block discard.

David Woodhouse
2008-08-08T13:43:18Z

Playing with the trim/punch/discard support, I tried the patch below. It
see it getting invoked at times, but when I create a large file and then
delete it, I don't see it getting invoked _enough_. And when I grep the
block device for the contents of the file, they're still there.

I have a suspicion my added code is only getting invoked for
metadata/tree extents, not the actual data extents. What'd I miss?

diff --git a/extent-tree.c b/extent-tree.c
index fff219e..e6908ad 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -18,6 +18,7 @@
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
+#include <linux/blkdev.h>
#include "hash.h"
#include "crc32c.h"
#include "ctree.h"
@@ -1743,6 +1744,22 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
ret = update_block_group(trans, root, bytenr, num_bytes, 0,
mark_free);
BUG_ON(ret);
+
+
+ u64 map_length = num_bytes;
+ struct btrfs_multi_bio *multi = NULL;
+ ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,
+ bytenr, &map_length, &multi, 0);
+ if (!ret) {
+ int i;
+ for (i=0; i< multi->num_stripes; i++) {
+ blkdev_issue_discard(multi->stripes[i].dev->bdev,
+ multi->stripes[i].physical >> 9,
+ min(map_length, num_bytes) >> 9,
+ NULL);
+ }
+ kfree(multi);
+ }
}
btrfs_free_path(path);
finish_current_insert(trans, extent_root);

--
David Woodhouse Open Source Technology Centre
David.Woodhouse@intel.com Intel Corporation