1 files changed, 72 insertions, 0 deletions

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 282150f74cfa..0a499d2c6191 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -89,6 +89,7 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/writeback.h> /* for inode_lock */
 
 #include <asm/atomic.h>
 
@@ -351,3 +352,74 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
 
         return ret;
 }
+
+/**
+ * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.
+ * @list: list of inodes being unmounted (sb->s_inodes)
+ *
+ * Called with inode_lock held, protecting the unmounting super block's list
+ * of inodes, and with iprune_mutex held, keeping shrink_icache_memory() at bay.
+ * We temporarily drop inode_lock, however, and CAN block.
+ */
+void fsnotify_unmount_inodes(struct list_head *list)
+{
+        struct inode *inode, *next_i, *need_iput = NULL;
+
+        list_for_each_entry_safe(inode, next_i, list, i_sb_list) {
+                struct inode *need_iput_tmp;
+
+                /*
+                 * We cannot __iget() an inode in state I_CLEAR, I_FREEING,
+                 * I_WILL_FREE, or I_NEW which is fine because by that point
+                 * the inode cannot have any associated watches.
+                 */
+                if (inode->i_state & (I_CLEAR|I_FREEING|I_WILL_FREE|I_NEW))
+                        continue;
+
+                /*
+                 * If i_count is zero, the inode cannot have any watches and
+                 * doing an __iget/iput with MS_ACTIVE clear would actually
+                 * evict all inodes with zero i_count from icache which is
+                 * unnecessarily violent and may in fact be illegal to do.
+                 */
+                if (!atomic_read(&inode->i_count))
+                        continue;
+
+                need_iput_tmp = need_iput;
+                need_iput = NULL;
+
+                /* In case fsnotify_inode_delete() drops a reference. */
+                if (inode != need_iput_tmp)
+                        __iget(inode);
+                else
+                        need_iput_tmp = NULL;
+
+                /* In case the dropping of a reference would nuke next_i. */
+                if ((&next_i->i_sb_list != list) &&
+                    atomic_read(&next_i->i_count) &&
+                    !(next_i->i_state & (I_CLEAR | I_FREEING | I_WILL_FREE))) {
+                        __iget(next_i);
+                        need_iput = next_i;
+                }
+
+                /*
+                 * We can safely drop inode_lock here because we hold
+                 * references on both inode and next_i.  Also no new inodes
+                 * will be added since the umount has begun.  Finally,
+                 * iprune_mutex keeps shrink_icache_memory() away.
+                 */
+                spin_unlock(&inode_lock);
+
+                if (need_iput_tmp)
+                        iput(need_iput_tmp);
+
+                /* for each watch, send FS_UNMOUNT and then remove it */
+                fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
+
+                fsnotify_inode_delete(inode);
+
+                iput(inode);
+
+                spin_lock(&inode_lock);
+        }
+}