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cifs: use workqueue instead of slow-work

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Workqueue can now handle high concurrency.  Use system_nrt_wq
instead of slow-work.

* Updated is_valid_oplock_break() to not call cifs_oplock_break_put()
  as advised by Steve French.  It might cause deadlock.  Instead,
  reference is increased after queueing succeeded and
  cifs_oplock_break() briefly grabs GlobalSMBSeslock before putting
  the cfile to make sure it doesn't put before the matching get is
  finished.

* Anton Blanchard reported that cifs conversion was using now gone
  system_single_wq.  Use system_nrt_wq which provides non-reentrance
  guarantee which is enough and much better.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Steve French <sfrench@samba.org>
Cc: Anton Blanchard <anton@samba.org>
This commit is contained in:
Tejun Heo
2010-07-20 22:09:02 +02:00
parent d098adfb7d
commit 9b64697246
6 changed files with 31 additions and 35 deletions
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20
fs/cifs/misc.c
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@@ -498,7 +498,6 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
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) &&
@@ -583,13 +582,18 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
pCifsInode->clientCanCacheAll = false;
if (pSMB->OplockLevel == 0)
pCifsInode->clientCanCacheRead = false;
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;
}
/*
* cifs_oplock_break_put() can't be called
* from here. Get reference after queueing
* succeeded. cifs_oplock_break() will
* synchronize using GlobalSMSSeslock.
*/
if (queue_work(system_nrt_wq,
&netfile->oplock_break))
cifs_oplock_break_get(netfile);
netfile->oplock_break_cancelled = false;
read_unlock(&GlobalSMBSeslock);
read_unlock(&cifs_tcp_ses_lock);
return true;