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 E047A757EA; Fri, 13 Jun 2025 18:31:58 +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=1749839519; cv=none; b=oca6us0iglvnlO4XUEX24stru1gmrijdETBVX8DU+Atroj6Jey63PJVR7rxBBqEAEKsPcJegseIjSqoTdKcB4rwpmRGohFXFXsv/tvns19QfPS5unWymDqMEoAGiCcZzXKRV7c4d9LBVAULoIeDvZUxbY2iJ1QnRpVGR9hHphTU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749839519; c=relaxed/simple; bh=V+b3KK+c56axkz87WdXsI7DXzzjg1n/07GkyarvOQrc=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=W5dHgT+kXSw0VZULsEFTj4ZmcNaZzAAewtpEHWfvOIx3Xupr63Vk48tfftmKhz3cd07le+gN0f4/OlknWD2ffkma4AaW24LIsedNutqdfpCcGgbiOEhBHvsU9ntyxKiQnjqP+sr9UGs1qmPPD9NY03UM7dHeW5l9lTf+I+umvPU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GjxZOL4n; 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="GjxZOL4n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6FFBC4CEE3; Fri, 13 Jun 2025 18:31:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749839518; bh=V+b3KK+c56axkz87WdXsI7DXzzjg1n/07GkyarvOQrc=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=GjxZOL4nxB7a+uZt/Zo4Avpv2ZB+KZvEQVVSNrWgWIk6sHdzaR3/rbRP8BYWFjP0a yu3YRVX8mdUxc90PuIvoKUocoV3WS25JS4ZQooxsG68StHM+/lfHv3p7djEUpsE3Z7 at8Gz8f/SEYmKqmcgzHOm1CxRsKbGqaSVHOdJHg3xgIFFO4D9yLzSdxA4FctK1pAcM B/VloJkwStE+7icMk1FDLs00F1ZF0zgHcu8FG0wuyIHG8nJk75+DZwyE3ZlXQFttZs Yyp9wLOjYSNqFzEaP/NJp9RvtYRWu2qlopx1sGNNMHUU5pl9vMUPPslznMqcWEyxbb pHXSgBBKm7G6g== Message-ID: <84376c8a7753a8242e9f5730128f0eaea7863b61.camel@kernel.org> Subject: Re: [PATCH 02/17] new helper: simple_start_creating() From: Jeff Layton To: Al Viro , linux-fsdevel@vger.kernel.org Cc: chuck.lever@oracle.com, linux-nfs@vger.kernel.org, neil@brown.name, torvalds@linux-foundation.org, trondmy@kernel.org Date: Fri, 13 Jun 2025 14:31:56 -0400 In-Reply-To: <20250613073432.1871345-2-viro@zeniv.linux.org.uk> References: <20250613073149.GI1647736@ZenIV> <20250613073432.1871345-1-viro@zeniv.linux.org.uk> <20250613073432.1871345-2-viro@zeniv.linux.org.uk> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2025-06-13 at 08:34 +0100, Al Viro wrote: > Set the things up for kernel-initiated creation of object in > a tree-in-dcache filesystem. With respect to locking it's > an equivalent of filename_create() - we either get a negative > dentry with locked parent, or ERR_PTR() and no locks taken. >=20 > tracefs and debugfs had that open-coded as part of their > object creation machinery; switched to calling new helper. >=20 > Signed-off-by: Al Viro > --- > fs/debugfs/inode.c | 21 ++------------------- > fs/libfs.c | 25 +++++++++++++++++++++++++ > fs/tracefs/inode.c | 15 ++------------- > include/linux/fs.h | 1 + > 4 files changed, 30 insertions(+), 32 deletions(-) >=20 > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c > index 30c4944e1862..08638e39bd12 100644 > --- a/fs/debugfs/inode.c > +++ b/fs/debugfs/inode.c > @@ -384,26 +384,9 @@ static struct dentry *start_creating(const char *nam= e, struct dentry *parent) > if (!parent) > parent =3D debugfs_mount->mnt_root; > =20 > - inode_lock(d_inode(parent)); > - if (unlikely(IS_DEADDIR(d_inode(parent)))) > - dentry =3D ERR_PTR(-ENOENT); > - else > - dentry =3D lookup_noperm(&QSTR(name), parent); > - if (!IS_ERR(dentry) && d_really_is_positive(dentry)) { > - if (d_is_dir(dentry)) > - pr_err("Directory '%s' with parent '%s' already present!\n", > - name, parent->d_name.name); > - else > - pr_err("File '%s' in directory '%s' already present!\n", > - name, parent->d_name.name); Any chance we could keep a pr_err() for this case? I was doing some debugfs work recently, and found it helpful. > - dput(dentry); > - dentry =3D ERR_PTR(-EEXIST); > - } > - > - if (IS_ERR(dentry)) { > - inode_unlock(d_inode(parent)); > + dentry =3D simple_start_creating(parent, name); > + if (IS_ERR(dentry)) > simple_release_fs(&debugfs_mount, &debugfs_mount_count); > - } > =20 > return dentry; > } > diff --git a/fs/libfs.c b/fs/libfs.c > index 42e226af6095..833ad5ed10f5 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -2260,3 +2260,28 @@ void stashed_dentry_prune(struct dentry *dentry) > */ > cmpxchg(stashed, dentry, NULL); > } > + > +/* parent must be held exclusive */ > +struct dentry *simple_start_creating(struct dentry *parent, const char *= name) > +{ > + struct dentry *dentry; > + struct inode *dir =3D d_inode(parent); > + > + inode_lock(dir); > + if (unlikely(IS_DEADDIR(dir))) { > + inode_unlock(dir); > + return ERR_PTR(-ENOENT); > + } > + dentry =3D lookup_noperm(&QSTR(name), parent); > + if (IS_ERR(dentry)) { > + inode_unlock(dir); > + return dentry; > + } > + if (dentry->d_inode) { > + dput(dentry); > + inode_unlock(dir); > + return ERR_PTR(-EEXIST); > + } > + return dentry; > +} > +EXPORT_SYMBOL(simple_start_creating); > diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c > index a3fd3cc591bd..4e5d091e9263 100644 > --- a/fs/tracefs/inode.c > +++ b/fs/tracefs/inode.c > @@ -551,20 +551,9 @@ struct dentry *tracefs_start_creating(const char *na= me, struct dentry *parent) > if (!parent) > parent =3D tracefs_mount->mnt_root; > =20 > - inode_lock(d_inode(parent)); > - if (unlikely(IS_DEADDIR(d_inode(parent)))) > - dentry =3D ERR_PTR(-ENOENT); > - else > - dentry =3D lookup_noperm(&QSTR(name), parent); > - if (!IS_ERR(dentry) && d_inode(dentry)) { > - dput(dentry); > - dentry =3D ERR_PTR(-EEXIST); > - } > - > - if (IS_ERR(dentry)) { > - inode_unlock(d_inode(parent)); > + dentry =3D simple_start_creating(parent, name); > + if (IS_ERR(dentry)) > simple_release_fs(&tracefs_mount, &tracefs_mount_count); > - } > =20 > return dentry; > } > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 96c7925a6551..9f75f8836bbd 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3619,6 +3619,7 @@ extern int simple_fill_super(struct super_block *, = unsigned long, > const struct tree_descr *); > extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mo= unt, int *count); > extern void simple_release_fs(struct vfsmount **mount, int *count); > +struct dentry *simple_start_creating(struct dentry *, const char *); > =20 > extern ssize_t simple_read_from_buffer(void __user *to, size_t count, > loff_t *ppos, const void *from, size_t available); --=20 Jeff Layton