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

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From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 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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Thread

[PATCHSET] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:00 +0100
  [PATCH 08/10] teach page_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 09/10] teach shmem_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 01/10] switch befs long symlinks to page_symlink_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 10/10] teach proc_self_get_link()/proc_thread_self_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 06/10] [vfs] don't put symlink bodies in pagecache into highmem Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
    Re: [PATCH 06/10] [vfs] don't put symlink bodies in pagecache into  highmem Dave Chinner <david@fromorbit.com> - 2015-11-20 00:10 +0100
  [PATCH 05/10] namei: page_getlink() and page_follow_link_light() are the same thing Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 03/10] udf: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 04/10] ufs: get rid of ->setattr() for symlinks Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100
  [PATCH 02/10] logfs: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-18 00:10 +0100

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