RE: [PATCH 13/14] d_path: prepend_path() is unlikely to return non-zero
From: Justin He <hidden>
Date: 2021-06-25 08:01:22
Also in:
linux-fsdevel, linux-s390, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Hi Al
quoted hunk ↗ jump to hunk
-----Original Message----- From: Al Viro <redacted> On Behalf Of Al Viro Sent: Wednesday, May 19, 2021 8:49 AM To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Justin He <redacted>; Petr Mladek <pmladek@suse.com>; Steven Rostedt [off-list ref]; Sergey Senozhatsky [off-list ref]; Andy Shevchenko [off-list ref]; Rasmus Villemoes [off-list ref]; Jonathan Corbet [off-list ref]; Heiko Carstens [off-list ref]; Vasily Gorbik [off-list ref]; Christian Borntraeger [off-list ref]; Eric W . Biederman [off-list ref]; Darrick J. Wong [off-list ref]; Peter Zijlstra (Intel) [off-list ref]; Ira Weiny [off-list ref]; Eric Biggers [off-list ref]; Ahmed S. Darwish [off-list ref]; open list:DOCUMENTATION <linux- doc@vger.kernel.org>; Linux Kernel Mailing List <linux- kernel@vger.kernel.org>; linux-s390 [off-list ref]; linux- fsdevel [off-list ref] Subject: [PATCH 13/14] d_path: prepend_path() is unlikely to return non- zero Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- fs/d_path.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)diff --git a/fs/d_path.c b/fs/d_path.c index ba629879a4bf..8a9cd44f6689 100644 --- a/fs/d_path.c +++ b/fs/d_path.c@@ -187,7 +187,7 @@ char *__d_path(const struct path *path, DECLARE_BUFFER(b, buf, buflen); prepend(&b, "", 1); - if (prepend_path(path, root, &b) > 0) + if (unlikely(prepend_path(path, root, &b) > 0)) return NULL; return extract_string(&b); }@@ -199,7 +199,7 @@ char *d_absolute_path(const struct path *path, DECLARE_BUFFER(b, buf, buflen); prepend(&b, "", 1); - if (prepend_path(path, &root, &b) > 1) + if (unlikely(prepend_path(path, &root, &b) > 1)) return ERR_PTR(-EINVAL); return extract_string(&b); }@@ -396,7 +396,7 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsignedlong, size) DECLARE_BUFFER(b, page, PATH_MAX); prepend(&b, "", 1); - if (prepend_path(&pwd, &root, &b) > 0) + if (unlikely(prepend_path(&pwd, &root, &b) > 0)) prepend(&b, "(unreachable)", 13); rcu_read_unlock(); -- 2.11.0
I tested it with a debugging patch as follows:
diff --git a/fs/d_path.c b/fs/d_path.c
index aea254ac9e1f..8eecd04be7bb 100644
--- a/fs/d_path.c
+++ b/fs/d_path.c@@ -210,6 +210,7 @@ static int prepend_path(const struct path *path, b = *p; read_seqbegin_or_lock(&rename_lock, &seq); error = __prepend_path(path->dentry, real_mount(path->mnt), root, &b); + printk("prepend=%d",error); if (!(seq & 1)) rcu_read_unlock(); if (need_seqretry(&rename_lock, seq)) {
Then the result seems a little different: root@entos-ampere-02:~# dmesg |grep prepend=1 |wc -l 7417 root@entos-ampere-02:~# dmesg |grep prepend=0 |wc -l 772 The kernel is 5.13.0-rc2+ + this series + my '%pD' series Any thoughts? --- Cheers, Jia He (Justin) IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.