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>

1 files changed, 107 insertions, 9 deletions

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);