Btrfs: add btrfs_alloc_device and switch to it

Currently btrfs_device is allocated ad-hoc in a few different places,
and as a result not all fields are initialized properly.  In particular,
readahead state is only initialized in device_list_add (at scan time),
and not in btrfs_init_new_device (when the new device is added with
'btrfs dev add').  Fix this by adding an allocation helper and switch
everybody but __btrfs_close_devices to it.  (__btrfs_close_devices is
dealt with in a later commit.)

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

2 files changed, 97 insertions, 57 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9b3595e370f8..4bc07d910e54 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -102,6 +102,27 @@ void btrfs_cleanup_fs_uuids(void)
         }
 }
 
+static struct btrfs_device *__alloc_device(void)
+{
+        struct btrfs_device *dev;
+
+        dev = kzalloc(sizeof(*dev), GFP_NOFS);
+        if (!dev)
+                return ERR_PTR(-ENOMEM);
+
+        INIT_LIST_HEAD(&dev->dev_list);
+        INIT_LIST_HEAD(&dev->dev_alloc_list);
+
+        spin_lock_init(&dev->io_lock);
+
+        spin_lock_init(&dev->reada_lock);
+        atomic_set(&dev->reada_in_flight, 0);
+        INIT_RADIX_TREE(&dev->reada_zones, GFP_NOFS & ~__GFP_WAIT);
+        INIT_RADIX_TREE(&dev->reada_extents, GFP_NOFS & ~__GFP_WAIT);
+
+        return dev;
+}
+
 static noinline struct btrfs_device *__find_device(struct list_head *head,
                                                    u64 devid, u8 *uuid)
 {
@@ -415,17 +436,12 @@ static noinline int device_list_add(const char *path,
                 if (fs_devices->opened)
                         return -EBUSY;
 
-                device = kzalloc(sizeof(*device), GFP_NOFS);
-                if (!device) {
+                device = btrfs_alloc_device(NULL, &devid,
+                                            disk_super->dev_item.uuid);
+                if (IS_ERR(device)) {
                         /* we can safely leave the fs_devices entry around */
-                        return -ENOMEM;
+                        return PTR_ERR(device);
                 }
-                device->devid = devid;
-                device->dev_stats_valid = 0;
-                device->work.func = pending_bios_fn;
-                memcpy(device->uuid, disk_super->dev_item.uuid,
-                       BTRFS_UUID_SIZE);
-                spin_lock_init(&device->io_lock);
 
                 name = rcu_string_strdup(path, GFP_NOFS);
                 if (!name) {
@@ -433,15 +449,6 @@ static noinline int device_list_add(const char *path,
                         return -ENOMEM;
                 }
                 rcu_assign_pointer(device->name, name);
-                INIT_LIST_HEAD(&device->dev_alloc_list);
-
-                /* init readahead state */
-                spin_lock_init(&device->reada_lock);
-                device->reada_curr_zone = NULL;
-                atomic_set(&device->reada_in_flight, 0);
-                device->reada_next = 0;
-                INIT_RADIX_TREE(&device->reada_zones, GFP_NOFS & ~__GFP_WAIT);
-                INIT_RADIX_TREE(&device->reada_extents, GFP_NOFS & ~__GFP_WAIT);
 
                 mutex_lock(&fs_devices->device_list_mutex);
                 list_add_rcu(&device->dev_list, &fs_devices->devices);
@@ -492,8 +499,9 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
         list_for_each_entry(orig_dev, &orig->devices, dev_list) {
                 struct rcu_string *name;
 
-                device = kzalloc(sizeof(*device), GFP_NOFS);
-                if (!device)
+                device = btrfs_alloc_device(NULL, &orig_dev->devid,
+                                            orig_dev->uuid);
+                if (IS_ERR(device))
                         goto error;
 
                 /*
@@ -507,13 +515,6 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
                 }
                 rcu_assign_pointer(device->name, name);
 
-                device->devid = orig_dev->devid;
-                device->work.func = pending_bios_fn;
-                memcpy(device->uuid, orig_dev->uuid, sizeof(device->uuid));
-                spin_lock_init(&device->io_lock);
-                INIT_LIST_HEAD(&device->dev_list);
-                INIT_LIST_HEAD(&device->dev_alloc_list);
-
                 list_add(&device->dev_list, &fs_devices->devices);
                 device->fs_devices = fs_devices;
                 fs_devices->num_devices++;
@@ -1959,10 +1960,10 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         }
         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
 
-        device = kzalloc(sizeof(*device), GFP_NOFS);
-        if (!device) {
+        device = btrfs_alloc_device(root->fs_info, NULL, NULL);
+        if (IS_ERR(device)) {
                 /* we can safely leave the fs_devices entry around */
-                ret = -ENOMEM;
+                ret = PTR_ERR(device);
                 goto error;
         }
 
@@ -1974,13 +1975,6 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         }
         rcu_assign_pointer(device->name, name);
 
