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>

1 files changed, 4 insertions, 29 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)