Btrfs: fix punch hole when no extent exists

I saw the warning in btrfs_drop_extent_cache where our end is less than our
start while running xfstests 68 in a loop.  This is because we
unconditionally do drop_end = min(end, extent_end) in
__btrfs_drop_extents(), even though we may not have found an extent in the
range we were looking to drop.  So keep track of wether or not we found
something, and if we didn't just use our end.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index d0fc4c5aaf156cc0adfcd467cbae8d03a1914b03..110d3cb7b6fe2ad84d05fe9367f6c17154e54232 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -609,6 +609,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
        int ret;
        int modify_tree = -1;
        int update_refs = (root->ref_cows || root == root->fs_info->tree_root);
+       int found = 0;
 
        if (drop_cache)
                btrfs_drop_extent_cache(inode, start, end - 1, 0);
@@ -674,6 +675,7 @@ next_slot:
                        goto next_slot;
                }
 
+               found = 1;
                search_start = max(key.offset, start);
                if (recow || !modify_tree) {
                        modify_tree = -1;
@@ -829,7 +831,7 @@ next_slot:
        }
 
        if (drop_end)
-               *drop_end = min(end, extent_end);
+               *drop_end = found ? min(end, extent_end) : end;
        btrfs_release_path(path);
        return ret;
 }