1 files changed, 36 insertions, 0 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index c2bbe1fb1326..1e519195d45b 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1710,3 +1710,39 @@ int __invalidate_device(struct block_device *bdev, bool kill_dirty)
         return res;
 }
 EXPORT_SYMBOL(__invalidate_device);
+
+void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
+{
+        struct inode *inode, *old_inode = NULL;
+
+        spin_lock(&inode_sb_list_lock);
+        list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
+                struct address_space *mapping = inode->i_mapping;
+
+                spin_lock(&inode->i_lock);
+                if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
+                    mapping->nrpages == 0) {
+                        spin_unlock(&inode->i_lock);
+                        continue;
+                }
+                __iget(inode);
+                spin_unlock(&inode->i_lock);
+                spin_unlock(&inode_sb_list_lock);
+                /*
+                 * We hold a reference to 'inode' so it couldn't have been
+                 * removed from s_inodes list while we dropped the
+                 * inode_sb_list_lock.  We cannot iput the inode now as we can
+                 * be holding the last reference and we cannot iput it under
+                 * inode_sb_list_lock. So we keep the reference and iput it
+                 * later.
+                 */
+                iput(old_inode);
+                old_inode = inode;
+
+                func(I_BDEV(inode), arg);
+
+                spin_lock(&inode_sb_list_lock);
+        }
+        spin_unlock(&inode_sb_list_lock);
+        iput(old_inode);
+}