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 <lizefan@xxxxxxxxxx>
---
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
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