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 ae784d7bf5f3017d68081d265af83479cc153f45..521e668c515cc280af3da574ea26800fde4411c7 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3746,6 +3746,7 @@ 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 c635bc2e04842977d005af89eabdbb09f550d469..d9dca8de25b476b5c91461b508baae74ab606122 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"
@@ -3222,6 +3223,16 @@ 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 205b55dd8bbe81e2ee21d94972baa7d9be430b6a..985a0cd28df8be2d18bb9abc9e729ed74fa56510 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4050,7 +4050,7 @@ 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;
        }