[PATCH 2/4] ksmbd: set SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY in tree connect

[Yunseong Kim <yunseong.kim@est.tech>]

Set the SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY capability in the tree
connect response for shares configured with the 'continuous availability'
option (KSMBD_SHARE_FLAG_CONTINUOUS_AVAILABILITY).

This capability is only advertised when persistent handles are also
enabled globally (SMB2_GLOBAL_CAP_PERSISTENT_HANDLES). It informs
clients that the share supports persistent handles, allowing them to
request SMB2_DHANDLE_FLAG_PERSISTENT in DH2Q create contexts.

Signed-off-by: Yunseong Kim <yunseong.kim@est.tech>
---
 fs/smb/server/smb2pdu.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index bd74b45ce0e7..b4bf36fb7183 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -2858,10 +2858,15 @@ int smb2_tree_connect(struct ksmbd_work *work)
 	rsp->StructureSize = cpu_to_le16(16);
 out_err1:
 	/*
-	 * A configured CA share is not continuously available until persistent
-	 * open recovery, ownership fencing, and failover are implemented.
+	 * Advertise Continuous Availability on shares configured with
+	 * the CA flag, when persistent handles are enabled globally.
 	 */
-	rsp->Capabilities = 0;
+	if (share && test_share_config_flag(share,
+					    KSMBD_SHARE_FLAG_CONTINUOUS_AVAILABILITY) &&
+	    conn->vals->req_capabilities & SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
+		rsp->Capabilities = cpu_to_le32(SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY);
+	else
+		rsp->Capabilities = 0;
 	rsp->Reserved = 0;
 	/* default manual caching */
 	rsp->ShareFlags = SMB2_SHAREFLAG_MANUAL_CACHING;

-- 
2.47.3