Btrfs: New data=ordered implementation

The old data=ordered code would force commit to wait until
all the data extents from the transaction were fully on disk.  This
introduced large latencies into the commit and stalled new writers
in the transaction for a long time.

The new code changes the way data allocations and extents work:

* When delayed allocation is filled, data extents are reserved, and
  the extent bit EXTENT_ORDERED is set on the entire range of the extent.
  A struct btrfs_ordered_extent is allocated an inserted into a per-inode
  rbtree to track the pending extents.

* As each page is written EXTENT_ORDERED is cleared on the bytes corresponding
  to that page.

* When all of the bytes corresponding to a single struct btrfs_ordered_extent
  are written, The previously reserved extent is inserted into the FS
  btree and into the extent allocation trees.  The checksums for the file
  data are also updated.

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

1 files changed, 60 insertions, 11 deletions

diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index 4fa78736423e..33292c5fe90c 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -20,24 +20,73 @@
 #define __BTRFS_ORDERED_DATA__
 
 struct btrfs_ordered_inode_tree {
-        rwlock_t lock;
+        struct mutex mutex;
         struct rb_root tree;
+        struct rb_node *last;
 };
 
+struct btrfs_sector_sum {
+        u64 offset;
+        u32 sum;
+};
+
+struct btrfs_ordered_sum {
+        u64 file_offset;
+        u64 len;
+        struct list_head list;
+        struct btrfs_sector_sum sums;
+};
+
+/* bits for the flags field */
+#define BTRFS_ORDERED_IO_DONE 0 /* set when all the pages are written */
+#define BTRFS_ORDERED_COMPLETE 1 /* set when removed from the tree */
+#define BTRFS_ORDERED_START 2 /* set when tree setup */
+
+struct btrfs_ordered_extent {
+        u64 file_offset;
+        u64 start;
+        u64 len;
+        unsigned long flags;
+        atomic_t refs;
+        struct list_head list;
+        struct inode *inode;
+        wait_queue_head_t wait;
+        struct rb_node rb_node;
+};
+
+
+static inline int btrfs_ordered_sum_size(struct btrfs_root *root, u64 bytes)
+{
+        unsigned long num_sectors = (bytes + root->sectorsize - 1) /
+                root->sectorsize;
+        return sizeof(struct btrfs_ordered_sum) +
+                num_sectors * sizeof(struct btrfs_sector_sum);
+}
+
 static inline void
 btrfs_ordered_inode_tree_init(struct btrfs_ordered_inode_tree *t)
 {
-        rwlock_init(&t->lock);
+        mutex_init(&t->mutex);
         t->tree.rb_node = NULL;
+        t->last = NULL;
 }
 
-int btrfs_add_ordered_inode(struct inode *inode);
-int btrfs_find_del_first_ordered_inode(struct btrfs_ordered_inode_tree *tree,
-                                       u64 *root_objectid, u64 *objectid,
-                                       struct inode **inode);
-int btrfs_find_first_ordered_inode(struct btrfs_ordered_inode_tree *tree,
-                                       u64 *root_objectid, u64 *objectid,
-                                       struct inode **inode);
-void btrfs_del_ordered_inode(struct inode *inode, int force);
-int btrfs_ordered_throttle(struct btrfs_root *root, struct inode *inode);
+int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry);
+int btrfs_remove_ordered_extent(struct inode *inode,
+                                struct btrfs_ordered_extent *entry);
+int btrfs_dec_test_ordered_pending(struct inode *inode,
+                                       u64 file_offset, u64 io_size);
+int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
+                             u64 start, u64 len);
+int btrfs_add_ordered_sum(struct inode *inode, struct btrfs_ordered_sum *sum);
+struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
+                                                         u64 file_offset);
+void btrfs_wait_ordered_extent(struct inode *inode,
+                               struct btrfs_ordered_extent *entry);
+void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);
+struct btrfs_ordered_extent *
+btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);
+int btrfs_add_ordered_pending(struct inode *inode,
+                              struct btrfs_ordered_extent *ordered,
+                              u64 start, u64 len);
 #endif