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[PATCH v2 09/11] 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 684dbc3..0605716 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 v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 02/11] logfs: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 08/11] teach page_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 10/11] teach proc_self_get_link()/proc_thread_self_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 11/11] teach nfs_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 06/11] don't put symlink bodies in pagecache into highmem Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 01/11] switch befs long symlinks to page_symlink_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 03/11] udf: don't duplicate page_symlink_inode_operations Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 09/11] teach shmem_get_link() to work in RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  [PATCH v2 04/11] ufs: get rid of ->setattr() for symlinks Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 06:40 +0100
  Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Linus Torvalds <torvalds@linux-foundation.org> - 2015-12-09 18:30 +0100
    Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-09 19:30 +0100
      Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-10 01:20 +0100
        Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Al Viro <viro@ZenIV.linux.org.uk> - 2015-12-10 03:50 +0100
          Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-12-11 08:50 +0100
  Re: [PATCHSET v2] ->follow_link() without dropping from RCU mode NeilBrown <neilb@suse.com> - 2015-12-09 23:00 +0100

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