Btrfs: Replace the transaction work queue with kthreads

This creates one kthread for commits and one kthread for
deleting old snapshots.  All the work queues are removed.

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

8 files changed, 136 insertions, 118 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 5edbcc09b3cc..40f0e0cb804b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1352,6 +1352,8 @@ again:
                                                 free_extent_buffer(tmp);
                                         goto again;
                                 } else {
+                                        if (tmp)
+                                                free_extent_buffer(tmp);
                                         b = read_node_slot(root, b, slot);
                                 }
                         }
@@ -3048,7 +3050,8 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
                 free_extent_buffer(c);
                 path->nodes[level] = next;
                 path->slots[level] = 0;
-                path->locks[level] = 1;
+                if (!path->skip_locking)
+                        path->locks[level] = 1;
                 if (!level)
                         break;
                 if (level == 1 && path->locks[1] && path->reada)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e9bbb53eda63..244fe86bcc55 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -23,7 +23,6 @@
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/fs.h>
-#include <linux/workqueue.h>
 #include <linux/completion.h>
 #include <linux/backing-dev.h>
 #include <asm/kmap_types.h>
@@ -519,15 +518,14 @@ struct btrfs_fs_info {
         struct backing_dev_info bdi;
         spinlock_t hash_lock;
         struct mutex trans_mutex;
+        struct mutex transaction_kthread_mutex;
+        struct mutex cleaner_mutex;
         struct mutex alloc_mutex;
         struct mutex chunk_mutex;
         struct mutex drop_mutex;
         struct list_head trans_list;
         struct list_head hashers;
         struct list_head dead_roots;
-        struct list_head end_io_work_list;
-        struct work_struct end_io_work;
-        spinlock_t end_io_work_lock;
         atomic_t nr_async_submits;
 
         /*
@@ -543,13 +541,10 @@ struct btrfs_fs_info {
         struct btrfs_workers workers;
         struct btrfs_workers endio_workers;
         struct btrfs_workers submit_workers;
+        struct task_struct *transaction_kthread;
+        struct task_struct *cleaner_kthread;
         int thread_pool_size;
 
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
-        struct work_struct trans_work;
-#else
-        struct delayed_work trans_work;
-#endif
         struct kobject super_kobj;
         struct completion kobj_unregister;
         int do_barriers;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 52569b57692d..31ca9f89388d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -16,6 +16,7 @@
  * Boston, MA 021110-1307, USA.
  */
 
+#include <linux/version.h>
 #include <linux/fs.h>
 #include <linux/blkdev.h>
 #include <linux/scatterlist.h>
@@ -24,6 +25,12 @@
 #include <linux/writeback.h>
 #include <linux/buffer_head.h> // for block_sync_page
 #include <linux/workqueue.h>
+#include <linux/kthread.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,20)
+# include <linux/freezer.h>
+#else
+# include <linux/sched.h>
+#endif
 #include "crc32c.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -1100,6 +1107,87 @@ static void end_workqueue_fn(struct btrfs_work *work)
 #endif
 }
 