-        ret = find_next_devid(root->fs_info, &device->devid);
-        if (ret) {
-                rcu_string_free(device->name);
-                kfree(device);
-                goto error;
-        }
-
         trans = btrfs_start_transaction(root, 0);
         if (IS_ERR(trans)) {
                 rcu_string_free(device->name);
@@ -1995,9 +1989,6 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         if (blk_queue_discard(q))
                 device->can_discard = 1;
         device->writeable = 1;
-        device->work.func = pending_bios_fn;
-        generate_random_uuid(device->uuid);
-        spin_lock_init(&device->io_lock);
         device->generation = trans->transid;
         device->io_width = root->sectorsize;
         device->io_align = root->sectorsize;
@@ -2124,6 +2115,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
         struct btrfs_fs_info *fs_info = root->fs_info;
         struct list_head *devices;
         struct rcu_string *name;
+        u64 devid = BTRFS_DEV_REPLACE_DEVID;
         int ret = 0;
 
         *device_out = NULL;
@@ -2145,9 +2137,9 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
                 }
         }
 
-        device = kzalloc(sizeof(*device), GFP_NOFS);
-        if (!device) {
-                ret = -ENOMEM;
+        device = btrfs_alloc_device(NULL, &devid, NULL);
+        if (IS_ERR(device)) {
+                ret = PTR_ERR(device);
                 goto error;
         }
 
@@ -2164,10 +2156,6 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
                 device->can_discard = 1;
         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
         device->writeable = 1;
-        device->work.func = pending_bios_fn;
-        generate_random_uuid(device->uuid);
-        device->devid = BTRFS_DEV_REPLACE_DEVID;
-        spin_lock_init(&device->io_lock);
         device->generation = 0;
         device->io_width = root->sectorsize;
         device->io_align = root->sectorsize;
@@ -5572,23 +5560,72 @@ static struct btrfs_device *add_missing_dev(struct btrfs_root *root,
         struct btrfs_device *device;
         struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
 
-        device = kzalloc(sizeof(*device), GFP_NOFS);
-        if (!device)
+        device = btrfs_alloc_device(NULL, &devid, dev_uuid);
+        if (IS_ERR(device))
                 return NULL;
-        list_add(&device->dev_list,
-                 &fs_devices->devices);
-        device->devid = devid;
-        device->work.func = pending_bios_fn;
+
+        list_add(&device->dev_list, &fs_devices->devices);
         device->fs_devices = fs_devices;
-        device->missing = 1;
         fs_devices->num_devices++;
+
+        device->missing = 1;
         fs_devices->missing_devices++;
-        spin_lock_init(&device->io_lock);
-        INIT_LIST_HEAD(&device->dev_alloc_list);
-        memcpy(device->uuid, dev_uuid, BTRFS_UUID_SIZE);
+
         return device;
 }
 
+/**
+ * btrfs_alloc_device - allocate struct btrfs_device
+ * @fs_info:    used only for generating a new devid, can be NULL if
+ *              devid is provided (i.e. @devid != NULL).
+ * @devid:      a pointer to devid for this device.  If NULL a new devid
+ *              is generated.
+ * @uuid:       a pointer to UUID for this device.  If NULL a new UUID
+ *              is generated.
+ *
+ * Return: a pointer to a new &struct btrfs_device on success; ERR_PTR()
+ * on error.  Returned struct is not linked onto any lists and can be
+ * destroyed with kfree() right away.
+ */
+struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
+                                        const u64 *devid,
+                                        const u8 *uuid)
+{
+        struct btrfs_device *dev;
+        u64 tmp;
+
+        if (!devid && !fs_info) {
+                WARN_ON(1);
+                return ERR_PTR(-EINVAL);
+        }
+
+        dev = __alloc_device();
+        if (IS_ERR(dev))
+                return dev;
+
+        if (devid)
+                tmp = *devid;
+        else {
+                int ret;
+
+                ret = find_next_devid(fs_info, &tmp);
+                if (ret) {
+                        kfree(dev);
+                        return ERR_PTR(ret);
+                }
+        }
+        dev->devid = tmp;
+
+        if (uuid)
+                memcpy(dev->uuid, uuid, BTRFS_UUID_SIZE);
+        else
+                generate_random_uuid(dev->uuid);
+
+        dev->work.func = pending_bios_fn;
+
+        return dev;
+}
+
 static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
                           struct extent_buffer *leaf,
                           struct btrfs_chunk *chunk)
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index d98b942c3896..b72f540c8b29 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -305,6 +305,9 @@ void btrfs_close_extra_devices(struct btrfs_fs_info *fs_info,
 int btrfs_find_device_missing_or_by_path(struct btrfs_root *root,
                                          char *device_path,
                                          struct btrfs_device **device);
+struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
+                                        const u64 *devid,
+                                        const u8 *uuid);
 int btrfs_rm_device(struct btrfs_root *root, char *device_path);
 void btrfs_cleanup_fs_uuids(void);
 int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len);