From 6cfc94a57260ae0ae13224301aa8303aa89a29d7 Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton@redhat.com>
Date: Sat, 12 Sep 2009 07:51:53 -0400
Subject: [PATCH] cifs: convert oplock breaks to use slow_work facility

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>
---
 fs/cifs/Kconfig     |    1 +
 fs/cifs/cifsfs.c    |   95 +++------------------------------------------------
 fs/cifs/cifsglob.h  |   12 +++----
 fs/cifs/cifsproto.h |    5 +--
 fs/cifs/cifssmb.c   |    1 +
 fs/cifs/connect.c   |    3 +-
 fs/cifs/dir.c       |    2 +
 fs/cifs/file.c      |   73 ++++++++++++++++++++++++++++++++++++++-
 fs/cifs/misc.c      |   29 +++++++++++-----
 fs/cifs/transport.c |   50 ---------------------------
 10 files changed, 107 insertions(+), 164 deletions(-)

diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 6994a0f..80f3525 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -2,6 +2,7 @@ config CIFS
 	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
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 3610e99..89142b3 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -64,9 +64,6 @@ unsigned int multiuser_mount = 0;
 unsigned int extended_security = CIFSSEC_DEF;
 /* unsigned int ntlmv2_support = 0; */
 unsigned int sign_CIFS_PDUs = 1;
-extern struct task_struct *oplockThread; /* remove sparse warning */
-struct task_struct *oplockThread = NULL;
-/* extern struct task_struct * dnotifyThread; remove sparse warning */
 static const struct super_operations cifs_super_ops;
 unsigned int CIFSMaxBufSize = CIFS_MAX_MSGSIZE;
 module_param(CIFSMaxBufSize, int, 0);
@@ -973,89 +970,12 @@ cifs_destroy_mids(void)
 	kmem_cache_destroy(cifs_oplock_cachep);
 }
 
-static int cifs_oplock_thread(void *dummyarg)
-{
-	struct oplock_q_entry *oplock_item;
-	struct cifsTconInfo *pTcon;
-	struct inode *inode;
-	__u16  netfid;
-	int rc, waitrc = 0;
-
-	set_freezable();
-	do {
-		if (try_to_freeze())
-			continue;
-
-		spin_lock(&cifs_oplock_lock);
-		if (list_empty(&cifs_oplock_list)) {
-			spin_unlock(&cifs_oplock_lock);
-			set_current_state(TASK_INTERRUPTIBLE);
-			schedule_timeout(39*HZ);
-		} else {
-			oplock_item = list_entry(cifs_oplock_list.next,
-						struct oplock_q_entry, qhead);
-			cFYI(1, ("found oplock item to write out"));
-			pTcon = oplock_item->tcon;
-			inode = oplock_item->pinode;
-			netfid = oplock_item->netfid;
-			spin_unlock(&cifs_oplock_lock);
-			DeleteOplockQEntry(oplock_item);
-			/* can not grab inode sem here since it would
-				deadlock when oplock received on delete
-				since vfs_unlink holds the i_mutex across
-				the call */
-			/* mutex_lock(&inode->i_mutex);*/
-			if (S_ISREG(inode->i_mode)) {
-#ifdef CONFIG_CIFS_EXPERIMENTAL
-				if (CIFS_I(inode)->clientCanCacheAll == 0)
-					break_lease(inode, FMODE_READ);
-				else if (CIFS_I(inode)->clientCanCacheRead == 0)
-					break_lease(inode, FMODE_WRITE);
-#endif
-				rc = filemap_fdatawrite(inode->i_mapping);
-				if (CIFS_I(inode)->clientCanCacheRead == 0) {
-					waitrc = filemap_fdatawait(
-							      inode->i_mapping);
-					invalidate_remote_inode(inode);
-				}
-				if (rc == 0)
-					rc = waitrc;
-			} else
-				rc = 0;
-			/* mutex_unlock(&inode->i_mutex);*/
-			if (rc)
-				CIFS_I(inode)->write_behind_rc = rc;
-			cFYI(1, ("Oplock flush inode %p rc %d",
-				inode, rc));
-
-				/* releasing stale oplock after recent reconnect
-				of smb session using a now incorrect file
-				handle is not a data integrity issue but do
-				not bother sending an oplock release if session
-				to server still is disconnected since oplock
-				already released by the server in that case */
-			if (!pTcon->need_reconnect) {
-				rc = CIFSSMBLock(0, pTcon, netfid,
-						0 /* len */ , 0 /* offset */, 0,
-						0, LOCKING_ANDX_OPLOCK_RELEASE,
-						false /* wait flag */);
-				cFYI(1, ("Oplock release rc = %d", rc));
-			}
-			set_current_state(TASK_INTERRUPTIBLE);
-			schedule_timeout(1);  /* yield in case q were corrupt */
-		}
-	} while (!kthread_should_stop());
-
-	return 0;
-}
-
 static int __init
 init_cifs(void)
 {
 	int rc = 0;
 	cifs_proc_init();
 	INIT_LIST_HEAD(&cifs_tcp_ses_list);
-	INIT_LIST_HEAD(&cifs_oplock_list);
 #ifdef CONFIG_CIFS_EXPERIMENTAL
 	INIT_LIST_HEAD(&GlobalDnotifyReqList);
 	INIT_LIST_HEAD(&GlobalDnotifyRsp_Q);
@@ -1084,7 +1004,6 @@ init_cifs(void)
 	rwlock_init(&GlobalSMBSeslock);
 	rwlock_init(&cifs_tcp_ses_lock);
 	spin_lock_init(&GlobalMid_Lock);
-	spin_lock_init(&cifs_oplock_lock);
 
