From: Ronnie Sahlberg <lsahlber@redhat.com>
Date: Thu, 14 Jun 2018 06:48:35 +1000
Subject: [PATCH] cifs: add lease tracking to the cached root fid
Git-commit: a93864d93977b99bda6c348a09b90a3d7ef8db3a
Patch-mainline: v4.18-rc1
References: bsc#1144333

Use a read lease for the cached root fid so that we can detect
when the content of the directory changes (via a break) at which time
we close the handle. On next access to the root the handle will be reopened
and cached again.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/cifsglob.h  | 12 +++++++++---
 fs/cifs/cifsproto.h |  1 +
 fs/cifs/cifssmb.c   |  8 ++++----
 fs/cifs/misc.c      |  7 ++++---
 fs/cifs/smb2misc.c  | 16 +++++++++++++++-
 fs/cifs/smb2ops.c   | 34 +++++++++++++++++++++++++---------
 6 files changed, 58 insertions(+), 20 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 1efa2e65bc1a..ff71fbd619bf 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -883,6 +883,14 @@ cap_unix(struct cifs_ses *ses)
 	return ses->server->vals->cap_unix & ses->capabilities;
 }
 
+struct cached_fid {
+	bool is_valid:1;	/* Do we have a useable root fid */
+	struct cifs_fid *fid;
+	struct mutex fid_mutex;
+	struct cifs_tcon *tcon;
+	struct work_struct lease_break;
+};
+
 /*
  * there is one of these for each connection to a resource on a particular
  * session
@@ -987,9 +995,7 @@ struct cifs_tcon {
 	struct fscache_cookie *fscache;	/* cookie for share */
 #endif
 	struct list_head pending_opens;	/* list of incomplete opens */
-	bool valid_root_fid:1;	/* Do we have a useable root fid */
-	struct mutex prfid_mutex; /* prevents reopen race after dead ses*/
-	struct cifs_fid *prfid;	/* handle to the directory at top of share */
+	struct cached_fid crfid; /* Cached root fid */
 	/* BB add field for back pointer to sb struct(s)? */
 };
 
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 4e0d183c3d10..3a13b44069fe 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -552,6 +552,7 @@ enum securityEnum cifs_select_sectype(struct TCP_Server_Info *,
 struct cifs_aio_ctx *cifs_aio_ctx_alloc(void);
 void cifs_aio_ctx_release(struct kref *refcount);
 int setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw);
+void smb2_cached_lease_break(struct work_struct *work);
 
 int cifs_alloc_hash(const char *name, struct crypto_shash **shash,
 		    struct sdesc **sdesc);
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 42329b25877d..d352da325de3 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -107,10 +107,10 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
 	}
 	spin_unlock(&tcon->open_file_lock);
 
-	mutex_lock(&tcon->prfid_mutex);
-	tcon->valid_root_fid = false;
-	memset(tcon->prfid, 0, sizeof(struct cifs_fid));
-	mutex_unlock(&tcon->prfid_mutex);
+	mutex_lock(&tcon->crfid.fid_mutex);
+	tcon->crfid.is_valid = false;
+	memset(tcon->crfid.fid, 0, sizeof(struct cifs_fid));
+	mutex_unlock(&tcon->crfid.fid_mutex);
 
 	/*
 	 * BB Add call to invalidate_inodes(sb) for all superblocks mounted
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index af29ade195c0..bb40f3c050f6 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -117,8 +117,9 @@ tconInfoAlloc(void)
 		INIT_LIST_HEAD(&ret_buf->openFileList);
 		INIT_LIST_HEAD(&ret_buf->tcon_list);
 		spin_lock_init(&ret_buf->open_file_lock);
-		mutex_init(&ret_buf->prfid_mutex);
-		ret_buf->prfid = kzalloc(sizeof(struct cifs_fid), GFP_KERNEL);
+		mutex_init(&ret_buf->crfid.fid_mutex);
+		ret_buf->crfid.fid = kzalloc(sizeof(struct cifs_fid),
+					     GFP_KERNEL);
 #ifdef CONFIG_CIFS_STATS
 		spin_lock_init(&ret_buf->stat_lock);
 #endif
@@ -136,7 +137,7 @@ tconInfoFree(struct cifs_tcon *buf_to_free)
 	atomic_dec(&tconInfoAllocCount);
 	kfree(buf_to_free->nativeFileSystem);
 	kzfree(buf_to_free->password);
-	kfree(buf_to_free->prfid);
+	kfree(buf_to_free->crfid.fid);
 	kfree(buf_to_free);
 }
 
