diff options
| author | Sage Weil <sage@redhat.com> | 2014-09-26 08:30:06 -0700 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2014-10-03 16:14:59 -0700 |
| commit | 42383020beb1cfb05f5d330cc311931bc4917a97 (patch) | |
| tree | 08e2411cd332c3c56323ac9ffc27164079e29daf /fs/btrfs/transaction.c | |
| parent | 656f30dba7ab8179c9a2e04293b0c7b383fa9ce9 (diff) | |
Btrfs: fix race in WAIT_SYNC ioctl
We check whether transid is already committed via last_trans_committed and
then search through trans_list for pending transactions. If
last_trans_committed is updated by btrfs_commit_transaction after we check
it (there is no locking), we will fail to find the committed transaction
and return EINVAL to the caller. This has been observed occasionally by
ceph-osd (which uses this ioctl heavily).
Fix by rechecking whether the provided transid <= last_trans_committed
after the search fails, and if so return 0.
Signed-off-by: Sage Weil <sage@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/transaction.c')
| -rw-r--r-- | fs/btrfs/transaction.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index a47b1000a6e..86ef8d79c19 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -609,7 +609,6 @@ int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid) if (transid <= root->fs_info->last_trans_committed) goto out; - ret = -EINVAL; /* find specified transaction */ spin_lock(&root->fs_info->trans_lock); list_for_each_entry(t, &root->fs_info->trans_list, list) { @@ -625,9 +624,16 @@ int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid) } } spin_unlock(&root->fs_info->trans_lock); - /* The specified transaction doesn't exist */ - if (!cur_trans) + + /* + * The specified transaction doesn't exist, or we + * raced with btrfs_commit_transaction + */ + if (!cur_trans) { + if (transid > root->fs_info->last_trans_committed) + ret = -EINVAL; goto out; + } } else { /* find newest transaction that is committing | committed */ spin_lock(&root->fs_info->trans_lock); |