vfs: split generic_forget_inode() so that hugetlbfs does not have to copy it

Hugetlbfs needs to do special things instead of truncate_inode_pages().
 Currently, it copied generic_forget_inode() except for
truncate_inode_pages() call which is asking for trouble (the code there
isn't trivial).  So create a separate function generic_detach_inode()
which does all the list magic done in generic_forget_inode() and call
it from hugetlbfs_forget_inode().

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 24 insertions, 31 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index eba6d552d9c9..478a169a262d 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -380,36 +380,11 @@ static void hugetlbfs_delete_inode(struct inode *inode)
 
 static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
 {
-        struct super_block *sb = inode->i_sb;
-
-        if (!hlist_unhashed(&inode->i_hash)) {
-                if (!(inode->i_state & (I_DIRTY|I_SYNC)))
-                        list_move(&inode->i_list, &inode_unused);
-                inodes_stat.nr_unused++;
-                if (!sb || (sb->s_flags & MS_ACTIVE)) {
-                        spin_unlock(&inode_lock);
-                        return;
-                }
-                inode->i_state |= I_WILL_FREE;
-                spin_unlock(&inode_lock);
-                /*
-                 * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
-                 * in our backing_dev_info.
-                 */
-                write_inode_now(inode, 1);
-                spin_lock(&inode_lock);
-                inode->i_state &= ~I_WILL_FREE;
-                inodes_stat.nr_unused--;
-                hlist_del_init(&inode->i_hash);
+        if (generic_detach_inode(inode)) {
+                truncate_hugepages(inode, 0);
+                clear_inode(inode);
+                destroy_inode(inode);
         }
-        list_del_init(&inode->i_list);
-        list_del_init(&inode->i_sb_list);
-        inode->i_state |= I_FREEING;
-        inodes_stat.nr_inodes--;
-        spin_unlock(&inode_lock);
-        truncate_hugepages(inode, 0);
-        clear_inode(inode);
-        destroy_inode(inode);
 }
 
 static void hugetlbfs_drop_inode(struct inode *inode)
diff --git a/fs/inode.c b/fs/inode.c
index 07d775ea6161..fa506d539653 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1241,7 +1241,16 @@ void generic_delete_inode(struct inode *inode)
 }
 EXPORT_SYMBOL(generic_delete_inode);
 
-static void generic_forget_inode(struct inode *inode)
+/**
+ *      generic_detach_inode - remove inode from inode lists
+ *      @inode: inode to remove
+ *
+ *      Remove inode from inode lists, write it if it's dirty. This is just an
+ *      internal VFS helper exported for hugetlbfs. Do not use!
+ *
+ *      Returns 1 if inode should be completely destroyed.
+ */
+int generic_detach_inode(struct inode *inode)
 {
         struct super_block *sb = inode->i_sb;
 
@@ -1251,7 +1260,7 @@ static void generic_forget_inode(struct inode *inode)
                 inodes_stat.nr_unused++;
                 if (sb->s_flags & MS_ACTIVE) {
                         spin_unlock(&inode_lock);
-                        return;
+                        return 0;
                 }
                 WARN_ON(inode->i_state & I_NEW);
                 inode->i_state |= I_WILL_FREE;
@@ -1269,6 +1278,14 @@ static void generic_forget_inode(struct inode *inode)
         inode->i_state |= I_FREEING;
         inodes_stat.nr_inodes--;
         spin_unlock(&inode_lock);
+        return 1;
+}
+EXPORT_SYMBOL_GPL(generic_detach_inode);
+
+static void generic_forget_inode(struct inode *inode)
+{
+        if (!generic_detach_inode(inode))
+                return;
         if (inode->i_data.nrpages)
                 truncate_inode_pages(&inode->i_data, 0);
         clear_inode(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 51803528b095..955e34615cb7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2156,6 +2156,7 @@ extern ino_t iunique(struct super_block *, ino_t);
 extern int inode_needs_sync(struct inode *inode);
 extern void generic_delete_inode(struct inode *inode);
 extern void generic_drop_inode(struct inode *inode);
+extern int generic_detach_inode(struct inode *inode);
 
 extern struct inode *ilookup5_nowait(struct super_block *sb,
                 unsigned long hashval, int (*test)(struct inode *, void *),