cifs: use workqueue instead of slow-work

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>

cifs: use workqueue instead of slow-work
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>
Tejun Heo
1 parent d098adfb7d
Showing 6 changed files with 31 additions and 35 deletions Side-by-side Diff
fs/cifs/Kconfig
fs/cifs/cifsfs.c
fs/cifs/cifsglob.h
fs/cifs/dir.c
fs/cifs/file.c
fs/cifs/misc.c
@@ -2,7 +2,6 @@
 	tristate "CIFS support (advanced network filesystem, SMBFS successor)"
 	depends on INET
 	select NLS
-	select SLOW_WORK
 	help
 	  This is the client VFS module for the Common Internet File System
 	  (CIFS) protocol which is the successor to the Server Message Block
@@ -917,15 +917,10 @@
 	if (rc)
 		goto out_unregister_key_type;
 #endif
-	rc = slow_work_register_user(THIS_MODULE);
-	if (rc)
-		goto out_unregister_resolver_key;
  
 	return 0;
  
- out_unregister_resolver_key:
 #ifdef CONFIG_CIFS_DFS_UPCALL
-	unregister_key_type(&key_type_dns_resolver);
  out_unregister_key_type:
 #endif
 #ifdef CONFIG_CIFS_UPCALL
@@ -19,7 +19,7 @@
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/slab.h>
-#include <linux/slow-work.h>
+#include <linux/workqueue.h>
 #include "cifs_fs_sb.h"
 #include "cifsacl.h"
 /*
@@ -363,7 +363,7 @@
 	atomic_t count;		/* reference count */
 	struct mutex fh_mutex; /* prevents reopen race after dead ses*/
 	struct cifs_search_info srch_inf;
-	struct slow_work oplock_break; /* slow_work job for oplock breaks */
+	struct work_struct oplock_break; /* work for oplock breaks */
 };
  
 /* Take a reference on the file private data */
@@ -732,5 +732,7 @@
 GLOBAL_EXTERN unsigned int cifs_min_small;  /* min size of small buf pool */
 GLOBAL_EXTERN unsigned int cifs_max_pending; /* MAX requests at once to server*/
  
-extern const struct slow_work_ops cifs_oplock_break_ops;
+void cifs_oplock_break(struct work_struct *work);
+void cifs_oplock_break_get(struct cifsFileInfo *cfile);
+void cifs_oplock_break_put(struct cifsFileInfo *cfile);
@@ -162,7 +162,7 @@
 	mutex_init(&pCifsFile->lock_mutex);
 	INIT_LIST_HEAD(&pCifsFile->llist);
 	atomic_set(&pCifsFile->count, 1);
-	slow_work_init(&pCifsFile->oplock_break, &cifs_oplock_break_ops);
+	INIT_WORK(&pCifsFile->oplock_break, cifs_oplock_break);
  
 	write_lock(&GlobalSMBSeslock);
 	list_add(&pCifsFile->tlist, &cifs_sb->tcon->openFileList);
@@ -2295,8 +2295,7 @@
 	return rc;
 }
  
-static void
-cifs_oplock_break(struct slow_work *work)
+void cifs_oplock_break(struct work_struct *work)
 {
 	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
 						  oplock_break);
  
  
  
  
  
  
@@ -2333,32 +2332,29 @@
 				 LOCKING_ANDX_OPLOCK_RELEASE, false);
 		cFYI(1, "Oplock release rc = %d", rc);
 	}
+
+	/*
+	 * We might have kicked in before is_valid_oplock_break()
+	 * finished grabbing reference for us.  Make sure it's done by
+	 * waiting for GlobalSMSSeslock.
+	 */
+	write_lock(&GlobalSMBSeslock);
+	write_unlock(&GlobalSMBSeslock);
+
+	cifs_oplock_break_put(cfile);
 }
  
-static int
-cifs_oplock_break_get(struct slow_work *work)
+void cifs_oplock_break_get(struct cifsFileInfo *cfile)
 {
-	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
-						  oplock_break);
 	mntget(cfile->mnt);
 	cifsFileInfo_get(cfile);
-	return 0;
 }
  
-static void
-cifs_oplock_break_put(struct slow_work *work)
+void cifs_oplock_break_put(struct cifsFileInfo *cfile)
 {
-	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
-						  oplock_break);
 	mntput(cfile->mnt);
 	cifsFileInfo_put(cfile);
 }
-
-const struct slow_work_ops cifs_oplock_break_ops = {
-	.get_ref	= cifs_oplock_break_get,
-	.put_ref	= cifs_oplock_break_put,
-	.execute	= cifs_oplock_break,
-};
  
