4 files changed, 124 insertions, 29 deletions

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 1be03d85d267..da7ac1432b15 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -418,7 +418,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
 
         /* the disk copy procedure reuses the scrub code */
         ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
-                              src_device->total_bytes,
+                              btrfs_device_get_total_bytes(src_device),
                               &dev_replace->scrub_progress, 0, 1);
 
         ret = btrfs_dev_replace_finishing(root->fs_info, ret);
@@ -555,11 +555,12 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
         memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
         memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
         memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
-        tgt_device->total_bytes = src_device->total_bytes;
-        tgt_device->disk_total_bytes = src_device->disk_total_bytes;
+        btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
+        btrfs_device_set_disk_total_bytes(tgt_device,
+                                          src_device->disk_total_bytes);
+        btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
         ASSERT(list_empty(&src_device->resized_list));
         tgt_device->commit_total_bytes = src_device->commit_total_bytes;
-        tgt_device->bytes_used = src_device->bytes_used;
         tgt_device->commit_bytes_used = src_device->bytes_used;
         if (fs_info->sb->s_bdev == src_device->bdev)
                 fs_info->sb->s_bdev = tgt_device->bdev;
@@ -650,6 +651,7 @@ void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
                               struct btrfs_ioctl_dev_replace_args *args)
 {
         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+        struct btrfs_device *srcdev;
 
         btrfs_dev_replace_lock(dev_replace);
         /* even if !dev_replace_is_valid, the values are good enough for
@@ -672,8 +674,9 @@ void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
                 break;
         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+                srcdev = dev_replace->srcdev;
                 args->status.progress_1000 = div64_u64(dev_replace->cursor_left,
-                        div64_u64(dev_replace->srcdev->total_bytes, 1000));
+                        div64_u64(btrfs_device_get_total_bytes(srcdev), 1000));
                 break;
         }
         btrfs_dev_replace_unlock(dev_replace);
@@ -832,7 +835,7 @@ static int btrfs_dev_replace_continue_on_mount(struct btrfs_fs_info *fs_info)
 
         ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
                               dev_replace->committed_cursor_left,
-                              dev_replace->srcdev->total_bytes,
+                              btrfs_device_get_total_bytes(dev_replace->srcdev),
                               &dev_replace->scrub_progress, 0, 1);
         ret = btrfs_dev_replace_finishing(fs_info, ret);
         WARN_ON(ret);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f60d1ca389f0..0ff212757b95 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1553,7 +1553,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
                 goto out_free;
         }
 
-        old_size = device->total_bytes;
+        old_size = btrfs_device_get_total_bytes(device);
 
         if (mod < 0) {
                 if (new_size > old_size) {
@@ -2740,8 +2740,8 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
         }
 
         di_args->devid = dev->devid;
-        di_args->bytes_used = dev->bytes_used;
-        di_args->total_bytes = dev->total_bytes;
+        di_args->bytes_used = btrfs_device_get_bytes_used(dev);
+        di_args->total_bytes = btrfs_device_get_total_bytes(dev);
         memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
         if (dev->name) {
                 struct rcu_string *name;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d8e4a3d1ad89..41da102cdcc0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1308,7 +1308,7 @@ again:
 
         if (device->bytes_used > 0) {
                 u64 len = btrfs_dev_extent_length(leaf, extent);
-                device->bytes_used -= len;
+                btrfs_device_set_bytes_used(device, device->bytes_used - len);
                 spin_lock(&root->fs_info->free_chunk_lock);
                 root->fs_info->free_chunk_space += len;
                 spin_unlock(&root->fs_info->free_chunk_lock);
@@ -1462,8 +1462,10 @@ static int btrfs_add_device(struct btrfs_trans_handle *trans,
         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
-        btrfs_set_device_total_bytes(leaf, dev_item, device->disk_total_bytes);
-        btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
+        btrfs_set_device_total_bytes(leaf, dev_item,
+                                     btrfs_device_get_disk_total_bytes(device));
+        btrfs_set_device_bytes_used(leaf, dev_item,
+                                    btrfs_device_get_bytes_used(device));
         btrfs_set_device_group(leaf, dev_item, 0);
         btrfs_set_device_seek_speed(leaf, dev_item, 0);
         btrfs_set_device_bandwidth(leaf, dev_item, 0);
@@ -2330,7 +2332,8 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
         }
 
