Fix some miscellaneous things in the new netfs lib[1]:
(1) The kerneldoc for netfs_readpage() shouldn't say netfs_page().
(2) netfs_readpage() can get an integer overflow on 32-bit when it
multiplies page_index(page) by PAGE_SIZE. It should use
page_offset() instead.
(3) netfs_write_begin() should also use page_offset() to avoid the same
overflow.
(4) Use page_mapping() in netfs_write_begin() rather than page->mapping.
Reported-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Link: https://lore.kernel.org/r/161789062190.6155.12711584466338493050.stgit@xxxxxxxxxxxxxxxxxxxxxx/ [1]
---
fs/netfs/read_helper.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 1d3b50c5db6d..568e26352309 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -933,7 +933,7 @@ void netfs_readahead(struct readahead_control *ractl,
EXPORT_SYMBOL(netfs_readahead);
/**
- * netfs_page - Helper to manage a readpage request
+ * netfs_readpage - Helper to manage a readpage request
* @file: The file to read from
* @page: The page to read
* @ops: The network filesystem's operations for the helper to use
@@ -968,7 +968,7 @@ int netfs_readpage(struct file *file,
return -ENOMEM;
}
rreq->mapping = page_file_mapping(page);
- rreq->start = page_index(page) * PAGE_SIZE;
+ rreq->start = page_offset(page);
rreq->len = thp_size(page);
if (ops->begin_cache_operation) {
@@ -1105,8 +1105,8 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
rreq = netfs_alloc_read_request(ops, netfs_priv, file);
if (!rreq)
goto error;
- rreq->mapping = page->mapping;
- rreq->start = page->index * PAGE_SIZE;
+ rreq->mapping = page_file_mapping(page);
+ rreq->start = page_offset(page);
rreq->len = thp_size(page);
rreq->no_unlock_page = page->index;
__set_bit(NETFS_RREQ_NO_UNLOCK_PAGE, &rreq->flags);
