[RFC PATCH V2 8/9] orangefs: use attach/clear_page_private

From: Guoqing Jiang
Date: Thu Apr 30 2020 - 17:53:03 EST


Since the new pair function is introduced, we can call them to clean the
code in orangefs.

Cc: Mike Marshall <hubcap@xxxxxxxxxxxx>
Cc: Martin Brandenburg <martin@xxxxxxxxxxxx>
Cc: devel@xxxxxxxxxxxxxxxxxx
Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
---
RFC -> RFC V2
1. change the name of new functions to attach/clear_page_private.
2. avoid potential use-after-free as suggested by Dave Chinner.

fs/orangefs/inode.c | 32 ++++++--------------------------
1 file changed, 6 insertions(+), 26 deletions(-)

diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c
index 12ae630fbed7..139c450aca68 100644
--- a/fs/orangefs/inode.c
+++ b/fs/orangefs/inode.c
@@ -62,12 +62,7 @@ static int orangefs_writepage_locked(struct page *page,
} else {
ret = 0;
}
- if (wr) {
- kfree(wr);
- set_page_private(page, 0);
- ClearPagePrivate(page);
- put_page(page);
- }
+ kfree(clear_page_private(page));
return ret;
}

@@ -409,9 +404,7 @@ static int orangefs_write_begin(struct file *file,
wr->len = len;
wr->uid = current_fsuid();
wr->gid = current_fsgid();
- SetPagePrivate(page);
- set_page_private(page, (unsigned long)wr);
- get_page(page);
+ attach_page_private(page, wr);
okay:
return 0;
}
@@ -459,18 +452,12 @@ static void orangefs_invalidatepage(struct page *page,
wr = (struct orangefs_write_range *)page_private(page);

if (offset == 0 && length == PAGE_SIZE) {
- kfree((struct orangefs_write_range *)page_private(page));
- set_page_private(page, 0);
- ClearPagePrivate(page);
- put_page(page);
+ kfree(clear_page_private(page));
return;
/* write range entirely within invalidate range (or equal) */
} else if (page_offset(page) + offset <= wr->pos &&
wr->pos + wr->len <= page_offset(page) + offset + length) {
- kfree((struct orangefs_write_range *)page_private(page));
- set_page_private(page, 0);
- ClearPagePrivate(page);
- put_page(page);
+ kfree(clear_page_private(page));
/* XXX is this right? only caller in fs */
cancel_dirty_page(page);
return;
@@ -535,12 +522,7 @@ static int orangefs_releasepage(struct page *page, gfp_t foo)

static void orangefs_freepage(struct page *page)
{
- if (PagePrivate(page)) {
- kfree((struct orangefs_write_range *)page_private(page));
- set_page_private(page, 0);
- ClearPagePrivate(page);
- put_page(page);
- }
+ kfree(clear_page_private(page));
}

static int orangefs_launder_page(struct page *page)
@@ -740,9 +722,7 @@ vm_fault_t orangefs_page_mkwrite(struct vm_fault *vmf)
wr->len = PAGE_SIZE;
wr->uid = current_fsuid();
wr->gid = current_fsgid();
- SetPagePrivate(page);
- set_page_private(page, (unsigned long)wr);
- get_page(page);
+ attach_page_private(page, wr);
okay:

file_update_time(vmf->vma->vm_file);
--
2.17.1