[PATCH] ext4: export information about first/last errors via /sys/fs/ext4/<dev>

["Theodore Ts'o" <tytso@xxxxxxx>]

Make {first,last}_error_{ino,block,line,func,errcode} available via
sysfs.

Also add a missing newline for {first,last}_error_time.

Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
---
 fs/ext4/sysfs.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index a990d28d191b..d218ebdafa4a 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -30,6 +30,9 @@ typedef enum {
 	attr_feature,
 	attr_pointer_ui,
 	attr_pointer_ul,
+	attr_pointer_u64,
+	attr_pointer_u8,
+	attr_pointer_string,
 	attr_pointer_atomic,
 	attr_journal_task,
 } attr_id_t;
@@ -47,6 +50,7 @@ struct ext4_attr {
 	struct attribute attr;
 	short attr_id;
 	short attr_ptr;
+	unsigned short attr_size;
 	union {
 		int offset;
 		void *explicit_ptr;
@@ -155,9 +159,29 @@ static struct ext4_attr ext4_attr_##_name = {			\
 	},							\
 }
 
+#define EXT4_ATTR_STRING(_name,_mode,_size,_struct,_elname)	\
+static struct ext4_attr ext4_attr_##_name = {			\
+	.attr = {.name = __stringify(_name), .mode = _mode },	\
+	.attr_id = attr_pointer_string,				\
+	.attr_size = _size,					\
+	.attr_ptr = ptr_##_struct##_offset,			\
+	.u = {							\
+		.offset = offsetof(struct _struct, _elname),\
+	},							\
+}
+
 #define EXT4_RO_ATTR_ES_UI(_name,_elname)				\
 	EXT4_ATTR_OFFSET(_name, 0444, pointer_ui, ext4_super_block, _elname)
 
+#define EXT4_RO_ATTR_ES_U8(_name,_elname)				\
+	EXT4_ATTR_OFFSET(_name, 0444, pointer_u8, ext4_super_block, _elname)
+
+#define EXT4_RO_ATTR_ES_U64(_name,_elname)				\
+	EXT4_ATTR_OFFSET(_name, 0444, pointer_u64, ext4_super_block, _elname)
+
+#define EXT4_RO_ATTR_ES_STRING(_name,_elname,_size)			\
+	EXT4_ATTR_STRING(_name, 0444, _size, ext4_super_block, _elname)
+
 #define EXT4_RW_ATTR_SBI_UI(_name,_elname)	\
 	EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)
 
@@ -202,6 +226,16 @@ EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
 EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail);
 #endif
 EXT4_RO_ATTR_ES_UI(errors_count, s_error_count);
+EXT4_RO_ATTR_ES_U8(first_error_errcode, s_first_error_errcode);
+EXT4_RO_ATTR_ES_U8(last_error_errcode, s_last_error_errcode);
+EXT4_RO_ATTR_ES_UI(first_error_ino, s_first_error_ino);
+EXT4_RO_ATTR_ES_UI(last_error_ino, s_last_error_ino);
+EXT4_RO_ATTR_ES_U64(first_error_block, s_first_error_block);
+EXT4_RO_ATTR_ES_U64(last_error_block, s_last_error_block);
+EXT4_RO_ATTR_ES_UI(first_error_line, s_first_error_line);
+EXT4_RO_ATTR_ES_UI(last_error_line, s_last_error_line);
+EXT4_RO_ATTR_ES_STRING(first_error_func, s_first_error_func, 32);
+EXT4_RO_ATTR_ES_STRING(last_error_func, s_last_error_func, 32);
 EXT4_ATTR(first_error_time, 0444, first_error_time);
 EXT4_ATTR(last_error_time, 0444, last_error_time);
 EXT4_ATTR(journal_task, 0444, journal_task);
@@ -232,6 +266,16 @@ static struct attribute *ext4_attrs[] = {
 	ATTR_LIST(msg_ratelimit_interval_ms),
 	ATTR_LIST(msg_ratelimit_burst),
 	ATTR_LIST(errors_count),
+	ATTR_LIST(first_error_ino),
+	ATTR_LIST(last_error_ino),
+	ATTR_LIST(first_error_block),
+	ATTR_LIST(last_error_block),
+	ATTR_LIST(first_error_line),
+	ATTR_LIST(last_error_line),
+	ATTR_LIST(first_error_func),
+	ATTR_LIST(last_error_func),
+	ATTR_LIST(first_error_errcode),
+	ATTR_LIST(last_error_errcode),
 	ATTR_LIST(first_error_time),
 	ATTR_LIST(last_error_time),
 	ATTR_LIST(journal_task),
@@ -290,7 +334,7 @@ static void *calc_ptr(struct ext4_attr *a, struct ext4_sb_info *sbi)
 
 static ssize_t __print_tstamp(char *buf, __le32 lo, __u8 hi)
 {
-	return snprintf(buf, PAGE_SIZE, "%lld",
+	return snprintf(buf, PAGE_SIZE, "%lld\n",
 			((time64_t)hi << 32) + le32_to_cpu(lo));
 }
 
@@ -333,6 +377,25 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
 			return 0;
 		return snprintf(buf, PAGE_SIZE, "%lu\n",
 				*((unsigned long *) ptr));
+	case attr_pointer_u8:
+		if (!ptr)
+			return 0;
+		return snprintf(buf, PAGE_SIZE, "%u\n",
+				*((unsigned char *) ptr));
+	case attr_pointer_u64:
+		if (!ptr)
+			return 0;
+		if (a->attr_ptr == ptr_ext4_super_block_offset)
+			return snprintf(buf, PAGE_SIZE, "%llu\n",
+					le64_to_cpup(ptr));
+		else
+			return snprintf(buf, PAGE_SIZE, "%llu\n",
+					*((unsigned long long *) ptr));
+	case attr_pointer_string:
+		if (!ptr)
+			return 0;
+		return snprintf(buf, PAGE_SIZE, "%.*s\n", a->attr_size,
+				(char *) ptr);
 	case attr_pointer_atomic:
 		if (!ptr)
 			return 0;
-- 
2.24.1