thr3ads.net - Btrfs devel - [PATCH] Btrfs: if we''ve already started a trans handle, use that one [Apr 2011]

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Josef Bacik

2011-Apr-13 19:17 UTC

[PATCH] Btrfs: if we''ve already started a trans handle, use that one

We currently track trans handles in current->journal_info, but we
don''t actually
use it.  This patch fixes it.  This will cover the case where we have multiple
people starting transactions down the call chain.  This keeps us from having to
allocate a new handle and all of that, we just increase the use count of the
current handle, save the old block_rsv, and return.  I tested this with xfstests
and it worked out fine.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 fs/btrfs/transaction.c |   17 +++++++++++++++++
 fs/btrfs/transaction.h |    2 ++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 70bfb26..46f4056 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -184,6 +184,15 @@ static struct btrfs_trans_handle *start_transaction(struct
btrfs_root *root,
 
 	if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 		return ERR_PTR(-EROFS);
+
+	if (current->journal_info) {
+		WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
+		h = current->journal_info;
+		h->use_count++;
+		h->orig_rsv = h->block_rsv;
+		h->block_rsv = NULL;
+		goto got_it;
+	}
 again:
 	h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 	if (!h)
@@ -213,7 +222,9 @@ again:
 	h->block_group = 0;
 	h->bytes_reserved = 0;
 	h->delayed_ref_updates = 0;
+	h->use_count = 1;
 	h->block_rsv = NULL;
+	h->orig_rsv = NULL;
 
 	smp_mb();
 	if (cur_trans->blocked && may_wait_transaction(root, type)) {
@@ -241,6 +252,7 @@ again:
 		}
 	}
 
+got_it:
 	if (type != TRANS_JOIN_NOLOCK)
 		mutex_lock(&root->fs_info->trans_mutex);
 	record_root_in_trans(h, root);
@@ -428,6 +440,11 @@ static int __btrfs_end_transaction(struct
btrfs_trans_handle *trans,
 	struct btrfs_fs_info *info = root->fs_info;
 	int count = 0;
 
+	if (--trans->use_count) {
+		trans->block_rsv = trans->orig_rsv;
+		return 0;
+	}
+
 	while (count < 4) {
 		unsigned long cur = trans->delayed_ref_updates;
 		trans->delayed_ref_updates = 0;
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 1f573f0..154314f 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -47,11 +47,13 @@ struct btrfs_trans_handle {
 	u64 transid;
 	u64 block_group;
 	u64 bytes_reserved;
+	unsigned long use_count;
 	unsigned long blocks_reserved;
 	unsigned long blocks_used;
 	unsigned long delayed_ref_updates;
 	struct btrfs_transaction *transaction;
 	struct btrfs_block_rsv *block_rsv;
+	struct btrfs_block_rsv *orig_rsv;
 };
 
 struct btrfs_pending_snapshot {
-- 
1.7.2.3

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Josef Bacik

2011-Apr-15 16:56 UTC

head link

[PATCH] Btrfs: if we''ve already started a trans handle, use that one

We currently track trans handles in current->journal_info, but we
don''t actually
use it.  This patch fixes it.  This will cover the case where we have multiple
people starting transactions down the call chain.  This keeps us from having to
allocate a new handle and all of that, we just increase the use count of the
current handle, save the old block_rsv, and return.  I tested this with xfstests
and it worked out fine.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 fs/btrfs/transaction.c |   17 +++++++++++++++++
 fs/btrfs/transaction.h |    2 ++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 70bfb26..46f4056 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -184,6 +184,15 @@ static struct btrfs_trans_handle *start_transaction(struct
btrfs_root *root,
 
 	if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 		return ERR_PTR(-EROFS);
+
+	if (current->journal_info) {
+		WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
+		h = current->journal_info;
+		h->use_count++;
+		h->orig_rsv = h->block_rsv;
+		h->block_rsv = NULL;
+		goto got_it;
+	}
 again:
 	h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 	if (!h)
@@ -213,7 +222,9 @@ again:
 	h->block_group = 0;
 	h->bytes_reserved = 0;
 	h->delayed_ref_updates = 0;
+	h->use_count = 1;
 	h->block_rsv = NULL;
+	h->orig_rsv = NULL;
 
 	smp_mb();
 	if (cur_trans->blocked && may_wait_transaction(root, type)) {
@@ -241,6 +252,7 @@ again:
 		}
 	}
 
+got_it:
 	if (type != TRANS_JOIN_NOLOCK)
 		mutex_lock(&root->fs_info->trans_mutex);
 	record_root_in_trans(h, root);
@@ -428,6 +440,11 @@ static int __btrfs_end_transaction(struct
btrfs_trans_handle *trans,
 	struct btrfs_fs_info *info = root->fs_info;
 	int count = 0;
 
