mm: add unmap_mapping_pages()
Several users of unmap_mapping_range() would prefer to express their
range in pages rather than bytes. Unfortuately, on a 32-bit kernel, you
have to remember to cast your page number to a 64-bit type before
shifting it, and four places in the current tree didn't remember to do
that. That's a sign of a bad interface.
Conveniently, unmap_mapping_range() actually converts from bytes into
pages, so hoist the guts of unmap_mapping_range() into a new function
unmap_mapping_pages() and convert the callers which want to use pages.
Link: http://lkml.kernel.org/r/20171206142627.GD32044@bombadil.infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reported-by: "zhangyi (F)" <yi.zhang@huawei.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index 82a0577..a6e5d6a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2799,8 +2799,37 @@ static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
}
/**
+ * unmap_mapping_pages() - Unmap pages from processes.
+ * @mapping: The address space containing pages to be unmapped.
+ * @start: Index of first page to be unmapped.
+ * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
+ * @even_cows: Whether to unmap even private COWed pages.
+ *
+ * Unmap the pages in this address space from any userspace process which
+ * has them mmaped. Generally, you want to remove COWed pages as well when
+ * a file is being truncated, but not when invalidating pages from the page
+ * cache.
+ */
+void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
+ pgoff_t nr, bool even_cows)
+{
+ struct zap_details details = { };
+
+ details.check_mapping = even_cows ? NULL : mapping;
+ details.first_index = start;
+ details.last_index = start + nr - 1;
+ if (details.last_index < details.first_index)
+ details.last_index = ULONG_MAX;
+
+ i_mmap_lock_write(mapping);
+ if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
+ unmap_mapping_range_tree(&mapping->i_mmap, &details);
+ i_mmap_unlock_write(mapping);
+}
+
+/**
* unmap_mapping_range - unmap the portion of all mmaps in the specified
- * address_space corresponding to the specified page range in the underlying
+ * address_space corresponding to the specified byte range in the underlying
* file.
*
* @mapping: the address space containing mmaps to be unmapped.
@@ -2818,7 +2847,6 @@ static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen, int even_cows)
{
- struct zap_details details = { };
pgoff_t hba = holebegin >> PAGE_SHIFT;
pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -2830,16 +2858,7 @@ void unmap_mapping_range(struct address_space *mapping,
hlen = ULONG_MAX - hba + 1;
}
- details.check_mapping = even_cows ? NULL : mapping;
- details.first_index = hba;
- details.last_index = hba + hlen - 1;
- if (details.last_index < details.first_index)
- details.last_index = ULONG_MAX;
-
- i_mmap_lock_write(mapping);
- if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
- unmap_mapping_range_tree(&mapping->i_mmap, &details);
- i_mmap_unlock_write(mapping);
+ unmap_mapping_pages(mapping, hba, hlen, even_cows);
}
EXPORT_SYMBOL(unmap_mapping_range);
