[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, 5 insertions, 5 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index b96de69f236b..908dd947b1ea 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1772,7 +1772,7 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
 
         dir->i_size -= BOGO_DIRENT_SIZE;
         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
-        inode->i_nlink--;
+        drop_nlink(inode);
         dput(dentry);   /* Undo the count from "create" - this does all the work */
         return 0;
 }
@@ -1782,8 +1782,8 @@ static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
         if (!simple_empty(dentry))
                 return -ENOTEMPTY;
 
-        dentry->d_inode->i_nlink--;
-        dir->i_nlink--;
+        drop_nlink(dentry->d_inode);
+        drop_nlink(dir);
         return shmem_unlink(dir, dentry);
 }
 
@@ -1804,9 +1804,9 @@ static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct
         if (new_dentry->d_inode) {
                 (void) shmem_unlink(new_dir, new_dentry);
                 if (they_are_dirs)
-                        old_dir->i_nlink--;
+                        drop_nlink(old_dir);
         } else if (they_are_dirs) {
-                old_dir->i_nlink--;
+                drop_nlink(old_dir);
                 new_dir->i_nlink++;
         }