+static int cleaner_kthread(void *arg)
+{
+        struct btrfs_root *root = arg;
+
+        do {
+                smp_mb();
+                if (root->fs_info->closing)
+                        break;
+
+                vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
+                mutex_lock(&root->fs_info->cleaner_mutex);
+printk("cleaner awake\n");
+                btrfs_clean_old_snapshots(root);
+printk("cleaner done\n");
+                mutex_unlock(&root->fs_info->cleaner_mutex);
+
+                if (freezing(current)) {
+                        refrigerator();
+                } else {
+                        smp_mb();
+                        if (root->fs_info->closing)
+                                break;
+                        set_current_state(TASK_INTERRUPTIBLE);
+                        schedule();
+                        __set_current_state(TASK_RUNNING);
+                }
+        } while (!kthread_should_stop());
+        return 0;
+}
+
+static int transaction_kthread(void *arg)
+{
+        struct btrfs_root *root = arg;
+        struct btrfs_trans_handle *trans;
+        struct btrfs_transaction *cur;
+        unsigned long now;
+        unsigned long delay;
+        int ret;
+
+        do {
+                smp_mb();
+                if (root->fs_info->closing)
+                        break;
+
+                delay = HZ * 30;
+                vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
+                mutex_lock(&root->fs_info->transaction_kthread_mutex);
+
+                mutex_lock(&root->fs_info->trans_mutex);
+                cur = root->fs_info->running_transaction;
+                if (!cur) {
+                        mutex_unlock(&root->fs_info->trans_mutex);
+                        goto sleep;
+                }
+                now = get_seconds();
+                if (now < cur->start_time || now - cur->start_time < 30) {
+                        mutex_unlock(&root->fs_info->trans_mutex);
+                        delay = HZ * 5;
+                        goto sleep;
+                }
+                mutex_unlock(&root->fs_info->trans_mutex);
+                btrfs_defrag_dirty_roots(root->fs_info);
+                trans = btrfs_start_transaction(root, 1);
+                ret = btrfs_commit_transaction(trans, root);
+sleep:
+                wake_up_process(root->fs_info->cleaner_kthread);
+                mutex_unlock(&root->fs_info->transaction_kthread_mutex);
+
+                if (freezing(current)) {
+                        refrigerator();
+                } else {
+                        if (root->fs_info->closing)
+                                break;
+                        set_current_state(TASK_INTERRUPTIBLE);
+                        schedule_timeout(delay);
+                        __set_current_state(TASK_RUNNING);
+                }
+        } while (!kthread_should_stop());
+        return 0;
+}
+
 struct btrfs_root *open_ctree(struct super_block *sb,
                               struct btrfs_fs_devices *fs_devices,
                               char *options)
@@ -1189,11 +1277,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                              fs_info->btree_inode->i_mapping, GFP_NOFS);
         fs_info->do_barriers = 1;
 
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
-        INIT_WORK(&fs_info->trans_work, btrfs_transaction_cleaner, fs_info);
-#else
-        INIT_DELAYED_WORK(&fs_info->trans_work, btrfs_transaction_cleaner);
-#endif
         BTRFS_I(fs_info->btree_inode)->root = tree_root;
         memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
                sizeof(struct btrfs_key));
@@ -1204,6 +1287,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         mutex_init(&fs_info->drop_mutex);
         mutex_init(&fs_info->alloc_mutex);
         mutex_init(&fs_info->chunk_mutex);
+        mutex_init(&fs_info->transaction_kthread_mutex);
+        mutex_init(&fs_info->cleaner_mutex);
 
 #if 0
         ret = add_hasher(fs_info, "crc32c");
@@ -1247,7 +1332,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         btrfs_start_workers(&fs_info->submit_workers, 1);
         btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
 
-
         err = -EINVAL;
         if (btrfs_super_num_devices(disk_super) > fs_devices->open_devices) {
                 printk("Btrfs: wanted %llu devices, but found %llu\n",
@@ -1341,9 +1425,22 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         fs_info->data_alloc_profile = (u64)-1;
         fs_info->metadata_alloc_profile = (u64)-1;
         fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
+        fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
+                                               "btrfs-cleaner");
+        if (!fs_info->cleaner_kthread)
+                goto fail_extent_root;
+
+        fs_info->transaction_kthread = kthread_run(transaction_kthread,
+                                                   tree_root,
+                                                   "btrfs-transaction");
+        if (!fs_info->transaction_kthread)
+                goto fail_trans_kthread;
+
 
         return tree_root;
 
+fail_trans_kthread:
+        kthread_stop(fs_info->cleaner_kthread);
 fail_extent_root:
         free_extent_buffer(extent_root->node);
 fail_tree_root:
@@ -1562,8 +1659,11 @@ int close_ctree(struct btrfs_root *root)
         fs_info->closing = 1;
         smp_mb();
 
-        btrfs_transaction_flush_work(root);
+        kthread_stop(root->fs_info->transaction_kthread);
+        kthread_stop(root->fs_info->cleaner_kthread);
+
         btrfs_defrag_dirty_roots(root->fs_info);
+        btrfs_clean_old_snapshots(root);
         trans = btrfs_start_transaction(root, 1);
         ret = btrfs_commit_transaction(trans, root);
         /* run commit again to  drop the original snapshot */
@@ -1574,8 +1674,6 @@ int close_ctree(struct btrfs_root *root)
 
         write_ctree_super(NULL, root);
 