 	if (cifs_max_pending < 2) {
 		cifs_max_pending = 2;
@@ -1119,18 +1038,15 @@ init_cifs(void)
 	if (rc)
 		goto out_unregister_key_type;
 #endif
-	oplockThread = kthread_run(cifs_oplock_thread, NULL, "cifsoplockd");
-	if (IS_ERR(oplockThread)) {
-		rc = PTR_ERR(oplockThread);
-		cERROR(1, ("error %d create oplock thread", rc));
-		goto out_unregister_dfs_key_type;
-	}
+	rc = slow_work_register_user();
+	if (rc)
+		goto out_unregister_resolver_key;
 
 	return 0;
 
- out_unregister_dfs_key_type:
-#ifdef CONFIG_CIFS_DFS_UPCALL
+ out_unregister_resolver_key:
 	unregister_key_type(&key_type_dns_resolver);
+#ifdef CONFIG_CIFS_DFS_UPCALL
  out_unregister_key_type:
 #endif
 #ifdef CONFIG_CIFS_UPCALL
@@ -1165,7 +1081,6 @@ exit_cifs(void)
 	cifs_destroy_inodecache();
 	cifs_destroy_mids();
 	cifs_destroy_request_bufs();
-	kthread_stop(oplockThread);
 }
 
 MODULE_AUTHOR("Steve French <sfrench@us.ibm.com>");
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 908b2de..c3280fa 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -18,6 +18,7 @@
  */
 #include <linux/in.h>
 #include <linux/in6.h>
+#include <linux/slow-work.h>
 #include "cifs_fs_sb.h"
 #include "cifsacl.h"
 /*
@@ -346,14 +347,16 @@ struct cifsFileInfo {
 	/* lock scope id (0 if none) */
 	struct file *pfile; /* needed for writepage */
 	struct inode *pInode; /* needed for oplock break */
+	struct cifsTconInfo *tcon;
 	struct mutex lock_mutex;
 	struct list_head llist; /* list of byte range locks we have. */
 	bool closePend:1;	/* file is marked to close */
 	bool invalidHandle:1;	/* file closed via session abend */
-	bool messageMode:1;	/* for pipes: message vs byte mode */
+	bool oplock_break_cancelled:1;
 	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 */
 };
 
