Btrfs: add new defrag-range ioctl.

The btrfs defrag ioctl was limited to doing the entire file.  This
commit adds a new interface that can defrag a specific range inside
the file.

It can also force compression on the file, allowing you to selectively
compress individual files after they were created, even when mount -o
compress isn't turned on.

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

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 7d10d1ccb0fe..3657925c2461 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -379,7 +379,8 @@ again:
          * change at any time if we discover bad compression ratios.
          */
         if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NOCOMPRESS) &&
-            btrfs_test_opt(root, COMPRESS)) {
+            (btrfs_test_opt(root, COMPRESS) ||
+             (BTRFS_I(inode)->force_compress))) {
                 WARN_ON(pages);
                 pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS);
 
@@ -483,8 +484,10 @@ again:
                 nr_pages_ret = 0;
 
                 /* flag the file so we don't compress in the future */
-                if (!btrfs_test_opt(root, FORCE_COMPRESS))
+                if (!btrfs_test_opt(root, FORCE_COMPRESS) &&
+                    !(BTRFS_I(inode)->force_compress)) {
                         BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
+                }
         }
         if (will_compress) {
                 *num_added += 1;
@@ -1211,7 +1214,8 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page,
         else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC)
                 ret = run_delalloc_nocow(inode, locked_page, start, end,
                                          page_started, 0, nr_written);
-        else if (!btrfs_test_opt(root, COMPRESS))
+        else if (!btrfs_test_opt(root, COMPRESS) &&
+                 !(BTRFS_I(inode)->force_compress))
                 ret = cow_file_range(inode, locked_page, start, end,
                                       page_started, nr_written, 1);
         else
@@ -3639,6 +3643,7 @@ static noinline void init_btrfs_i(struct inode *inode)
         bi->index_cnt = (u64)-1;
         bi->last_unlink_trans = 0;
         bi->ordered_data_close = 0;
+        bi->force_compress = 0;
         extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
         extent_io_tree_init(&BTRFS_I(inode)->io_tree,
                              inode->i_mapping, GFP_NOFS);