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authorFilipe Manana <fdmanana@suse.com>2021-04-22 12:09:21 +0100
committerDavid Sterba <dsterba@suse.com>2021-04-28 20:09:42 +0200
commitffb7c2e923cb3232454a513dcb5636e73091aa88 (patch)
tree490fc01140619e10896a89755c892a900bbb331b /fs
parentadbd914dcde0b03bfc08ffe40b81f31b0457833f (diff)
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btrfs: do not consider send context as valid when trying to flush qgroups
At qgroup.c:try_flush_qgroup() we are asserting that current->journal_info is either NULL or has the value BTRFS_SEND_TRANS_STUB. However allowing for BTRFS_SEND_TRANS_STUB makes no sense because: 1) It is misleading, because send operations are read-only and do not ever need to reserve qgroup space; 2) We already assert that current->journal_info != BTRFS_SEND_TRANS_STUB at transaction.c:start_transaction(); 3) On a kernel without CONFIG_BTRFS_ASSERT=y set, it would result in a crash if try_flush_qgroup() is ever called in a send context, because at transaction.c:start_transaction we cast current->journal_info into a struct btrfs_trans_handle pointer and then dereference it. So just do allow a send context at try_flush_qgroup() and update the comment about it. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/qgroup.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 2319c923c9e6..b1caf5acf1e2 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -3545,11 +3545,15 @@ static int try_flush_qgroup(struct btrfs_root *root)
struct btrfs_trans_handle *trans;
int ret;
- /* Can't hold an open transaction or we run the risk of deadlocking */
- ASSERT(current->journal_info == NULL ||
- current->journal_info == BTRFS_SEND_TRANS_STUB);
- if (WARN_ON(current->journal_info &&
- current->journal_info != BTRFS_SEND_TRANS_STUB))
+ /*
+ * Can't hold an open transaction or we run the risk of deadlocking,
+ * and can't either be under the context of a send operation (where
+ * current->journal_info is set to BTRFS_SEND_TRANS_STUB), as that
+ * would result in a crash when starting a transaction and does not
+ * make sense either (send is a read-only operation).
+ */
+ ASSERT(current->journal_info == NULL);
+ if (WARN_ON(current->journal_info))
return 0;
/*