From: Krzysztof Opasiak <k.opasiak@xxxxxxxxxxx>
This change is necessary for the SCSI target usb gadget composed with
configfs. In this case configfs will be used for two different purposes:
to compose a usb gadget and to configure the target part. If an instance
of tcm function is created in $CONFIGFS_ROOT/usb_gadget/<gadget>/functions
a tpg can be created in $CONFIGFS_ROOT/target/usb_gadget/<wwn>/, but after
a tpg is created the tcm function must not be removed until its
corresponding tpg is gone. While the configfs_depend/undepend_item() are
meant exactly for creating this kind of dependencies, they are not suitable
if the other kernel subsystem happens to be another subsystem in configfs,
so this patch adds unlocked versions meant for configfs callbacks.
Signed-off-by: Krzysztof Opasiak <k.opasiak@xxxxxxxxxxx>
[updated the commit log]
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
---
fs/configfs/dir.c | 29 +++++++++++++++++++++++++++++
include/linux/configfs.h | 9 +++++++++
2 files changed, 38 insertions(+)
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index c81ce7f..1e1ae76 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1152,6 +1152,35 @@ void configfs_undepend_item(struct configfs_subsystem *subsys,
}
EXPORT_SYMBOL(configfs_undepend_item);
+int configfs_depend_item_unlocked(struct config_item *target)
+{
+ struct configfs_dirent *sd;
+ int ret = -ENOENT;
+
+ spin_lock(&configfs_dirent_lock);
+ BUG_ON(!target->ci_dentry);
+
+ sd = target->ci_dentry->d_fsdata;
+ if ((sd->s_type & CONFIGFS_DIR) &&
+ ((sd->s_type & CONFIGFS_USET_DROPPING) ||
+ (sd->s_type & CONFIGFS_USET_CREATING)))
+ goto out_unlock_dirent_lock;
+
+ sd->s_dependent_count += 1;
+ ret = 0;
+
+out_unlock_dirent_lock:
+ spin_unlock(&configfs_dirent_lock);
+ return ret;
+}
+EXPORT_SYMBOL(configfs_depend_item_unlocked);
+
+void configfs_undepend_item_unlocked(struct config_item *target)
+{
+ configfs_undepend_item(NULL, target);
+}
+EXPORT_SYMBOL(configfs_undepend_item_unlocked);
+
static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
int ret = 0;
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index a8a335b..76b045d 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -202,4 +202,13 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
+/*
+ * These functions can sleep and can alloc with GFP_KERNEL
+ * NOTE: These should be called only underneath configfs callbacks.
+ * WARNING: These cannot be called on newly created item
+ * (in make_group()/make_item callback)
+ */
+int configfs_depend_item_unlocked(struct config_item *target);
+void configfs_undepend_item_unlocked(struct config_item *target);
+
#endif /* _CONFIGFS_H_ */
--
1.9.1
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