From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 522E0338931; Wed, 12 Nov 2025 15:01:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762959713; cv=none; b=QI/94osqJNJx7V7CYg9RyPj7XgqfAHPDZKRePqiA9JdEP+fuk+63w1PuYa1R8YP2cnMuiCfywUGVhtE0aKDANJNUPCMrfClOzvWAotXZ1RzHIvxZW2t4+GiJ4iYjQ6XgVMI+Nw0Eoq1ejeE5vbnYX0r3ESlDbMRreDOdswUgxUg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762959713; c=relaxed/simple; bh=tayKidNgtaY6pxZsm4DyMV+Bgmlb1U0dE3JcZxYSgvU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=eG37dBQj8foRcWMaewDX+V3cDE2/bjpbvnbJ3QmgbTKf+Iuz70wbvhDvlFMi/QtNS3eVbSO1r1tceKV7B4Q+4uXGlVevPqVGcRq7ohF8ohkWbsZag+inmllFpbFgdz5xu1RWAcVHwiPU2StTLO7G6K+tDu3hihUAbBCkKA+t0dI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WSPBb516; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WSPBb516" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3422FC4CEF1; Wed, 12 Nov 2025 15:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762959713; bh=tayKidNgtaY6pxZsm4DyMV+Bgmlb1U0dE3JcZxYSgvU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=WSPBb516MWVdmkiqvFGBfI1FA5tAQVTSSlpiKtlby0DXsfFNUJEbfq0SreQp7+MOH P+h7mZWEZAITD31QqNOfaPN0Aq1FRIUyCaW7qvoo8H2hO84Vy9lkTgQXsUWcrXePsn m2oOV7SA5XQqNOi+yQKdU3PfUZKkZMpRSndLpD+WkiSQXO9RGkyMnt5k8kLJ4OcGUt wHgAmubqHRREiEkVmYqy/PbVm17EHc/vEzdy1BnW2uCCLsRtAOGq4mzm1T/QvcjUUu eAxCUyDpM+oj4aKMCSvsq0N0CC2M0wlLynRQL6O3h8yc6wEvw61Lxtx6/aQSRXkgI5 e3oOOhqoFDLOg== Message-ID: <4a5c4bf1a299f487c4f97e0054293cbeff139fa7.camel@kernel.org> Subject: Re: [PATCH v5 08/14] VFS: add start_creating_killable() and start_removing_killable() From: Jeff Layton To: NeilBrown , Alexander Viro , Christian Brauner , Amir Goldstein Cc: Jan Kara , linux-fsdevel@vger.kernel.org, Chris Mason , David Sterba , David Howells , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Tyler Hicks , Miklos Szeredi , Chuck Lever , Olga Kornievskaia , Dai Ngo , Namjae Jeon , Steve French , Sergey Senozhatsky , Carlos Maiolino , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Ondrej Mosnacek , Mateusz Guzik , Lorenzo Stoakes , Stefan Berger , "Darrick J. Wong" , linux-kernel@vger.kernel.org, netfs@lists.linux.dev, ecryptfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Date: Wed, 12 Nov 2025 10:01:49 -0500 In-Reply-To: <20251106005333.956321-9-neilb@ownmail.net> References: <20251106005333.956321-1-neilb@ownmail.net> <20251106005333.956321-9-neilb@ownmail.net> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn 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DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.1 (3.58.1-1.fc43) Precedence: bulk X-Mailing-List: netfs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2025-11-06 at 11:50 +1100, NeilBrown wrote: > From: NeilBrown >=20 > These are similar to start_creating() and start_removing(), but allow a > fatal signal to abort waiting for the lock. >=20 > They are used in btrfs for subvol creation and removal. >=20 > btrfs_may_create() no longer needs IS_DEADDIR() and > start_creating_killable() includes that check. >=20 > Reviewed-by: Amir Goldstein > Signed-off-by: NeilBrown > --- > fs/btrfs/ioctl.c | 41 +++++++--------------- > fs/namei.c | 80 +++++++++++++++++++++++++++++++++++++++++-- > include/linux/namei.h | 6 ++++ > 3 files changed, 95 insertions(+), 32 deletions(-) >=20 > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index 8cb7d5a462ef..d0c3bb0423bb 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -904,14 +904,9 @@ static noinline int btrfs_mksubvol(struct dentry *pa= rent, > struct fscrypt_str name_str =3D FSTR_INIT((char *)qname->name, qname->l= en); > int ret; > =20 > - ret =3D down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT); > - if (ret =3D=3D -EINTR) > - return ret; > - > - dentry =3D lookup_one(idmap, qname, parent); > - ret =3D PTR_ERR(dentry); > + dentry =3D start_creating_killable(idmap, parent, qname); > if (IS_ERR(dentry)) > - goto out_unlock; > + return PTR_ERR(dentry); > =20 > ret =3D btrfs_may_create(idmap, dir, dentry); > if (ret) > @@ -940,9 +935,7 @@ static noinline int btrfs_mksubvol(struct dentry *par= ent, > out_up_read: > up_read(&fs_info->subvol_sem); > out_dput: > - dput(dentry); > -out_unlock: > - btrfs_inode_unlock(BTRFS_I(dir), 0); > + end_creating(dentry, parent); > return ret; > } > =20 > @@ -2417,18 +2410,10 @@ static noinline int btrfs_ioctl_snap_destroy(stru= ct file *file, > goto free_subvol_name; > } > =20 > - ret =3D down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT); > - if (ret =3D=3D -EINTR) > - goto free_subvol_name; > - dentry =3D lookup_one(idmap, &QSTR(subvol_name), parent); > + dentry =3D start_removing_killable(idmap, parent, &QSTR(subvol_name)); > if (IS_ERR(dentry)) { > ret =3D PTR_ERR(dentry); > - goto out_unlock_dir; > - } > - > - if (d_really_is_negative(dentry)) { > - ret =3D -ENOENT; > - goto out_dput; > + goto out_end_removing; > } > =20 > inode =3D d_inode(dentry); > @@ -2449,7 +2434,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct= file *file, > */ > ret =3D -EPERM; > if (!btrfs_test_opt(fs_info, USER_SUBVOL_RM_ALLOWED)) > - goto out_dput; > + goto out_end_removing; > =20 > /* > * Do not allow deletion if the parent dir is the same > @@ -2460,21 +2445,21 @@ static noinline int btrfs_ioctl_snap_destroy(stru= ct file *file, > */ > ret =3D -EINVAL; > if (root =3D=3D dest) > - goto out_dput; > + goto out_end_removing; > =20 > ret =3D inode_permission(idmap, inode, MAY_WRITE | MAY_EXEC); > if (ret) > - goto out_dput; > + goto out_end_removing; > } > =20 > /* check if subvolume may be deleted by a user */ > ret =3D btrfs_may_delete(idmap, dir, dentry, 1); > if (ret) > - goto out_dput; > + goto out_end_removing; > =20 > if (btrfs_ino(BTRFS_I(inode)) !=3D BTRFS_FIRST_FREE_OBJECTID) { > ret =3D -EINVAL; > - goto out_dput; > + goto out_end_removing; > } > =20 > btrfs_inode_lock(BTRFS_I(inode), 0); > @@ -2483,10 +2468,8 @@ static noinline int btrfs_ioctl_snap_destroy(struc= t file *file, > if (!ret) > d_delete_notify(dir, dentry); > =20 > -out_dput: > - dput(dentry); > -out_unlock_dir: > - btrfs_inode_unlock(BTRFS_I(dir), 0); > +out_end_removing: > + end_removing(dentry); > free_subvol_name: > kfree(subvol_name_ptr); > free_parent: > diff --git a/fs/namei.c b/fs/namei.c > index 729b42fb143b..e70d056b9543 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -2778,19 +2778,33 @@ static int filename_parentat(int dfd, struct file= name *name, > * Returns: a locked dentry, or an error. > * > */ > -struct dentry *start_dirop(struct dentry *parent, struct qstr *name, > - unsigned int lookup_flags) > +static struct dentry *__start_dirop(struct dentry *parent, struct qstr *= name, > + unsigned int lookup_flags, > + unsigned int state) > { > struct dentry *dentry; > struct inode *dir =3D d_inode(parent); > =20 > - inode_lock_nested(dir, I_MUTEX_PARENT); > + if (state =3D=3D TASK_KILLABLE) { > + int ret =3D down_write_killable_nested(&dir->i_rwsem, > + I_MUTEX_PARENT); > + if (ret) > + return ERR_PTR(ret); > + } else { > + inode_lock_nested(dir, I_MUTEX_PARENT); > + } > dentry =3D lookup_one_qstr_excl(name, parent, lookup_flags); > if (IS_ERR(dentry)) > inode_unlock(dir); > return