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	Btrfs: Go back to kmaps instead of page_address in extent_buffers
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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					 1 changed files with 19 additions and 31 deletions
				
			
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			@ -1867,7 +1867,6 @@ sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
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	if (!em || IS_ERR(em))
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		return 0;
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	// XXX(hch): block 0 is valid in some cases, e.g. XFS RT device
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	if (em->block_start == EXTENT_MAP_INLINE ||
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	    em->block_start == EXTENT_MAP_HOLE)
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		return 0;
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			@ -2199,10 +2198,9 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
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		WARN_ON(!PageUptodate(page));
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		cur = min(len, (PAGE_CACHE_SIZE - offset));
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		// kaddr = kmap_atomic(page, KM_USER0);
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		kaddr = page_address(page);
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		kaddr = kmap_atomic(page, KM_USER0);
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		memcpy(dst, kaddr + offset, cur);
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		// kunmap_atomic(kaddr, KM_USER0);
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		kunmap_atomic(kaddr, KM_USER0);
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		dst += cur;
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		len -= cur;
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			@ -2237,8 +2235,7 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
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		*map_start = (i << PAGE_CACHE_SHIFT) - start_offset;
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	}
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	// kaddr = kmap_atomic(eb->pages[i], km);
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	kaddr = page_address(extent_buffer_page(eb, i));
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	kaddr = kmap_atomic(extent_buffer_page(eb, i), km);
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	*token = kaddr;
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	*map = kaddr + offset;
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	*map_len = PAGE_CACHE_SIZE - offset;
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			@ -2248,7 +2245,7 @@ EXPORT_SYMBOL(map_extent_buffer);
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void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
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{
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	// kunmap_atomic(token, km);
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	kunmap_atomic(token, km);
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}
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EXPORT_SYMBOL(unmap_extent_buffer);
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			@ -2278,10 +2275,9 @@ int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
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		cur = min(len, (PAGE_CACHE_SIZE - offset));
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		// kaddr = kmap_atomic(page, KM_USER0);
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		kaddr = page_address(page);
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		kaddr = kmap_atomic(page, KM_USER0);
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		ret = memcmp(ptr, kaddr + offset, cur);
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		// kunmap_atomic(kaddr, KM_USER0);
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		kunmap_atomic(kaddr, KM_USER0);
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		if (ret)
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			break;
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			@ -2317,10 +2313,9 @@ void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
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		WARN_ON(!PageUptodate(page));
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		cur = min(len, PAGE_CACHE_SIZE - offset);
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		// kaddr = kmap_atomic(page, KM_USER0);
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		kaddr = page_address(page);
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		kaddr = kmap_atomic(page, KM_USER0);
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		memcpy(kaddr + offset, src, cur);
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		// kunmap_atomic(kaddr, KM_USER0);
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		kunmap_atomic(kaddr, KM_USER0);
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		src += cur;
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		len -= cur;
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			@ -2352,10 +2347,9 @@ void memset_extent_buffer(struct extent_buffer *eb, char c,
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		WARN_ON(!PageUptodate(page));
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		cur = min(len, PAGE_CACHE_SIZE - offset);
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		// kaddr = kmap_atomic(page, KM_USER0);
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		kaddr = page_address(page);
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		kaddr = kmap_atomic(page, KM_USER0);
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		memset(kaddr + offset, c, cur);
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		// kunmap_atomic(kaddr, KM_USER0);
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		kunmap_atomic(kaddr, KM_USER0);
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		len -= cur;
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		offset = 0;
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			@ -2388,10 +2382,9 @@ void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
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		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
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		// kaddr = kmap_atomic(page, KM_USER1);
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		kaddr = page_address(page);
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		kaddr = kmap_atomic(page, KM_USER1);
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		read_extent_buffer(src, kaddr + offset, src_offset, cur);
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		// kunmap_atomic(kaddr, KM_USER1);
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		kunmap_atomic(kaddr, KM_USER1);
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		src_offset += cur;
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		len -= cur;
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			@ -2405,43 +2398,38 @@ static void move_pages(struct page *dst_page, struct page *src_page,
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		       unsigned long dst_off, unsigned long src_off,
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		       unsigned long len)
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{
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	// char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
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	char *dst_kaddr = page_address(dst_page);
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	char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
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	if (dst_page == src_page) {
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		memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
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	} else {
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		// char *src_kaddr = kmap_atomic(src_page, KM_USER1);
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		char *src_kaddr = page_address(src_page);
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		char *src_kaddr = kmap_atomic(src_page, KM_USER1);
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		char *p = dst_kaddr + dst_off + len;
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		char *s = src_kaddr + src_off + len;
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		while (len--)
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			*--p = *--s;
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		// kunmap_atomic(src_kaddr, KM_USER1);
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		kunmap_atomic(src_kaddr, KM_USER1);
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	}
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	// kunmap_atomic(dst_kaddr, KM_USER0);
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	kunmap_atomic(dst_kaddr, KM_USER0);
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}
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static void copy_pages(struct page *dst_page, struct page *src_page,
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		       unsigned long dst_off, unsigned long src_off,
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		       unsigned long len)
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{
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	//kmap_atomic(dst_page, KM_USER0);
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	char *dst_kaddr = page_address(dst_page);
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	char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
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	char *src_kaddr;
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	if (dst_page != src_page)
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		src_kaddr = page_address(src_page); // kmap_atomic(src_page, KM_USER1);
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		src_kaddr = kmap_atomic(src_page, KM_USER1);
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	else
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		src_kaddr = dst_kaddr;
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	memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
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	/*
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	kunmap_atomic(dst_kaddr, KM_USER0);
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	if (dst_page != src_page)
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		kunmap_atomic(src_kaddr, KM_USER1);
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	*/
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}
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void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
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			@ -2537,7 +2525,7 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
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		cur = min(len, src_off_in_page + 1);
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		cur = min(cur, dst_off_in_page + 1);
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// printk("move pages orig dst %lu src %lu len %lu, this %lu %lu %lu\n", dst_offset, src_offset, len, dst_off_in_page - cur + 1, src_off_in_page - cur + 1, cur);
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		move_pages(extent_buffer_page(dst, dst_i),
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			   extent_buffer_page(dst, src_i),
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			   dst_off_in_page - cur + 1,
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