Btrfs: autodetect SSD devices

During mount, btrfs will check the queue nonrot flag
for all the devices found in the FS.  If they are all
non-rotating, SSD mode is enabled by default.

If the FS was mounted with -o nossd, the non-rotating
flag is ignored.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 5c3ff6d02fd7..3c1f7310421e 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -107,6 +107,11 @@ struct btrfs_fs_devices {
         int seeding;
 
         int opened;
+
+        /* set when we find or add a device that doesn't have the
+         * nonrot flag set
+         */
+        int rotating;
 };
 
 struct btrfs_bio_stripe {