don't put symlink bodies in pagecache into highmem

kmap() in page_follow_link_light() needed to go - allowing to hold
an arbitrary number of kmaps for long is a great way to deadlocking
the system.

new helper (inode_nohighmem(inode)) needs to be used for pagecache
symlinks inodes; done for all in-tree cases.  page_follow_link_light()
instrumented to yell about anything missed.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ea433a7f4bca..b3bd912df6bf 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4283,6 +4283,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                         inode->i_op = &ext4_symlink_inode_operations;
                         ext4_set_aops(inode);
                 }
+                inode_nohighmem(inode);
         } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
               S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
                 inode->i_op = &ext4_special_inode_operations;