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>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b9d8788..5fa7d7d 100644 (file)
--- 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)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e572cf4..f4dfbb7 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1850,6 +1850,14 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        if (IS_ERR(fs_info->transaction_kthread))
                goto fail_cleaner;
 
+       if (!btrfs_test_opt(tree_root, SSD) &&
+           !btrfs_test_opt(tree_root, NOSSD) &&
+           !fs_info->fs_devices->rotating) {
+               printk(KERN_INFO "Btrfs detected SSD devices, enabling SSD "
+                      "mode\n");
+               btrfs_set_opt(fs_info->mount_opt, SSD);
+       }
+
        if (btrfs_super_log_root(disk_super) != 0) {
                u64 bytenr = btrfs_super_log_root(disk_super);
 
@@ -1893,6 +1901,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        fs_info->fs_root = btrfs_read_fs_root_no_name(fs_info, &location);
        if (!fs_info->fs_root)
                goto fail_trans_kthread;
+
        return tree_root;
 
 fail_trans_kthread:

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7f5b288..3427db2 100644 (file)
--- 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))

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 27d5f37..3f4a593 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -605,6 +605,9 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                device->in_fs_metadata = 0;
                device->mode = flags;
 
+               if (!blk_queue_nonrot(bdev_get_queue(bdev)))
+                       fs_devices->rotating = 1;
+
                fs_devices->open_devices++;
                if (device->writeable) {
                        fs_devices->rw_devices++;
@@ -1473,6 +1476,9 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
        root->fs_info->fs_devices->rw_devices++;
        root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;
 
+       if (!blk_queue_nonrot(bdev_get_queue(bdev)))
+               root->fs_info->fs_devices->rotating = 1;
+
        total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
        btrfs_set_super_total_bytes(&root->fs_info->super_copy,
                                    total_bytes + device->total_bytes);

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 5c3ff6d..3c1f731 100644 (file)
--- 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 {