UBI: use debugfs for the extra checks knobs

This patch introduces debugfs support to UBI. All the UBI stuff is kept in the
"ubi" debugfs directory, which contains per-UBI device "ubi/ubiX"
sub-directories, containing debugging files. This file also creates
"ubi/ubiX/chk_gen" and "ubi/ubiX/chk_io" knobs for switching general and I/O
extra checks on and off. And it removes the 'debug_chks' UBI module parameters.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 8c1b1c7..e23d611 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -1146,7 +1146,7 @@
 {
 	int err;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	err = ubi_io_is_bad(ubi, pnum);
@@ -1173,7 +1173,7 @@
 	int err;
 	uint32_t magic;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	magic = be32_to_cpu(ec_hdr->magic);
@@ -1211,7 +1211,7 @@
 	uint32_t crc, hdr_crc;
 	struct ubi_ec_hdr *ec_hdr;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
@@ -1255,7 +1255,7 @@
 	int err;
 	uint32_t magic;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	magic = be32_to_cpu(vid_hdr->magic);
@@ -1296,7 +1296,7 @@
 	struct ubi_vid_hdr *vid_hdr;
 	void *p;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
@@ -1348,7 +1348,7 @@
 	void *buf1;
 	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	buf1 = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);
@@ -1412,7 +1412,7 @@
 	void *buf;
 	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	buf = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);