* [PATCH] walk_component(): get inode in lookup_slow branch statement block
@ 2022-06-22 8:51 sunliming
2022-06-22 10:34 ` Al Viro
0 siblings, 1 reply; 7+ messages in thread
From: sunliming @ 2022-06-22 8:51 UTC (permalink / raw)
To: viro; +Cc: linux-fsdevel, linux-kernel, sunliming, kelulanainsley, sunliming
The inode variable is used as a parameter by the step_into function,
but is not assigned a value in the sub-lookup_slow branch path. So
get the inode in the sub-lookup_slow branch path.
Signed-off-by: sunliming <sunliming@kylinos.cn>
---
fs/namei.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/namei.c b/fs/namei.c
index 1f28d3f463c3..a1a3e9514f46 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2014,6 +2014,8 @@ static const char *walk_component(struct nameidata *nd, int flags)
dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags);
if (IS_ERR(dentry))
return ERR_CAST(dentry);
+
+ inode = d_backing_inode(dentry);
}
if (!(flags & WALK_MORE) && nd->depth)
put_link(nd);
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] walk_component(): get inode in lookup_slow branch statement block
2022-06-22 8:51 [PATCH] walk_component(): get inode in lookup_slow branch statement block sunliming
@ 2022-06-22 10:34 ` Al Viro
2022-06-23 3:26 ` sunliming
2022-06-23 3:44 ` sunliming
0 siblings, 2 replies; 7+ messages in thread
From: Al Viro @ 2022-06-22 10:34 UTC (permalink / raw)
To: sunliming; +Cc: linux-fsdevel, linux-kernel, sunliming, kelulanainsley
On Wed, Jun 22, 2022 at 04:51:46PM +0800, sunliming wrote:
> The inode variable is used as a parameter by the step_into function,
> but is not assigned a value in the sub-lookup_slow branch path. So
> get the inode in the sub-lookup_slow branch path.
Take a good look at handle_mounts() and the things it does when
*not* in RCU mode (i.e. LOOKUP_RCU is not set). Specifically,
*inode = d_backing_inode(path->dentry);
*seqp = 0; /* out of RCU mode, so the value doesn't matter */
this part.
IOW, the values passed to step_into() in inode/seq are overridden unless
we stay in RCU mode. And if we'd been through lookup_slow(), we'd been
out of RCU mode since before we called step_into().
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] walk_component(): get inode in lookup_slow branch statement block
2022-06-22 10:34 ` Al Viro
@ 2022-06-23 3:26 ` sunliming
2022-06-23 3:44 ` sunliming
1 sibling, 0 replies; 7+ messages in thread
From: sunliming @ 2022-06-23 3:26 UTC (permalink / raw)
To: Al Viro; +Cc: linux-fsdevel, linux-kernel, sunliming
Al Viro <viro@zeniv.linux.org.uk> 于2022年6月22日周三 18:35写道：
>
> On Wed, Jun 22, 2022 at 04:51:46PM +0800, sunliming wrote:
> > The inode variable is used as a parameter by the step_into function,
> > but is not assigned a value in the sub-lookup_slow branch path. So
> > get the inode in the sub-lookup_slow branch path.
>
> Take a good look at handle_mounts() and the things it does when
> *not* in RCU mode (i.e. LOOKUP_RCU is not set). Specifically,
> *inode = d_backing_inode(path->dentry);
> *seqp = 0; /* out of RCU mode, so the value doesn't matter */
> this part.
>
> IOW, the values passed to step_into() in inode/seq are overridden unless
> we stay in RCU mode. And if we'd been through lookup_slow(), we'd been
> out of RCU mode since before we called step_into().
OK，I got it.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] walk_component(): get inode in lookup_slow branch statement block
2022-06-22 10:34 ` Al Viro
2022-06-23 3:26 ` sunliming
@ 2022-06-23 3:44 ` sunliming
2022-06-23 3:48 ` Al Viro
1 sibling, 1 reply; 7+ messages in thread
From: sunliming @ 2022-06-23 3:44 UTC (permalink / raw)
To: Al Viro; +Cc: linux-fsdevel, linux-kernel, sunliming
Al Viro <viro@zeniv.linux.org.uk> 于2022年6月22日周三 18:35写道：
>
> On Wed, Jun 22, 2022 at 04:51:46PM +0800, sunliming wrote:
> > The inode variable is used as a parameter by the step_into function,
> > but is not assigned a value in the sub-lookup_slow branch path. So
> > get the inode in the sub-lookup_slow branch path.
>
> Take a good look at handle_mounts() and the things it does when
> *not* in RCU mode (i.e. LOOKUP_RCU is not set). Specifically,
> *inode = d_backing_inode(path->dentry);
> *seqp = 0; /* out of RCU mode, so the value doesn't matter */
> this part.
>
> IOW, the values passed to step_into() in inode/seq are overridden unless
> we stay in RCU mode. And if we'd been through lookup_slow(), we'd been
> out of RCU mode since before we called step_into().
