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, 3 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7f5b2889949a..3427db28f6fe 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -184,6 +184,7 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                 case Opt_nossd:
                         printk(KERN_INFO "btrfs: not using ssd allocation "
                                "scheme\n");
+                        btrfs_set_opt(info->mount_opt, NOSSD);
                         btrfs_clear_opt(info->mount_opt, SSD);
                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
                         break;
@@ -438,6 +439,8 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
         if (btrfs_test_opt(root, COMPRESS))
                 seq_puts(seq, ",compress");
+        if (btrfs_test_opt(root, NOSSD))
+                seq_puts(seq, ",nossd");
         if (btrfs_test_opt(root, SSD_SPREAD))
                 seq_puts(seq, ",ssd_spread");
         else if (btrfs_test_opt(root, SSD))