2014-02-14 08:57:59

by Zefan Li

Subject: [PATCH] kernfs: fix kernfs_node_from_dentry()

Currently kernfs_node_from_dentry() returns NULL for root dentry,
because root_dentry->d_op == NULL.

Due to this bug cgroupstats_build() returns -EINVAL for root cgroup.

# mount -t cgroup -o cpuacct /cgroup
# Documentation/accounting/getdelays -C /cgroup
fatal reply error, errno -22

With this fix:

# Documentation/accounting/getdelays -C /cgroup
sleeping 305, blocked 0, running 1, stopped 0, uninterruptible 1

Signed-off-by: Li Zefan <[email protected]>
---
fs/kernfs/dir.c | 2 +-
fs/kernfs/kernfs-internal.h | 1 +
fs/kernfs/mount.c | 2 +-
3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 939684e..300f57b 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -501,7 +501,7 @@ const struct dentry_operations kernfs_dops = {
*/
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
{
- if (dentry->d_op == &kernfs_dops)
+ if (dentry->d_sb->s_op == &kernfs_sops)
return dentry->d_fsdata;
return NULL;
}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index a91d7a1..8be13b2 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -65,6 +65,7 @@ struct kernfs_super_info {
};
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))

+extern const struct super_operations kernfs_sops;
extern struct kmem_cache *kernfs_node_cache;

/*
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index e5b28b0..405279b 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -39,7 +39,7 @@ static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
return 0;
}

-static const struct super_operations kernfs_sops = {
+const struct super_operations kernfs_sops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.evict_inode = kernfs_evict_inode,
--
1.8.0.2

2014-02-14 16:03:08

by Tejun Heo

Subject: Re: [PATCH] kernfs: fix kernfs_node_from_dentry()

On Fri, Feb 14, 2014 at 04:57:27PM +0800, Li Zefan wrote:
> Currently kernfs_node_from_dentry() returns NULL for root dentry,
> because root_dentry->d_op == NULL.
>
> Due to this bug cgroupstats_build() returns -EINVAL for root cgroup.
>
> # mount -t cgroup -o cpuacct /cgroup
> # Documentation/accounting/getdelays -C /cgroup
> fatal reply error, errno -22
>
> With this fix:
>
> # Documentation/accounting/getdelays -C /cgroup
> sleeping 305, blocked 0, running 1, stopped 0, uninterruptible 1
>
> Signed-off-by: Li Zefan <[email protected]>

Acked-by: Tejun Heo <[email protected]>

Thanks!

--
tejun

2014-02-14 22:03:23

by Greg Kroah-Hartman

Subject: Re: [PATCH] kernfs: fix kernfs_node_from_dentry()

On Fri, Feb 14, 2014 at 11:03:01AM -0500, Tejun Heo wrote:
> On Fri, Feb 14, 2014 at 04:57:27PM +0800, Li Zefan wrote:
> > Currently kernfs_node_from_dentry() returns NULL for root dentry,
> > because root_dentry->d_op == NULL.
> >
> > Due to this bug cgroupstats_build() returns -EINVAL for root cgroup.
> >
> > # mount -t cgroup -o cpuacct /cgroup
> > # Documentation/accounting/getdelays -C /cgroup
> > fatal reply error, errno -22
> >
> > With this fix:
> >
> > # Documentation/accounting/getdelays -C /cgroup
> > sleeping 305, blocked 0, running 1, stopped 0, uninterruptible 1
> >
> > Signed-off-by: Li Zefan <[email protected]>
>
> Acked-by: Tejun Heo <[email protected]>

Is this needed for 3.14-final or 3.15-rc1?

thanks,

greg k-h

2014-02-14 22:04:31

by Tejun Heo

Subject: Re: [PATCH] kernfs: fix kernfs_node_from_dentry()

On Fri, Feb 14, 2014 at 02:04:40PM -0800, Greg Kroah-Hartman wrote:
> On Fri, Feb 14, 2014 at 11:03:01AM -0500, Tejun Heo wrote:
> > On Fri, Feb 14, 2014 at 04:57:27PM +0800, Li Zefan wrote:
> > > Currently kernfs_node_from_dentry() returns NULL for root dentry,
> > > because root_dentry->d_op == NULL.
> > >
> > > Due to this bug cgroupstats_build() returns -EINVAL for root cgroup.
> > >
> > > # mount -t cgroup -o cpuacct /cgroup
> > > # Documentation/accounting/getdelays -C /cgroup
> > > fatal reply error, errno -22
> > >
> > > With this fix:
> > >
> > > # Documentation/accounting/getdelays -C /cgroup
> > > sleeping 305, blocked 0, running 1, stopped 0, uninterruptible 1
> > >
> > > Signed-off-by: Li Zefan <[email protected]>
> >
> > Acked-by: Tejun Heo <[email protected]>
>
> Is this needed for 3.14-final or 3.15-rc1?

3.15-rc1, so, driver-core-next.

Thanks.

--
tejun