On 01/02/2021 16:49, Filipe Manana wrote: > On Wed, Jan 27, 2021 at 6:48 PM Naohiro Aota <[email protected]> wrote: >> >> This is the 3/3 patch to enable tree-log on ZONED mode. >> >> The allocation order of nodes of "fs_info->log_root_tree" and nodes of >> "root->log_root" is not the same as the writing order of them. So, the >> writing causes unaligned write errors. >> >> This patch reorders the allocation of them by delaying allocation of the >> root node of "fs_info->log_root_tree," so that the node buffers can go out >> sequentially to devices. >> >> Reviewed-by: Josef Bacik <[email protected]> >> Signed-off-by: Johannes Thumshirn <[email protected]> >> Signed-off-by: Naohiro Aota <[email protected]> >> --- >> fs/btrfs/disk-io.c | 7 ------- >> fs/btrfs/tree-log.c | 24 ++++++++++++++++++------ >> 2 files changed, 18 insertions(+), 13 deletions(-) >> >> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >> index c3b5cfe4d928..d2b30716de84 100644 >> --- a/fs/btrfs/disk-io.c >> +++ b/fs/btrfs/disk-io.c >> @@ -1241,18 +1241,11 @@ int btrfs_init_log_root_tree(struct >> btrfs_trans_handle *trans, >> struct btrfs_fs_info *fs_info) >> { >> struct btrfs_root *log_root; >> - int ret; >> >> log_root = alloc_log_tree(trans, fs_info); >> if (IS_ERR(log_root)) >> return PTR_ERR(log_root); >> >> - ret = btrfs_alloc_log_tree_node(trans, log_root); >> - if (ret) { >> - btrfs_put_root(log_root); >> - return ret; >> - } >> - >> WARN_ON(fs_info->log_root_tree); >> fs_info->log_root_tree = log_root; >> return 0; >> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c >> index 71a1c0b5bc26..d8315363dc1e 100644 >> --- a/fs/btrfs/tree-log.c >> +++ b/fs/btrfs/tree-log.c >> @@ -3159,6 +3159,16 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, >> list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]); >> root_log_ctx.log_transid = log_root_tree->log_transid; >> >> + mutex_lock(&fs_info->tree_log_mutex); >> + if (!log_root_tree->node) { >> + ret = btrfs_alloc_log_tree_node(trans, log_root_tree); >> + if (ret) { >> + mutex_unlock(&fs_info->tree_log_mutex); >> + goto out; >> + } >> + } >> + mutex_unlock(&fs_info->tree_log_mutex); > > Hum, so this now has an impact for non-zoned mode. > > It reduces the parallelism between a previous transaction finishing > its commit and an fsync started in the current transaction. > > A transaction commit releases fs_info->tree_log_mutex after it commits > the super block. > > By taking that mutex here, we wait for the transaction commit to write > the super blocks before we update the log root, start writeback of log > tree nodes and wait for the writeback to complete. > > Before this change, we would do those 3 things before waiting for the > previous transaction to commit the super blocks. > > So this undoes part of what was made by the following commit: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=47876f7ceffa0e6af7476e052b3c061f1f2c1d9f > > Which landed in 5.10. This patch and the rest of the patchset was > based on pre 5.10 code - was this missed because of that? > Or is there some other reason to have to do things this way for non-zoned > mode? > > I think we should preserve the behaviour for non-zoned mode - i.e. any > reason why not allocating log_root_tree->node at the top of start > log_trans(), while under the protection of tree_root->log_mutex? > > My impression is that this, and the other patch with the subject > "btrfs: serialize log transaction on ZONED mode", are out of sync with > the changes in 5.10. > > Thanks, sorry for the late review.
Yes this code has been under development for quite some time and we probably missed this upstream update. We will be sending a fix ASAP.