| Message ID | 1386001014-8226-1-git-send-email-wangshilong1991@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello Sebastian, Would you please apply this patch in your test box and see if the problem still exist. Thanks, Wang 2013/12/3 Wang Shilong <wangshilong1991@gmail.com>: > From: Wang Shilong <wangsl.fnst@cn.fujitsu.com> > > We came a race condition when scrubbing superblocks, the story is: > > In commiting transaction, we will update last_trans_commited after > writting superblocks. if a scrub start after writting superblocks > and before last_trans_commited, generation mismatch happens! > > We fix it by protecting writting superblock and updating last_trans_commited > with tree_log_mutex. > > Reported-by: Sebastian Ochmann <ochmann@informatik.uni-bonn.de> > Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> > --- > fs/btrfs/scrub.c | 11 +++++++---- > fs/btrfs/transaction.c | 13 ++++++++++--- > 2 files changed, 17 insertions(+), 7 deletions(-) > > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c > index 561e2f1..afa2f01 100644 > --- a/fs/btrfs/scrub.c > +++ b/fs/btrfs/scrub.c > @@ -2932,12 +2932,15 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, > atomic_inc(&fs_info->scrubs_running); > mutex_unlock(&fs_info->scrub_lock); > > + /* > + * by holding tree_log_mutex while scrubbing supers > + * we can avoid generation mismatch. See comments in commiting > + * transaction when updating last_trans_commited. > + */ > if (!is_dev_replace) { > - /* > - * by holding device list mutex, we can > - * kick off writing super in log tree sync. > - */ > + mutex_lock(&fs_info->tree_log_mutex); > ret = scrub_supers(sctx, dev); > + mutex_unlock(&fs_info->tree_log_mutex); > } > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > > diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c > index c6a872a..052eb22 100644 > --- a/fs/btrfs/transaction.c > +++ b/fs/btrfs/transaction.c > @@ -1898,15 +1898,22 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, > goto cleanup_transaction; > } > > + btrfs_finish_extent_commit(trans, root); > + > + /* > + * we must gurantee last_trans_commited update is protected by > + * tree_log_mutex with write_ctree_super together, otherwise, > + * scubbing super will come in before updating last_trans_commited > + * and we will get generation mismatch when scrubbing superblocks. > + */ > + root->fs_info->last_trans_committed = cur_trans->transid; > + > /* > * the super is written, we can safely allow the tree-loggers > * to go about their business > */ > mutex_unlock(&root->fs_info->tree_log_mutex); > > - btrfs_finish_extent_commit(trans, root); > - > - root->fs_info->last_trans_committed = cur_trans->transid; > /* > * We needn't acquire the lock here because there is no other task > * which can change it. > -- > 1.8.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 561e2f1..afa2f01 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2932,12 +2932,15 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, atomic_inc(&fs_info->scrubs_running); mutex_unlock(&fs_info->scrub_lock); + /* + * by holding tree_log_mutex while scrubbing supers + * we can avoid generation mismatch. See comments in commiting + * transaction when updating last_trans_commited. + */ if (!is_dev_replace) { - /* - * by holding device list mutex, we can - * kick off writing super in log tree sync. - */ + mutex_lock(&fs_info->tree_log_mutex); ret = scrub_supers(sctx, dev); + mutex_unlock(&fs_info->tree_log_mutex); } mutex_unlock(&fs_info->fs_devices->device_list_mutex); diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index c6a872a..052eb22 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1898,15 +1898,22 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, goto cleanup_transaction; } + btrfs_finish_extent_commit(trans, root); + + /* + * we must gurantee last_trans_commited update is protected by + * tree_log_mutex with write_ctree_super together, otherwise, + * scubbing super will come in before updating last_trans_commited + * and we will get generation mismatch when scrubbing superblocks. + */ + root->fs_info->last_trans_committed = cur_trans->transid; + /* * the super is written, we can safely allow the tree-loggers * to go about their business */ mutex_unlock(&root->fs_info->tree_log_mutex); - btrfs_finish_extent_commit(trans, root); - - root->fs_info->last_trans_committed = cur_trans->transid; /* * We needn't acquire the lock here because there is no other task * which can change it.