1 files changed, 17 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 3c5f2fcd82c1..a595f8775c37 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -517,6 +517,9 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                         fs_devices->rw_devices--;
                 }
 
+                if (device->can_discard)
+                        fs_devices->num_can_discard--;
+
                 new_device = kmalloc(sizeof(*new_device), GFP_NOFS);
                 BUG_ON(!new_device);
                 memcpy(new_device, device, sizeof(*new_device));
@@ -525,6 +528,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                 new_device->bdev = NULL;
                 new_device->writeable = 0;
                 new_device->in_fs_metadata = 0;
+                new_device->can_discard = 0;
                 list_replace_rcu(&device->dev_list, &new_device->dev_list);
 
                 call_rcu(&device->rcu, free_device);
@@ -564,6 +568,7 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                                 fmode_t flags, void *holder)
 {
+        struct request_queue *q;
         struct block_device *bdev;
         struct list_head *head = &fs_devices->devices;
         struct btrfs_device *device;
@@ -620,6 +625,12 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                         seeding = 0;
                 }
 
+                q = bdev_get_queue(bdev);
+                if (blk_queue_discard(q)) {
+                        device->can_discard = 1;
+                        fs_devices->num_can_discard++;
+                }
+
                 device->bdev = bdev;
                 device->in_fs_metadata = 0;
                 device->mode = flags;
@@ -1560,6 +1571,7 @@ error:
 
 int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 {
+        struct request_queue *q;
         struct btrfs_trans_handle *trans;
         struct btrfs_device *device;
         struct block_device *bdev;
@@ -1629,6 +1641,9 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 
         lock_chunks(root);
 
+        q = bdev_get_queue(bdev);
+        if (blk_queue_discard(q))
+                device->can_discard = 1;
         device->writeable = 1;
         device->work.func = pending_bios_fn;
         generate_random_uuid(device->uuid);
@@ -1664,6 +1679,8 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         root->fs_info->fs_devices->num_devices++;
         root->fs_info->fs_devices->open_devices++;
         root->fs_info->fs_devices->rw_devices++;
+        if (device->can_discard)
+                root->fs_info->fs_devices->num_can_discard++;
         root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;
 
         if (!blk_queue_nonrot(bdev_get_queue(bdev)))