From: Christophe JAILLET <christophe.jaillet@wanadoo.fr> To: Mark Fasheh <mark@fasheh.com>, Joel Becker <jlbec@evilplan.org>, Joseph Qi <joseph.qi@linux.alibaba.com> Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET <christophe.jaillet@wanadoo.fr>, ocfs2-devel@oss.oracle.com Subject: [PATCH 2/3] ocfs2: Remove a useless spinlock Date: Tue, 19 Jul 2022 12:01:35 +0200 [thread overview] Message-ID: <8ba7004d330cbe5f626539a8a3bff696d0c4285e.1658224839.git.christophe.jaillet@wanadoo.fr> (raw) In-Reply-To: <bd6796635e58f9c47cf857573c3b9474a00ce26a.1658224839.git.christophe.jaillet@wanadoo.fr> 'node_map_lock' is a spinlock only used to protect calls to set_bit(), clear_bit() and test_bit(). {set|clear}_bit() are already atomic and don't need this extra spinlock. test_bit() only reads the bitmap for a given bit. Remove this useless spinlock. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- test_bit() is NOT documented as an atomic function. However, I can't see how it could return a wrong result here. So review with care. There is maybe something I don't think about that is lurking here. --- fs/ocfs2/heartbeat.c | 11 ++++------- fs/ocfs2/ocfs2.h | 2 -- 2 files changed, 4 insertions(+), 9 deletions(-) diff --git a/fs/ocfs2/heartbeat.c b/fs/ocfs2/heartbeat.c index 1d72e0788943..4863ad35c242 100644 --- a/fs/ocfs2/heartbeat.c +++ b/fs/ocfs2/heartbeat.c @@ -35,7 +35,6 @@ static void ocfs2_node_map_init(struct ocfs2_node_map *map) void ocfs2_init_node_maps(struct ocfs2_super *osb) { - spin_lock_init(&osb->node_map_lock); ocfs2_node_map_init(&osb->osb_recovering_orphan_dirs); } @@ -67,9 +66,8 @@ void ocfs2_node_map_set_bit(struct ocfs2_super *osb, if (bit==-1) return; BUG_ON(bit >= map->num_nodes); - spin_lock(&osb->node_map_lock); + set_bit(bit, map->map); - spin_unlock(&osb->node_map_lock); } void ocfs2_node_map_clear_bit(struct ocfs2_super *osb, @@ -79,9 +77,8 @@ void ocfs2_node_map_clear_bit(struct ocfs2_super *osb, if (bit==-1) return; BUG_ON(bit >= map->num_nodes); - spin_lock(&osb->node_map_lock); + clear_bit(bit, map->map); - spin_unlock(&osb->node_map_lock); } int ocfs2_node_map_test_bit(struct ocfs2_super *osb, @@ -89,13 +86,13 @@ int ocfs2_node_map_test_bit(struct ocfs2_super *osb, int bit) { int ret; + if (bit >= map->num_nodes) { mlog(ML_ERROR, "bit=%d map->num_nodes=%d\n", bit, map->num_nodes); BUG(); } - spin_lock(&osb->node_map_lock); + ret = test_bit(bit, map->map); - spin_unlock(&osb->node_map_lock); return ret; } diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h index 740b64238312..1df193b97c30 100644 --- a/fs/ocfs2/ocfs2.h +++ b/fs/ocfs2/ocfs2.h @@ -302,8 +302,6 @@ struct ocfs2_super u32 *slot_recovery_generations; - spinlock_t node_map_lock; - u64 root_blkno; u64 system_dir_blkno; u64 bitmap_blkno; -- 2.34.1
WARNING: multiple messages have this Message-ID (diff)
From: Christophe JAILLET via Ocfs2-devel <ocfs2-devel@oss.oracle.com> To: Mark Fasheh <mark@fasheh.com>, Joel Becker <jlbec@evilplan.org>, Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: [Ocfs2-devel] [PATCH 2/3] ocfs2: Remove a useless spinlock Date: Tue, 19 Jul 2022 12:01:35 +0200 [thread overview] Message-ID: <8ba7004d330cbe5f626539a8a3bff696d0c4285e.1658224839.git.christophe.jaillet@wanadoo.fr> (raw) In-Reply-To: <bd6796635e58f9c47cf857573c3b9474a00ce26a.1658224839.git.christophe.jaillet@wanadoo.fr> 'node_map_lock' is a spinlock only used to protect calls to set_bit(), clear_bit() and test_bit(). {set|clear}_bit() are already atomic and don't need this extra spinlock. test_bit() only reads the bitmap for a given bit. Remove this useless spinlock. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> --- test_bit() is NOT documented as an atomic function. However, I can't see how it could return a wrong result here. So review with care. There is maybe something I don't think about that is lurking here. --- fs/ocfs2/heartbeat.c | 11 ++++------- fs/ocfs2/ocfs2.h | 2 -- 2 files changed, 4 insertions(+), 9 deletions(-) diff --git a/fs/ocfs2/heartbeat.c b/fs/ocfs2/heartbeat.c index 1d72e0788943..4863ad35c242 100644 --- a/fs/ocfs2/heartbeat.c +++ b/fs/ocfs2/heartbeat.c @@ -35,7 +35,6 @@ static void ocfs2_node_map_init(struct ocfs2_node_map *map) void ocfs2_init_node_maps(struct ocfs2_super *osb) { - spin_lock_init(&osb->node_map_lock); ocfs2_node_map_init(&osb->osb_recovering_orphan_dirs); } @@ -67,9 +66,8 @@ void ocfs2_node_map_set_bit(struct ocfs2_super *osb, if (bit==-1) return; BUG_ON(bit >= map->num_nodes); - spin_lock(&osb->node_map_lock); + set_bit(bit, map->map); - spin_unlock(&osb->node_map_lock); } void ocfs2_node_map_clear_bit(struct ocfs2_super *osb, @@ -79,9 +77,8 @@ void ocfs2_node_map_clear_bit(struct ocfs2_super *osb, if (bit==-1) return; BUG_ON(bit >= map->num_nodes); - spin_lock(&osb->node_map_lock); + clear_bit(bit, map->map); - spin_unlock(&osb->node_map_lock); } int ocfs2_node_map_test_bit(struct ocfs2_super *osb, @@ -89,13 +86,13 @@ int ocfs2_node_map_test_bit(struct ocfs2_super *osb, int bit) { int ret; + if (bit >= map->num_nodes) { mlog(ML_ERROR, "bit=%d map->num_nodes=%d\n", bit, map->num_nodes); BUG(); } - spin_lock(&osb->node_map_lock); + ret = test_bit(bit, map->map); - spin_unlock(&osb->node_map_lock); return ret; } diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h index 740b64238312..1df193b97c30 100644 --- a/fs/ocfs2/ocfs2.h +++ b/fs/ocfs2/ocfs2.h @@ -302,8 +302,6 @@ struct ocfs2_super u32 *slot_recovery_generations; - spinlock_t node_map_lock; - u64 root_blkno; u64 system_dir_blkno; u64 bitmap_blkno; -- 2.34.1 _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
next prev parent reply other threads:[~2022-07-19 10:02 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-19 10:01 [PATCH 1/3] ocfs2: Remove some useless functions Christophe JAILLET 2022-07-19 10:01 ` [Ocfs2-devel] " Christophe JAILLET via Ocfs2-devel 2022-07-19 10:01 ` Christophe JAILLET [this message] 2022-07-19 10:01 ` [Ocfs2-devel] [PATCH 2/3] ocfs2: Remove a useless spinlock Christophe JAILLET via Ocfs2-devel 2022-07-19 10:24 ` David Laight 2022-07-19 10:24 ` [Ocfs2-devel] " David Laight via Ocfs2-devel 2022-07-19 13:25 ` Christophe JAILLET via Ocfs2-devel 2022-07-19 13:25 ` Christophe JAILLET 2022-07-19 14:19 ` [Ocfs2-devel] " David Laight via Ocfs2-devel 2022-07-19 14:19 ` David Laight 2022-07-20 1:59 ` Joseph Qi 2022-07-20 1:59 ` [Ocfs2-devel] " Joseph Qi via Ocfs2-devel 2022-07-20 8:26 ` Marion & Christophe JAILLET 2022-07-20 8:26 ` [Ocfs2-devel] " Marion & Christophe JAILLET via Ocfs2-devel 2022-07-20 9:48 ` Joseph Qi 2022-07-20 9:48 ` [Ocfs2-devel] " Joseph Qi via Ocfs2-devel 2022-07-20 13:32 ` Christophe JAILLET 2022-07-20 13:32 ` [Ocfs2-devel] " Christophe JAILLET via Ocfs2-devel 2022-07-21 1:53 ` Joseph Qi 2022-07-21 1:53 ` [Ocfs2-devel] " Joseph Qi via Ocfs2-devel 2022-07-19 10:05 ` [PATCH 3/3] ocfs2: use the bitmap API to simplify code Christophe JAILLET 2022-07-19 10:05 ` [Ocfs2-devel] " Christophe JAILLET via Ocfs2-devel 2022-07-20 2:06 ` Joseph Qi 2022-07-20 2:06 ` [Ocfs2-devel] " Joseph Qi via Ocfs2-devel 2022-07-20 2:03 ` [PATCH 1/3] ocfs2: Remove some useless functions Joseph Qi 2022-07-20 2:03 ` [Ocfs2-devel] " Joseph Qi via Ocfs2-devel
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