 
-        if (i_size_read(bdev->bd_inode) < srcdev->total_bytes) {
+        if (i_size_read(bdev->bd_inode) <
+            btrfs_device_get_total_bytes(srcdev)) {
                 btrfs_err(fs_info, "target device is smaller than source device!");
                 ret = -EINVAL;
                 goto error;
@@ -2360,11 +2363,11 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
         device->io_width = root->sectorsize;
         device->io_align = root->sectorsize;
         device->sector_size = root->sectorsize;
-        device->total_bytes = srcdev->total_bytes;
-        device->disk_total_bytes = srcdev->disk_total_bytes;
+        device->total_bytes = btrfs_device_get_total_bytes(srcdev);
+        device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
+        device->bytes_used = btrfs_device_get_bytes_used(srcdev);
         ASSERT(list_empty(&srcdev->resized_list));
         device->commit_total_bytes = srcdev->commit_total_bytes;
-        device->bytes_used = srcdev->bytes_used;
         device->commit_bytes_used = device->bytes_used;
         device->dev_root = fs_info->dev_root;
         device->bdev = bdev;
@@ -2435,8 +2438,10 @@ static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
         btrfs_set_device_io_align(leaf, dev_item, device->io_align);
         btrfs_set_device_io_width(leaf, dev_item, device->io_width);
         btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
-        btrfs_set_device_total_bytes(leaf, dev_item, device->disk_total_bytes);
-        btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
+        btrfs_set_device_total_bytes(leaf, dev_item,
+                                     btrfs_device_get_disk_total_bytes(device));
+        btrfs_set_device_bytes_used(leaf, dev_item,
+                                    btrfs_device_get_bytes_used(device));
         btrfs_mark_buffer_dirty(leaf);
 
 out:
@@ -2464,8 +2469,8 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
         btrfs_set_super_total_bytes(super_copy, old_total + diff);
         device->fs_devices->total_rw_bytes += diff;
 
-        device->total_bytes = new_size;
-        device->disk_total_bytes = new_size;
+        btrfs_device_set_total_bytes(device, new_size);
+        btrfs_device_set_disk_total_bytes(device, new_size);
         btrfs_clear_space_info_full(device->dev_root->fs_info);
         if (list_empty(&device->resized_list))
                 list_add_tail(&device->resized_list,
@@ -3110,11 +3115,12 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
         /* step one make some room on all the devices */
         devices = &fs_info->fs_devices->devices;
         list_for_each_entry(device, devices, dev_list) {
-                old_size = device->total_bytes;
+                old_size = btrfs_device_get_total_bytes(device);
                 size_to_free = div_factor(old_size, 1);
                 size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
                 if (!device->writeable ||
-                    device->total_bytes - device->bytes_used > size_to_free ||
+                    btrfs_device_get_total_bytes(device) -
+                    btrfs_device_get_bytes_used(device) > size_to_free ||
                     device->is_tgtdev_for_dev_replace)
                         continue;
 
@@ -3920,8 +3926,8 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
         struct btrfs_key key;
         struct btrfs_super_block *super_copy = root->fs_info->super_copy;
         u64 old_total = btrfs_super_total_bytes(super_copy);
-        u64 old_size = device->total_bytes;
-        u64 diff = device->total_bytes - new_size;
+        u64 old_size = btrfs_device_get_total_bytes(device);
+        u64 diff = old_size - new_size;
 
         if (device->is_tgtdev_for_dev_replace)
                 return -EINVAL;
@@ -3934,7 +3940,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 
         lock_chunks(root);
 
-        device->total_bytes = new_size;
+        btrfs_device_set_total_bytes(device, new_size);
         if (device->writeable) {
                 device->fs_devices->total_rw_bytes -= diff;
                 spin_lock(&root->fs_info->free_chunk_lock);
@@ -4000,7 +4006,7 @@ again:
                 ret = -ENOSPC;
                 lock_chunks(root);
 
-                device->total_bytes = old_size;
+                btrfs_device_set_total_bytes(device, old_size);
                 if (device->writeable)
                         device->fs_devices->total_rw_bytes += diff;
                 spin_lock(&root->fs_info->free_chunk_lock);
@@ -4018,7 +4024,7 @@ again:
         }
 
         lock_chunks(root);
-        device->disk_total_bytes = new_size;
+        btrfs_device_set_disk_total_bytes(device, new_size);
         if (list_empty(&device->resized_list))
                 list_add_tail(&device->resized_list,
                               &root->fs_info->fs_devices->resized_devices);
@@ -4429,8 +4435,10 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         if (ret)
                 goto error_del_extent;
 
