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-rw-r--r--mm/truncate.c336
1 files changed, 336 insertions, 0 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
new file mode 100644
index 000000000000..c9a63f0b69a2
--- /dev/null
+++ b/mm/truncate.c
@@ -0,0 +1,336 @@
+/*
+ * mm/truncate.c - code for taking down pages from address_spaces
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 10Sep2002 akpm@zip.com.au
+ * Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/buffer_head.h> /* grr. try_to_release_page,
+ block_invalidatepage */
+
+
+static int do_invalidatepage(struct page *page, unsigned long offset)
+{
+ int (*invalidatepage)(struct page *, unsigned long);
+ invalidatepage = page->mapping->a_ops->invalidatepage;
+ if (invalidatepage == NULL)
+ invalidatepage = block_invalidatepage;
+ return (*invalidatepage)(page, offset);
+}
+
+static inline void truncate_partial_page(struct page *page, unsigned partial)
+{
+ memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
+ if (PagePrivate(page))
+ do_invalidatepage(page, partial);
+}
+
+/*
+ * If truncate cannot remove the fs-private metadata from the page, the page
+ * becomes anonymous. It will be left on the LRU and may even be mapped into
+ * user pagetables if we're racing with filemap_nopage().
+ *
+ * We need to bale out if page->mapping is no longer equal to the original
+ * mapping. This happens a) when the VM reclaimed the page while we waited on
+ * its lock, b) when a concurrent invalidate_inode_pages got there first and
+ * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
+ */
+static void
+truncate_complete_page(struct address_space *mapping, struct page *page)
+{
+ if (page->mapping != mapping)
+ return;
+
+ if (PagePrivate(page))
+ do_invalidatepage(page, 0);
+
+ clear_page_dirty(page);
+ ClearPageUptodate(page);
+ ClearPageMappedToDisk(page);
+ remove_from_page_cache(page);
+ page_cache_release(page); /* pagecache ref */
+}
+
+/*
+ * This is for invalidate_inode_pages(). That function can be called at
+ * any time, and is not supposed to throw away dirty pages. But pages can
+ * be marked dirty at any time too. So we re-check the dirtiness inside
+ * ->tree_lock. That provides exclusion against the __set_page_dirty
+ * functions.
+ *
+ * Returns non-zero if the page was successfully invalidated.
+ */
+static int
+invalidate_complete_page(struct address_space *mapping, struct page *page)
+{
+ if (page->mapping != mapping)
+ return 0;
+
+ if (PagePrivate(page) && !try_to_release_page(page, 0))
+ return 0;
+
+ write_lock_irq(&mapping->tree_lock);
+ if (PageDirty(page)) {
+ write_unlock_irq(&mapping->tree_lock);
+ return 0;
+ }
+
+ BUG_ON(PagePrivate(page));
+ __remove_from_page_cache(page);
+ write_unlock_irq(&mapping->tree_lock);
+ ClearPageUptodate(page);
+ page_cache_release(page); /* pagecache ref */
+ return 1;
+}
+
+/**
+ * truncate_inode_pages - truncate *all* the pages from an offset
+ * @mapping: mapping to truncate
+ * @lstart: offset from 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 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
+ * will wait. This is to prevent as much IO as possible in the affected region.
+ * The first pass will remove most pages, so the search cost of the second pass
+ * is low.
+ *
+ * When looking at page->index outside the page lock we need to be careful to
+ * copy it into a local to avoid races (it could change at any time).
+ *
+ * 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)
+{
+ const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
+ const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
+ struct pagevec pvec;
+ pgoff_t next;
+ int i;
+
+ if (mapping->nrpages == 0)
+ return;
+
+ pagevec_init(&pvec, 0);
+ next = start;
+ while (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 > next)
+ next = page_index;
+ next++;
+ if (TestSetPageLocked(page))
+ continue;
+ if (PageWriteback(page)) {
+ unlock_page(page);
+ continue;
+ }
+ truncate_complete_page(mapping, page);
+ unlock_page(page);
+ }
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+
+ if (partial) {
+ struct page *page = find_lock_page(mapping, start - 1);
+ if (page) {
+ wait_on_page_writeback(page);
+ truncate_partial_page(page, partial);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ }
+
+ next = start;
+ for ( ; ; ) {
+ cond_resched();
+ if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ if (next == start)
+ break;
+ next = start;
+ continue;
+ }
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+
+ lock_page(page);
+ wait_on_page_writeback(page);
+ if (page->index > next)
+ next = page->index;
+ next++;
+ truncate_complete_page(mapping, page);
+ unlock_page(page);
+ }
+ pagevec_release(&pvec);
+ }
+}
+
+EXPORT_SYMBOL(truncate_inode_pages);
+
+/**
+ * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
+ * @mapping: the address_space which holds the pages to invalidate
+ * @start: the offset 'from' which to invalidate
+ * @end: the offset 'to' which to invalidate (inclusive)
+ *
+ * This function only removes the unlocked pages, if you want to
+ * remove all the pages of one inode, you must call truncate_inode_pages.
