David, could you fold the below incremental diff to this patch? Or, I
can send a full replacement patch.
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 8be3164d4c5d..4e72794342c0 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -143,6 +143,7 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *tree_root = fs_info->tree_root;
const bool zoned = btrfs_is_zoned(fs_info);
int ret = 0;
+ bool created = false;
/*
* First check if the log root tree was already created. If not, create
@@ -152,8 +153,10 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
mutex_lock(&tree_root->log_mutex);
if (!fs_info->log_root_tree) {
ret = btrfs_init_log_root_tree(trans, fs_info);
- if (!ret)
+ if (!ret) {
set_bit(BTRFS_ROOT_HAS_LOG_TREE, &tree_root->state);
+ created = true;
+ }
}
mutex_unlock(&tree_root->log_mutex);
if (ret)
@@ -183,16 +186,16 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
set_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
}
} else {
- if (zoned) {
- mutex_lock(&fs_info->tree_log_mutex);
- if (fs_info->log_root_tree)
- ret = -EAGAIN;
- else
- ret = btrfs_init_log_root_tree(trans, fs_info);
- mutex_unlock(&fs_info->tree_log_mutex);
- }
- if (ret)
+ /*
+ * This means fs_info->log_root_tree was already created
+ * for some other FS trees. Do the full commit not to mix
+ * nodes from multiple log transactions to do sequential
+ * writing.
+ */
+ if (zoned && !created) {
+ ret = -EAGAIN;
goto out;
+ }
ret = btrfs_add_log_tree(trans, root);
if (ret)
On Thu, Feb 04, 2021 at 07:22:19PM +0900, Naohiro Aota wrote:
> This is the 2/3 patch to enable tree-log on zoned filesystems.
>
> Since we can start more than one log transactions per subvolume
> simultaneously, nodes from multiple transactions can be allocated
> interleaved. Such mixed allocation results in non-sequential writes at the
> time of a log transaction commit. The nodes of the global log root tree
> (fs_info->log_root_tree), also have the same problem with mixed
> allocation.
>
> Serializes log transactions by waiting for a committing transaction when
> someone tries to start a new transaction, to avoid the mixed allocation
> problem. We must also wait for running log transactions from another
> subvolume, but there is no easy way to detect which subvolume root is
> running a log transaction. So, this patch forbids starting a new log
> transaction when other subvolumes already allocated the global log root
> tree.
>
> Cc: Filipe Manana <fdmanana@xxxxxxxxx>
> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
> ---
> fs/btrfs/tree-log.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index c02eeeac439c..8be3164d4c5d 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -105,6 +105,7 @@ static noinline int replay_dir_deletes(struct btrfs_trans_handle *trans,
> struct btrfs_root *log,
> struct btrfs_path *path,
> u64 dirid, int del_all);
> +static void wait_log_commit(struct btrfs_root *root, int transid);
>
> /*
> * tree logging is a special write ahead log used to make sure that
> @@ -140,6 +141,7 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
> {
> struct btrfs_fs_info *fs_info = root->fs_info;
> struct btrfs_root *tree_root = fs_info->tree_root;
> + const bool zoned = btrfs_is_zoned(fs_info);
> int ret = 0;
>
> /*
> @@ -160,12 +162,20 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
>
> mutex_lock(&root->log_mutex);
>
> +again:
> if (root->log_root) {
> + int index = (root->log_transid + 1) % 2;
> +
> if (btrfs_need_log_full_commit(trans)) {
> ret = -EAGAIN;
> goto out;
> }
>
> + if (zoned && atomic_read(&root->log_commit[index])) {
> + wait_log_commit(root, root->log_transid - 1);
> + goto again;
> + }
> +
> if (!root->log_start_pid) {
> clear_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
> root->log_start_pid = current->pid;
> @@ -173,6 +183,17 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
> set_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
> }
> } else {
> + if (zoned) {
> + mutex_lock(&fs_info->tree_log_mutex);
> + if (fs_info->log_root_tree)
> + ret = -EAGAIN;
> + else
> + ret = btrfs_init_log_root_tree(trans, fs_info);
> + mutex_unlock(&fs_info->tree_log_mutex);
> + }
> + if (ret)
> + goto out;
> +
> ret = btrfs_add_log_tree(trans, root);
> if (ret)
> goto out;
> @@ -201,14 +222,22 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
> */
> static int join_running_log_trans(struct btrfs_root *root)
> {
> + const bool zoned = btrfs_is_zoned(root->fs_info);
> int ret = -ENOENT;
>
> if (!test_bit(BTRFS_ROOT_HAS_LOG_TREE, &root->state))
> return ret;
>
> mutex_lock(&root->log_mutex);
> +again:
> if (root->log_root) {
> + int index = (root->log_transid + 1) % 2;
> +
> ret = 0;
> + if (zoned && atomic_read(&root->log_commit[index])) {
> + wait_log_commit(root, root->log_transid - 1);
> + goto again;
> + }
> atomic_inc(&root->log_writers);
> }
> mutex_unlock(&root->log_mutex);
> --
> 2.30.0
>
