sysfs: implement SYSFS_FLAG_REMOVED flag

Implement SYSFS_FLAG_REMOVED flag which currently is used only to
improve sanity check in sysfs_deactivate().  The flag will be used to
make directory entries reclamiable.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 5 insertions, 1 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index eb9bc0a8717b..f2ea00683ec9 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -171,7 +171,7 @@ void sysfs_deactivate(struct sysfs_dirent *sd)
         DECLARE_COMPLETION_ONSTACK(wait);
         int v;
 
-        BUG_ON(sd->s_sibling);
+        BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
         sd->s_sibling = (void *)&wait;
 
         /* atomic_add_return() is a mb(), put_active() will always see
@@ -506,6 +506,7 @@ static void remove_dir(struct dentry * d)
         mutex_lock(&parent->d_inode->i_mutex);
 
         sysfs_unlink_sibling(sd);
+        sd->s_flags |= SYSFS_FLAG_REMOVED;
 
         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
                  atomic_read(&d->d_count));
@@ -540,6 +541,7 @@ static void __sysfs_remove_dir(struct dentry *dentry)
                 struct sysfs_dirent *sd = *pos;
 
                 if (sysfs_type(sd) && (sysfs_type(sd) & SYSFS_NOT_PINNED)) {
+                        sd->s_flags |= SYSFS_FLAG_REMOVED;
                         *pos = sd->s_sibling;
                         sd->s_sibling = removed;
                         removed = sd;
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index ee3a5d957051..e2f6ef138d20 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -296,6 +296,7 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
                 if (!sysfs_type(sd))
                         continue;
                 if (!strcmp(sd->s_name, name)) {
+                        sd->s_flags |= SYSFS_FLAG_REMOVED;
                         *pos = sd->s_sibling;
                         sd->s_sibling = NULL;
                         found = 1;
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 58135509023e..2a6df6444e69 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -84,6 +84,7 @@ struct sysfs_ops {
 #define SYSFS_COPY_NAME         (SYSFS_DIR | SYSFS_KOBJ_LINK)
 
 #define SYSFS_FLAG_MASK         ~SYSFS_TYPE_MASK
+#define SYSFS_FLAG_REMOVED      0x0100
 
 #ifdef CONFIG_SYSFS