[PATCH 09/10] teach shmem_get_link() to work in RCU mode

From: Al Viro
Date: Tue Nov 17 2015 - 18:01:53 EST


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index e8220cf..e1ea5b5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2501,12 +2501,20 @@ static const char *shmem_get_link(struct dentry *dentry,
{
struct page *page = NULL;
int error;
- if (!dentry)
- return ERR_PTR(-ECHILD);
- error = shmem_getpage(inode, 0, &page, SGP_READ, NULL);
- if (error)
- return ERR_PTR(error);
- unlock_page(page);
+ if (!dentry) {
+ page = find_get_page(inode->i_mapping, 0);
+ if (!page)
+ return ERR_PTR(-ECHILD);
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-ECHILD);
+ }
+ } else {
+ error = shmem_getpage(inode, 0, &page, SGP_READ, NULL);
+ if (error)
+ return ERR_PTR(error);
+ unlock_page(page);
+ }
*cookie = page;
return page_address(page);
}
--
2.1.4

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