* [PATCH] fs/dcache: prevent repeated locking
@ 2021-12-07 10:16 cgel.zte
2021-12-07 13:17 ` Matthew Wilcox
0 siblings, 1 reply; 4+ messages in thread
From: cgel.zte @ 2021-12-07 10:16 UTC (permalink / raw)
To: viro; +Cc: linux-fsdevel, linux-kernel, Lv Ruyi, Zeal Robot
From: Lv Ruyi <lv.ruyi@zte.com.cn>
Move the spin_lock above the restart to prevent to lock twice
when the code goto restart.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn>
---
fs/dcache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index c84269c6e8bf..8580d51b397a 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1102,8 +1102,8 @@ struct dentry *d_find_alias_rcu(struct inode *inode)
void d_prune_aliases(struct inode *inode)
{
struct dentry *dentry;
-restart:
spin_lock(&inode->i_lock);
+restart:
hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
spin_lock(&dentry->d_lock);
if (!dentry->d_lockref.count) {
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] fs/dcache: prevent repeated locking
2021-12-07 10:16 [PATCH] fs/dcache: prevent repeated locking cgel.zte
@ 2021-12-07 13:17 ` Matthew Wilcox
2021-12-07 21:25 ` Eric Biggers
0 siblings, 1 reply; 4+ messages in thread
From: Matthew Wilcox @ 2021-12-07 13:17 UTC (permalink / raw)
To: cgel.zte; +Cc: viro, linux-fsdevel, linux-kernel, Lv Ruyi, Zeal Robot
On Tue, Dec 07, 2021 at 10:16:46AM +0000, cgel.zte@gmail.com wrote:
> From: Lv Ruyi <lv.ruyi@zte.com.cn>
>
> Move the spin_lock above the restart to prevent to lock twice
> when the code goto restart.
This is madness.
void d_prune_aliases(struct inode *inode)
spin_lock(&inode->i_lock);
if (likely(!dentry->d_lockref.count)) {
__dentry_kill(dentry);
goto restart;
...
static void __dentry_kill(struct dentry *dentry)
if (dentry->d_inode)
dentry_unlink_inode(dentry);
...
static void dentry_unlink_inode(struct dentry * dentry)
spin_unlock(&inode->i_lock);
Did you even test this patch?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] fs/dcache: prevent repeated locking
2021-12-07 13:17 ` Matthew Wilcox
@ 2021-12-07 21:25 ` Eric Biggers
2021-12-07 22:11 ` Matthew Wilcox
0 siblings, 1 reply; 4+ messages in thread
From: Eric Biggers @ 2021-12-07 21:25 UTC (permalink / raw)
To: Matthew Wilcox
Cc: cgel.zte, viro, linux-fsdevel, linux-kernel, Lv Ruyi, Zeal Robot
On Tue, Dec 07, 2021 at 01:17:41PM +0000, Matthew Wilcox wrote:
> On Tue, Dec 07, 2021 at 10:16:46AM +0000, cgel.zte@gmail.com wrote:
> > From: Lv Ruyi <lv.ruyi@zte.com.cn>
> >
> > Move the spin_lock above the restart to prevent to lock twice
> > when the code goto restart.
>
> This is madness.
>
> void d_prune_aliases(struct inode *inode)
> spin_lock(&inode->i_lock);
> if (likely(!dentry->d_lockref.count)) {
> __dentry_kill(dentry);
> goto restart;
> ...
> static void __dentry_kill(struct dentry *dentry)
> if (dentry->d_inode)
> dentry_unlink_inode(dentry);
> ...
> static void dentry_unlink_inode(struct dentry * dentry)
> spin_unlock(&inode->i_lock);
>
> Did you even test this patch?
This same wrong patch has been sent several times before. I think it's fair to
say that this code could use a comment, e.g.:
/* i_lock was dropped */
goto restart;
- Eric
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] fs/dcache: prevent repeated locking
2021-12-07 21:25 ` Eric Biggers
@ 2021-12-07 22:11 ` Matthew Wilcox
0 siblings, 0 replies; 4+ messages in thread
From: Matthew Wilcox @ 2021-12-07 22:11 UTC (permalink / raw)
To: Eric Biggers
Cc: cgel.zte, viro, linux-fsdevel, linux-kernel, Lv Ruyi, Zeal Robot
On Tue, Dec 07, 2021 at 01:25:18PM -0800, Eric Biggers wrote:
> On Tue, Dec 07, 2021 at 01:17:41PM +0000, Matthew Wilcox wrote:
> > On Tue, Dec 07, 2021 at 10:16:46AM +0000, cgel.zte@gmail.com wrote:
> > > From: Lv Ruyi <lv.ruyi@zte.com.cn>
> > >
> > > Move the spin_lock above the restart to prevent to lock twice
> > > when the code goto restart.
> >
> > This is madness.
> >
> > void d_prune_aliases(struct inode *inode)
> > spin_lock(&inode->i_lock);
> > if (likely(!dentry->d_lockref.count)) {
> > __dentry_kill(dentry);
> > goto restart;
> > ...
> > static void __dentry_kill(struct dentry *dentry)
> > if (dentry->d_inode)
> > dentry_unlink_inode(dentry);
> > ...
> > static void dentry_unlink_inode(struct dentry * dentry)
> > spin_unlock(&inode->i_lock);
> >
> > Did you even test this patch?
>
> This same wrong patch has been sent several times before. I think it's fair to
> say that this code could use a comment, e.g.:
>
> /* i_lock was dropped */
> goto restart;
Not sure that'll do much good. It seems to be fools running some script
that they haven't the wit to understand.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-12-07 22:11 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-12-07 10:16 [PATCH] fs/dcache: prevent repeated locking cgel.zte
2021-12-07 13:17 ` Matthew Wilcox
2021-12-07 21:25 ` Eric Biggers
2021-12-07 22:11 ` Matthew Wilcox
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