fscache: put reference of parent's usage and n_children

PATCH In review Kinglong Mee 4 participants 10 messages Apr 10, 2015 – Apr 14, 2015 4 messages not in the archive

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Kinglong Mee

author

2015-04-10 13:01 UTC #0 lore raw

PATCH 1/1 fscache: put reference of parent's usage and n_children

If netfs exist, fscache must put the reference of parent's usage and n_children, otherwise, never be decreased.

Signed-off-by Kinglong Mee <[email protected]>

---
 fs/fscache/netfs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

fs/fscache/netfs.c +1 -2

index 6d941f5..b16afba 100644
@@ -71,8 +71,7 @@ already_registered:
 	up_write(&fscache_addremove_sem);
 
 	if (ret < 0) {
-		netfs->primary_index->parent = NULL;
-		__fscache_cookie_put(netfs->primary_index);
+		fscache_relinquish_cookie(netfs->primary_index, 0);
 		netfs->primary_index = NULL;
 	}

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David Howells

2015-04-13 11:33 UTC #2 lore raw

Quoted 2 lines · Kinglong Mee

If netfs exist, fscache must put the reference of parent's usage and n_children, otherwise, never be decreased.

Good catch. Though it might be preferable to only increment the counters if the list_add() is done.

David
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Kinglong Mee

2015-04-13 12:23 UTC #3 lore raw

Quoted 7 lines · David Howells

Quoted 2 lines · Kinglong Mee
If netfs exist, fscache must put the reference of parent's usage and n_children, otherwise, never be decreased.
Good catch. Though it might be preferable to only increment the counters if the list_add() is done.

Thanks for your comments, that's great.
I will update and resend those two patch.

Thanks,
Kinglong Mee

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David Howells

2015-04-13 12:44 UTC #5 lore raw

Quoted 5 lines · Kinglong Mee

Quoted 2 lines
Good catch. Though it might be preferable to only increment the counters if the list_add() is done.
Thanks for your comments, that's great.
I will update and resend those two patch.

In fact, kmem_cache_free() can be called instead of fscache_relinquish_cookie() in that case.

David
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Kinglong Mee

author

2015-04-13 13:01 UTC #7 lore raw

PATCH v2 1/2 FSCACHE: Increase reference of parent after registering netfs success

If netfs exist, fscache should not increase the reference of parent's usage and n_children, otherwise, never be decreased.

v2: thanks David's suggest,
move increasing reference of parent if success use kmem_cache_free() freeing primary_index directly

Signed-off-by Kinglong Mee <[email protected]>

---
 fs/fscache/netfs.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

fs/fscache/netfs.c +5 -6

index 6d941f5..bea1f2e 100644
@@ -43,13 +43,9 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	atomic_set(&netfs->primary_index->n_active, 1);
 
 	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
-	netfs->primary_index->parent		= &fscache_fsdef_index;
 	netfs->primary_index->netfs_data	= netfs;
 	netfs->primary_index->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
-
 	spin_lock_init(&netfs->primary_index->lock);
 	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);

@@ -62,6 +58,10 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 			goto already_registered;
 	}
 
+	netfs->primary_index->parent = &fscache_fsdef_index;
+	atomic_inc(&netfs->primary_index->parent->usage);
+	atomic_inc(&netfs->primary_index->parent->n_children);
+
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;

@@ -71,8 +71,7 @@ already_registered:
 	up_write(&fscache_addremove_sem);
 
 	if (ret < 0) {
-		netfs->primary_index->parent = NULL;
-		__fscache_cookie_put(netfs->primary_index);
+		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
 		netfs->primary_index = NULL;
 	}

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Kinglong Mee

2015-04-13 13:01 UTC #8 lore raw

PATCH v2 2/2 FSCACHE: Don't override netfs's primary_index if registering failed

In reply to David Howells

Only override netfs->primary_index when registering success.

v2: according to the change of 1/2

Signed-off-by Kinglong Mee <[email protected]>

---
 fs/fscache/netfs.c | 35 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 18 deletions(-)

fs/fscache/netfs.c +17 ~~-18~~

index bea1f2e..166fdc3 100644
@@ -22,6 +22,7 @@ static LIST_HEAD(fscache_netfs_list);
 int __fscache_register_netfs(struct fscache_netfs *netfs)
 {
 	struct fscache_netfs *ptr;
+	struct fscache_cookie *cookie;
 	int ret;
 
 	_enter("{%s}", netfs->name);

@@ -29,25 +30,24 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	INIT_LIST_HEAD(&netfs->link);
 
 	/* allocate a cookie for the primary index */
-	netfs->primary_index =
-		kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
+	cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
 
-	if (!netfs->primary_index) {
+	if (!cookie) {
 		_leave(" = -ENOMEM");
 		return -ENOMEM;
 	}
 
 	/* initialise the primary index cookie */
-	atomic_set(&netfs->primary_index->usage, 1);
-	atomic_set(&netfs->primary_index->n_children, 0);
-	atomic_set(&netfs->primary_index->n_active, 1);
+	atomic_set(&cookie->usage, 1);
+	atomic_set(&cookie->n_children, 0);
+	atomic_set(&cookie->n_active, 1);
 
-	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
-	netfs->primary_index->netfs_data	= netfs;
-	netfs->primary_index->flags		= 1 << FSCACHE_COOKIE_ENABLED;
+	cookie->def		= &fscache_fsdef_netfs_def;
+	cookie->netfs_data	= netfs;
+	cookie->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 
-	spin_lock_init(&netfs->primary_index->lock);
-	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
+	spin_lock_init(&cookie->lock);
+	INIT_HLIST_HEAD(&cookie->backing_objects);
 
