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>
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 191e622..0241b25 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -32,7 +32,6 @@
extern mempool_t *cifs_sm_req_poolp;
extern mempool_t *cifs_req_poolp;
-extern struct task_struct *oplockThread;
/* The xid serves as a useful identifier for each incoming vfs request,
in a similar way to the mid which is useful to track each sent smb,
@@ -500,6 +499,7 @@
struct cifsTconInfo *tcon;
struct cifsInodeInfo *pCifsInode;
struct cifsFileInfo *netfile;
+ int rc;
cFYI(1, ("Checking for oplock break or dnotify response"));
if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
@@ -569,19 +569,30 @@
if (pSMB->Fid != netfile->netfid)
continue;
- read_unlock(&GlobalSMBSeslock);
- read_unlock(&cifs_tcp_ses_lock);
+ /*
+ * don't do anything if file is about to be
+ * closed anyway.
+ */
+ if (netfile->closePend) {
+ read_unlock(&GlobalSMBSeslock);
+ read_unlock(&cifs_tcp_ses_lock);
+ return true;
+ }
+
cFYI(1, ("file id match, oplock break"));
pCifsInode = CIFS_I(netfile->pInode);
pCifsInode->clientCanCacheAll = false;
if (pSMB->OplockLevel == 0)
pCifsInode->clientCanCacheRead = false;
- AllocOplockQEntry(netfile->pInode,
- netfile->netfid, tcon);
- cFYI(1, ("about to wake up oplock thread"));
- if (oplockThread)
- wake_up_process(oplockThread);
-
+ rc = slow_work_enqueue(&netfile->oplock_break);
+ if (rc) {
+ cERROR(1, ("failed to enqueue oplock "
+ "break: %d\n", rc));
+ } else {
+ netfile->oplock_break_cancelled = false;
+ }
+ read_unlock(&GlobalSMBSeslock);
+ read_unlock(&cifs_tcp_ses_lock);
return true;
}
read_unlock(&GlobalSMBSeslock);