It might be more appropriate and easier to understand to do this
before parameter passing in the top-level walk_component function？
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] walk_component(): get inode in lookup_slow branch statement block
2022-06-23 3:44 ` sunliming
@ 2022-06-23 3:48 ` Al Viro
2022-06-23 9:57 ` sunliming
0 siblings, 1 reply; 7+ messages in thread
From: Al Viro @ 2022-06-23 3:48 UTC (permalink / raw)
To: sunliming; +Cc: linux-fsdevel, linux-kernel, sunliming
On Thu, Jun 23, 2022 at 11:44:29AM +0800, sunliming wrote:
> Al Viro <viro@zeniv.linux.org.uk> 于2022年6月22日周三 18:35写道：
> >
> > On Wed, Jun 22, 2022 at 04:51:46PM +0800, sunliming wrote:
> > > The inode variable is used as a parameter by the step_into function,
> > > but is not assigned a value in the sub-lookup_slow branch path. So
> > > get the inode in the sub-lookup_slow branch path.
> >
> > Take a good look at handle_mounts() and the things it does when
> > *not* in RCU mode (i.e. LOOKUP_RCU is not set). Specifically,
> > *inode = d_backing_inode(path->dentry);
> > *seqp = 0; /* out of RCU mode, so the value doesn't matter */
> > this part.
> >
> > IOW, the values passed to step_into() in inode/seq are overridden unless
> > we stay in RCU mode. And if we'd been through lookup_slow(), we'd been
> > out of RCU mode since before we called step_into().
>
> It might be more appropriate and easier to understand to do this
> before parameter passing in the top-level walk_component function？
It's possible to fall out of RCU mode *inside* step_into(), so we need
it done there anyway. Unfortunately ;-/
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] walk_component(): get inode in lookup_slow branch statement block
2022-06-23 3:48 ` Al Viro
@ 2022-06-23 9:57 ` sunliming
0 siblings, 0 replies; 7+ messages in thread
From: sunliming @ 2022-06-23 9:57 UTC (permalink / raw)
To: Al Viro; +Cc: linux-fsdevel, linux-kernel, sunliming
Al Viro <viro@zeniv.linux.org.uk> 于2022年6月23日周四 11:48写道：
>
> On Thu, Jun 23, 2022 at 11:44:29AM +0800, sunliming wrote:
> > Al Viro <viro@zeniv.linux.org.uk> 于2022年6月22日周三 18:35写道：
> > >
> > > On Wed, Jun 22, 2022 at 04:51:46PM +0800, sunliming wrote:
> > > > The inode variable is used as a parameter by the step_into function,
> > > > but is not assigned a value in the sub-lookup_slow branch path. So
> > > > get the inode in the sub-lookup_slow branch path.
> > >
> > > Take a good look at handle_mounts() and the things it does when
> > > *not* in RCU mode (i.e. LOOKUP_RCU is not set). Specifically,
> > > *inode = d_backing_inode(path->dentry);
> > > *seqp = 0; /* out of RCU mode, so the value doesn't matter */
> > > this part.
> > >
> > > IOW, the values passed to step_into() in inode/seq are overridden unless
> > > we stay in RCU mode. And if we'd been through lookup_slow(), we'd been
> > > out of RCU mode since before we called step_into().
> >
> > It might be more appropriate and easier to understand to do this
> > before parameter passing in the top-level walk_component function？
>
> It's possible to fall out of RCU mode *inside* step_into(), so we need
> it done there anyway. Unfortunately ;-/
Thanks for your explanation
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH] walk_component(): get inode in lookup_slow branch statement block
@ 2022-06-22 8:53 sunliming
0 siblings, 0 replies; 7+ messages in thread
From: sunliming @ 2022-06-22 8:53 UTC (permalink / raw)
To: viro; +Cc: linux-fsdevel, linux-kernel, sunliming, kelulanainsley
The inode variable is used as a parameter by the step_into function,
but is not assigned a value in the sub-lookup_slow branch path. So
get the inode in the sub-lookup_slow branch path.
Signed-off-by: sunliming <sunliming@kylinos.cn>
---
fs/namei.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/namei.c b/fs/namei.c
index 1f28d3f463c3..a1a3e9514f46 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2014,6 +2014,8 @@ static const char *walk_component(struct nameidata *nd, int flags)
dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags);
if (IS_ERR(dentry))
return ERR_CAST(dentry);
+
+ inode = d_backing_inode(dentry);
}
if (!(flags & WALK_MORE) && nd->depth)
put_link(nd);
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-06-23 9:58 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2022-06-22 8:51 [PATCH] walk_component(): get inode in lookup_slow branch statement block sunliming
2022-06-22 10:34 ` Al Viro
2022-06-23 3:26 ` sunliming
2022-06-23 3:44 ` sunliming
2022-06-23 3:48 ` Al Viro
2022-06-23 9:57 ` sunliming
2022-06-22 8:53 sunliming
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