btrfs: relocation: Introduce error injection points for cancelling balance

Introduce a new error injection point, should_cancel_balance().

It's just a wrapper of atomic_read(&fs_info->balance_cancel_req), but
allows us to override the return value.

Currently there are only one locations using this function:
- btrfs_balance()
  It checks cancel before each block group.

There are other locations checking fs_info->balance_cancel_req, but they
are not used as an indicator to exit, so there is no need to use the
wrapper.

But there will be more locations coming, and some locations can cause
kernel panic if not handled properly.

So introduce this error injection to provide better test interface.

Signed-off-by: Qu Wenruo <wqu@suse.com>
(cherry picked from commit 6d2751364569f885ca795e37882690a78ac9f149)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index fb92c35edadb2ec19f60f671a60d1f6d599db1c1..d7928df484bde0450079d5a8287ae1b82041b171 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3346,6 +3346,7 @@ void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
                              u64 *bytes_to_reserve);
 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
                              struct btrfs_pending_snapshot *pending);
+int should_cancel_balance(struct btrfs_fs_info *fs_info);
 
 /* scrub.c */
 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 048e1b5914593f37915332247983bd6c9296d911..5460bbbe2da6f47672533b34eb3b12a3529674e2 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -9,6 +9,7 @@
 #include <linux/blkdev.h>
 #include <linux/rbtree.h>
 #include <linux/slab.h>
+#include <linux/error-injection.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -3253,6 +3254,16 @@ int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
        return ret;
 }
 
+/*
+ * This wrapper is to allow error injection to fully test all cancel
+ * call sites.
+ */
+int should_cancel_balance(struct btrfs_fs_info *fs_info)
+{
+       return atomic_read(&fs_info->balance_cancel_req);
+}
+ALLOW_ERROR_INJECTION(should_cancel_balance, TRUE);
+
 static int relocate_file_extent_cluster(struct inode *inode,
                                        struct file_extent_cluster *cluster)
 {

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6d14c62dbdf4fbe55f1f50e0b1431ee742711538..919987257244883109a40f38bd8a043bbcc800e9 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3856,7 +3856,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info,
 
        if (btrfs_fs_closing(fs_info) ||
            atomic_read(&fs_info->balance_pause_req) ||
-           atomic_read(&fs_info->balance_cancel_req)) {
+           should_cancel_balance(fs_info)) {
                ret = -EINVAL;
                goto out;
        }