From: Marios Makassikis mmakassikis@freebox.fr
[ Upstream commit 807252f028c59b9a3bac4d62ad84761548c10f11 ]
Running smb2.rename test from Samba smbtorture suite against a kernel built with lockdep triggers a "possible recursive locking detected" warning.
This is because mnt_want_write() is called twice with no mnt_drop_write() in between: -> ksmbd_vfs_mkdir() -> ksmbd_vfs_kern_path_create() -> kern_path_create() -> filename_create() -> mnt_want_write() -> mnt_want_write()
Fix this by removing the mnt_want_write/mnt_drop_write calls from vfs helpers that call kern_path_create().
Full lockdep trace below:
============================================ WARNING: possible recursive locking detected 6.6.0-rc5 #775 Not tainted -------------------------------------------- kworker/1:1/32 is trying to acquire lock: ffff888005ac83f8 (sb_writers#5){.+.+}-{0:0}, at: ksmbd_vfs_mkdir+0xe1/0x410
but task is already holding lock: ffff888005ac83f8 (sb_writers#5){.+.+}-{0:0}, at: filename_create+0xb6/0x260
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(sb_writers#5); lock(sb_writers#5);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by kworker/1:1/32: #0: ffff8880064e4138 ((wq_completion)ksmbd-io){+.+.}-{0:0}, at: process_one_work+0x40e/0x980 #1: ffff888005b0fdd0 ((work_completion)(&work->work)){+.+.}-{0:0}, at: process_one_work+0x40e/0x980 #2: ffff888005ac83f8 (sb_writers#5){.+.+}-{0:0}, at: filename_create+0xb6/0x260 #3: ffff8880057ce760 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x123/0x260
Cc: stable@vger.kernel.org Fixes: 40b268d384a2 ("ksmbd: add mnt_want_write to ksmbd vfs functions") Signed-off-by: Marios Makassikis mmakassikis@freebox.fr Acked-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com --- fs/smb/server/vfs.c | 23 +++-------------------- 1 file changed, 3 insertions(+), 20 deletions(-)
diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c index 071c344dd033..e2e454eba409 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -174,10 +174,6 @@ int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode) return err; }
- err = mnt_want_write(path.mnt); - if (err) - goto out_err; - mode |= S_IFREG; err = vfs_create(mnt_user_ns(path.mnt), d_inode(path.dentry), dentry, mode, true); @@ -187,9 +183,7 @@ int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode) } else { pr_err("File(%s): creation failed (err:%d)\n", name, err); } - mnt_drop_write(path.mnt);
-out_err: done_path_create(&path, dentry); return err; } @@ -220,10 +214,6 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode) return err; }
- err = mnt_want_write(path.mnt); - if (err) - goto out_err2; - user_ns = mnt_user_ns(path.mnt); mode |= S_IFDIR; err = vfs_mkdir(user_ns, d_inode(path.dentry), dentry, mode); @@ -234,21 +224,19 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode) dentry->d_name.len); if (IS_ERR(d)) { err = PTR_ERR(d); - goto out_err1; + goto out_err; } if (unlikely(d_is_negative(d))) { dput(d); err = -ENOENT; - goto out_err1; + goto out_err; }
ksmbd_vfs_inherit_owner(work, d_inode(path.dentry), d_inode(d)); dput(d); }
-out_err1: - mnt_drop_write(path.mnt); -out_err2: +out_err: done_path_create(&path, dentry); if (err) pr_err("mkdir(%s): creation failed (err:%d)\n", name, err); @@ -666,16 +654,11 @@ int ksmbd_vfs_link(struct ksmbd_work *work, const char *oldname, goto out3; }
- err = mnt_want_write(newpath.mnt); - if (err) - goto out3; - err = vfs_link(oldpath.dentry, mnt_user_ns(newpath.mnt), d_inode(newpath.dentry), dentry, NULL); if (err) ksmbd_debug(VFS, "vfs_link failed err %d\n", err); - mnt_drop_write(newpath.mnt);
out3: done_path_create(&newpath, dentry);