[PATCH v14 124/138] fs: Convert vfs_dedupe_file_range_compare to folios

Matthew Wilcox (Oracle)
2021-07-15T05:18:03Z

We still only operate on a single page of data at a time due to using
kmap(). A more complex implementation would work on each page in a folio,
but it's not clear that such a complex implementation would be worthwhile.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/remap_range.c | 116 ++++++++++++++++++++++-------------------------
1 file changed, 55 insertions(+), 61 deletions(-)

diff --git a/fs/remap_range.c b/fs/remap_range.c
index e4a5fdd7ad7b..886e6ed2c6c2 100644
--- a/fs/remap_range.c
+++ b/fs/remap_range.c
@@ -158,41 +158,41 @@ static int generic_remap_check_len(struct inode *inode_in,
}

/* Read a page's worth of file data into the page cache. */
-static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
+static struct folio *vfs_dedupe_get_folio(struct inode *inode, loff_t pos)
{
- struct page *page;
+ struct folio *folio;

- page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);
- if (IS_ERR(page))
- return page;
- if (!PageUptodate(page)) {
- put_page(page);
+ folio = read_mapping_folio(inode->i_mapping, pos >> PAGE_SHIFT, NULL);
+ if (IS_ERR(folio))
+ return folio;
+ if (!folio_test_uptodate(folio)) {
+ folio_put(folio);
return ERR_PTR(-EIO);
}
- return page;
+ return folio;
}

/*
- * Lock two pages, ensuring that we lock in offset order if the pages are from
- * the same file.
+ * Lock two folios, ensuring that we lock in offset order if the folios
+ * are from the same file.
*/
-static void vfs_lock_two_pages(struct page *page1, struct page *page2)
+static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2)
{
/* Always lock in order of increasing index. */
- if (page1->index > page2->index)
- swap(page1, page2);
+ if (folio1->index > folio2->index)
+ swap(folio1, folio2);

- lock_page(page1);
- if (page1 != page2)
- lock_page(page2);
+ folio_lock(folio1);
+ if (folio1 != folio2)
+ folio_lock(folio2);
}

-/* Unlock two pages, being careful not to unlock the same page twice. */
-static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
+/* Unlock two folios, being careful not to unlock the same folio twice. */
+static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2)
{
- unlock_page(page1);
- if (page1 != page2)
- unlock_page(page2);
+ folio_unlock(folio1);
+ if (folio1 != folio2)
+ folio_unlock(folio2);
}

/*
@@ -200,77 +200,71 @@ static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
* Caller must have locked both inodes to prevent write races.
*/
static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
- struct inode *dest, loff_t destoff,
+ struct inode *dest, loff_t dstoff,
loff_t len, bool *is_same)
{
- loff_t src_poff;
- loff_t dest_poff;
- void *src_addr;
- void *dest_addr;
- struct page *src_page;
- struct page *dest_page;
- loff_t cmp_len;
- bool same;
- int error;
-
- error = -EINVAL;
- same = true;
+ bool same = true;
+ int error = -EINVAL;
+
while (len) {
- src_poff = srcoff & (PAGE_SIZE - 1);
- dest_poff = destoff & (PAGE_SIZE - 1);
- cmp_len = min(PAGE_SIZE - src_poff,
- PAGE_SIZE - dest_poff);
+ struct folio *src_folio, *dst_folio;
+ void *src_addr, *dst_addr;
+ loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
+ PAGE_SIZE - offset_in_page(dstoff));
+
cmp_len = min(cmp_len, len);
if (cmp_len <= 0)
goto out_error;

- src_page = vfs_dedupe_get_page(src, srcoff);
- if (IS_ERR(src_page)) {
- error = PTR_ERR(src_page);
+ src_folio = vfs_dedupe_get_folio(src, srcoff);
+ if (IS_ERR(src_folio)) {
+ error = PTR_ERR(src_folio);
goto out_error;
}
- dest_page = vfs_dedupe_get_page(dest, destoff);
- if (IS_ERR(dest_page)) {
- error = PTR_ERR(dest_page);
- put_page(src_page);
+ dst_folio = vfs_dedupe_get_folio(dest, dstoff);
+ if (IS_ERR(dst_folio)) {
+ error = PTR_ERR(dst_folio);
+ folio_put(src_folio);
goto out_error;
}

- vfs_lock_two_pages(src_page, dest_page);
+ vfs_lock_two_folios(src_folio, dst_folio);

/*
- * Now that we've locked both pages, make sure they're still
+ * Now that we've locked both folios, make sure they're still
* mapped to the file data we're interested in. If not,
* someone is invalidating pages on us and we lose.
*/
- if (!PageUptodate(src_page) || !PageUptodate(dest_page) ||
- src_page->mapping != src->i_mapping ||
- dest_page->mapping != dest->i_mapping) {
+ if (!folio_test_uptodate(src_folio) || !folio_test_uptodate(dst_folio) ||
+ src_folio->mapping != src->i_mapping ||
+ dst_folio->mapping != dest->i_mapping) {
same = false;
goto unlock;
}

- src_addr = kmap_atomic(src_page);
- dest_addr = kmap_atomic(dest_page);
+ src_addr = kmap_local_folio(src_folio,
+ offset_in_folio(src_folio, srcoff));
+ dst_addr = kmap_local_folio(dst_folio,
+ offset_in_folio(dst_folio, dstoff));

- flush_dcache_page(src_page);
- flush_dcache_page(dest_page);
+ flush_dcache_folio(src_folio);
+ flush_dcache_folio(dst_folio);

- if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
+ if (memcmp(src_addr, dst_addr, cmp_len))
same = false;

- kunmap_atomic(dest_addr);
- kunmap_atomic(src_addr);
+ kunmap_local(dst_addr);
+ kunmap_local(src_addr);
unlock:
- vfs_unlock_two_pages(src_page, dest_page);
- put_page(dest_page);
- put_page(src_page);
+ vfs_unlock_two_folios(src_folio, dst_folio);
+ folio_put(dst_folio);
+ folio_put(src_folio);

if (!same)
break;

srcoff += cmp_len;
- destoff += cmp_len;
+ dstoff += cmp_len;
len -= cmp_len;
}

--
2.30.2