Btrfs: Split the extent_map code into two parts

There is now extent_map for mapping offsets in the file to disk and
extent_io for state tracking, IO submission and extent_bufers.

The new extent_map code shifts from [start,end] pairs to [start,len], and
pushes the locking out into the caller.  This allows a few performance
optimizations and is easier to use.

A number of extent_map usage bugs were fixed, mostly with failing
to remove extent_map entries when changing the file.

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

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 8b52c69fda2e..f8a1016600b1 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -468,10 +468,15 @@ static int __init init_btrfs_fs(void)
         err = btrfs_init_cachep();
         if (err)
                 goto free_transaction_sys;
-        err = extent_map_init();
+
+        err = extent_io_init();
         if (err)
                 goto free_cachep;
 
+        err = extent_map_init();
+        if (err)
+                goto free_extent_io;
+
         err = register_filesystem(&btrfs_fs_type);
         if (err)
                 goto free_extent_map;
@@ -479,6 +484,8 @@ static int __init init_btrfs_fs(void)
 
 free_extent_map:
         extent_map_exit();
+free_extent_io:
+        extent_io_exit();
 free_cachep:
         btrfs_destroy_cachep();
 free_transaction_sys:
@@ -492,6 +499,7 @@ static void __exit exit_btrfs_fs(void)
         btrfs_exit_transaction_sys();
         btrfs_destroy_cachep();
         extent_map_exit();
+        extent_io_exit();
         unregister_filesystem(&btrfs_fs_type);
         btrfs_exit_sysfs();
 }