+	if (--trans->use_count) {
+		trans->block_rsv = trans->orig_rsv;
+		return 0;
+	}
+
 	while (count < 4) {
 		unsigned long cur = trans->delayed_ref_updates;
 		trans->delayed_ref_updates = 0;
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 1f573f0..154314f 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -47,11 +47,13 @@ struct btrfs_trans_handle {
 	u64 transid;
 	u64 block_group;
 	u64 bytes_reserved;
+	unsigned long use_count;
 	unsigned long blocks_reserved;
 	unsigned long blocks_used;
 	unsigned long delayed_ref_updates;
 	struct btrfs_transaction *transaction;
 	struct btrfs_block_rsv *block_rsv;
+	struct btrfs_block_rsv *orig_rsv;
 };
 
 struct btrfs_pending_snapshot {
-- 
1.7.2.3

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Chris Mason

2011-Apr-15 17:36 UTC

head link

Re: [PATCH] Btrfs: if we''ve already started a trans handle, use that one

Excerpts from Josef Bacik''s message of 2011-04-15 12:56:15
-0400:> We currently track trans handles in current->journal_info, but we
don''t actually
> use it.  This patch fixes it.  This will cover the case where we have
multiple
> people starting transactions down the call chain.  This keeps us from
having to
> allocate a new handle and all of that, we just increase the use count of
the
> current handle, save the old block_rsv, and return.  I tested this with
xfstests
> and it worked out fine.  Thanks,
Just curious, which call stacks are currently nesting transactions?

-chris
> 
> Signed-off-by: Josef Bacik <josef@redhat.com>
> ---
>  fs/btrfs/transaction.c |   17 +++++++++++++++++
>  fs/btrfs/transaction.h |    2 ++
>  2 files changed, 19 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index 70bfb26..46f4056 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -184,6 +184,15 @@ static struct btrfs_trans_handle
*start_transaction(struct btrfs_root *root,
>  
>      if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
>          return ERR_PTR(-EROFS);
> +
> +    if (current->journal_info) {
> +        WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
> +        h = current->journal_info;
> +        h->use_count++;
> +        h->orig_rsv = h->block_rsv;
> +        h->block_rsv = NULL;
> +        goto got_it;
> +    }
>  again:
>      h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
>      if (!h)
> @@ -213,7 +222,9 @@ again:
>      h->block_group = 0;
>      h->bytes_reserved = 0;
>      h->delayed_ref_updates = 0;
> +    h->use_count = 1;
>      h->block_rsv = NULL;
> +    h->orig_rsv = NULL;
>  
>      smp_mb();
>      if (cur_trans->blocked && may_wait_transaction(root, type))
{
> @@ -241,6 +252,7 @@ again:
>          }
>      }
>  
> +got_it:
>      if (type != TRANS_JOIN_NOLOCK)
>          mutex_lock(&root->fs_info->trans_mutex);
>      record_root_in_trans(h, root);
> @@ -428,6 +440,11 @@ static int __btrfs_end_transaction(struct
btrfs_trans_handle *trans,
>      struct btrfs_fs_info *info = root->fs_info;
>      int count = 0;
>  
> +    if (--trans->use_count) {
> +        trans->block_rsv = trans->orig_rsv;
> +        return 0;
> +    }
> +
>      while (count < 4) {
>          unsigned long cur = trans->delayed_ref_updates;
>          trans->delayed_ref_updates = 0;
> diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
> index 1f573f0..154314f 100644
> --- a/fs/btrfs/transaction.h
> +++ b/fs/btrfs/transaction.h
> @@ -47,11 +47,13 @@ struct btrfs_trans_handle {
>      u64 transid;
>      u64 block_group;
>      u64 bytes_reserved;
> +    unsigned long use_count;
>      unsigned long blocks_reserved;
>      unsigned long blocks_used;
>      unsigned long delayed_ref_updates;
>      struct btrfs_transaction *transaction;
>      struct btrfs_block_rsv *block_rsv;
> +    struct btrfs_block_rsv *orig_rsv;
>  };
>  
>  struct btrfs_pending_snapshot {--
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Josef Bacik

2011-Apr-15 18:12 UTC

head link

Re: [PATCH] Btrfs: if we''ve already started a trans handle, use that one

On 04/15/2011 01:36 PM, Chris Mason wrote:> Excerpts from Josef Bacik''s message of 2011-04-15 12:56:15 -0400:
>> We currently track trans handles in current->journal_info, but we
don''t actually
>> use it.  This patch fixes it.  This will cover the case where we have
multiple
>> people starting transactions down the call chain.  This keeps us from
having to
>> allocate a new handle and all of that, we just increase the use count
of the
>> current handle, save the old block_rsv, and return.  I tested this with
xfstests
>> and it worked out fine.  Thanks,
>
> Just curious, which call stacks are currently nesting transactions?
>
The one that kept getting me in trouble was the run_delalloc_nocow which 
could possibly call cow_file_range.  I didn''t notice any others, but I 
didn''t really look all that hard either.  Thanks,

Josef
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Btrfs devel - Apr 2011 - [PATCH] Btrfs: if we've already started a trans handle, use that one

[PATCH] Btrfs: if we''ve already started a trans handle, use that one

[PATCH] Btrfs: if we''ve already started a trans handle, use that one

Re: [PATCH] Btrfs: if we''ve already started a trans handle, use that one

Re: [PATCH] Btrfs: if we''ve already started a trans handle, use that one