cifs: convert oplock breaks to use slow_work facility (try #4)

This is the fourth respin of the patch to convert oplock breaks to
use the slow_work facility.

A customer of ours was testing a backport of one of the earlier
patchsets, and hit a "Busy inodes after umount..." problem. An oplock
break job had raced with a umount, and the superblock got torn down and
its memory reused. When the oplock break job tried to dereference the
inode->i_sb, the kernel oopsed.

This patchset has the oplock break job hold an inode and vfsmount
reference until the oplock break completes.  With this, there should be
no need to take a tcon reference (the vfsmount implicitly holds one
already).

Currently, when an oplock break comes in there's a chance that the
oplock break job won't occur if the allocation of the oplock_q_entry
fails. There are also some rather nasty races in the allocation and
handling these structs.

Rather than allocating oplock queue entries when an oplock break comes
in, add a few extra fields to the cifsFileInfo struct. Get rid of the
dedicated cifs_oplock_thread as well and queue the oplock break job to
the slow_work thread pool.

This approach also has the advantage that the oplock break jobs can
potentially run in parallel rather than be serialized like they are
today.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 0 insertions, 50 deletions

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 1da4ab250eae..07b8e71544ee 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -103,56 +103,6 @@ DeleteMidQEntry(struct mid_q_entry *midEntry)
         mempool_free(midEntry, cifs_mid_poolp);
 }
 
-struct oplock_q_entry *
-AllocOplockQEntry(struct inode *pinode, __u16 fid, struct cifsTconInfo *tcon)
-{
-        struct oplock_q_entry *temp;
-        if ((pinode == NULL) || (tcon == NULL)) {
-                cERROR(1, ("Null parms passed to AllocOplockQEntry"));
-                return NULL;
-        }
-        temp = (struct oplock_q_entry *) kmem_cache_alloc(cifs_oplock_cachep,
-                                                       GFP_KERNEL);
-        if (temp == NULL)
-                return temp;
-        else {
-                temp->pinode = pinode;
-                temp->tcon = tcon;
-                temp->netfid = fid;
-                spin_lock(&cifs_oplock_lock);
-                list_add_tail(&temp->qhead, &cifs_oplock_list);
-                spin_unlock(&cifs_oplock_lock);
-        }
-        return temp;
-}
-
-void DeleteOplockQEntry(struct oplock_q_entry *oplockEntry)
-{
-        spin_lock(&cifs_oplock_lock);
-    /* should we check if list empty first? */
-        list_del(&oplockEntry->qhead);
-        spin_unlock(&cifs_oplock_lock);
-        kmem_cache_free(cifs_oplock_cachep, oplockEntry);
-}
-
-
-void DeleteTconOplockQEntries(struct cifsTconInfo *tcon)
-{
-        struct oplock_q_entry *temp;
-
-        if (tcon == NULL)
-                return;
-
-        spin_lock(&cifs_oplock_lock);
-        list_for_each_entry(temp, &cifs_oplock_list, qhead) {
-                if ((temp->tcon) && (temp->tcon == tcon)) {
-                        list_del(&temp->qhead);
-                        kmem_cache_free(cifs_oplock_cachep, temp);
-                }
-        }
-        spin_unlock(&cifs_oplock_lock);
-}
-
 static int
 smb_sendv(struct TCP_Server_Info *server, struct kvec *iov, int n_vec)
 {