xfs: add xlog sysfs kobject and attribute handlers

Embed a kobject into the xfs log data structure (xlog). This creates a
'log' subdirectory for every XFS mount instance in sysfs. The lifecycle
of the log kobject is tied to the lifecycle of the log.

Also define a set of generic attribute handlers associated with the log
kobject in preparation for the addition of attributes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

4 files changed, 64 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 7647818b8c8a..149a4a575a09 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -34,6 +34,7 @@
 #include "xfs_trace.h"
 #include "xfs_fsops.h"
 #include "xfs_cksum.h"
+#include "xfs_sysfs.h"
 
 kmem_zone_t     *xfs_log_ticket_zone;
 
@@ -707,6 +708,11 @@ xfs_log_mount(
                 }
         }
 
+        error = xfs_sysfs_init(&mp->m_log->l_kobj, &xfs_log_ktype, &mp->m_kobj,
+                               "log");
+        if (error)
+                goto out_destroy_ail;
+
         /* Normal transactions can now occur */
         mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
 
@@ -947,6 +953,9 @@ xfs_log_unmount(
         xfs_log_quiesce(mp);
 
         xfs_trans_ail_destroy(mp);
+
+        xfs_sysfs_del(&mp->m_log->l_kobj);
+
         xlog_dealloc_log(mp->m_log);
 }
 
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 9bc403a9e54f..db7cbdeb2b42 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -405,6 +405,8 @@ struct xlog {
         struct xlog_grant_head  l_reserve_head;
         struct xlog_grant_head  l_write_head;
 
+        struct xfs_kobj         l_kobj;
+
         /* The following field are used for debugging; need to hold icloglock */
 #ifdef DEBUG
         char                    *l_iclog_bak[XLOG_MAX_ICLOGS];
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index ae9aa7a1a06a..88361d76f73a 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -18,6 +18,9 @@
 
 #include "xfs.h"
 #include "xfs_sysfs.h"
+#include "xfs_log_format.h"
+#include "xfs_log.h"
+#include "xfs_log_priv.h"
 
 struct xfs_sysfs_attr {
         struct attribute attr;
@@ -47,3 +50,52 @@ to_attr(struct attribute *attr)
 struct kobj_type xfs_mp_ktype = {
         .release = xfs_sysfs_release,
 };
+
+/* xlog */
+
+static struct attribute *xfs_log_attrs[] = {
+        NULL,
+};
+
+static inline struct xlog *
+to_xlog(struct kobject *kobject)
+{
+        struct xfs_kobj *kobj = to_kobj(kobject);
+        return container_of(kobj, struct xlog, l_kobj);
+}
+
+STATIC ssize_t
+xfs_log_show(
+        struct kobject          *kobject,
+        struct attribute        *attr,
+        char                    *buf)
+{
+        struct xlog *log = to_xlog(kobject);
+        struct xfs_sysfs_attr *xfs_attr = to_attr(attr);
+
+        return xfs_attr->show ? xfs_attr->show(buf, log) : 0;
+}
+
+STATIC ssize_t
+xfs_log_store(
+        struct kobject          *kobject,
+        struct attribute        *attr,
+        const char              *buf,
+        size_t                  count)
+{
+        struct xlog *log = to_xlog(kobject);
+        struct xfs_sysfs_attr *xfs_attr = to_attr(attr);
+
+        return xfs_attr->store ? xfs_attr->store(buf, count, log) : 0;
+}
+
+static struct sysfs_ops xfs_log_ops = {
+        .show = xfs_log_show,
+        .store = xfs_log_store,
+};
+
+struct kobj_type xfs_log_ktype = {
+        .release = xfs_sysfs_release,
+        .sysfs_ops = &xfs_log_ops,
+        .default_attrs = xfs_log_attrs,
+};
diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h
index 4bd5fff75d0f..54a2091183c0 100644
--- a/fs/xfs/xfs_sysfs.h
+++ b/fs/xfs/xfs_sysfs.h
@@ -20,6 +20,7 @@
 #define __XFS_SYSFS_H__
 
 extern struct kobj_type xfs_mp_ktype;   /* xfs_mount */
+extern struct kobj_type xfs_log_ktype;  /* xlog */
 
 static inline struct xfs_kobj *
 to_kobj(struct kobject *kobject)