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, 10 insertions, 6 deletions

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 484df6850747..2a8d84b727ce 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -315,9 +315,10 @@ fail:
 	return err;
 }
 
-static const char *f2fs_follow_link(struct dentry *dentry, void **cookie)
+static const char *f2fs_get_link(struct dentry *dentry,
+				 struct inode *inode, void **cookie)
 {
-	const char *link = page_follow_link_light(dentry, cookie);
+	const char *link = page_get_link(dentry, inode, cookie);
 	if (!IS_ERR(link) && !*link) {
 		/* this is broken symlink case */
 		page_put_link(NULL, *cookie);
@@ -924,18 +925,21 @@ static int f2fs_rename2(struct inode *old_dir, struct dentry *old_dentry,
 }
 
 #ifdef CONFIG_F2FS_FS_ENCRYPTION
-static const char *f2fs_encrypted_follow_link(struct dentry *dentry, void **cookie)
+static const char *f2fs_encrypted_get_link(struct dentry *dentry,
+					   struct inode *inode, void **cookie)
 {
 	struct page *cpage = NULL;
 	char *caddr, *paddr = NULL;
 	struct f2fs_str cstr;
 	struct f2fs_str pstr = FSTR_INIT(NULL, 0);
-	struct inode *inode = d_inode(dentry);
 	struct f2fs_encrypted_symlink_data *sd;
 	loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
 	u32 max_size = inode->i_sb->s_blocksize;
 	int res;
 
+	if (!dentry)
+		return ERR_PTR(-ECHILD);
+
 	res = f2fs_get_encryption_info(inode);
 	if (res)
 		return ERR_PTR(res);
@@ -994,7 +998,7 @@ errout:
 
 const struct inode_operations f2fs_encrypted_symlink_inode_operations = {
 	.readlink       = generic_readlink,
-	.follow_link    = f2fs_encrypted_follow_link,
+	.get_link       = f2fs_encrypted_get_link,
 	.put_link       = kfree_put_link,
 	.getattr	= f2fs_getattr,
 	.setattr	= f2fs_setattr,
@@ -1030,7 +1034,7 @@ const struct inode_operations f2fs_dir_inode_operations = {
 
 const struct inode_operations f2fs_symlink_inode_operations = {
 	.readlink       = generic_readlink,
-	.follow_link    = f2fs_follow_link,
+	.get_link       = f2fs_get_link,
 	.put_link       = page_put_link,
 	.getattr	= f2fs_getattr,
 	.setattr	= f2fs_setattr,