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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f26f450sm35657715f8f.10.2026.06.15.02.37.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Jun 2026 02:37:09 -0700 (PDT) Date: Mon, 15 Jun 2026 10:37:07 +0100 From: David Laight To: Jori Koolstra Cc: Christian Brauner , Jan Kara , Al Viro , NeilBrown , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 02/12] fs/namei.c: move create error && negative dentry case in lookup_open up Message-ID: <20260615103707.1a55bab6@pumpkin> In-Reply-To: <20260614164438.2980769-3-jkoolstra@xs4all.nl> References: <20260614164438.2980769-1-jkoolstra@xs4all.nl> <20260614164438.2980769-3-jkoolstra@xs4all.nl> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 14 Jun 2026 18:44:28 +0200 Jori Koolstra wrote: > O_CREAT is stripped when create_error is set in lookup_open(), so when > lookup does not return an inode, the case > > if (!dentry->d_inode && (open_flag & O_CREAT)) > > is always skipped. We can get rid of this cognitive step by handling the > error case first. You've just added an extra test into a normal/fast path. OTOH the test isn't ideal the compiler needs to reverse the order of the arguments to the && in spite of the unlikely(). Perhaps: if (dentry->d_inode) return dentry; if (open_flag & O_CREAT) { ... } else { if (unlikely(create_error)) { error = create_error(); goto out_dput; } } return dentry; -- David > > Signed-off-by: Jori Koolstra > --- > fs/namei.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index 64b91ed9efb7..f169d1123b17 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4499,6 +4499,11 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file, > } > } > > + if (unlikely(create_error) && !dentry->d_inode) { > + error = create_error; > + goto out_dput; > + } > + > /* Negative dentry, just create the file */ > if (!dentry->d_inode && (open_flag & O_CREAT)) { > /* but break the directory lease first! */ > @@ -4518,10 +4523,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file, > if (error) > goto out_dput; > } > - if (unlikely(create_error) && !dentry->d_inode) { > - error = create_error; > - goto out_dput; > - } > + > return dentry; > > out_dput: