
diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
index af06e6b6ceaa..8f2613f779ed 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -65,6 +65,17 @@ int btrfs_write_out_cache(struct btrfs_root *root,
                           struct btrfs_block_group_cache *block_group,
                           struct btrfs_path *path);
 
+struct inode *lookup_free_ino_inode(struct btrfs_root *root,
+                                    struct btrfs_path *path);
+int create_free_ino_inode(struct btrfs_root *root,
+                          struct btrfs_trans_handle *trans,
+                          struct btrfs_path *path);
+int load_free_ino_cache(struct btrfs_fs_info *fs_info,
+                        struct btrfs_root *root);
+int btrfs_write_out_ino_cache(struct btrfs_root *root,
+                              struct btrfs_trans_handle *trans,
+                              struct btrfs_path *path);
+
 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group);
 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
                            u64 bytenr, u64 size);
diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index 5be62df90c4f..7967e85c72f5 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -137,6 +137,7 @@ out:
 static void start_caching(struct btrfs_root *root)
 {
         struct task_struct *tsk;
+        int ret;
 
         spin_lock(&root->cache_lock);
         if (root->cached != BTRFS_CACHE_NO) {
@@ -147,6 +148,14 @@ static void start_caching(struct btrfs_root *root)
         root->cached = BTRFS_CACHE_STARTED;
         spin_unlock(&root->cache_lock);
 
+        ret = load_free_ino_cache(root->fs_info, root);
+        if (ret == 1) {
+                spin_lock(&root->cache_lock);
+                root->cached = BTRFS_CACHE_FINISHED;
+                spin_unlock(&root->cache_lock);
+                return;
+        }
+
         tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
                           root->root_key.objectid);
         BUG_ON(IS_ERR(tsk));
@@ -352,6 +361,84 @@ void btrfs_init_free_ino_ctl(struct btrfs_root *root)
         pinned->op = &pinned_free_ino_op;
 }
 
+int btrfs_save_ino_cache(struct btrfs_root *root,
+                         struct btrfs_trans_handle *trans)
+{
+        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+        struct btrfs_path *path;
+        struct inode *inode;
+        u64 alloc_hint = 0;
+        int ret;
+        int prealloc;
+        bool retry = false;
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return -ENOMEM;
+again:
+        inode = lookup_free_ino_inode(root, path);
+        if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
+                ret = PTR_ERR(inode);
+                goto out;
+        }
+
+        if (IS_ERR(inode)) {
+                BUG_ON(retry);
+                retry = true;
+
+                ret = create_free_ino_inode(root, trans, path);
+                if (ret)
+                        goto out;
+                goto again;
+        }
+
+        BTRFS_I(inode)->generation = 0;
+        ret = btrfs_update_inode(trans, root, inode);
+        WARN_ON(ret);
+
+        if (i_size_read(inode) > 0) {
+                ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
+                if (ret)
+                        goto out_put;
+        }
+
+        spin_lock(&root->cache_lock);
+        if (root->cached != BTRFS_CACHE_FINISHED) {
+                ret = -1;
+                spin_unlock(&root->cache_lock);
+                goto out_put;
+        }
+        spin_unlock(&root->cache_lock);
+
+        spin_lock(&ctl->tree_lock);
+        prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
+        prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
+        prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
+        spin_unlock(&ctl->tree_lock);
+
+        /* Just to make sure we have enough space */
+        prealloc += 8 * PAGE_CACHE_SIZE;
+
+        ret = btrfs_check_data_free_space(inode, prealloc);
+        if (ret)
+                goto out_put;
+
+        ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
+                                              prealloc, prealloc, &alloc_hint);
+        if (ret)
+                goto out_put;
+        btrfs_free_reserved_data_space(inode, prealloc);
+
+out_put:
+        iput(inode);
+out:
+        if (ret == 0)
+                ret = btrfs_write_out_ino_cache(root, trans, path);
+
+        btrfs_free_path(path);
+        return ret;
+}
+
 static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
 {
         struct btrfs_path *path;
diff --git a/fs/btrfs/inode-map.h b/fs/btrfs/inode-map.h
index eb918451b492..ddb347bfee23 100644
--- a/fs/btrfs/inode-map.h
+++ b/fs/btrfs/inode-map.h
@@ -5,6 +5,8 @@ void btrfs_init_free_ino_ctl(struct btrfs_root *root);
 void btrfs_unpin_free_ino(struct btrfs_root *root);
 void btrfs_return_ino(struct btrfs_root *root, u64 objectid);
 int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid);
+int btrfs_save_ino_cache(struct btrfs_root *root,
+                         struct btrfs_trans_handle *trans);
 
 int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid);
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index adec22884a3e..b78d3ab789ca 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -745,6 +745,15 @@ static u64 get_extent_allocation_hint(struct inode *inode, u64 start,
         return alloc_hint;
 }
 
+static inline bool is_free_space_inode(struct btrfs_root *root,
+                                       struct inode *inode)
+{
+        if (root == root->fs_info->tree_root ||
+            BTRFS_I(inode)->location.objectid == BTRFS_FREE_INO_OBJECTID)
+                return true;
+        return false;
+}
+
 /*
  * when extent_io.c finds a delayed allocation range in the file,
  * the call backs end up in this code.  The basic idea is to
@@ -777,7 +786,7 @@ static noinline int cow_file_range(struct inode *inode,
         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
         int ret = 0;
 
