Btrfs: early fsync support

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

7 files changed, 62 insertions, 5 deletions

diff --git a/fs/btrfs/TODO b/fs/btrfs/TODO
index 8d7e5a3ed629..5ff2cef9f028 100644
--- a/fs/btrfs/TODO
+++ b/fs/btrfs/TODO
@@ -7,6 +7,7 @@
 * Get rid of struct ctree_path, limiting tree levels held at one time
 * Add generation number to key pointer in nodes
 * Add parent pointer back to extent map.
+* Implement real list of pending transactions
 * Release
 * Do real tree locking
 * Add extent mirroring (backup copies of blocks)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d628a3b9441c..047a84762d93 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -256,6 +256,7 @@ struct btrfs_fs_info {
         struct inode *btree_inode;
         struct mutex trans_mutex;
         struct mutex fs_mutex;
+        struct list_head trans_list;
         struct crypto_hash *hash_tfm;
         spinlock_t hash_lock;
         struct kobject kobj;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 11e17a2f736b..b666c3571aee 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -528,6 +528,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         init_bit_radix(&fs_info->pending_del_radix);
         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
         INIT_RADIX_TREE(&fs_info->dev_radix, GFP_NOFS);
+        INIT_LIST_HEAD(&fs_info->trans_list);
         sb_set_blocksize(sb, 4096);
         fs_info->running_transaction = NULL;
         fs_info->tree_root = tree_root;
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 72be9836932f..a42943bd9179 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -100,7 +100,6 @@ int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
         BUG_ON(refs == 0);
         if (refs == 1) {
                 ret = btrfs_del_item(trans, root, path);
-printk("deleting root %Lu %Lu %u\n", key->objectid, key->offset, key->flags);
         } else {
                 btrfs_set_root_refs(ri, refs - 1);
 printk("ref now %u root %Lu %Lu %u\n", refs -1, key->objectid, key->offset, key->flags);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index dff2db0d1dc2..f99c764a59db 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -11,6 +11,7 @@
 #include <linux/mpage.h>
 #include <linux/swap.h>
 #include <linux/writeback.h>
+#include <linux/statfs.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -932,6 +933,26 @@ out_unlock:
         return err;
 }
 
+static int btrfs_sync_file(struct file *file,
+                           struct dentry *dentry, int datasync)
+{
+        struct inode *inode = dentry->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        int ret;
+        struct btrfs_trans_handle *trans;
+
+        mutex_lock(&root->fs_info->fs_mutex);
+        trans = btrfs_start_transaction(root, 1);
+        if (!trans) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        ret = btrfs_commit_transaction(trans, root);
+        mutex_unlock(&root->fs_info->fs_mutex);
+out:
+        return ret > 0 ? EIO : ret;
+}
+
 static int btrfs_sync_fs(struct super_block *sb, int wait)
 {
         struct btrfs_trans_handle *trans;
@@ -2353,6 +2374,19 @@ static int btrfs_getattr(struct vfsmount *mnt,
         return 0;
 }
 
+static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+        struct btrfs_root *root = btrfs_sb(dentry->d_sb);
+        struct btrfs_super_block *disk_super = root->fs_info->disk_super;
+
+        buf->f_namelen = BTRFS_NAME_LEN;
+        buf->f_blocks = btrfs_super_total_blocks(disk_super);
+        buf->f_bfree = buf->f_blocks - btrfs_super_blocks_used(disk_super);
+        buf->f_bavail = buf->f_bfree;
+        buf->f_bsize = dentry->d_sb->s_blocksize;
+        buf->f_type = BTRFS_SUPER_MAGIC;
+        return 0;
+}
 static struct file_system_type btrfs_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "btrfs",
@@ -2362,7 +2396,6 @@ static struct file_system_type btrfs_fs_type = {
 };
 
 static struct super_operations btrfs_super_ops = {
-        .statfs         = simple_statfs,
         .delete_inode   = btrfs_delete_inode,
         .put_super      = btrfs_put_super,
         .read_inode     = btrfs_read_locked_inode,
@@ -2371,6 +2404,7 @@ static struct super_operations btrfs_super_ops = {
         .write_inode    = btrfs_write_inode,
         .alloc_inode    = btrfs_alloc_inode,
         .destroy_inode  = btrfs_destroy_inode,
+        .statfs         = btrfs_statfs,
 };
 
 static struct inode_operations btrfs_dir_inode_operations = {
@@ -2413,6 +2447,7 @@ static struct file_operations btrfs_file_operations = {
         .mmap           = generic_file_mmap,
         .open           = generic_file_open,
         .ioctl          = btrfs_ioctl,
+        .fsync          = btrfs_sync_file,
 };
 
 static int __init init_btrfs_fs(void)
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8740752f3845..078cb9cbf9dd 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -19,6 +19,7 @@ static void put_transaction(struct btrfs_transaction *transaction)
         if (transaction->use_count == 0) {
                 WARN_ON(total_trans == 0);
                 total_trans--;
+                list_del_init(&transaction->list);
                 memset(transaction, 0, sizeof(*transaction));
                 kmem_cache_free(btrfs_transaction_cachep, transaction);
         }
@@ -43,6 +44,7 @@ static int join_transaction(struct btrfs_root *root)
                 cur_trans->in_commit = 0;
                 cur_trans->use_count = 1;
                 cur_trans->commit_done = 0;
+                list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
         }
         cur_trans->num_writers++;
         return 0;
@@ -236,6 +238,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 {
         int ret = 0;
         struct btrfs_transaction *cur_trans;
+        struct btrfs_transaction *prev_trans = NULL;
         struct list_head dirty_fs_roots;
         DEFINE_WAIT(wait);
 
@@ -272,13 +275,29 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
         cur_trans = root->fs_info->running_transaction;
         root->fs_info->running_transaction = NULL;
-        btrfs_set_super_generation(root->fs_info->disk_super,
-                                   root->fs_info->generation + 1);
+        if (cur_trans->list.prev != &root->fs_info->trans_list) {
+                prev_trans = list_entry(cur_trans->list.prev,
+                                        struct btrfs_transaction, list);
+                if (prev_trans->commit_done)
+                        prev_trans = NULL;
+                else
+                        prev_trans->use_count++;
+        }
         mutex_unlock(&root->fs_info->trans_mutex);
+        mutex_unlock(&root->fs_info->fs_mutex);
         ret = btrfs_write_and_wait_transaction(trans, root);
+        if (prev_trans) {
+                mutex_lock(&root->fs_info->trans_mutex);
+                wait_for_commit(root, prev_trans);
+                put_transaction(prev_trans);
+                mutex_unlock(&root->fs_info->trans_mutex);
+        }
+        btrfs_set_super_generation(root->fs_info->disk_super,
+                                   cur_trans->transid);
         BUG_ON(ret);
-
         write_ctree_super(trans, root);
+
+        mutex_lock(&root->fs_info->fs_mutex);
         btrfs_finish_extent_commit(trans, root);
         mutex_lock(&root->fs_info->trans_mutex);
         cur_trans->commit_done = 1;
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 4f1496ae6f24..3cc29900a074 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -8,6 +8,7 @@ struct btrfs_transaction {
         int use_count;
         int commit_done;
         int magic;
+        struct list_head list;
         wait_queue_head_t writer_wait;
         wait_queue_head_t commit_wait;
 };