Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs fix from Al Viro:
 "Don't put symlink bodies in pagecache into highmem"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  Make sure that highmem pages are not added to symlink page cache

3 files changed, 8 insertions, 5 deletions

diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 0f88e6020487..f1b87d8aa2da 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -508,7 +508,11 @@ in your dentry operations instead.
 [mandatory]
         any symlink that might use page_follow_link_light/page_put_link() must
         have inode_nohighmem(inode) called before anything might start playing with
-        its pagecache.
+        its pagecache.  No highmem pages should end up in the pagecache of such
+        symlinks.  That includes any preseeding that might be done during symlink
+        creation.  __page_symlink() will honour the mapping gfp flags, so once
+        you've done inode_nohighmem() it's safe to use, but if you allocate and
+        insert the page manually, make sure to use the right gfp flags.
 --
 [mandatory]
         ->follow_link() is replaced with ->get_link(); same API, except that
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ce5a21861074..8a0530921685 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1894,15 +1894,14 @@ int nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
         attr.ia_mode = S_IFLNK | S_IRWXUGO;
         attr.ia_valid = ATTR_MODE;
 
-        page = alloc_page(GFP_HIGHUSER);
+        page = alloc_page(GFP_USER);
         if (!page)
                 return -ENOMEM;
 
-        kaddr = kmap_atomic(page);
+        kaddr = page_address(page);
         memcpy(kaddr, symname, pathlen);
         if (pathlen < PAGE_SIZE)
                 memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
-        kunmap_atomic(kaddr);
 
         trace_nfs_symlink_enter(dir, dentry);
         error = NFS_PROTO(dir)->symlink(dir, dentry, page, pathlen, &attr);
diff --git a/mm/shmem.c b/mm/shmem.c
index 5813b7fa85b6..642471b0ddea 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2469,6 +2469,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
                 inode->i_op = &shmem_short_symlink_operations;
                 inode->i_link = info->symlink;
         } else {
+                inode_nohighmem(inode);
                 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
                 if (error) {
                         iput(inode);
@@ -2476,7 +2477,6 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
                 }
                 inode->i_mapping->a_ops = &shmem_aops;
                 inode->i_op = &shmem_symlink_inode_operations;
-                inode_nohighmem(inode);
                 memcpy(page_address(page), symname, len);
                 SetPageUptodate(page);
                 set_page_dirty(page);