 const struct address_space_operations cifs_addr_ops = {
 	.readpage = cifs_readpage,
@@ -498,7 +498,6 @@
 	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 @@
 				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;
...	...	@@ -2,7 +2,6 @@
2	2	tristate "CIFS support (advanced network filesystem, SMBFS successor)"
3	3	depends on INET
4	4	select NLS
5		- select SLOW_WORK
6	5	help
7	6	This is the client VFS module for the Common Internet File System
8	7	(CIFS) protocol which is the successor to the Server Message Block
...	...	@@ -917,15 +917,10 @@
917	917	if (rc)
918	918	goto out_unregister_key_type;
919	919	#endif
920		- rc = slow_work_register_user(THIS_MODULE);
921		- if (rc)
922		- goto out_unregister_resolver_key;
923	920
924	921	return 0;
925	922
926		- out_unregister_resolver_key:
927	923	#ifdef CONFIG_CIFS_DFS_UPCALL
928		- unregister_key_type(&key_type_dns_resolver);
929	924	out_unregister_key_type:
930	925	#endif
931	926	#ifdef CONFIG_CIFS_UPCALL
...	...	@@ -19,7 +19,7 @@
19	19	#include <linux/in.h>
20	20	#include <linux/in6.h>
21	21	#include <linux/slab.h>
22		-#include <linux/slow-work.h>
	22	+#include <linux/workqueue.h>
23	23	#include "cifs_fs_sb.h"
24	24	#include "cifsacl.h"
25	25	/*
...	...	@@ -363,7 +363,7 @@
363	363	atomic_t count; /* reference count */
364	364	struct mutex fh_mutex; /* prevents reopen race after dead ses*/
365	365	struct cifs_search_info srch_inf;
366		- struct slow_work oplock_break; /* slow_work job for oplock breaks */
	366	+ struct work_struct oplock_break; /* work for oplock breaks */
367	367	};
368	368
369	369	/* Take a reference on the file private data */
...	...	@@ -732,5 +732,7 @@
732	732	GLOBAL_EXTERN unsigned int cifs_min_small; /* min size of small buf pool */
733	733	GLOBAL_EXTERN unsigned int cifs_max_pending; /* MAX requests at once to server*/
734	734
735		-extern const struct slow_work_ops cifs_oplock_break_ops;
	735	+void cifs_oplock_break(struct work_struct *work);
	736	+void cifs_oplock_break_get(struct cifsFileInfo *cfile);
	737	+void cifs_oplock_break_put(struct cifsFileInfo *cfile);
...	...	@@ -162,7 +162,7 @@
162	162	mutex_init(&pCifsFile->lock_mutex);
163	163	INIT_LIST_HEAD(&pCifsFile->llist);
164	164	atomic_set(&pCifsFile->count, 1);
165		- slow_work_init(&pCifsFile->oplock_break, &cifs_oplock_break_ops);
	165	+ INIT_WORK(&pCifsFile->oplock_break, cifs_oplock_break);
166	166
167	167	write_lock(&GlobalSMBSeslock);
168	168	list_add(&pCifsFile->tlist, &cifs_sb->tcon->openFileList);
...	...	@@ -2295,8 +2295,7 @@
2295	2295	return rc;
2296	2296	}
2297	2297
2298		-static void
2299		-cifs_oplock_break(struct slow_work *work)
	2298	+void cifs_oplock_break(struct work_struct *work)
2300	2299	{
2301	2300	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
2302	2301	oplock_break);
2303	2302
2304	2303
2305	2304
2306	2305
2307	2306
2308	2307
...	...	@@ -2333,32 +2332,29 @@
2333	2332	LOCKING_ANDX_OPLOCK_RELEASE, false);
2334	2333	cFYI(1, "Oplock release rc = %d", rc);
2335	2334	}
	2335	+
	2336	+ /*
	2337	+ * We might have kicked in before is_valid_oplock_break()
	2338	+ * finished grabbing reference for us. Make sure it's done by
	2339	+ * waiting for GlobalSMSSeslock.
	2340	+ */
	2341	+ write_lock(&GlobalSMBSeslock);
	2342	+ write_unlock(&GlobalSMBSeslock);
	2343	+
	2344	+ cifs_oplock_break_put(cfile);
2336	2345	}
2337	2346
2338		-static int
2339		-cifs_oplock_break_get(struct slow_work *work)
	2347	+void cifs_oplock_break_get(struct cifsFileInfo *cfile)
2340	2348	{
2341		- struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
2342		- oplock_break);
2343	2349	mntget(cfile->mnt);
2344	2350	cifsFileInfo_get(cfile);
2345		- return 0;
2346	2351	}
2347	2352
2348		-static void
2349		-cifs_oplock_break_put(struct slow_work *work)
	2353	+void cifs_oplock_break_put(struct cifsFileInfo *cfile)
2350	2354	{
2351		- struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
2352		- oplock_break);
2353	2355	mntput(cfile->mnt);
2354	2356	cifsFileInfo_put(cfile);
2355	2357	}
2356		-
2357		-const struct slow_work_ops cifs_oplock_break_ops = {
2358		- .get_ref = cifs_oplock_break_get,
2359		- .put_ref = cifs_oplock_break_put,
2360		- .execute = cifs_oplock_break,
2361		-};
2362	2358
2363	2359	const struct address_space_operations cifs_addr_ops = {
2364	2360	.readpage = cifs_readpage,
...	...	@@ -498,7 +498,6 @@
498	498	struct cifsTconInfo *tcon;
499	499	struct cifsInodeInfo *pCifsInode;
500	500	struct cifsFileInfo *netfile;
501		- int rc;
502	501
503	502	cFYI(1, "Checking for oplock break or dnotify response");
504	503	if ((pSMB->hdr.Command == SMB_COM_NT_TRANSACT) &&
...	...	@@ -583,13 +582,18 @@
583	582	pCifsInode->clientCanCacheAll = false;
584	583	if (pSMB->OplockLevel == 0)
585	584	pCifsInode->clientCanCacheRead = false;
586		- rc = slow_work_enqueue(&netfile->oplock_break);
587		- if (rc) {
588		- cERROR(1, "failed to enqueue oplock "
589		- "break: %d\n", rc);
590		- } else {
591		- netfile->oplock_break_cancelled = false;
592		- }
	585	+
	586	+ /*
	587	+ * cifs_oplock_break_put() can't be called
	588	+ * from here. Get reference after queueing
	589	+ * succeeded. cifs_oplock_break() will
	590	+ * synchronize using GlobalSMSSeslock.
	591	+ */
	592	+ if (queue_work(system_nrt_wq,
	593	+ &netfile->oplock_break))
	594	+ cifs_oplock_break_get(netfile);
	595	+ netfile->oplock_break_cancelled = false;
	596	+
593	597	read_unlock(&GlobalSMBSeslock);
594	598	read_unlock(&cifs_tcp_ses_lock);
595	599	return true;