Btrfs: add balance progress reporting

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

4 files changed, 84 insertions, 5 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 85e546ffe3c7..1e7a9bac31ab 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3065,7 +3065,7 @@ out:
         return ret;
 }
 
-void update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
+void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
                                struct btrfs_ioctl_balance_args *bargs)
 {
         struct btrfs_balance_control *bctl = fs_info->balance_ctl;
@@ -3082,6 +3082,14 @@ void update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
         memcpy(&bargs->data, &bctl->data, sizeof(bargs->data));
         memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta));
         memcpy(&bargs->sys, &bctl->sys, sizeof(bargs->sys));
+
+        if (lock) {
+                spin_lock(&fs_info->balance_lock);
+                memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
+                spin_unlock(&fs_info->balance_lock);
+        } else {
+                memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
+        }
 }
 
 static long btrfs_ioctl_balance(struct btrfs_root *root, void __user *arg)
@@ -3181,6 +3189,39 @@ static long btrfs_ioctl_balance_ctl(struct btrfs_root *root, int cmd)
         return -EINVAL;
 }
 
+static long btrfs_ioctl_balance_progress(struct btrfs_root *root,
+                                         void __user *arg)
+{
+        struct btrfs_fs_info *fs_info = root->fs_info;
+        struct btrfs_ioctl_balance_args *bargs;
+        int ret = 0;
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        mutex_lock(&fs_info->balance_mutex);
+        if (!fs_info->balance_ctl) {
+                ret = -ENOTCONN;
+                goto out;
+        }
+
+        bargs = kzalloc(sizeof(*bargs), GFP_NOFS);
+        if (!bargs) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        update_ioctl_balance_args(fs_info, 1, bargs);
+
+        if (copy_to_user(arg, bargs, sizeof(*bargs)))
+                ret = -EFAULT;
+
+        kfree(bargs);
+out:
+        mutex_unlock(&fs_info->balance_mutex);
+        return ret;
+}
+
 long btrfs_ioctl(struct file *file, unsigned int
                 cmd, unsigned long arg)
 {
@@ -3261,6 +3302,8 @@ long btrfs_ioctl(struct file *file, unsigned int
                 return btrfs_ioctl_balance(root, argp);
         case BTRFS_IOC_BALANCE_CTL:
                 return btrfs_ioctl_balance_ctl(root, arg);
+        case BTRFS_IOC_BALANCE_PROGRESS:
+                return btrfs_ioctl_balance_progress(root, argp);
         }
 
         return -ENOTTY;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index cd19d10794b9..4f69028a68c4 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -324,6 +324,8 @@ struct btrfs_ioctl_logical_ino_args {
 #define BTRFS_IOC_BALANCE_V2 _IOWR(BTRFS_IOCTL_MAGIC, 32, \
                                    struct btrfs_ioctl_balance_args)
 #define BTRFS_IOC_BALANCE_CTL _IOW(BTRFS_IOCTL_MAGIC, 33, int)
+#define BTRFS_IOC_BALANCE_PROGRESS _IOR(BTRFS_IOCTL_MAGIC, 34, \
+                                        struct btrfs_ioctl_balance_args)
 #define BTRFS_IOC_INO_PATHS _IOWR(BTRFS_IOCTL_MAGIC, 35, \
                                         struct btrfs_ioctl_ino_path_args)
 #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c32667318ae4..d73439b4d7da 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2441,6 +2441,7 @@ static u64 div_factor(u64 num, int factor)
 
 static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 {
+        struct btrfs_balance_control *bctl = fs_info->balance_ctl;
         struct btrfs_root *chunk_root = fs_info->chunk_root;
         struct btrfs_root *dev_root = fs_info->dev_root;
         struct list_head *devices;
@@ -2456,6 +2457,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
         int slot;
         int ret;
         int enospc_errors = 0;
+        bool counting = true;
 
         /* step one make some room on all the devices */
         devices = &fs_info->fs_devices->devices;
@@ -2487,12 +2489,18 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
                 ret = -ENOMEM;
                 goto error;
         }
+
+        /* zero out stat counters */
+        spin_lock(&fs_info->balance_lock);
+        memset(&bctl->stat, 0, sizeof(bctl->stat));
+        spin_unlock(&fs_info->balance_lock);
+again:
         key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
         key.offset = (u64)-1;
         key.type = BTRFS_CHUNK_ITEM_KEY;
 
         while (1) {
-                if (atomic_read(&fs_info->balance_pause_req) ||
+                if ((!counting && atomic_read(&fs_info->balance_pause_req)) ||
                     atomic_read(&fs_info->balance_cancel_req)) {
                         ret = -ECANCELED;
                         goto error;
@@ -2529,24 +2537,47 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 
                 chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
 
+                if (!counting) {
+                        spin_lock(&fs_info->balance_lock);
+                        bctl->stat.considered++;
+                        spin_unlock(&fs_info->balance_lock);
+                }
+
                 ret = should_balance_chunk(chunk_root, leaf, chunk,
                                            found_key.offset);
                 btrfs_release_path(path);
                 if (!ret)
                         goto loop;
 
+                if (counting) {
+                        spin_lock(&fs_info->balance_lock);
+                        bctl->stat.expected++;
+                        spin_unlock(&fs_info->balance_lock);
+                        goto loop;
+                }
+
                 ret = btrfs_relocate_chunk(chunk_root,
                                            chunk_root->root_key.objectid,
                                            found_key.objectid,
                                            found_key.offset);
                 if (ret && ret != -ENOSPC)
                         goto error;
-                if (ret == -ENOSPC)
+                if (ret == -ENOSPC) {
                         enospc_errors++;
+                } else {
+                        spin_lock(&fs_info->balance_lock);
+                        bctl->stat.completed++;
+                        spin_unlock(&fs_info->balance_lock);
+                }
 loop:
                 key.offset = found_key.offset - 1;
         }
 
+        if (counting) {
+                btrfs_release_path(path);
+                counting = false;
+                goto again;
+        }
 error:
         btrfs_free_path(path);
         if (enospc_errors) {
@@ -2576,7 +2607,7 @@ static void __cancel_balance(struct btrfs_fs_info *fs_info)
         BUG_ON(ret);
 }
 
-void update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
+void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
                                struct btrfs_ioctl_balance_args *bargs);
 
 /*
@@ -2706,7 +2737,7 @@ do_balance:
 
         if (bargs) {
                 memset(bargs, 0, sizeof(*bargs));
-                update_ioctl_balance_args(fs_info, bargs);
+                update_ioctl_balance_args(fs_info, 0, bargs);
         }
 
         if ((ret && ret != -ECANCELED && ret != -ENOSPC) ||
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index caa9abd218ef..6faec9dd1f93 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -218,6 +218,7 @@ struct map_lookup {
 #define BTRFS_BALANCE_ARGS_SOFT         (1ULL << 9)
 
 struct btrfs_balance_args;
+struct btrfs_balance_progress;
 struct btrfs_balance_control {
         struct btrfs_fs_info *fs_info;
 
@@ -226,6 +227,8 @@ struct btrfs_balance_control {
         struct btrfs_balance_args sys;
 
         u64 flags;
+
+        struct btrfs_balance_progress stat;
 };
 
 int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,