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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-05-28 00:59:22 +0300
committerMatthew Wilcox (Oracle) <willy@infradead.org>2022-01-08 08:28:41 +0300
commitb9a8a4195c7d3a51235a4fc974a46ad4e9689ffd (patch)
tree48f7ce0a78ed104be739fb45bfca21cbaf351a44 /mm/truncate.c
parentf6357c3a9d3ea5a00c5bf52845b633d649da6722 (diff)
downloadlinux-b9a8a4195c7d3a51235a4fc974a46ad4e9689ffd.tar.xz
truncate,shmem: Handle truncates that split large folios
Handle folio splitting in the parts of the truncation functions which already handle partial pages. Factor all that code out into a new function called truncate_inode_partial_folio(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Diffstat (limited to 'mm/truncate.c')
-rw-r--r--mm/truncate.c117
1 files changed, 75 insertions, 42 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index 2d1dae085acb..5c87cdc70e7b 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -229,6 +229,58 @@ int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
}
/*
+ * Handle partial folios. The folio may be entirely within the
+ * range if a split has raced with us. If not, we zero the part of the
+ * folio that's within the [start, end] range, and then split the folio if
+ * it's large. split_page_range() will discard pages which now lie beyond
+ * i_size, and we rely on the caller to discard pages which lie within a
+ * newly created hole.
+ *
+ * Returns false if splitting failed so the caller can avoid
+ * discarding the entire folio which is stubbornly unsplit.
+ */
+bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
+{
+ loff_t pos = folio_pos(folio);
+ unsigned int offset, length;
+
+ if (pos < start)
+ offset = start - pos;
+ else
+ offset = 0;
+ length = folio_size(folio);
+ if (pos + length <= (u64)end)
+ length = length - offset;
+ else
+ length = end + 1 - pos - offset;
+
+ folio_wait_writeback(folio);
+ if (length == folio_size(folio)) {
+ truncate_inode_folio(folio->mapping, folio);
+ return true;
+ }
+
+ /*
+ * We may be zeroing pages we're about to discard, but it avoids
+ * doing a complex calculation here, and then doing the zeroing
+ * anyway if the page split fails.
+ */
+ folio_zero_range(folio, offset, length);
+
+ cleancache_invalidate_page(folio->mapping, &folio->page);
+ if (folio_has_private(folio))
+ do_invalidatepage(&folio->page, offset, length);
+ if (!folio_test_large(folio))
+ return true;
+ if (split_huge_page(&folio->page) == 0)
+ return true;
+ if (folio_test_dirty(folio))
+ return false;
+ truncate_inode_folio(folio->mapping, folio);
+ return true;
+}
+
+/*
* Used to get rid of pages on hardware memory corruption.
*/
int generic_error_remove_page(struct address_space *mapping, struct page *page)
@@ -294,20 +346,16 @@ void truncate_inode_pages_range(struct address_space *mapping,
{
pgoff_t start; /* inclusive */
pgoff_t end; /* exclusive */
- unsigned int partial_start; /* inclusive */
- unsigned int partial_end; /* exclusive */
struct folio_batch fbatch;
pgoff_t indices[PAGEVEC_SIZE];
pgoff_t index;
int i;
+ struct folio *folio;
+ bool same_folio;
if (mapping_empty(mapping))
goto out;
- /* Offsets within partial pages */
- partial_start = lstart & (PAGE_SIZE - 1);
- partial_end = (lend + 1) & (PAGE_SIZE - 1);
-
/*
* 'start' and 'end' always covers the range of pages to be fully
* truncated. Partial pages are covered with 'partial_start' at the
@@ -340,47 +388,32 @@ void truncate_inode_pages_range(struct address_space *mapping,
cond_resched();
}
- if (partial_start) {
- struct page *page = find_lock_page(mapping, start - 1);
- if (page) {
- unsigned int top = PAGE_SIZE;
- if (start > end) {
- /* Truncation within a single page */
- top = partial_end;
- partial_end = 0;
- }
- wait_on_page_writeback(page);
- zero_user_segment(page, partial_start, top);
- cleancache_invalidate_page(mapping, page);
- if (page_has_private(page))
- do_invalidatepage(page, partial_start,
- top - partial_start);
- unlock_page(page);
- put_page(page);
+ same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
+ folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
+ if (folio) {
+ same_folio = lend < folio_pos(folio) + folio_size(folio);
+ if (!truncate_inode_partial_folio(folio, lstart, lend)) {
+ start = folio->index + folio_nr_pages(folio);
+ if (same_folio)
+ end = folio->index;
}
+ folio_unlock(folio);
+ folio_put(folio);
+ folio = NULL;
}
- if (partial_end) {
- struct page *page = find_lock_page(mapping, end);
- if (page) {
- wait_on_page_writeback(page);
- zero_user_segment(page, 0, partial_end);
- cleancache_invalidate_page(mapping, page);
- if (page_has_private(page))
- do_invalidatepage(page, 0,
- partial_end);
- unlock_page(page);
- put_page(page);
- }
+
+ if (!same_folio)
+ folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
+ FGP_LOCK, 0);
+ if (folio) {
+ if (!truncate_inode_partial_folio(folio, lstart, lend))
+ end = folio->index;
+ folio_unlock(folio);
+ folio_put(folio);
}
- /*
- * If the truncation happened within a single page no pages
- * will be released, just zeroed, so we can bail out now.
- */
- if (start >= end)
- goto out;
index = start;
- for ( ; ; ) {
+ while (index < end) {
cond_resched();
if (!find_get_entries(mapping, index, end - 1, &fbatch,
indices)) {