[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, 5 deletions

diff --git a/fs/msdos/namei.c b/fs/msdos/namei.c
index d220165d4918..635613f2f65a 100644
--- a/fs/msdos/namei.c
+++ b/fs/msdos/namei.c
@@ -343,7 +343,7 @@ static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
         if (err)
                 goto out;
-        dir->i_nlink--;
+        drop_nlink(dir);
 
         inode->i_nlink = 0;
         inode->i_ctime = CURRENT_TIME_SEC;
@@ -549,7 +549,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
                         if (err)
                                 goto error_dotdot;
                 }
-                old_dir->i_nlink--;
+                drop_nlink(old_dir);
                 if (!new_inode)
                         new_dir->i_nlink++;
         }
@@ -566,10 +566,9 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
                 mark_inode_dirty(old_dir);
 
         if (new_inode) {
+                drop_nlink(new_inode);
                 if (is_dir)
-                        new_inode->i_nlink -= 2;
-                else
-                        new_inode->i_nlink--;
+                        drop_nlink(new_inode);
                 new_inode->i_ctime = ts;
         }
 out: