[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, 6 insertions, 8 deletions

diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c
index 295268ad231b..088b85976ac0 100644
--- a/fs/jfs/namei.c
+++ b/fs/jfs/namei.c
@@ -393,9 +393,8 @@ static int jfs_rmdir(struct inode *dip, struct dentry *dentry)
         /* update parent directory's link count corresponding
          * to ".." entry of the target directory deleted
          */
-        dip->i_nlink--;
         dip->i_ctime = dip->i_mtime = CURRENT_TIME;
-        mark_inode_dirty(dip);
+        inode_dec_link_count(dip);
 
         /*
          * OS/2 could have created EA and/or ACL
@@ -515,8 +514,7 @@ static int jfs_unlink(struct inode *dip, struct dentry *dentry)
         mark_inode_dirty(dip);
 
         /* update target's inode */
-        ip->i_nlink--;
-        mark_inode_dirty(ip);
+        inode_dec_link_count(ip);
 
         /*
          *      commit zero link count object
@@ -835,7 +833,7 @@ static int jfs_link(struct dentry *old_dentry,
         rc = txCommit(tid, 2, &iplist[0], 0);
 
         if (rc) {
-                ip->i_nlink--;
+                ip->i_nlink--; /* never instantiated */
                 iput(ip);
         } else
                 d_instantiate(dentry, ip);
@@ -1155,9 +1153,9 @@ static int jfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                               old_ip->i_ino, JFS_RENAME);
                 if (rc)
                         goto out4;
-                new_ip->i_nlink--;
+                drop_nlink(new_ip);
                 if (S_ISDIR(new_ip->i_mode)) {
-                        new_ip->i_nlink--;
+                        drop_nlink(new_ip);
                         if (new_ip->i_nlink) {
                                 mutex_unlock(&JFS_IP(new_ip)->commit_mutex);
                                 if (old_dir != new_dir)
@@ -1223,7 +1221,7 @@ static int jfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                 goto out4;
         }
         if (S_ISDIR(old_ip->i_mode)) {
-                old_dir->i_nlink--;
+                drop_nlink(old_dir);
                 if (old_dir != new_dir) {
                         /*
                          * Change inode number of parent for moved directory