* [PATCH] fs: remove useless d_unhashed() retry in d_alloc_parallel()
@ 2025-02-13 12:21 Jinliang Zheng
2025-02-13 13:20 ` Al Viro
0 siblings, 1 reply; 3+ messages in thread
From: Jinliang Zheng @ 2025-02-13 12:21 UTC (permalink / raw)
To: viro, brauner, jack; +Cc: alexjlzheng, linux-fsdevel, linux-kernel
After commit 45f78b0a2743 ("fs/dcache: Move the wakeup from
__d_lookup_done() to the caller."), we will only wake up
d_wait_lookup() after adding dentry to dentry_hashtable.
Therefore, there is no need to keep retries about d_unhashed()
in d_alloc_parallel().
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
---
fs/dcache.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index e3634916ffb9..543833eedd8c 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2584,8 +2584,6 @@ struct dentry *d_alloc_parallel(struct dentry *parent,
goto mismatch;
if (unlikely(dentry->d_parent != parent))
goto mismatch;
- if (unlikely(d_unhashed(dentry)))
- goto mismatch;
if (unlikely(!d_same_name(dentry, parent, name)))
goto mismatch;
/* OK, it *is* a hashed match; return it */
--
2.48.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] fs: remove useless d_unhashed() retry in d_alloc_parallel()
2025-02-13 12:21 [PATCH] fs: remove useless d_unhashed() retry in d_alloc_parallel() Jinliang Zheng
@ 2025-02-13 13:20 ` Al Viro
2025-02-14 1:43 ` Jinliang Zheng
0 siblings, 1 reply; 3+ messages in thread
From: Al Viro @ 2025-02-13 13:20 UTC (permalink / raw)
To: Jinliang Zheng; +Cc: brauner, jack, alexjlzheng, linux-fsdevel, linux-kernel
On Thu, Feb 13, 2025 at 08:21:37PM +0800, Jinliang Zheng wrote:
> After commit 45f78b0a2743 ("fs/dcache: Move the wakeup from
> __d_lookup_done() to the caller."), we will only wake up
> d_wait_lookup() after adding dentry to dentry_hashtable.
Not true. d_lookup_done() might be called without having
*ever* hashed the sucker.
Just think for a moment - what, for example, should happen
if ->lookup() fails? Would you have d_alloc_parallel()
coming during that ->lookup() (while dentry is in in-lookup
hash) hang forever?
NAK.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] fs: remove useless d_unhashed() retry in d_alloc_parallel()
2025-02-13 13:20 ` Al Viro
@ 2025-02-14 1:43 ` Jinliang Zheng
0 siblings, 0 replies; 3+ messages in thread
From: Jinliang Zheng @ 2025-02-14 1:43 UTC (permalink / raw)
To: viro; +Cc: alexjlzheng, alexjlzheng, brauner, jack, linux-fsdevel,
linux-kernel
On Thu, 13 Feb 2025 13:20:06 +0000, Al Viro wrote:
> On Thu, Feb 14, 2025 at 08:21:37PM +0800, Jinliang Zheng wrote:
> > After commit 45f78b0a2743 ("fs/dcache: Move the wakeup from
> > __d_lookup_done() to the caller."), we will only wake up
> > d_wait_lookup() after adding dentry to dentry_hashtable.
>
> Not true. d_lookup_done() might be called without having
> *ever* hashed the sucker.
>
> Just think for a moment - what, for example, should happen
> if ->lookup() fails? Would you have d_alloc_parallel()
> coming during that ->lookup() (while dentry is in in-lookup
> hash) hang forever?
Haha, yes, my bad. Thanks for pointing out my mistake.
Thank you, :)
Jinliang Zheng
>
> NAK.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-02-13 12:21 [PATCH] fs: remove useless d_unhashed() retry in d_alloc_parallel() Jinliang Zheng
2025-02-13 13:20 ` Al Viro
2025-02-14 1:43 ` Jinliang Zheng
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