ksmbd: fix possible deadlock in smb2_open

[ 8743.393379] ======================================================
[ 8743.393385] WARNING: possible circular locking dependency detected
[ 8743.393391] 6.4.0-rc1+ #11 Tainted: G OE
[ 8743.393397] ------------------------------------------------------
[ 8743.393402] kworker/0:2/12921 is trying to acquire lock:
[ 8743.393408] ffff888127a14460 (sb_writers#8){.+.+}-{0:0}, at: ksmbd_vfs_setxattr+0x3d/0xd0 [ksmbd]
[ 8743.393510]
but task is already holding lock:
[ 8743.393515] ffff8880360d97f0 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: ksmbd_vfs_kern_path_locked+0x181/0x670 [ksmbd]
[ 8743.393618]
which lock already depends on the new lock.

[ 8743.393623]
the existing dependency chain (in reverse order) is:
[ 8743.393628]
-> #1 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}:
[ 8743.393648] down_write_nested+0x9a/0x1b0
[ 8743.393660] filename_create+0x128/0x270
[ 8743.393670] do_mkdirat+0xab/0x1f0
[ 8743.393680] __x64_sys_mkdir+0x47/0x60
[ 8743.393690] do_syscall_64+0x5d/0x90
[ 8743.393701] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[ 8743.393711]
-> #0 (sb_writers#8){.+.+}-{0:0}:
[ 8743.393728] __lock_acquire+0x2201/0x3b80
[ 8743.393737] lock_acquire+0x18f/0x440
[ 8743.393746] mnt_want_write+0x5f/0x240
[ 8743.393755] ksmbd_vfs_setxattr+0x3d/0xd0 [ksmbd]
[ 8743.393839] ksmbd_vfs_set_dos_attrib_xattr+0xcc/0x110 [ksmbd]
[ 8743.393924] compat_ksmbd_vfs_set_dos_attrib_xattr+0x39/0x50 [ksmbd]
[ 8743.394010] smb2_open+0x3432/0x3cc0 [ksmbd]
[ 8743.394099] handle_ksmbd_work+0x2c9/0x7b0 [ksmbd]
[ 8743.394187] process_one_work+0x65a/0xb30
[ 8743.394198] worker_thread+0x2cf/0x700
[ 8743.394209] kthread+0x1ad/0x1f0
[ 8743.394218] ret_from_fork+0x29/0x50

This patch add mnt_want_write() above parent inode lock and remove
nested mnt_want_write calls in smb2_open().

Fixes: 40b268d384a2 ("ksmbd: add mnt_want_write to ksmbd vfs functions")
Cc: stable@vger.kernel.org
Reported-by: Marios Makassikis <mmakassikis@freebox.fr>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: add support for read compound

MacOS sends a compound request including read to the server
(e.g. open-read-close). So far, ksmbd has not handled read as
a compound request. For compatibility between ksmbd and an OS that
supports SMB, This patch provides compound support for read requests.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: check if a mount point is crossed during path lookup

Since commit 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and
->d_name"), ksmbd can not lookup cross mount points. If last component is
a cross mount point during path lookup, check if it is crossed to follow it
down. And allow path lookup to cross a mount point when a crossmnt
parameter is set to 'yes' in smb.conf.

Cc: stable@vger.kernel.org
Fixes: 74d7970febf7 ("ksmbd: fix racy issue from using ->d_parent and ->d_name")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: Change the return value of ksmbd_vfs_query_maximal_access to void

The return value of ksmbd_vfs_query_maximal_access is meaningless,
it is better to modify it to void.

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: add mnt_want_write to ksmbd vfs functions

ksmbd is doing write access using vfs helpers. There are the cases that
mnt_want_write() is not called in vfs helper. This patch add missing
mnt_want_write() to ksmbd vfs functions.

Cc: stable@vger.kernel.org
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: move client and server files to common directory fs/smb

Move CIFS/SMB3 related client and server files (cifs.ko and ksmbd.ko
and helper modules) to new fs/smb subdirectory:

fs/cifs --> fs/smb/client
fs/ksmbd --> fs/smb/server
fs/smbfs_common --> fs/smb/common

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>