Btrfs: Add mount -o ssd, which includes optimizations for seek free storage

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

6 files changed, 47 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index fa65fe027e45..7a588ba2b747 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -351,6 +351,7 @@ struct btrfs_fs_info {
         spinlock_t delalloc_lock;
         spinlock_t new_trans_lock;
         u64 delalloc_bytes;
+        u64 last_alloc;
 };
 /*
  * in ram representation of the tree.  extent_root is used for all allocations
@@ -444,6 +445,7 @@ struct btrfs_root {
 #define BTRFS_MOUNT_NODATASUM           (1 << 0)
 #define BTRFS_MOUNT_NODATACOW           (1 << 1)
 #define BTRFS_MOUNT_NOBARRIER           (1 << 2)
+#define BTRFS_MOUNT_SSD                 (1 << 3)
 
 #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 731a534f81f5..5d1f9bca2712 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -193,6 +193,7 @@ int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
         }
         eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
         read_extent_buffer_pages(tree, eb, start + PAGE_CACHE_SIZE, 1);
+        btrfs_clear_buffer_defrag(eb);
         found_start = btrfs_header_bytenr(eb);
         if (found_start != start) {
                 printk("warning: eb start incorrect %Lu buffer %Lu len %lu\n",
@@ -676,6 +677,8 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         fs_info->do_barriers = 1;
         fs_info->closing = 0;
         fs_info->total_pinned = 0;
+        fs_info->last_alloc = 0;
+
 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
         INIT_WORK(&fs_info->trans_work, btrfs_transaction_cleaner, fs_info);
 #else
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2c569b4d59d4..b69a46691a96 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1431,6 +1431,19 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
                 data = BTRFS_BLOCK_GROUP_MIXED;
         }
 
+        /* for SSD, cluster allocations together as much as possible */
+        if (btrfs_test_opt(root, SSD)) {
+                if (!data) {
+                        if (root->fs_info->last_alloc)
+                                hint_byte = root->fs_info->last_alloc;
+                        else {
+                                hint_byte = hint_byte &
+                                        ~((u64)BTRFS_BLOCK_GROUP_SIZE - 1);
+                                empty_size += 16 * 1024 * 1024;
+                        }
+                }
+        }
+
         search_end = min(search_end,
                          btrfs_super_total_bytes(&info->super_copy));
         if (hint_byte) {
@@ -1456,6 +1469,19 @@ check_failed:
         }
         search_start = find_search_start(root, &block_group, search_start,
                                          total_needed, data);
+
+        if (!data && btrfs_test_opt(root, SSD) && info->last_alloc &&
+            search_start != info->last_alloc) {
+                info->last_alloc = 0;
+                if (!empty_size) {
+                        empty_size += 16 * 1024 * 1024;
+                        total_needed += empty_size;
+                }
+                search_start = find_search_start(root, &block_group,
+                                                 search_start, total_needed,
+                                                 data);
+        }
+
         search_start = stripe_align(root, search_start);
         cached_start = search_start;
         btrfs_init_path(path);
@@ -1610,6 +1636,8 @@ enospc:
 error:
         btrfs_release_path(root, path);
         btrfs_free_path(path);
+        if (btrfs_test_opt(root, SSD) && !ret && !data)
+                info->last_alloc = ins->objectid + ins->offset;
         return ret;
 }
 /*
@@ -1778,7 +1806,8 @@ struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                         buf->start, buf->start + buf->len - 1,
                         EXTENT_CSUM, GFP_NOFS);
         buf->flags |= EXTENT_CSUM;
-        btrfs_set_buffer_defrag(buf);
+        if (!btrfs_test_opt(root, SSD))
+                btrfs_set_buffer_defrag(buf);
         trans->blocks_used++;
         return buf;
 }
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index e506de3168bc..b6982f0133cf 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -64,7 +64,7 @@ static void btrfs_put_super (struct super_block * sb)
 
 enum {
         Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
-        Opt_alloc_start, Opt_nobarrier, Opt_err,
+        Opt_alloc_start, Opt_nobarrier, Opt_ssd, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -74,6 +74,7 @@ static match_table_t tokens = {
         {Opt_nobarrier, "nobarrier"},
         {Opt_max_extent, "max_extent=%s"},
         {Opt_alloc_start, "alloc_start=%s"},
+        {Opt_ssd, "ssd"},
         {Opt_err, NULL}
 };
 
@@ -149,6 +150,12 @@ static int parse_options (char * options,
                                 btrfs_set_opt(info->mount_opt, NODATASUM);
                         }
                         break;
+                case Opt_ssd:
+                        if (info) {
+                                printk("btrfs: use ssd allocation scheme\n");
+                                btrfs_set_opt(info->mount_opt, SSD);
+                        }
+                        break;
                 case Opt_nobarrier:
                         if (info) {
                                 printk("btrfs: turning off barriers\n");
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index b6bbfc179c29..163c01a24498 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -57,6 +57,7 @@ static int join_transaction(struct btrfs_root *root)
                 BUG_ON(!cur_trans);
                 root->fs_info->generation++;
                 root->fs_info->running_transaction = cur_trans;
+                root->fs_info->last_alloc = 0;
                 cur_trans->num_writers = 1;
                 cur_trans->num_joined = 0;
                 cur_trans->transid = root->fs_info->generation;
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index 5c58630dce03..5935cbd8f2b8 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -179,6 +179,9 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
         if (root->ref_cows == 0 && !is_extent)
                 goto out;
 
+        if (btrfs_test_opt(root, SSD))
+                goto out;
+
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;