dentry; > } > =20 > +struct dentry *start_dirop(struct dentry *parent, struct qstr *name, > + unsigned int lookup_flags) > +{ > + return __start_dirop(parent, name, lookup_flags, TASK_NORMAL); > +} > + > /** > * end_dirop - signal completion of a dirop > * @de: the dentry which was returned by start_dirop or similar. > @@ -3275,6 +3289,66 @@ struct dentry *start_removing(struct mnt_idmap *id= map, struct dentry *parent, > } > EXPORT_SYMBOL(start_removing); > =20 > +/** > + * start_creating_killable - prepare to create a given name with permiss= ion checking > + * @idmap: idmap of the mount > + * @parent: directory in which to prepare to create the name > + * @name: the name to be created > + * > + * Locks are taken and a lookup in performed prior to creating > + * an object in a directory. Permission checking (MAY_EXEC) is performe= d > + * against @idmap. > + * > + * If the name already exists, a positive dentry is returned. > + * > + * If a signal is received or was already pending, the function aborts > + * with -EINTR; > + * > + * Returns: a negative or positive dentry, or an error. > + */ > +struct dentry *start_creating_killable(struct mnt_idmap *idmap, > + struct dentry *parent, > + struct qstr *name) > +{ > + int err =3D lookup_one_common(idmap, name, parent); > + > + if (err) > + return ERR_PTR(err); > + return __start_dirop(parent, name, LOOKUP_CREATE, TASK_KILLABLE); > +} > +EXPORT_SYMBOL(start_creating_killable); > + > +/** > + * start_removing_killable - prepare to remove a given name with permiss= ion checking > + * @idmap: idmap of the mount > + * @parent: directory in which to find the name > + * @name: the name to be removed > + * > + * Locks are taken and a lookup in performed prior to removing > + * an object from a directory. Permission checking (MAY_EXEC) is perfor= med > + * against @idmap. > + * > + * If the name doesn't exist, an error is returned. > + * > + * end_removing() should be called when removal is complete, or aborted. > + * > + * If a signal is received or was already pending, the function aborts > + * with -EINTR; > + * > + * Returns: a positive dentry, or an error. > + */ > +struct dentry *start_removing_killable(struct mnt_idmap *idmap, > + struct dentry *parent, > + struct qstr *name) > +{ > + int err =3D lookup_one_common(idmap, name, parent); > + > + if (err) > + return ERR_PTR(err); > + return __start_dirop(parent, name, 0, TASK_KILLABLE); > +} > +EXPORT_SYMBOL(start_removing_killable); > + > /** > * start_creating_noperm - prepare to create a given name without permis= sion checking > * @parent: directory in which to prepare to create the name > diff --git a/include/linux/namei.h b/include/linux/namei.h > index d089e4e8fdd0..196c66156a8a 100644 > --- a/include/linux/namei.h > +++ b/include/linux/namei.h > @@ -93,6 +93,12 @@ struct dentry *start_creating(struct mnt_idmap *idmap,= struct dentry *parent, > struct qstr *name); > struct dentry *start_removing(struct mnt_idmap *idmap, struct dentry *pa= rent, > struct qstr *name); > +struct dentry *start_creating_killable(struct mnt_idmap *idmap, > + struct dentry *parent, > + struct qstr *name); > +struct dentry *start_removing_killable(struct mnt_idmap *idmap, > + struct dentry *parent, > + struct qstr *name); > struct dentry *start_creating_noperm(struct dentry *parent, struct qstr = *name); > struct dentry *start_removing_noperm(struct dentry *parent, struct qstr = *name); > struct dentry *start_removing_dentry(struct dentry *parent, Nice. Maybe we can start using the killable versions in more places this way! Reviewed-by: Jeff Layton