Btrfs: Add mount -o nodatasum to turn of file data checksumming

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

4 files changed, 34 insertions, 9 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 052555ced44d..5e255cabfd10 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -321,6 +321,7 @@ struct btrfs_fs_info {
 
         u64 generation;
         u64 last_trans_committed;
+        unsigned long mount_opt;
         struct btrfs_transaction *running_transaction;
         struct btrfs_super_block super_copy;
         struct extent_buffer *sb_buffer;
@@ -429,6 +430,13 @@ struct btrfs_root {
  */
 #define BTRFS_STRING_ITEM_KEY   253
 
+#define BTRFS_MOUNT_NODATASUM           0x1
+
+#define btrfs_clear_opt(o, opt)         ((o) &= ~BTRFS_MOUNT_##opt)
+#define btrfs_set_opt(o, opt)           ((o) |= BTRFS_MOUNT_##opt)
+#define btrfs_test_opt(root, opt)       ((root)->fs_info->mount_opt & \
+                                         BTRFS_MOUNT_##opt)
+
 /* some macros to generate set/get funcs for the struct fields.  This
  * assumes there is a lefoo_to_cpu for every type, so lets make a simple
  * one for u8:
@@ -906,12 +914,6 @@ static inline u32 btrfs_level_size(struct btrfs_root *root, int level) {
         ((unsigned long)(btrfs_leaf_data(leaf) + \
         btrfs_item_offset_nr(leaf, slot)))
 
-/* mount option defines and helpers */
-#define BTRFS_MOUNT_SUBVOL              0x000001
-#define btrfs_clear_opt(o, opt)         o &= ~BTRFS_MOUNT_##opt
-#define btrfs_set_opt(o, opt)           o |= BTRFS_MOUNT_##opt
-#define btrfs_test_opt(sb, opt)         (BTRFS_SB(sb)->s_mount_opt & \
-                                         BTRFS_MOUNT_##opt)
 /* extent-tree.c */
 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 60a30da6af00..4338b00c2a25 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -568,6 +568,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         fs_info->tree_root = tree_root;
         fs_info->extent_root = extent_root;
         fs_info->sb = sb;
+        fs_info->mount_opt = 0;
         fs_info->btree_inode = new_inode(sb);
         fs_info->btree_inode->i_ino = 1;
         fs_info->btree_inode->i_nlink = 1;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e535c50e669b..11885cb114e2 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -116,10 +116,13 @@ int btrfs_writepage_io_hook(struct page *page, u64 start, u64 end)
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct btrfs_trans_handle *trans;
         char *kaddr;
-        int ret;
+        int ret = 0;
         u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
         size_t offset = start - page_start;
 
+        if (btrfs_test_opt(root, NODATASUM))
+                return 0;
+
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, inode);
@@ -143,6 +146,9 @@ int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
         struct btrfs_path *path = NULL;
         u32 csum;
 
+        if (btrfs_test_opt(root, NODATASUM))
+                return 0;
+
         mutex_lock(&root->fs_info->fs_mutex);
         path = btrfs_alloc_path();
         item = btrfs_lookup_csum(NULL, root, path, inode->i_ino, start, 0);
@@ -176,6 +182,9 @@ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
         u32 csum = ~(u32)0;
         unsigned long flags;
 
+        if (btrfs_test_opt(root, NODATASUM))
+                return 0;
+
         ret = get_state_private(em_tree, start, &private);
         local_irq_save(flags);
         kaddr = kmap_atomic(page, KM_IRQ0);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index ffa02872c4d6..ad4f280ec777 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -61,11 +61,12 @@ static void btrfs_put_super (struct super_block * sb)
 }
 
 enum {
-        Opt_subvol, Opt_err,
+        Opt_subvol, Opt_nodatasum, Opt_err,
 };
 
 static match_table_t tokens = {
         {Opt_subvol, "subvol=%s"},
+        {Opt_nodatasum, "nodatasum"},
         {Opt_err, NULL}
 };
 
@@ -74,7 +75,12 @@ static int parse_options (char * options,
                           char **subvol_name)
 {
         char * p;
+        struct btrfs_fs_info *info = NULL;
         substring_t args[MAX_OPT_ARGS];
+
+        if (root)
+                info = root->fs_info;
+
         if (!options)
                 return 1;
 
@@ -86,7 +92,12 @@ static int parse_options (char * options,
                 token = match_token(p, tokens, args);
                 switch (token) {
                 case Opt_subvol:
-                        *subvol_name = match_strdup(&args[0]);
+                        if (subvol_name)
+                                *subvol_name = match_strdup(&args[0]);
+                        break;
+                case Opt_nodatasum:
+                        if (root)
+                                btrfs_set_opt(info->mount_opt, NODATASUM);
                         break;
                 default:
                         return 0;
@@ -143,6 +154,8 @@ static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
                 goto fail_close;
         }
 
+        parse_options((char *)data, tree_root, NULL);
+
         /* this does the super kobj at the same time */
         err = btrfs_sysfs_add_super(tree_root->fs_info);
         if (err)