-        BUG_ON(root == root->fs_info->tree_root);
+        BUG_ON(is_free_space_inode(root, inode));
         trans = btrfs_join_transaction(root, 1);
         BUG_ON(IS_ERR(trans));
         btrfs_set_trans_block_group(trans, inode);
@@ -1048,17 +1057,18 @@ static noinline int run_delalloc_nocow(struct inode *inode,
         int type;
         int nocow;
         int check_prev = 1;
-        bool nolock = false;
+        bool nolock;
         u64 ino = btrfs_ino(inode);
 
         path = btrfs_alloc_path();
         BUG_ON(!path);
-        if (root == root->fs_info->tree_root) {
-                nolock = true;
+
+        nolock = is_free_space_inode(root, inode);
+
+        if (nolock)
                 trans = btrfs_join_transaction_nolock(root, 1);
-        } else {
+        else
                 trans = btrfs_join_transaction(root, 1);
-        }
         BUG_ON(IS_ERR(trans));
 
         cow_start = (u64)-1;
@@ -1316,8 +1326,7 @@ static int btrfs_set_bit_hook(struct inode *inode,
         if (!(state->state & EXTENT_DELALLOC) && (*bits & EXTENT_DELALLOC)) {
                 struct btrfs_root *root = BTRFS_I(inode)->root;
                 u64 len = state->end + 1 - state->start;
-                int do_list = (root->root_key.objectid !=
-                               BTRFS_ROOT_TREE_OBJECTID);
+                bool do_list = !is_free_space_inode(root, inode);
 
                 if (*bits & EXTENT_FIRST_DELALLOC)
                         *bits &= ~EXTENT_FIRST_DELALLOC;
@@ -1350,8 +1359,7 @@ static int btrfs_clear_bit_hook(struct inode *inode,
         if ((state->state & EXTENT_DELALLOC) && (*bits & EXTENT_DELALLOC)) {
                 struct btrfs_root *root = BTRFS_I(inode)->root;
                 u64 len = state->end + 1 - state->start;
-                int do_list = (root->root_key.objectid !=
-                               BTRFS_ROOT_TREE_OBJECTID);
+                bool do_list = !is_free_space_inode(root, inode);
 
                 if (*bits & EXTENT_FIRST_DELALLOC)
                         *bits &= ~EXTENT_FIRST_DELALLOC;
@@ -1458,7 +1466,7 @@ static int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 
         skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
 
-        if (root == root->fs_info->tree_root)
+        if (is_free_space_inode(root, inode))
                 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 2);
         else
                 ret = btrfs_bio_wq_end_io(root->fs_info, bio, 0);
@@ -1701,7 +1709,7 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
         struct extent_state *cached_state = NULL;
         int compress_type = 0;
         int ret;
-        bool nolock = false;
+        bool nolock;
 
         ret = btrfs_dec_test_ordered_pending(inode, &ordered_extent, start,
                                              end - start + 1);
@@ -1709,7 +1717,7 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
                 return 0;
         BUG_ON(!ordered_extent);
 
-        nolock = (root == root->fs_info->tree_root);
+        nolock = is_free_space_inode(root, inode);
 
         if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
                 BUG_ON(!list_empty(&ordered_extent->list));
@@ -3473,7 +3481,9 @@ delete:
 
                 if (path->slots[0] == 0 ||
                     path->slots[0] != pending_del_slot) {
-                        if (root->ref_cows) {
+                        if (root->ref_cows &&
+                            BTRFS_I(inode)->location.objectid !=
+                                                BTRFS_FREE_INO_OBJECTID) {
                                 err = -EAGAIN;
                                 goto out;
                         }
@@ -3765,7 +3775,7 @@ void btrfs_evict_inode(struct inode *inode)
 
         truncate_inode_pages(&inode->i_data, 0);
         if (inode->i_nlink && (btrfs_root_refs(&root->root_item) != 0 ||
-                               root == root->fs_info->tree_root))
+                               is_free_space_inode(root, inode)))
                 goto no_delete;
 
         if (is_bad_inode(inode)) {
@@ -4382,7 +4392,8 @@ int btrfs_write_inode(struct inode *inode, struct writeback_control *wbc)
                 return 0;
 
         smp_mb();
-        nolock = (root->fs_info->closing && root == root->fs_info->tree_root);
+        if (root->fs_info->closing && is_free_space_inode(root, inode))
+                nolock = true;
 
         if (wbc->sync_mode == WB_SYNC_ALL) {
                 if (nolock)
@@ -6900,7 +6911,7 @@ int btrfs_drop_inode(struct inode *inode)
         struct btrfs_root *root = BTRFS_I(inode)->root;
 
         if (btrfs_root_refs(&root->root_item) == 0 &&
-            root != root->fs_info->tree_root)
+            !is_free_space_inode(root, inode))
                 return 1;
         else
                 return generic_drop_inode(inode);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f4c1184b7f1a..4d1dbcbbaf41 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -761,6 +761,8 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
                         btrfs_update_reloc_root(trans, root);
                         btrfs_orphan_commit_root(trans, root);
 
+                        btrfs_save_ino_cache(root, trans);
+
                         if (root->commit_root != root->node) {
                                 mutex_lock(&root->fs_commit_mutex);
                                 switch_commit_root(root);