CIFS: Do not reset lease state to NONE on lease break

commit 7b9b9edb49ad377b1e06abf14354c227e9ac4b06 upstream.

Currently on lease break the client sets a caching level twice:
when oplock is detected and when oplock is processed. While the
1st attempt sets the level to the value provided by the server,
the 2nd one resets the level to None unconditionally.
This happens because the oplock/lease processing code was changed
to avoid races between page cache flushes and oplock breaks.
The commit c11f1df5003d534 ("cifs: Wait for writebacks to complete
before attempting write.") fixed the races for oplocks but didn't
apply the same changes for leases resulting in overwriting the
server granted value to None. Fix this by properly processing
lease breaks.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
[bwh: Backported to 3.16: drop change in smb311_operations]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

2 files changed, 25 insertions, 5 deletions

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index ed976a94791c..1485ab8c2d65 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -420,7 +420,6 @@ smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
 	__u8 lease_state;
 	struct list_head *tmp;
 	struct cifsFileInfo *cfile;
-	struct TCP_Server_Info *server = tcon->ses->server;
 	struct cifs_pending_open *open;
 	struct cifsInodeInfo *cinode;
 	int ack_req = le32_to_cpu(rsp->Flags &
@@ -440,13 +439,25 @@ smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
 		cifs_dbg(FYI, "lease key match, lease break 0x%d\n",
 			 le32_to_cpu(rsp->NewLeaseState));
 
-		server->ops->set_oplock_level(cinode, lease_state, 0, NULL);
-
 		if (ack_req)
 			cfile->oplock_break_cancelled = false;
 		else
 			cfile->oplock_break_cancelled = true;
 
+		set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK, &cinode->flags);
+
+		/*
+		 * Set or clear flags depending on the lease state being READ.
+		 * HANDLE caching flag should be added when the client starts
+		 * to defer closing remote file handles with HANDLE leases.
+		 */
+		if (lease_state & SMB2_LEASE_READ_CACHING_HE)
+			set_bit(CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
+				&cinode->flags);
+		else
+			clear_bit(CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
+				  &cinode->flags);
+
 		queue_work(cifsoplockd_wq, &cfile->oplock_break);
 		kfree(lw);
 		return true;
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 46bea6c44ec8..376ccd96127f 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -962,6 +962,15 @@ smb2_downgrade_oplock(struct TCP_Server_Info *server,
 }
 
 static void
+smb21_downgrade_oplock(struct TCP_Server_Info *server,
+		       struct cifsInodeInfo *cinode, bool set_level2)
+{
+	server->ops->set_oplock_level(cinode,
+				      set_level2 ? SMB2_LEASE_READ_CACHING_HE :
+				      0, 0, NULL);
+}
+
+static void
 smb2_set_oplock_level(struct cifsInodeInfo *cinode, __u32 oplock,
 		      unsigned int epoch, bool *purge_cache)
 {
@@ -1253,7 +1262,7 @@ struct smb_version_operations smb21_operations = {
 	.print_stats = smb2_print_stats,
 	.is_oplock_break = smb2_is_valid_oplock_break,
 	.handle_cancelled_mid = smb2_handle_cancelled_mid,
-	.downgrade_oplock = smb2_downgrade_oplock,
+	.downgrade_oplock = smb21_downgrade_oplock,
 	.need_neg = smb2_need_neg,
 	.negotiate = smb2_negotiate,
 	.negotiate_wsize = smb2_negotiate_wsize,
@@ -1331,7 +1340,7 @@ struct smb_version_operations smb30_operations = {
 	.dump_share_caps = smb2_dump_share_caps,
 	.is_oplock_break = smb2_is_valid_oplock_break,
 	.handle_cancelled_mid = smb2_handle_cancelled_mid,
-	.downgrade_oplock = smb2_downgrade_oplock,
+	.downgrade_oplock = smb21_downgrade_oplock,
 	.need_neg = smb2_need_neg,
 	.negotiate = smb2_negotiate,
 	.negotiate_wsize = smb2_negotiate_wsize,