-        btrfs_transaction_flush_work(root);
-
         if (fs_info->delalloc_bytes) {
                 printk("btrfs: at unmount delalloc count %Lu\n",
                        fs_info->delalloc_bytes);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6274f30031db..89cc4f611869 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1216,15 +1216,16 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
         if (ret == -ENOSPC) {
 printk("space info full %Lu\n", flags);
                 space_info->full = 1;
-                goto out;
+                goto out_unlock;
         }
         BUG_ON(ret);
 
         ret = btrfs_make_block_group(trans, extent_root, 0, flags,
                      BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes);
         BUG_ON(ret);
-out:
+out_unlock:
         mutex_unlock(&extent_root->fs_info->chunk_mutex);
+out:
         return 0;
 }
 
@@ -2274,7 +2275,8 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
                         free_extent_buffer(next);
                         mutex_unlock(&root->fs_info->alloc_mutex);
 
-                        reada_walk_down(root, cur, path->slots[*level]);
+                        if (path->slots[*level] == 0)
+                                reada_walk_down(root, cur, path->slots[*level]);
 
                         next = read_tree_block(root, bytenr, blocksize,
                                                ptr_gen);
@@ -2446,8 +2448,6 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
                         break;
                 if (wret < 0)
                         ret = wret;
-                ret = -EAGAIN;
-                break;
         }
         for (i = 0; i <= orig_level; i++) {
                 if (path->nodes[i]) {
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b61ded7a20c9..726d6871fa13 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -340,7 +340,6 @@ static int btrfs_fill_super(struct super_block * sb,
                 goto fail_close;
 
         sb->s_root = root_dentry;
-        btrfs_transaction_queue_work(tree_root, HZ * 30);
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,25)
         save_mount_options(sb, data);
@@ -416,9 +415,7 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
                 goto error_free_subvol_name;
 
         bdev = fs_devices->latest_bdev;
-        btrfs_lock_volumes();
         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
-        btrfs_unlock_volumes();
         if (IS_ERR(s))
                 goto error_s;
 
@@ -530,13 +527,15 @@ out:
 static void btrfs_write_super_lockfs(struct super_block *sb)
 {
         struct btrfs_root *root = btrfs_sb(sb);
-        btrfs_transaction_flush_work(root);
+        mutex_lock(&root->fs_info->transaction_kthread_mutex);
+        mutex_lock(&root->fs_info->cleaner_mutex);
 }
 
 static void btrfs_unlockfs(struct super_block *sb)
 {
         struct btrfs_root *root = btrfs_sb(sb);
-        btrfs_transaction_queue_work(root, HZ * 30);
+        mutex_unlock(&root->fs_info->cleaner_mutex);
+        mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 }
 
 static struct super_operations btrfs_super_ops = {
@@ -589,10 +588,9 @@ static int __init init_btrfs_fs(void)
         if (err)
                 return err;
 
-        btrfs_init_transaction_sys();
         err = btrfs_init_cachep();
         if (err)
-                goto free_transaction_sys;
+                goto free_sysfs;
 
         err = extent_io_init();
         if (err)
@@ -618,15 +616,13 @@ free_extent_io:
         extent_io_exit();
 free_cachep:
         btrfs_destroy_cachep();
-free_transaction_sys:
-        btrfs_exit_transaction_sys();
+free_sysfs:
         btrfs_exit_sysfs();
         return err;
 }
 
 static void __exit exit_btrfs_fs(void)
 {
-        btrfs_exit_transaction_sys();
         btrfs_destroy_cachep();
         extent_map_exit();
         extent_io_exit();
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 69ed5f85a387..0c53ff775b92 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -29,8 +29,6 @@ static int total_trans = 0;
 extern struct kmem_cache *btrfs_trans_handle_cachep;
 extern struct kmem_cache *btrfs_transaction_cachep;
 
-static struct workqueue_struct *trans_wq;
-
 #define BTRFS_ROOT_TRANS_TAG 0
 #define BTRFS_ROOT_DEFRAG_TAG 1
 
