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authorRichard Yao <[email protected]>2015-12-03 14:15:16 -0500
committerBrian Behlendorf <[email protected]>2015-12-08 13:24:47 -0800
commita430c11f0b1ef16ca5edf3059e4082709277376c (patch)
treeb16f8abb6b7c13c0fc73b9538a3181014683fb52 /include
parent1683e75edc1fdca1eba53f16ca08ce32c5e736d1 (diff)
Make taskq_member() use ->journal_info
The ->journal_info pointer in the task_struct is reserved for use by filesystems and because the kernel can have multiple file systems on the same stack due to direct reclaim, each filesystem that touches ->journal_info in a callback function will save the value at the start of its frame and restore it at the end of its frame. This allows us to safely use ->journal_info to store a pointer to the taskq's struct in taskq threads so that ZFS code paths can detect the presence of a taskq. This could break if the ZFS code were to use taskq_member from the context of direct reclaim. However, there are no such uses of it in that manner, so this is safe. This eliminates an O(N) list traversal under a spinlock with an O(1) unlocked pointer comparison. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: tuxoko <[email protected]> Signed-off-by: Tim Chase <[email protected]> Closes #500
Diffstat (limited to 'include')
-rw-r--r--include/sys/taskq.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/sys/taskq.h b/include/sys/taskq.h
index a43a86da6..65f911245 100644
--- a/include/sys/taskq.h
+++ b/include/sys/taskq.h
@@ -124,7 +124,7 @@ extern void taskq_wait_id(taskq_t *, taskqid_t);
extern void taskq_wait_outstanding(taskq_t *, taskqid_t);
extern void taskq_wait(taskq_t *);
extern int taskq_cancel_id(taskq_t *, taskqid_t);
-extern int taskq_member(taskq_t *, void *);
+#define taskq_member(taskq, thread) ((taskq) == ((thread)->journal_info))
#define taskq_create_proc(name, nthreads, pri, min, max, proc, flags) \
taskq_create(name, nthreads, pri, min, max, flags)