 	/* check the netfs type is not already present */
 	down_write(&fscache_addremove_sem);

@@ -58,10 +58,11 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 			goto already_registered;
 	}
 
-	netfs->primary_index->parent = &fscache_fsdef_index;
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
+	cookie->parent = &fscache_fsdef_index;
+	atomic_inc(&cookie->parent->usage);
+	atomic_inc(&cookie->parent->n_children);
 
+	netfs->primary_index = cookie;
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;

@@ -70,10 +71,8 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 already_registered:
 	up_write(&fscache_addremove_sem);
 
-	if (ret < 0) {
-		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
-		netfs->primary_index = NULL;
-	}
+	if (ret < 0)
+		kmem_cache_free(fscache_cookie_jar, cookie);
 
 	_leave(" = %d", ret);
 	return ret;

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David Howells

2015-04-13 13:12 UTC #10 lore raw

Re: [PATCH v2 1/2] FSCACHE: Increase reference of parent after registering netfs success

Review

Quoted 1 line · Kinglong Mee

(quoted diff) +0 -1

-	netfs->primary_index->parent		= &fscache_fsdef_index;

fscache_fsdef_index is a static variable so leave this where it is.

David
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Kinglong Mee

2015-04-13 13:35 UTC #11 lore raw

PATCH v3 1/2 FSCACHE: Increase reference of parent after registering, netfs success

If netfs exist, fscache should not increase the reference of parent's usage and n_children, otherwise, never be decreased.

v2: thanks David's suggest,
move increasing reference of parent if success use kmem_cache_free() freeing primary_index directly

v3: don't move "netfs->primary_index->parent = &fscache_fsdef_index;"

Signed-off-by Kinglong Mee <[email protected]>

---
 fs/fscache/netfs.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

fs/fscache/netfs.c +4 -5

index 6d941f5..458cc96 100644
@@ -47,9 +47,6 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	netfs->primary_index->netfs_data	= netfs;
 	netfs->primary_index->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
-
 	spin_lock_init(&netfs->primary_index->lock);
 	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);

@@ -62,6 +59,9 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 			goto already_registered;
 	}
 
+	atomic_inc(&netfs->primary_index->parent->usage);
+	atomic_inc(&netfs->primary_index->parent->n_children);
+
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;

@@ -71,8 +71,7 @@ already_registered:
 	up_write(&fscache_addremove_sem);
 
 	if (ret < 0) {
-		netfs->primary_index->parent = NULL;
-		__fscache_cookie_put(netfs->primary_index);
+		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
 		netfs->primary_index = NULL;
 	}

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David Howells

2015-04-14 09:34 UTC #12 lore raw

Re: [PATCH v3 1/2] FSCACHE: Increase reference of parent after registering, netfs success

Applied here:

http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache

David

Kinglong Mee

2015-04-13 13:35 UTC #13 lore raw

PATCH v3 2/2 FSCACHE: Don't override netfs's primary_index if registering failed

In reply to David Howells

Only override netfs->primary_index when registering success.

v2,v3: according to the change of [PATH 1/2]

Signed-off-by Kinglong Mee <[email protected]>

---
 fs/fscache/netfs.c | 35 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 18 deletions(-)

fs/fscache/netfs.c +17 ~~-18~~

index 458cc96..9b28649 100644
@@ -22,6 +22,7 @@ static LIST_HEAD(fscache_netfs_list);
 int __fscache_register_netfs(struct fscache_netfs *netfs)
 {
 	struct fscache_netfs *ptr;
+	struct fscache_cookie *cookie;
 	int ret;
 
 	_enter("{%s}", netfs->name);

@@ -29,26 +30,25 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	INIT_LIST_HEAD(&netfs->link);
 
 	/* allocate a cookie for the primary index */
-	netfs->primary_index =
-		kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
+	cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
 
-	if (!netfs->primary_index) {
+	if (!cookie) {
 		_leave(" = -ENOMEM");
 		return -ENOMEM;
 	}
 
 	/* initialise the primary index cookie */
-	atomic_set(&netfs->primary_index->usage, 1);
-	atomic_set(&netfs->primary_index->n_children, 0);
-	atomic_set(&netfs->primary_index->n_active, 1);
+	atomic_set(&cookie->usage, 1);
+	atomic_set(&cookie->n_children, 0);
+	atomic_set(&cookie->n_active, 1);
 
-	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
-	netfs->primary_index->parent		= &fscache_fsdef_index;
-	netfs->primary_index->netfs_data	= netfs;
-	netfs->primary_index->flags		= 1 << FSCACHE_COOKIE_ENABLED;
+	cookie->def		= &fscache_fsdef_netfs_def;
+	cookie->parent		= &fscache_fsdef_index;
+	cookie->netfs_data	= netfs;
+	cookie->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 
-	spin_lock_init(&netfs->primary_index->lock);
-	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
+	spin_lock_init(&cookie->lock);
+	INIT_HLIST_HEAD(&cookie->backing_objects);
 
 	/* check the netfs type is not already present */
 	down_write(&fscache_addremove_sem);

@@ -59,9 +59,10 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 			goto already_registered;
 	}
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
+	atomic_inc(&cookie->parent->usage);
+	atomic_inc(&cookie->parent->n_children);
 
+	netfs->primary_index = cookie;
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;

@@ -70,10 +71,8 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 already_registered:
 	up_write(&fscache_addremove_sem);
 
-	if (ret < 0) {
-		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
-		netfs->primary_index = NULL;
-	}
+	if (ret < 0)
+		kmem_cache_free(fscache_cookie_jar, cookie);
 
 	_leave(" = %d", ret);
 	return ret;

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