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, 1 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b9d8788b299e..5fa7d7d287a4 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1101,6 +1101,7 @@ struct btrfs_root {
 #define BTRFS_MOUNT_NOTREELOG           (1 << 6)
 #define BTRFS_MOUNT_FLUSHONCOMMIT       (1 << 7)
 #define BTRFS_MOUNT_SSD_SPREAD          (1 << 8)
+#define BTRFS_MOUNT_NOSSD               (1 << 9)
 
 #define btrfs_clear_opt(o, opt)         ((o) &= ~BTRFS_MOUNT_##opt)
 #define btrfs_set_opt(o, opt)           ((o) |= BTRFS_MOUNT_##opt)