@@ -807,81 +805,15 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root)
 {
         struct list_head dirty_roots;
         INIT_LIST_HEAD(&dirty_roots);
-
+again:
         mutex_lock(&root->fs_info->trans_mutex);
         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
         mutex_unlock(&root->fs_info->trans_mutex);
 
         if (!list_empty(&dirty_roots)) {
                 drop_dirty_roots(root, &dirty_roots);
+                goto again;
         }
         return 0;
 }
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
-void btrfs_transaction_cleaner(void *p)
-#else
-void btrfs_transaction_cleaner(struct work_struct *work)
-#endif
-{
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
-        struct btrfs_fs_info *fs_info = p;
-#else
-        struct btrfs_fs_info *fs_info = container_of(work,
-                                                     struct btrfs_fs_info,
-                                                     trans_work.work);
-
-#endif
-        struct btrfs_root *root = fs_info->tree_root;
-        struct btrfs_transaction *cur;
-        struct btrfs_trans_handle *trans;
-        unsigned long now;
-        unsigned long delay = HZ * 30;
-        int ret;
-
-        smp_mb();
-        if (root->fs_info->closing)
-                goto out;
-
-        mutex_lock(&root->fs_info->trans_mutex);
-        cur = root->fs_info->running_transaction;
-        if (!cur) {
-                mutex_unlock(&root->fs_info->trans_mutex);
-                goto out;
-        }
-        now = get_seconds();
-        if (now < cur->start_time || now - cur->start_time < 30) {
-                mutex_unlock(&root->fs_info->trans_mutex);
-                delay = HZ * 5;
-                goto out;
-        }
-        mutex_unlock(&root->fs_info->trans_mutex);
-        btrfs_defrag_dirty_roots(root->fs_info);
-        trans = btrfs_start_transaction(root, 1);
-        ret = btrfs_commit_transaction(trans, root);
-out:
-        btrfs_clean_old_snapshots(root);
-        btrfs_transaction_queue_work(root, delay);
-}
-
-void btrfs_transaction_queue_work(struct btrfs_root *root, int delay)
-{
-        if (!root->fs_info->closing)
-                queue_delayed_work(trans_wq, &root->fs_info->trans_work, delay);
-}
-
-void btrfs_transaction_flush_work(struct btrfs_root *root)
-{
-        cancel_delayed_work(&root->fs_info->trans_work);
-        flush_workqueue(trans_wq);
-}
-
-void __init btrfs_init_transaction_sys(void)
-{
-        trans_wq = create_workqueue("btrfs-transaction");
-}
-
-void btrfs_exit_transaction_sys(void)
-{
-        destroy_workqueue(trans_wq);
-}
 
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 52559b51b181..e1e5a06b65f4 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -82,16 +82,6 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root);
 
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
-void btrfs_transaction_cleaner(void *p);
-#else
-void btrfs_transaction_cleaner(struct work_struct *work);
-#endif
-
-void btrfs_transaction_flush_work(struct btrfs_root *root);
-void btrfs_transaction_queue_work(struct btrfs_root *root, int delay);
-void btrfs_init_transaction_sys(void);
-void btrfs_exit_transaction_sys(void);
 int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest,
                         struct list_head *dead_list);
 int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 869864ddcc29..4e7cee27aab5 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -271,13 +271,17 @@ again:
         list_for_each(cur, head) {
                 device = list_entry(cur, struct btrfs_device, dev_list);
                 if (!device->in_fs_metadata) {
-                        if (device->bdev) {
-                                close_bdev_excl(device->bdev);
-                                fs_devices->open_devices--;
-                        }
+                        struct block_device *bdev;
                         list_del(&device->dev_list);
                         list_del(&device->dev_alloc_list);
                         fs_devices->num_devices--;
+                        if (device->bdev) {
+                                bdev = device->bdev;
+                                fs_devices->open_devices--;
+                                mutex_unlock(&uuid_mutex);
+                                close_bdev_excl(bdev);
+                                mutex_lock(&uuid_mutex);
+                        }
                         kfree(device->name);
                         kfree(device);
                         goto again;