ext4: add debugging trigger for ext4_error()
Make it easy to test whether or not the error handling subsystem in
ext4 is working correctly. This allows us to simulate an ext4_error()
by echoing a string to /sys/fs/ext4/<dev>/trigger_fs_error.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: ksumrall@google.com
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 628cfcd..9f1ae6b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2473,6 +2473,23 @@
return count;
}
+static ssize_t trigger_test_error(struct ext4_attr *a,
+ struct ext4_sb_info *sbi,
+ const char *buf, size_t count)
+{
+ int len = count;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (len && buf[len-1] == '\n')
+ len--;
+
+ if (len)
+ ext4_error(sbi->s_sb, "%.*s", len, buf);
+ return count;
+}
+
#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname) \
static struct ext4_attr ext4_attr_##_name = { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
@@ -2503,6 +2520,7 @@
EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
EXT4_RW_ATTR_SBI_UI(max_writeback_mb_bump, s_max_writeback_mb_bump);
+EXT4_ATTR(trigger_fs_error, 0200, NULL, trigger_test_error);
static struct attribute *ext4_attrs[] = {
ATTR_LIST(delayed_allocation_blocks),
@@ -2517,6 +2535,7 @@
ATTR_LIST(mb_stream_req),
ATTR_LIST(mb_group_prealloc),
ATTR_LIST(max_writeback_mb_bump),
+ ATTR_LIST(trigger_fs_error),
NULL,
};
@@ -3087,6 +3106,7 @@
goto out_free_orig;
}
sb->s_fs_info = sbi;
+ sbi->s_sb = sb;
sbi->s_mount_opt = 0;
sbi->s_resuid = EXT4_DEF_RESUID;
sbi->s_resgid = EXT4_DEF_RESGID;