ANDROID: Incremental fs: Add INCFS_IOC_GET_LAST_READ_ERROR

Bug: 184291759
Test: incfs_test passes
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Change-Id: If46e91f9c992337d53970573c238be965187761e

fs/incfs/data_mgmt.c

@@ -73,6 +73,7 @@ struct mount_info *incfs_alloc_mount_info(struct super_block *sb,
 	spin_lock_init(&mi->mi_per_uid_read_timeouts_lock);
 	mutex_init(&mi->mi_zstd_workspace_mutex);
 	INIT_DELAYED_WORK(&mi->mi_zstd_cleanup_work, zstd_free_workspace);
+	mutex_init(&mi->mi_le_mutex);
 
 	node = incfs_add_sysfs_node(options->sysfs_name);
 	if (IS_ERR(node)) {
@@ -1246,6 +1247,27 @@ out:
 	return 0;
 }
 
+static int incfs_update_sysfs_error(struct file *file, int index, int result,
+				struct mount_info *mi, struct data_file *df)
+{
+	int error;
+
+	if (result >= 0)
+		return 0;
+
+	error = mutex_lock_interruptible(&mi->mi_le_mutex);
+	if (error)
+		return error;
+
+	mi->mi_le_file_id = df->df_id;
+	mi->mi_le_time_us = ktime_to_us(ktime_get());
+	mi->mi_le_page = index;
+	mi->mi_le_errno = result;
+	mutex_unlock(&mi->mi_le_mutex);
+
+	return 0;
+}
+
 ssize_t incfs_read_data_file_block(struct mem_range dst, struct file *f,
 			int index, struct mem_range tmp,
 			struct incfs_read_data_file_timeouts *timeouts)
@@ -1317,6 +1339,8 @@ out:
 			mi->mi_sysfs_node->isn_reads_failed_hash_verification++;
 		else if (result < 0)
 			mi->mi_sysfs_node->isn_reads_failed_other++;
+
+		incfs_update_sysfs_error(f, index, result, mi, df);
 	}
 
 	return result;

fs/incfs/data_mgmt.h

@@ -192,6 +192,13 @@ struct mount_info {
 
 	/* sysfs node */
 	struct incfs_sysfs_node *mi_sysfs_node;
+
+	/* Last error information */
+	struct mutex	mi_le_mutex;
+	incfs_uuid_t	mi_le_file_id;
+	u64		mi_le_time_us;
+	u32		mi_le_page;
+	u32		mi_le_errno;
 };
 
 struct data_file_block {

fs/incfs/pseudo_files.c

@@ -991,6 +991,28 @@ out:
 	return error;
 }
 
+static long ioctl_get_last_read_error(struct mount_info *mi, void __user *arg)
+{
+	struct incfs_get_last_read_error_args __user *args_usr_ptr = arg;
+	struct incfs_get_last_read_error_args args = {};
+	int error;
+
+	error = mutex_lock_interruptible(&mi->mi_le_mutex);
+	if (error)
+		return error;
+
+	args.file_id_out = mi->mi_le_file_id;
+	args.time_us_out = mi->mi_le_time_us;
+	args.page_out = mi->mi_le_page;
+	args.errno_out = mi->mi_le_errno;
+
+	mutex_unlock(&mi->mi_le_mutex);
+	if (copy_to_user(args_usr_ptr, &args, sizeof(args)) > 0)
+		error = -EFAULT;
+
+	return error;
+}
+
 static long pending_reads_dispatch_ioctl(struct file *f, unsigned int req,
 					unsigned long arg)
 {
@@ -1007,6 +1029,8 @@ static long pending_reads_dispatch_ioctl(struct file *f, unsigned int req,
 		return ioctl_get_read_timeouts(mi, (void __user *)arg);
 	case INCFS_IOC_SET_READ_TIMEOUTS:
 		return ioctl_set_read_timeouts(mi, (void __user *)arg);
+	case INCFS_IOC_GET_LAST_READ_ERROR:
+		return ioctl_get_last_read_error(mi, (void __user *)arg);
 	default:
 		return -EINVAL;
 	}

include/uapi/linux/incrementalfs.h

@@ -134,6 +134,13 @@
 #define INCFS_IOC_SET_READ_TIMEOUTS \
 	_IOW(INCFS_IOCTL_BASE_CODE, 38, struct incfs_set_read_timeouts_args)
 
+/*
+ * Get last read error
+ * May only be called on .pending_reads file
+ */
+#define INCFS_IOC_GET_LAST_READ_ERROR \
+	_IOW(INCFS_IOCTL_BASE_CODE, 39, struct incfs_get_last_read_error_args)
+
 /* ===== sysfs feature flags ===== */
 /*
  * Each flag is represented by a file in /sys/fs/incremental-fs/features
@@ -556,5 +563,24 @@ struct incfs_set_read_timeouts_args {
 	__u32 timeouts_array_size;
 };
 
+/*
+ * Get last read error struct
+ * Arguments for INCFS_IOC_GET_LAST_READ_ERROR
+ */
+struct incfs_get_last_read_error_args {
+	/* File id of last file that had a read error */
+	incfs_uuid_t	file_id_out;
+
+	/* Time of last read error, in us, from CLOCK_MONOTONIC */
+	__u64	time_us_out;
+
+	/* Index of page that was being read at last read error */
+	__u32	page_out;
+
+	/* errno of last read error */
+	__u32	errno_out;
+
+	__u64	reserved;
+};
 
 #endif /* _UAPI_LINUX_INCREMENTALFS_H */

tools/testing/selftests/filesystems/incfs/incfs_test.c

@@ -4378,6 +4378,24 @@ out:
 	return result;
 }
 
+static int ioctl_test_last_error(int cmd_fd, const incfs_uuid_t *file_id,
+				 int page, int error)
+{
+	int result = TEST_FAILURE;
+	struct incfs_get_last_read_error_args glre;
+
+	TESTEQUAL(ioctl(cmd_fd, INCFS_IOC_GET_LAST_READ_ERROR, &glre), 0);
+	if (file_id)
+		TESTEQUAL(memcmp(&glre.file_id_out, file_id, sizeof(*file_id)),
+			  0);
+
+	TESTEQUAL(glre.page_out, page);
+	TESTEQUAL(glre.errno_out, error);
+	result = TEST_SUCCESS;
+out:
+	return result;
+}
+
 static int sysfs_test(const char *mount_dir)
 {
 	int result = TEST_FAILURE;
@@ -4417,8 +4435,10 @@ static int sysfs_test(const char *mount_dir)
 		  0);
 	TEST(filename = concat_file_name(mount_dir, file.name), filename);
 	TEST(fd = open(filename, O_RDONLY | O_CLOEXEC), fd != -1);
+	TESTEQUAL(ioctl_test_last_error(cmd_fd, NULL, 0, 0), 0);
 	TESTEQUAL(sysfs_test_value("reads_failed_timed_out", 0), 0);
 	TEST(read(fd, NULL, 1), -1);
+	TESTEQUAL(ioctl_test_last_error(cmd_fd, &file.id, 0, -ETIME), 0);
 	TESTEQUAL(sysfs_test_value("reads_failed_timed_out", 2), 0);
 
 	TESTEQUAL(emit_test_file_data(mount_dir, &file), 0);