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Subject[PATCH 05/13] x86, dax: replace clear_pmem() with open coded memset + dax_ops->flush
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The clear_pmem() helper simply combines a memset() plus a cache flush.
Now that the flush routine is optionally provided by the dax device
driver we can avoid unnecessary cache management on dax devices fronting
volatile memory.

With clear_pmem() gone we can follow on with a patch to make pmem cache
management completely defined within the pmem driver.

Cc: <x86@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
arch/x86/include/asm/pmem.h | 13 -------------
fs/dax.c | 5 ++++-
include/linux/pmem.h | 21 ---------------------
3 files changed, 4 insertions(+), 35 deletions(-)

diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index 0ca5e693f4a2..ab4983df7bff 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -64,19 +64,6 @@ static inline void arch_wb_cache_pmem(void *addr, size_t size)
clwb(p);
}

-/**
- * arch_clear_pmem - zero a PMEM memory range
- * @addr: virtual start address
- * @size: number of bytes to zero
- *
- * Write zeros into the memory range starting at 'addr' for 'size' bytes.
- */
-static inline void arch_clear_pmem(void *addr, size_t size)
-{
- memset(addr, 0, size);
- arch_wb_cache_pmem(addr, size);
-}
-
static inline void arch_invalidate_pmem(void *addr, size_t size)
{
clflush_cache_range(addr, size);
diff --git a/fs/dax.c b/fs/dax.c
index 160024e403f6..8883ce4d391e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -986,6 +986,7 @@ static bool dax_range_is_aligned(struct block_device *bdev,
int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
unsigned int offset, unsigned int length)
{
+ const struct dax_operations *dax_ops = to_dax_ops(bdev);
struct blk_dax_ctl dax = {
.sector = sector,
.size = PAGE_SIZE,
@@ -999,7 +1000,9 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
} else {
if (dax_map_atomic(bdev, &dax) < 0)
return PTR_ERR(dax.addr);
- clear_pmem(dax.addr + offset, length);
+ memset(dax.addr + offset, 0, length);
+ if (dax_ops->flush)
+ dax_ops->flush(dax.addr + offset, length);
dax_unmap_atomic(bdev, &dax);
}
return 0;
diff --git a/include/linux/pmem.h b/include/linux/pmem.h
index 9d542a5600e4..772bd02a5b52 100644
--- a/include/linux/pmem.h
+++ b/include/linux/pmem.h
@@ -31,11 +31,6 @@ static inline void arch_memcpy_to_pmem(void *dst, const void *src, size_t n)
BUG();
}

-static inline void arch_clear_pmem(void *addr, size_t size)
-{
- BUG();
-}
-
static inline void arch_wb_cache_pmem(void *addr, size_t size)
{
BUG();
@@ -73,22 +68,6 @@ static inline void memcpy_to_pmem(void *dst, const void *src, size_t n)
}

/**
- * clear_pmem - zero a PMEM memory range
- * @addr: virtual start address
- * @size: number of bytes to zero
- *
- * Write zeros into the memory range starting at 'addr' for 'size' bytes.
- * See blkdev_issue_flush() note for memcpy_to_pmem().
- */
-static inline void clear_pmem(void *addr, size_t size)
-{
- if (arch_has_pmem_api())
- arch_clear_pmem(addr, size);
- else
- memset(addr, 0, size);
-}
-
-/**
* invalidate_pmem - flush a pmem range from the cache hierarchy
* @addr: virtual start address
* @size: bytes to invalidate (internally aligned to cache line size)
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