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>
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 06d4434..4fba54b 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -50,7 +50,7 @@
int (*rename2) (struct inode *, struct dentry *,
struct inode *, struct dentry *, unsigned int);
int (*readlink) (struct dentry *, char __user *,int);
- const char *(*follow_link) (struct dentry *, void **);
+ const char *(*get_link) (struct dentry *, struct inode *, void **);
void (*put_link) (struct inode *, void *);
void (*truncate) (struct inode *);
int (*permission) (struct inode *, int, unsigned int);
@@ -83,7 +83,7 @@
rename: yes (all) (see below)
rename2: yes (all) (see below)
readlink: no
-follow_link: no
+get_link: no
put_link: no
setattr: yes
permission: no (may not block if called in rcu-walk mode)
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 3eb7c35..cf92a8c 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -509,3 +509,9 @@
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.
+--
+[mandatory]
+ ->follow_link() is replaced with ->get_link(); same API, except that
+ * ->get_link() gets inode as a separate argument
+ * ->get_link() may be called in RCU mode - in that case NULL
+ dentry is passed