 /* Take a reference on the file private data */
@@ -670,12 +673,6 @@ GLOBAL_EXTERN rwlock_t		cifs_tcp_ses_lock;
  */
 GLOBAL_EXTERN rwlock_t GlobalSMBSeslock;
 
-/* Global list of oplocks */
-GLOBAL_EXTERN struct list_head cifs_oplock_list;
-
-/* Protects the cifs_oplock_list */
-GLOBAL_EXTERN spinlock_t cifs_oplock_lock;
-
 /* Outstanding dir notify requests */
 GLOBAL_EXTERN struct list_head GlobalDnotifyReqList;
 /* DirNotify response queue */
@@ -726,3 +723,4 @@ GLOBAL_EXTERN unsigned int cifs_min_rcv;    /* min size of big ntwrk buf pool */
 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;
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index bf3ae88..9b682e3 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -86,10 +86,6 @@ extern int CIFS_SessSetup(unsigned int xid, struct cifsSesInfo *ses,
 			     const int stage,
 			     const struct nls_table *nls_cp);
 extern __u16 GetNextMid(struct TCP_Server_Info *server);
-extern struct oplock_q_entry *AllocOplockQEntry(struct inode *, u16,
-						 struct cifsTconInfo *);
-extern void DeleteOplockQEntry(struct oplock_q_entry *);
-extern void DeleteTconOplockQEntries(struct cifsTconInfo *);
 extern struct timespec cifs_NTtimeToUnix(__le64 utc_nanoseconds_since_1601);
 extern u64 cifs_UnixTimeToNT(struct timespec);
 extern struct timespec cnvrtDosUnixTm(__le16 le_date, __le16 le_time,
@@ -117,6 +113,7 @@ extern void cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb,
 			      const char *path, const __u16 *pfid);
 extern int mode_to_acl(struct inode *inode, const char *path, __u64);
 
+void cifs_put_tcon(struct cifsTconInfo *tcon);
 extern int cifs_mount(struct super_block *, struct cifs_sb_info *, char *,
 			const char *);
 extern int cifs_umount(struct super_block *, struct cifs_sb_info *);
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 301e307..941441d 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -94,6 +94,7 @@ static void mark_open_files_invalid(struct cifsTconInfo *pTcon)
 	list_for_each_safe(tmp, tmp1, &pTcon->openFileList) {
 		open_file = list_entry(tmp, struct cifsFileInfo, tlist);
 		open_file->invalidHandle = true;
+		open_file->oplock_break_cancelled = true;
 	}
 	write_unlock(&GlobalSMBSeslock);
 	/* BB Add call to invalidate_inodes(sb) for all superblocks mounted
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 9c91c8b..056af6f 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1645,7 +1645,7 @@ cifs_find_tcon(struct cifsSesInfo *ses, const char *unc)
 	return NULL;
 }
 
-static void
+void
 cifs_put_tcon(struct cifsTconInfo *tcon)
 {
 	int xid;
@@ -1664,7 +1664,6 @@ cifs_put_tcon(struct cifsTconInfo *tcon)
 	CIFSSMBTDis(xid, tcon);
 	_FreeXid(xid);
 
-	DeleteTconOplockQEntries(tcon);
 	tconInfoFree(tcon);
 	cifs_put_smb_ses(ses);
 }
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 3643550..cbe20f2 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -148,12 +148,14 @@ cifs_fill_fileinfo(struct inode *newinode, __u16 fileHandle,
 	pCifsFile->netfid = fileHandle;
 	pCifsFile->pid = current->tgid;
 	pCifsFile->pInode = igrab(newinode);
+	pCifsFile->tcon = tcon;
 	pCifsFile->invalidHandle = false;
 	pCifsFile->closePend = false;
 	mutex_init(&pCifsFile->fh_mutex);
 	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);
 
 	/* set the following in open now
 			pCifsFile->pfile = file; */
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index b976cea..5af63dd 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -41,7 +41,7 @@
 
 static inline struct cifsFileInfo *cifs_init_private(
 	struct cifsFileInfo *private_data, struct inode *inode,
-	struct file *file, __u16 netfid)
+	struct cifsTconInfo *tcon, struct file *file, __u16 netfid)
 {
 	memset(private_data, 0, sizeof(struct cifsFileInfo));
 	private_data->netfid = netfid;
@@ -51,11 +51,13 @@ static inline struct cifsFileInfo *cifs_init_private(
 	INIT_LIST_HEAD(&private_data->llist);
 	private_data->pfile = file; /* needed for writepage */
 	private_data->pInode = igrab(inode);
+	private_data->tcon = tcon;
 	private_data->invalidHandle = false;
 	private_data->closePend = false;
 	/* Initialize reference count to one.  The private data is
 	freed on the release of the last reference */
 	atomic_set(&private_data->count, 1);
+	slow_work_init(&private_data->oplock_break, &cifs_oplock_break_ops);
 
 	return private_data;
 }
@@ -423,7 +425,8 @@ int cifs_open(struct inode *inode, struct file *file)
 		rc = -ENOMEM;
 		goto out;
 	}
-	pCifsFile = cifs_init_private(file->private_data, inode, file, netfid);
+	pCifsFile = cifs_init_private(file->private_data, inode, tcon, file,
+					netfid);
 	write_lock(&GlobalSMBSeslock);
 	list_add(&pCifsFile->tlist, &tcon->openFileList);
 
@@ -2312,6 +2315,72 @@ out:
 	return rc;
 }
 
+static void
+cifs_oplock_break(struct slow_work *work)
+{
+	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
+						  oplock_break);
+	struct inode *inode = cfile->pInode;
+	struct cifsInodeInfo *cinode = CIFS_I(inode);
+	int rc, waitrc = 0;
+
+	if (inode && S_ISREG(inode->i_mode)) {
+#ifdef CONFIG_CIFS_EXPERIMENTAL
+		if (cinode->clientCanCacheAll == 0)
+			break_lease(inode, FMODE_READ);
+		else if (cinode->clientCanCacheRead == 0)
+			break_lease(inode, FMODE_WRITE);
+#endif
+		rc = filemap_fdatawrite(inode->i_mapping);
+		if (cinode->clientCanCacheRead == 0) {
+			waitrc = filemap_fdatawait(inode->i_mapping);
+			invalidate_remote_inode(inode);
+		}
+		if (!rc)
+			rc = waitrc;
+		if (rc)
+			cinode->write_behind_rc = rc;
+		cFYI(1, ("Oplock flush inode %p rc %d", inode, rc));
+	}
+
+	/*
+	 * releasing stale oplock after recent reconnect of smb session using
+	 * a now incorrect file handle is not a data integrity issue but do
+	 * not bother sending an oplock release if session to server still is
+	 * disconnected since oplock already released by the server
+	 */
+	if (!cfile->closePend && !cfile->oplock_break_cancelled) {
+		rc = CIFSSMBLock(0, cfile->tcon, cfile->netfid, 0, 0, 0, 0,
+				 LOCKING_ANDX_OPLOCK_RELEASE, false);
+		cFYI(1, ("Oplock release rc = %d", rc));
+	}
+}
+
+static int
+cifs_oplock_break_get(struct slow_work *work)
+{
+	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
+						  oplock_break);
+	cifsFileInfo_get(cfile);
+	++cfile->tcon->tc_count;
+	return 0;
+}
+
+static void
+cifs_oplock_break_put(struct slow_work *work)
+{
+	struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
+						  oplock_break);
+	cifsFileInfo_put(cfile);
+	cifs_put_tcon(cfile->tcon);
+}
+
+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,
 	.readpages = cifs_readpages,
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 @@ 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) &&
@@ -569,19 +569,30 @@ is_valid_oplock_break(struct smb_hdr *buf, struct TCP_Server_Info *srv)
 				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);
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 1da4ab2..07b8e71 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)
 {
-- 
1.6.0.6

