[v2,1/4] btrfs: relocation: Introduce error injection points for cancelling balance
diff mbox series

Message ID 20200211053729.20807-2-wqu@suse.com
State New
Headers show
Series
  • btrfs: Make balance cancelling response faster
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Commit Message

Qu Wenruo Feb. 11, 2020, 5:37 a.m. UTC
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>
---
 fs/btrfs/ctree.h      |  1 +
 fs/btrfs/relocation.c | 11 +++++++++++
 fs/btrfs/volumes.c    |  2 +-
 3 files changed, 13 insertions(+), 1 deletion(-)

Comments

Josef Bacik Feb. 13, 2020, 8 p.m. UTC | #1
On 2/11/20 12:37 AM, Qu Wenruo wrote:
> 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>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef

Patch
diff mbox series

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 36df977b64d9..d8e12ca15bb6 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3401,6 +3401,7 @@  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 995d4b8b1cfd..475479d50cc3 100644
--- 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"
@@ -3264,6 +3265,16 @@  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 9cfc668f91f4..cd61f4e29d9e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3904,7 +3904,7 @@  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;
 	}