+ *
+ * invalidate_mapping_pages() will not block on IO activity. It will not
+ * invalidate pages which are dirty, locked, under writeback or mapped into
+ * pagetables.
+ */
+unsigned long invalidate_mapping_pages(struct address_space *mapping,
+ pgoff_t start, pgoff_t end)
+{
+ struct pagevec pvec;
+ pgoff_t next = start;
+ unsigned long ret = 0;
+ int i;
+
+ pagevec_init(&pvec, 0);
+ while (next <= end &&
+ pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+
+ if (TestSetPageLocked(page)) {
+ next++;
+ continue;
+ }
+ if (page->index > next)
+ next = page->index;
+ next++;
+ if (PageDirty(page) || PageWriteback(page))
+ goto unlock;
+ if (page_mapped(page))
+ goto unlock;
+ ret += invalidate_complete_page(mapping, page);
+unlock:
+ unlock_page(page);
+ if (next > end)
+ break;
+ }
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+ return ret;
+}
+
+unsigned long invalidate_inode_pages(struct address_space *mapping)
+{
+ return invalidate_mapping_pages(mapping, 0, ~0UL);
+}
+
+EXPORT_SYMBOL(invalidate_inode_pages);
+
+/**
+ * invalidate_inode_pages2_range - remove range of pages from an address_space
+ * @mapping - the address_space
+ * @start: the page offset 'from' which to invalidate
+ * @end: the page offset 'to' which to invalidate (inclusive)
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Returns -EIO if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2_range(struct address_space *mapping,
+ pgoff_t start, pgoff_t end)
+{
+ struct pagevec pvec;
+ pgoff_t next;
+ int i;
+ int ret = 0;
+ int did_range_unmap = 0;
+ int wrapped = 0;
+
+ pagevec_init(&pvec, 0);
+ next = start;
+ while (next <= end && !ret && !wrapped &&
+ pagevec_lookup(&pvec, mapping, next,
+ min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
+ for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+ pgoff_t page_index;
+ int was_dirty;
+
+ lock_page(page);
+ if (page->mapping != mapping) {
+ unlock_page(page);
+ continue;
+ }
+ page_index = page->index;
+ next = page_index + 1;
+ if (next == 0)
+ wrapped = 1;
+ if (page_index > end) {
+ unlock_page(page);
+ break;
+ }
+ wait_on_page_writeback(page);
+ while (page_mapped(page)) {
+ if (!did_range_unmap) {
+ /*
+ * Zap the rest of the file in one hit.
+ */
+ unmap_mapping_range(mapping,
+ page_index << PAGE_CACHE_SHIFT,
+ (end - page_index + 1)
+ << PAGE_CACHE_SHIFT,
+ 0);
+ did_range_unmap = 1;
+ } else {
+ /*
+ * Just zap this page
+ */
+ unmap_mapping_range(mapping,
+ page_index << PAGE_CACHE_SHIFT,
+ PAGE_CACHE_SIZE, 0);
+ }
+ }
+ was_dirty = test_clear_page_dirty(page);
+ if (!invalidate_complete_page(mapping, page)) {
+ if (was_dirty)
+ set_page_dirty(page);
+ ret = -EIO;
+ }
+ unlock_page(page);
+ }
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
+
+/**
+ * invalidate_inode_pages2 - remove all pages from an address_space
+ * @mapping - the address_space
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Returns -EIO if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2(struct address_space *mapping)
+{
+ return invalidate_inode_pages2_range(mapping, 0, -1);
+}
+EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
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