ext4: add a new ioctl EXT4_IOC_GETSTATE

The new ioctl EXT4_IOC_GETSTATE returns some of the dynamic state of
an ext4 inode for debugging purposes.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

2 files changed, 28 insertions, 0 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index b22f24f1d365..ee296797bcd2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -651,6 +651,7 @@ enum {
 #define EXT4_IOC_GET_ENCRYPTION_POLICY  FS_IOC_GET_ENCRYPTION_POLICY
 /* ioctl codes 19--39 are reserved for fscrypt */
 #define EXT4_IOC_CLEAR_ES_CACHE         _IO('f', 40)
+#define EXT4_IOC_GETSTATE               _IOW('f', 41, __u32)
 
 #define EXT4_IOC_FSGETXATTR             FS_IOC_FSGETXATTR
 #define EXT4_IOC_FSSETXATTR             FS_IOC_FSSETXATTR
@@ -664,6 +665,16 @@ enum {
 #define EXT4_GOING_FLAGS_LOGFLUSH               0x1     /* flush log but not data */
 #define EXT4_GOING_FLAGS_NOLOGFLUSH             0x2     /* don't flush log nor data */
 
+/*
+ * Flags returned by EXT4_IOC_GETSTATE
+ *
+ * We only expose to userspace a subset of the state flags in
+ * i_state_flags
+ */
+#define EXT4_STATE_FLAG_EXT_PRECACHED   0x00000001
+#define EXT4_STATE_FLAG_NEW             0x00000002
+#define EXT4_STATE_FLAG_NEWENTRY        0x00000004
+#define EXT4_STATE_FLAG_DA_ALLOC_CLOSE  0x00000008
 
 #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
 /*
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 15b1047878ab..ffb7bde4900d 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -1123,6 +1123,22 @@ resizefs_out:
                 return 0;
         }
 
+        case EXT4_IOC_GETSTATE:
+        {
+                __u32   state = 0;
+
+                if (ext4_test_inode_state(inode, EXT4_STATE_EXT_PRECACHED))
+                        state |= EXT4_STATE_FLAG_EXT_PRECACHED;
+                if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
+                        state |= EXT4_STATE_FLAG_NEW;
+                if (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
+                        state |= EXT4_STATE_FLAG_NEWENTRY;
+                if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE))
+                        state |= EXT4_STATE_FLAG_DA_ALLOC_CLOSE;
+
+                return put_user(state, (__u32 __user *) arg);
+        }
+
         case EXT4_IOC_FSGETXATTR:
         {
                 struct fsxattr fa;
@@ -1242,6 +1258,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         case EXT4_IOC_SHUTDOWN:
         case FS_IOC_GETFSMAP:
         case EXT4_IOC_CLEAR_ES_CACHE:
+        case EXT4_IOC_GETSTATE:
                 break;
         default:
                 return -ENOIOCTLCMD;