use the XArray directly instead of using the pagevec abstraction.
The code is simpler and more efficient.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/shmem.c | 61 +++++++++++++++++++++---------------------------------
1 file changed, 24 insertions(+), 37 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index a7bbc4ed9677..0f9f149f4b5e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2659,53 +2659,40 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
}
/*
- * llseek SEEK_DATA or SEEK_HOLE through the page cache.
+ * llseek SEEK_DATA or SEEK_HOLE through the page cache. We don't need
+ * to get a reference on the page because this interface is racy anyway.
+ * The page we find will have had the state at some point.
*/
static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
pgoff_t index, pgoff_t end, int whence)
{
+ XA_STATE(xas, &mapping->i_pages, index);
struct page *page;
- struct pagevec pvec;
- pgoff_t indices[PAGEVEC_SIZE];
- bool done = false;
- int i;
- pagevec_init(&pvec);
- pvec.nr = 1; /* start small: we may be there already */
- while (!done) {
- pvec.nr = find_get_entries(mapping, index,
- pvec.nr, pvec.pages, indices);
- if (!pvec.nr) {
- if (whence == SEEK_DATA)
- index = end;
- break;
+ rcu_read_lock();
+ if (whence == SEEK_DATA) {
+ for (;;) {
+ page = xas_find(&xas, end);
+ if (xas_retry(&xas, page))
+ continue;
+ if (!page || xa_is_value(page) || PageUptodate(page))
+ break;
}
- for (i = 0; i < pvec.nr; i++, index++) {
- if (index < indices[i]) {
- if (whence == SEEK_HOLE) {
- done = true;
- break;
- }
- index = indices[i];
- }
- page = pvec.pages[i];
- if (page && !xa_is_value(page)) {
- if (!PageUptodate(page))
- page = NULL;
- }
- if (index >= end ||
- (page && whence == SEEK_DATA) ||
- (!page && whence == SEEK_HOLE)) {
- done = true;
+ } else /* SEEK_HOLE */ {
+ for (;;) {
+ page = xas_next(&xas);
+ if (xas_retry(&xas, page))
+ continue;
+ if (!xa_is_value(page) &&
+ (!page || !PageUptodate(page)))
+ break;
+ if (xas.xa_index >= end)
break;
- }
}
- pagevec_remove_exceptionals(&pvec);
- pagevec_release(&pvec);
- pvec.nr = PAGEVEC_SIZE;
- cond_resched();
}
- return index;
+ rcu_read_unlock();
+
+ return xas.xa_index;
}
static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
--
2.28.0
