replace ->follow_link() with new method that could stay in RCU mode

new method: ->get_link(); replacement of ->follow_link().  The differences
are:
	* inode and dentry are passed separately
	* might be called both in RCU and non-RCU mode;
the former is indicated by passing it a NULL dentry.
	* when called that way it isn't allowed to block
and should return ERR_PTR(-ECHILD) if it needs to be called
in non-RCU mode.

It's a flagday change - the old method is gone, all in-tree instances
converted.  Conversion isn't hard; said that, so far very few instances
do not immediately bail out when called in RCU mode.  That'll change
in the next commits.

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

1 files changed, 5 insertions, 4 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index c7cbfb092e94..8dc37fc4b6df 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1092,14 +1092,15 @@ simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
 }
 EXPORT_SYMBOL(simple_nosetlease);
 
-const char *simple_follow_link(struct dentry *dentry, void **cookie)
+const char *simple_get_link(struct dentry *dentry, struct inode *inode,
+			    void **cookie)
 {
-	return d_inode(dentry)->i_link;
+	return inode->i_link;
 }
-EXPORT_SYMBOL(simple_follow_link);
+EXPORT_SYMBOL(simple_get_link);
 
 const struct inode_operations simple_symlink_inode_operations = {
-	.follow_link = simple_follow_link,
+	.get_link = simple_get_link,
 	.readlink = generic_readlink
 };
 EXPORT_SYMBOL(simple_symlink_inode_operations);