5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pali Rohár <pali@kernel.org>

[ Upstream commit b460249b9a1dab7a9f58483e5349d045ad6d585c ]

To query root path (without msearch wildcard) it is needed to
send pattern '\' instead of '' (empty string).

This allows to use CIFSFindFirst() to query information about root path
which is being used in followup changes.

This change fixes the stat() syscall called on the root path on the mount.
It is because stat() syscall uses the cifs_query_path_info() function and
it can fallback to the CIFSFindFirst() usage with msearch=false.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cifs/cifssmb.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index f924f05b1829..ea444c8d0c40 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c

@@ -4544,6 +4544,12 @@ CIFSFindFirst(const unsigned int xid, struct cifs_tcon *tcon,
 			pSMB->FileName[name_len] = 0;
 			pSMB->FileName[name_len+1] = 0;
 			name_len += 2;
+		} else if (!searchName[0]) {
+			pSMB->FileName[0] = CIFS_DIR_SEP(cifs_sb);
+			pSMB->FileName[1] = 0;
+			pSMB->FileName[2] = 0;
+			pSMB->FileName[3] = 0;
+			name_len = 4;
 		}
 	} else {
 		name_len = copy_path_name(pSMB->FileName, searchName);

@@ -4555,6 +4561,10 @@ CIFSFindFirst(const unsigned int xid, struct cifs_tcon *tcon,
 			pSMB->FileName[name_len] = '*';
 			pSMB->FileName[name_len+1] = 0;
 			name_len += 2;
+		} else if (!searchName[0]) {
+			pSMB->FileName[0] = CIFS_DIR_SEP(cifs_sb);
+			pSMB->FileName[1] = 0;
+			name_len = 2;
 		}
 	}
 

-- 
2.39.5