cifs: only write 64kb at a time when fallocating a small region of a file

stable inclusion
from stable-5.10.54
commit c26372b8a8c301d56204cddb9aedfa2c67adac17
bugzilla: 175586 https://gitee.com/openeuler/kernel/issues/I4DVDU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c26372b8a8c301d56204cddb9aedfa2c67adac17

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

[ Upstream commit 2485bd75 ]

We only allow sending single credit writes through the SMB2_write() synchronous
api so split this into smaller chunks.

Fixes: 966a3cb7 ("cifs: improve fallocate emulation")
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reported-by: NNamjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/cifs/smb2ops.c

@@ -3466,7 +3466,7 @@ static int smb3_simple_fallocate_write_range(unsigned int xid,
 					     char *buf)
 {
 	struct cifs_io_parms io_parms = {0};
-	int nbytes;
+	int rc, nbytes;
 	struct kvec iov[2];
 
 	io_parms.netfid = cfile->fid.netfid;
@@ -3474,13 +3474,25 @@ static int smb3_simple_fallocate_write_range(unsigned int xid,
 	io_parms.tcon = tcon;
 	io_parms.persistent_fid = cfile->fid.persistent_fid;
 	io_parms.volatile_fid = cfile->fid.volatile_fid;
-	io_parms.offset = off;
-	io_parms.length = len;
 
-	/* iov[0] is reserved for smb header */
-	iov[1].iov_base = buf;
-	iov[1].iov_len = io_parms.length;
-	return SMB2_write(xid, &io_parms, &nbytes, iov, 1);
+	while (len) {
+		io_parms.offset = off;
+		io_parms.length = len;
+		if (io_parms.length > SMB2_MAX_BUFFER_SIZE)
+			io_parms.length = SMB2_MAX_BUFFER_SIZE;
+		/* iov[0] is reserved for smb header */
+		iov[1].iov_base = buf;
+		iov[1].iov_len = io_parms.length;
+		rc = SMB2_write(xid, &io_parms, &nbytes, iov, 1);
+		if (rc)
+			break;
+		if (nbytes > len)
+			return -EINVAL;
+		buf += nbytes;
+		off += nbytes;
+		len -= nbytes;
+	}
+	return rc;
 }
 
 static int smb3_simple_fallocate_range(unsigned int xid,