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(cst-prg-23-145.cust.vodafone.cz. [46.135.23.145]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b7cfa29f51esm1944829766b.14.2025.12.17.03.23.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 03:23:49 -0800 (PST) From: Mateusz Guzik To: brauner@kernel.org, viro@zeniv.linux.org.uk Cc: jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, clm@meta.com, Mateusz Guzik Subject: [RFC PATCH v2] fs: touch up symlink clean up in lookup Date: Wed, 17 Dec 2025 12:23:45 +0100 Message-ID: <20251217112345.2340007-1-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Provide links_cleanup_rcu() and links_cleanup_ref() for rcu- and ref- walks respectively. The somewhat misleading drop_links() gets renamed to links_issue_delayed_ca= lls(), which spells out what it is actually doing. There are no changes in behavior, this however should be less error-prone going forward. Signed-off-by: Mateusz Guzik --- fs/namei.c | 45 ++++++++++++++++++++++++++++++++------------- 1 file changed, 32 insertions(+), 13 deletions(-) v2: - remove the mindless copy-paste in links_cleanup_ref, instead only move path_puts on the symlinks this performs path_put on nd->path later, which should not be a material difference. this assumes the LOOKUP_CACHED fixup is applied: https://lore.kernel.org/linux-fsdevel/20251217104854.GU1712166@ZenIV/T/#mff= 14d1dd88729f40fa94ada8beaa64e0c41097ff technically the 2 patches could be combined, but I did not want to do it given the bug Chris, can you feed this thing into the magic llm? Better yet, is it something I can use myself? I passed the known buggy patch to gcc -fanalyze and clang --analyze and neither managed to point out any issues. diff --git a/fs/namei.c b/fs/namei.c index 69d0aa9ad2a8..7d1722cebe99 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -766,7 +766,7 @@ static bool path_connected(struct vfsmount *mnt, struct= dentry *dentry) return is_subdir(dentry, mnt->mnt_root); } =20 -static void drop_links(struct nameidata *nd) +static void links_issue_delayed_calls(struct nameidata *nd) { int i =3D nd->depth; while (i--) { @@ -774,6 +774,29 @@ static void drop_links(struct nameidata *nd) do_delayed_call(&last->done); clear_delayed_call(&last->done); } +} + +static void links_cleanup_rcu(struct nameidata *nd) +{ + VFS_BUG_ON(!(nd->flags & LOOKUP_RCU)); + + if (likely(!nd->depth)) + return; + + links_issue_delayed_calls(nd); + nd->depth =3D 0; +} + +static void links_cleanup_ref(struct nameidata *nd) +{ + VFS_BUG_ON(nd->flags & LOOKUP_RCU); + + if (likely(!nd->depth)) + return; + + links_issue_delayed_calls(nd); + for (int i =3D 0; i < nd->depth; i++) + path_put(&nd->stack[i].link); nd->depth =3D 0; } =20 @@ -786,20 +809,16 @@ static void leave_rcu(struct nameidata *nd) =20 static void terminate_walk(struct nameidata *nd) { - int depth =3D nd->depth; - if (unlikely(depth)) - drop_links(nd); - if (!(nd->flags & LOOKUP_RCU)) { - int i; + if (nd->flags & LOOKUP_RCU) { + links_cleanup_rcu(nd); + leave_rcu(nd); + } else { + links_cleanup_ref(nd); path_put(&nd->path); - for (i =3D 0; i < depth; i++) - path_put(&nd->stack[i].link); if (nd->state & ND_ROOT_GRABBED) { path_put(&nd->root); nd->state &=3D ~ND_ROOT_GRABBED; } - } else { - leave_rcu(nd); } VFS_BUG_ON(nd->depth); nd->path.mnt =3D NULL; @@ -838,7 +857,7 @@ static bool legitimize_links(struct nameidata *nd) for (i =3D 0; i < nd->depth; i++) { struct saved *last =3D nd->stack + i; if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { - drop_links(nd); + links_issue_delayed_calls(nd); nd->depth =3D i + 1; return false; } @@ -884,7 +903,7 @@ static bool try_to_unlazy(struct nameidata *nd) BUG_ON(!(nd->flags & LOOKUP_RCU)); =20 if (unlikely(nd->flags & LOOKUP_CACHED)) { - drop_links(nd); + links_cleanup_rcu(nd); goto out1; } if (unlikely(nd->depth && !legitimize_links(nd))) @@ -923,7 +942,7 @@ static bool try_to_unlazy_next(struct nameidata *nd, st= ruct dentry *dentry) BUG_ON(!(nd->flags & LOOKUP_RCU)); =20 if (unlikely(nd->flags & LOOKUP_CACHED)) { - drop_links(nd); + links_cleanup_rcu(nd); goto out2; } if (unlikely(nd->depth && !legitimize_links(nd))) --=20 2.48.1