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index e2bec47c6845..0de87ca33e2e 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -492,10 +492,11 @@ cifs_ses_oplock_break(struct work_struct *work)
 {
 	struct smb2_lease_break_work *lw = container_of(work,
 				struct smb2_lease_break_work, lease_break);
-	int rc;
+	int rc = 0;
 
 	rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
 			      lw->lease_state);
+
 	cifs_dbg(FYI, "Lease release rc %d\n", rc);
 	cifs_put_tlink(lw->tlink);
 	kfree(lw);
@@ -561,6 +562,7 @@ smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
 
 		open->oplock = lease_state;
 	}
+
 	return found;
 }
 
@@ -603,6 +605,18 @@ smb2_is_valid_lease_break(char *buffer)
 					return true;
 				}
 				spin_unlock(&tcon->open_file_lock);
+
+				if (tcon->crfid.is_valid &&
+				    !memcmp(rsp->LeaseKey,
+					    tcon->crfid.fid->lease_key,
+					    SMB2_LEASE_KEY_SIZE)) {
+					INIT_WORK(&tcon->crfid.lease_break,
+						  smb2_cached_lease_break);
+					queue_work(cifsiod_wq,
+						   &tcon->crfid.lease_break);
+					spin_unlock(&cifs_tcp_ses_lock);
+					return true;
+				}
 			}
 		}
 	}
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index b15f5957d645..682bcfa246be 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -323,6 +323,21 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon)
 }
 #endif /* STATS2 */
 
+void
+smb2_cached_lease_break(struct work_struct *work)
+{
+	struct cached_fid *cfid = container_of(work,
+				struct cached_fid, lease_break);
+	mutex_lock(&cfid->fid_mutex);
+	if (cfid->is_valid) {
+		cifs_dbg(FYI, "clear cached root file handle\n");
+		SMB2_close(0, cfid->tcon, cfid->fid->persistent_fid,
+			   cfid->fid->volatile_fid);
+		cfid->is_valid = false;
+	}
+	mutex_unlock(&cfid->fid_mutex);
+}
+
 /*
  * Open the directory at the root of a share
  */
@@ -331,13 +346,13 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
 	struct cifs_open_parms oparams;
 	int rc;
 	__le16 srch_path = 0; /* Null - since an open of top of share */
-	u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
+	u8 oplock = SMB2_OPLOCK_LEVEL_II;
 
-	mutex_lock(&tcon->prfid_mutex);
-	if (tcon->valid_root_fid) {
+	mutex_lock(&tcon->crfid.fid_mutex);
+	if (tcon->crfid.is_valid) {
 		cifs_dbg(FYI, "found a cached root file handle\n");
-		memcpy(pfid, tcon->prfid, sizeof(struct cifs_fid));
-		mutex_unlock(&tcon->prfid_mutex);
+		memcpy(pfid, tcon->crfid.fid, sizeof(struct cifs_fid));
+		mutex_unlock(&tcon->crfid.fid_mutex);
 		return 0;
 	}
 
@@ -350,10 +365,11 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
 
 	rc = SMB2_open(xid, &oparams, &srch_path, &oplock, NULL, NULL, NULL);
 	if (rc == 0) {
-		memcpy(tcon->prfid, pfid, sizeof(struct cifs_fid));
-		tcon->valid_root_fid = true;
+		memcpy(tcon->crfid.fid, pfid, sizeof(struct cifs_fid));
+		tcon->crfid.tcon = tcon;
+		tcon->crfid.is_valid = true;
 	}
-	mutex_unlock(&tcon->prfid_mutex);
+	mutex_unlock(&tcon->crfid.fid_mutex);
 	return rc;
 }
 
@@ -436,7 +452,7 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
 	struct cifs_open_parms oparms;
 	struct cifs_fid fid;
 
-	if ((*full_path == 0) && tcon->valid_root_fid)
+	if ((*full_path == 0) && tcon->crfid.is_valid)
 		return 0;
 
 	utf16_path = cifs_convert_path_to_utf16(full_path, cifs_sb);
-- 
2.16.4