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-rw-r--r--include/linux/mm.h2
-rw-r--r--mm/truncate.c44
2 files changed, 39 insertions, 7 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a06a84d..92acae9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -896,6 +896,8 @@ extern unsigned long do_brk(unsigned long, unsigned long);
/* filemap.c */
extern unsigned long page_unuse(struct page *);
extern void truncate_inode_pages(struct address_space *, loff_t);
+extern void truncate_inode_pages_range(struct address_space *,
+ loff_t lstart, loff_t lend);
/* generic vm_area_ops exported for stackable file systems */
extern struct page *filemap_nopage(struct vm_area_struct *, unsigned long, int *);
diff --git a/mm/truncate.c b/mm/truncate.c
index 9173ab50..7dee327 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -82,12 +82,15 @@ invalidate_complete_page(struct address_space *mapping, struct page *page)
}
/**
- * truncate_inode_pages - truncate *all* the pages from an offset
+ * truncate_inode_pages - truncate range of pages specified by start and
+ * end byte offsets
* @mapping: mapping to truncate
* @lstart: offset from which to truncate
+ * @lend: offset to which to truncate
*
- * Truncate the page cache at a set offset, removing the pages that are beyond
- * that offset (and zeroing out partial pages).
+ * Truncate the page cache, removing the pages that are between
+ * specified offsets (and zeroing out partial page
+ * (if lstart is not page aligned)).
*
* Truncate takes two passes - the first pass is nonblocking. It will not
* block on page locks and it will not block on writeback. The second pass
@@ -101,12 +104,12 @@ invalidate_complete_page(struct address_space *mapping, struct page *page)
* We pass down the cache-hot hint to the page freeing code. Even if the
* mapping is large, it is probably the case that the final pages are the most
* recently touched, and freeing happens in ascending file offset order.
- *
- * Called under (and serialised by) inode->i_sem.
*/
-void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
+void truncate_inode_pages_range(struct address_space *mapping,
+ loff_t lstart, loff_t lend)
{
const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
+ pgoff_t end;
const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
struct pagevec pvec;
pgoff_t next;
@@ -115,13 +118,22 @@ void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
if (mapping->nrpages == 0)
return;
+ BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
+ end = (lend >> PAGE_CACHE_SHIFT);
+
pagevec_init(&pvec, 0);
next = start;
- while (pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ while (next <= end &&
+ pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t page_index = page->index;
+ if (page_index > end) {
+ next = page_index;
+ break;
+ }
+
if (page_index > next)
next = page_index;
next++;
@@ -157,9 +169,15 @@ void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
next = start;
continue;
}
+ if (pvec.pages[0]->index > end) {
+ pagevec_release(&pvec);
+ break;
+ }
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
+ if (page->index > end)
+ break;
lock_page(page);
wait_on_page_writeback(page);
if (page->index > next)
@@ -171,7 +189,19 @@ void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
pagevec_release(&pvec);
}
}
+EXPORT_SYMBOL(truncate_inode_pages_range);
+/**
+ * truncate_inode_pages - truncate *all* the pages from an offset
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ *
+ * Called under (and serialised by) inode->i_sem.
+ */
+void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
+{
+ truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
+}
EXPORT_SYMBOL(truncate_inode_pages);
/**
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