[PATCH] r/o bind mounts: unlink: monitor i_nlink

When a filesystem decrements i_nlink to zero, it means that a write must be
performed in order to drop the inode from the filesystem.

We're shortly going to have keep filesystems from being remounted r/o between
the time that this i_nlink decrement and that write occurs.

So, add a little helper function to do the decrements.  We'll tie into it in a
bit to note when i_nlink hits zero.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c
index df3d152f0493..88002e45a6b4 100644
--- a/drivers/usb/core/inode.c
+++ b/drivers/usb/core/inode.c
@@ -332,7 +332,7 @@ static int usbfs_unlink (struct inode *dir, struct dentry *dentry)
 {
         struct inode *inode = dentry->d_inode;
         mutex_lock(&inode->i_mutex);
-        dentry->d_inode->i_nlink--;
+        drop_nlink(dentry->d_inode);
         dput(dentry);
         mutex_unlock(&inode->i_mutex);
         d_delete(dentry);
@@ -347,10 +347,11 @@ static int usbfs_rmdir(struct inode *dir, struct dentry *dentry)
         mutex_lock(&inode->i_mutex);
         dentry_unhash(dentry);
         if (usbfs_empty(dentry)) {
-                dentry->d_inode->i_nlink -= 2;
+                drop_nlink(dentry->d_inode);
+                drop_nlink(dentry->d_inode);
                 dput(dentry);
                 inode->i_flags |= S_DEAD;
-                dir->i_nlink--;
+                drop_nlink(dir);
                 error = 0;
         }
         mutex_unlock(&inode->i_mutex);