Btrfs: fix truncate_space_check

commit dc95f7bfc57fa4b75a77d0da84d5db249d74aa3f upstream.

truncate_space_check is using btrfs_csum_bytes_to_leaves() but forgetting to
multiply by nodesize so we get an actual byte count.  We need a tracepoint here
so that we have the matching reserve for the release that will come later.  Also
add a comment to make clear what the intent of truncate_space_check is.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d96f5cf38a2dd2a8e227ad93ff22f7a678611034..0a4a2c141caa4432c895c94e064295efcc6845ed 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4211,11 +4211,20 @@ static int truncate_space_check(struct btrfs_trans_handle *trans,
 {
        int ret;
 
+       /*
+        * This is only used to apply pressure to the enospc system, we don't
+        * intend to use this reservation at all.
+        */
        bytes_deleted = btrfs_csum_bytes_to_leaves(root, bytes_deleted);
+       bytes_deleted *= root->nodesize;
        ret = btrfs_block_rsv_add(root, &root->fs_info->trans_block_rsv,
                                  bytes_deleted, BTRFS_RESERVE_NO_FLUSH);
-       if (!ret)
+       if (!ret) {
+               trace_btrfs_space_reservation(root->fs_info, "transaction",
+                                             trans->transid,
+                                             bytes_deleted, 1);
                trans->bytes_reserved += bytes_deleted;
+       }
        return ret;
 
 }