137 lines
4.6 KiB
Diff
137 lines
4.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Tony Hutter <hutter2@llnl.gov>
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Date: Wed, 15 Aug 2018 11:58:54 -0700
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Subject: [PATCH] Add rwsem_tryupgrade for 4.9.20-rt16 kernel (SPL)
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(This is the SPL backported code from 11d0525cb)
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The RT rwsem implementation was changed to allow multiple readers
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as of the 4.9.20-rt16 patch set. This results in a build failure
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because the existing implementation was forced to directly access
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the rwsem structure which has changed.
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While this could be accommodated by adding additional compatibility
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code. This patch resolves the build issue by simply assuming the
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rwsem can never be upgraded. This functionality is a performance
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optimization and all callers must already handle this case.
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Converting the last remaining use of __SPIN_LOCK_UNLOCKED to
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spin_lock_init() was additionally required to get a clean build.
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Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
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Closes #7589
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Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
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---
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include/sys/isa_defs.h | 8 ++++++++
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include/sys/rwlock.h | 10 +++++-----
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module/spl/spl-rwlock.c | 19 ++++++++++++++-----
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module/spl/spl-vnode.c | 2 ++
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4 files changed, 29 insertions(+), 10 deletions(-)
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diff --git a/include/sys/isa_defs.h b/include/sys/isa_defs.h
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index 5559782..13dcb35 100644
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--- a/include/sys/isa_defs.h
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+++ b/include/sys/isa_defs.h
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@@ -210,6 +210,14 @@
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#include <sys/byteorder.h>
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+/*
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+ * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS will be defined by the Linux
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+ * kernel for architectures which support efficient unaligned access.
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+ */
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+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
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+#define HAVE_EFFICIENT_UNALIGNED_ACCESS
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+#endif
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+
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#if defined(__LITTLE_ENDIAN) && !defined(_LITTLE_ENDIAN)
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#define _LITTLE_ENDIAN __LITTLE_ENDIAN
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#endif
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diff --git a/include/sys/rwlock.h b/include/sys/rwlock.h
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index 325dfc4..2699229 100644
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--- a/include/sys/rwlock.h
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+++ b/include/sys/rwlock.h
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@@ -135,7 +135,7 @@ RW_LOCK_HELD(krwlock_t *rwp)
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}
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/*
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- * The following functions must be a #define and not static inline.
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+ * The following functions must be a #define and not static inline.
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* This ensures that the native linux semaphore functions (down/up)
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* will be correctly located in the users code which is important
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* for the built in kernel lock analysis tools
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@@ -151,10 +151,10 @@ RW_LOCK_HELD(krwlock_t *rwp)
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spl_rw_set_type(rwp, type); \
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})
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-#define rw_destroy(rwp) \
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-({ \
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- VERIFY(!RW_LOCK_HELD(rwp)); \
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-})
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+/*
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+ * The Linux rwsem implementation does not require a matching destroy.
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+ */
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+#define rw_destroy(rwp) ((void) 0)
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#define rw_tryenter(rwp, rw) \
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({ \
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diff --git a/module/spl/spl-rwlock.c b/module/spl/spl-rwlock.c
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index bf7ee2f..ac28c91 100644
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--- a/module/spl/spl-rwlock.c
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+++ b/module/spl/spl-rwlock.c
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@@ -34,16 +34,24 @@
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static int
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__rwsem_tryupgrade(struct rw_semaphore *rwsem)
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{
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-
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+#if defined(READER_BIAS) && defined(WRITER_BIAS)
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+ /*
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+ * After the 4.9.20-rt16 kernel the realtime patch series lifted the
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+ * single reader restriction. While this could be accommodated by
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+ * adding additional compatibility code assume the rwsem can never
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+ * be upgraded. All caller must already cleanly handle this case.
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+ */
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+ return (0);
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+#else
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ASSERT((struct task_struct *)
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((unsigned long)rwsem->lock.owner & ~RT_MUTEX_OWNER_MASKALL) ==
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current);
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/*
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- * Under the realtime patch series, rwsem is implemented as a
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- * single mutex held by readers and writers alike. However,
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- * this implementation would prevent a thread from taking a
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- * read lock twice, as the mutex would already be locked on
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+ * Prior to 4.9.20-rt16 kernel the realtime patch series, rwsem is
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+ * implemented as a single mutex held by readers and writers alike.
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+ * However, this implementation would prevent a thread from taking
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+ * a read lock twice, as the mutex would already be locked on
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* the second attempt. Therefore the implementation allows a
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* single thread to take a rwsem as read lock multiple times
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* tracking that nesting as read_depth counter.
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@@ -59,6 +67,7 @@ __rwsem_tryupgrade(struct rw_semaphore *rwsem)
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return (1);
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}
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return (0);
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+#endif
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}
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#elif defined(CONFIG_RWSEM_GENERIC_SPINLOCK)
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static int
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diff --git a/module/spl/spl-vnode.c b/module/spl/spl-vnode.c
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index 74ae8fe..cd0015f 100644
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--- a/module/spl/spl-vnode.c
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+++ b/module/spl/spl-vnode.c
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@@ -670,6 +670,8 @@ vn_file_cache_destructor(void *buf, void *cdrarg)
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int
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spl_vn_init(void)
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{
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+ spin_lock_init(&vn_file_lock);
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+
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vn_cache = kmem_cache_create("spl_vn_cache",
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sizeof (struct vnode), 64, vn_cache_constructor,
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vn_cache_destructor, NULL, NULL, NULL, 0);
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--
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2.11.0
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