Re: [PATCH v15 40/42] btrfs: zoned: serialize log transaction on zoned filesystems
On Fri, Feb 05, 2021 at 06:15:16PM +0900, Naohiro Aota wrote: > David, could you fold the below incremental diff to this patch? Or, I > can send a full replacement patch. Folded to the patch, thanks.
Re: [PATCH v15 40/42] btrfs: zoned: serialize log transaction on zoned filesystems
On Fri, Feb 5, 2021 at 9:15 AM Naohiro Aota wrote:
>
> 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)
>
Ok, with this, it looks good to me and you can have,
Reviewed-by: Filipe Manana
Thanks.
>
> 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
> > Reviewed-by: Josef Bacik
> > Signed-off-by: Naohiro Aota
> > ---
> > 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;
> >
Re: [PATCH v15 40/42] btrfs: zoned: serialize log transaction on zoned filesystems
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
> Reviewed-by: Josef Bacik
> Signed-off-by: Naohiro Aota
> ---
> 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);
>
Re: [PATCH v15 40/42] btrfs: zoned: serialize log transaction on zoned filesystems
On Thu, Feb 04, 2021 at 11:50:45AM +, Filipe Manana wrote:
> On Thu, Feb 4, 2021 at 10:23 AM 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
> > Reviewed-by: Josef Bacik
> > Signed-off-by: Naohiro Aota
> > ---
> > 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);
> > + }
>
> So, nothing here changed since v14 - all my comments still apply [1]
> This is based on pre-5.10 code and is broken as it is - it results in
> every fsync falling back to a transaction commit, defeating the
> purpose of all the patches that deal with log trees on zoned
> filesystems.
>
> Thanks.
>
> [1]
> https://lore.kernel.org/linux-btrfs/cal3q7h5pv416fvwthohe+m3l5b-z_n6_zgqqxsuq5vc5fsa...@mail.gmail.com/
Yes...
As noted in the cover letter, there is a fix for this issue
itself. However, the fix revealed other failures in fsync() path.
But, with further investigation, I found the failures are not really
related to zoned fsync() code. So, I will soon post two patches (one
incremental for this one, and one to deal with a regression case)..
>
>
> > + 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
Re: [PATCH v15 40/42] btrfs: zoned: serialize log transaction on zoned filesystems
On Thu, Feb 4, 2021 at 10:23 AM 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
> Reviewed-by: Josef Bacik
> Signed-off-by: Naohiro Aota
> ---
> 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);
> + }
So, nothing here changed since v14 - all my comments still apply [1]
This is based on pre-5.10 code and is broken as it is - it results in
every fsync falling back to a transaction commit, defeating the
purpose of all the patches that deal with log trees on zoned
filesystems.
Thanks.
[1]
https://lore.kernel.org/linux-btrfs/cal3q7h5pv416fvwthohe+m3l5b-z_n6_zgqqxsuq5vc5fsa...@mail.gmail.com/
> + 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
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