-        for (i = 0; i < map->num_stripes; i++)
-                map->stripes[i].dev->bytes_used += stripe_size;
+        for (i = 0; i < map->num_stripes; i++) {
+                num_bytes = map->stripes[i].dev->bytes_used + stripe_size;
+                btrfs_device_set_bytes_used(map->stripes[i].dev, num_bytes);
+        }
 
         spin_lock(&extent_root->fs_info->free_chunk_lock);
         extent_root->fs_info->free_chunk_space -= (stripe_size *
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index f79d532fedb0..76600a3fedbe 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -32,6 +32,19 @@ struct btrfs_pending_bios {
         struct bio *tail;
 };
 
+/*
+ * Use sequence counter to get consistent device stat data on
+ * 32-bit processors.
+ */
+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
+#include <linux/seqlock.h>
+#define __BTRFS_NEED_DEVICE_DATA_ORDERED
+#define btrfs_device_data_ordered_init(device)  \
+        seqcount_init(&device->data_seqcount)
+#else
+#define btrfs_device_data_ordered_init(device) do { } while (0)
+#endif
+
 struct btrfs_device {
         struct list_head dev_list;
         struct list_head dev_alloc_list;
@@ -61,6 +74,10 @@ struct btrfs_device {
         int can_discard;
         int is_tgtdev_for_dev_replace;
 
+#ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED
+        seqcount_t data_seqcount;
+#endif
+
         /* the internal btrfs device id */
         u64 devid;
 
@@ -133,6 +150,73 @@ struct btrfs_device {
         atomic_t dev_stat_values[BTRFS_DEV_STAT_VALUES_MAX];
 };
 
+/*
+ * If we read those variants at the context of their own lock, we needn't
+ * use the following helpers, reading them directly is safe.
+ */
+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
+#define BTRFS_DEVICE_GETSET_FUNCS(name)                                 \
+static inline u64                                                       \
+btrfs_device_get_##name(const struct btrfs_device *dev)                 \
+{                                                                       \
+        u64 size;                                                       \
+        unsigned int seq;                                               \
+                                                                        \
+        do {                                                            \
+                seq = read_seqcount_begin(&dev->data_seqcount);         \
+                size = dev->name;                                       \
+        } while (read_seqcount_retry(&dev->data_seqcount, seq));        \
+        return size;                                                    \
+}                                                                       \
+                                                                        \
+static inline void                                                      \
+btrfs_device_set_##name(struct btrfs_device *dev, u64 size)             \
+{                                                                       \
+        preempt_disable();                                              \
+        write_seqcount_begin(&dev->data_seqcount);                      \
+        dev->name = size;                                               \
+        write_seqcount_end(&dev->data_seqcount);                        \
+        preempt_enable();                                               \
+}
+#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
+#define BTRFS_DEVICE_GETSET_FUNCS(name)                                 \
+static inline u64                                                       \
+btrfs_device_get_##name(const struct btrfs_device *dev)                 \
+{                                                                       \
+        u64 size;                                                       \
+                                                                        \
+        preempt_disable();                                              \
+        size = dev->name;                                               \
+        preempt_enable();                                               \
+        return size;                                                    \
+}                                                                       \
+                                                                        \
+static inline void                                                      \
+btrfs_device_set_##name(struct btrfs_device *dev, u64 size)             \
+{                                                                       \
+        preempt_disable();                                              \
+        dev->name = size;                                               \
+        preempt_enable();                                               \
+}
+#else
+#define BTRFS_DEVICE_GETSET_FUNCS(name)                                 \
+static inline u64                                                       \
+btrfs_device_get_##name(const struct btrfs_device *dev)                 \
+{                                                                       \
+        return dev->name;                                               \
+}                                                                       \
+                                                                        \
+static inline void                                                      \
+btrfs_device_set_##name(struct btrfs_device *dev, u64 size)             \
+{                                                                       \
+        dev->name = size;                                               \
+}
+#endif
+
+BTRFS_DEVICE_GETSET_FUNCS(total_bytes);
+BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
+BTRFS_DEVICE_GETSET_FUNCS(bytes_used);
+
 struct btrfs_fs_devices {
         u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */