From: Michal Rostecki <mroste...@suse.com>

Add the btrfs_check_mixed() function which checks if the filesystem has
the mixed type of devices (non-rotational and rotational). This
information is going to be used in roundrobin raid1 read policy.

Signed-off-by: Michal Rostecki <mroste...@suse.com>
---
 fs/btrfs/volumes.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
 fs/btrfs/volumes.h |  7 +++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1ac364a2f105..1ad30a595722 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -617,6 +617,35 @@ static int btrfs_free_stale_devices(const char *path,
        return ret;
 }
 
+/*
+ * Checks if after adding the new device the filesystem is going to have mixed
+ * types of devices (non-rotational and rotational).
+ *
+ * @fs_devices:          list of devices
+ * @new_device_rotating: if the new device is rotational
+ *
+ * Returns true if there are mixed types of devices, otherwise returns false.
+ */
+static bool btrfs_check_mixed(struct btrfs_fs_devices *fs_devices,
+                             bool new_device_rotating)
+{
+       struct btrfs_device *device, *prev_device;
+
+       list_for_each_entry(device, &fs_devices->devices, dev_list) {
+               if (prev_device == NULL &&
+                   device->rotating != new_device_rotating)
+                       return true;
+               if (prev_device != NULL &&
+                   (device->rotating != prev_device->rotating ||
+                    device->rotating != new_device_rotating))
+                       return true;
+
+               prev_device = device;
+       }
+
+       return false;
+}
+
 /*
  * This is only used on mount, and we are protected from competing things
  * messing with our fs_devices by the uuid_mutex, thus we do not need the
@@ -629,6 +658,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices 
*fs_devices,
        struct request_queue *q;
        struct block_device *bdev;
        struct btrfs_super_block *disk_super;
+       bool rotating;
        u64 devid;
        int ret;
 
@@ -669,8 +699,12 @@ static int btrfs_open_one_device(struct btrfs_fs_devices 
*fs_devices,
        }
 
        q = bdev_get_queue(bdev);
-       if (!blk_queue_nonrot(q))
+       rotating = !blk_queue_nonrot(q);
+       device->rotating = rotating;
+       if (rotating)
                fs_devices->rotating = true;
+       if (!fs_devices->mixed)
+               fs_devices->mixed = btrfs_check_mixed(fs_devices, rotating);
 
        device->bdev = bdev;
        clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
@@ -2418,6 +2452,7 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info 
*fs_info)
        fs_devices->open_devices = 0;
        fs_devices->missing_devices = 0;
        fs_devices->rotating = false;
+       fs_devices->mixed = false;
        list_add(&seed_devices->seed_list, &fs_devices->seed_list);
 
        generate_random_uuid(fs_devices->fsid);
@@ -2522,6 +2557,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, 
const char *device_path
        int seeding_dev = 0;
        int ret = 0;
        bool locked = false;
+       bool rotating;
 
        if (sb_rdonly(sb) && !fs_devices->seeding)
                return -EROFS;
@@ -2621,8 +2657,12 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, 
const char *device_path
 
        atomic64_add(device->total_bytes, &fs_info->free_chunk_space);
 
-       if (!blk_queue_nonrot(q))
+       rotating = !blk_queue_nonrot(q);
+       device->rotating = rotating;
+       if (rotating)
                fs_devices->rotating = true;
+       if (!fs_devices->mixed)
+               fs_devices->mixed = btrfs_check_mixed(fs_devices, rotating);
 
        orig_super_total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
        btrfs_set_super_total_bytes(fs_info->super_copy,
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 6e544317a377..594f1207281c 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -147,6 +147,9 @@ struct btrfs_device {
        /* I/O stats for raid1 mirror selection */
        struct percpu_counter inflight;
        atomic_t last_offset;
+
+       /* If the device is rotational */
+       bool rotating;
 };
 
 /*
@@ -274,6 +277,10 @@ struct btrfs_fs_devices {
         * nonrot flag set
         */
        bool rotating;
+       /* Set when we find or add both nonrot and rot disks in the
+        * filesystem
+        */
+       bool mixed;
 
        struct btrfs_fs_info *fs_info;
        /* sysfs kobjects */
-- 
2.30.0

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