linux-kernel - Re: [PATCH 1/7] [RFC] UBI: Export next

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Message-ID: <1337173272.24809.52.camel@sauron.fi.intel.com>
Date:	Wed, 16 May 2012 16:01:12 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Richard Weinberger <richard@....at>
Cc:	linux-mtd@...ts.infradead.org, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, Heinz.Egger@...utronix.de,
	tim.bird@...sony.com
Subject: Re: [PATCH 1/7] [RFC] UBI: Export next_sqnum()

On Tue, 2012-05-15 at 19:11 +0200, Richard Weinberger wrote:
> The fastmap mechanism needs to read the next sequence nummber
> directly.
> 
> Signed-off-by: Richard Weinberger <richard@....at>

I started looking at the code, and made some notes at the same time and
few minor changes - here is the diff which you can apply on top of your
patches.

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 2399511..2f5c362 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -869,15 +869,22 @@ static int attach_by_fastmap(struct ubi_device *ubi)
 
 	fm_start = ubi_find_fastmap(ubi);
 	if (fm_start < 0)
+		/* TODO: instead, return 1 which means that fall-back to
+		 * scanning is needed */
 		return -ENOENT;
 
+	/* TODO: we need to re-name scan.h to attach.h, scan_info to
+	 * attach_info, si to ai, seb to aeb, and so on - because we share the
+	 * same data structures between scanning and fastmap, so the word
+	 * "scan" is not very sensible to have in the name any more.
+	 */
 	si = ubi_read_fastmap(ubi, fm_start);
 	if (IS_ERR(si))
 		return PTR_ERR(si);
 
-	ubi->bad_peb_count = 0;
+	/* TODO: the rest looks very much like attach_by_scanning() - we
+	 * need to re-structure the code and avoid duplication */
 	ubi->good_peb_count = ubi->peb_count;
-	ubi->corr_peb_count = 0;
 	ubi->max_ec = si->max_ec;
 	ubi->mean_ec = si->mean_ec;
 	ubi_msg("max. sequence number:       %llu", si->max_sqnum);
@@ -888,6 +895,7 @@ static int attach_by_fastmap(struct ubi_device *ubi)
 		goto out_si;
 	}
 
+	/* TODO: the _scan suffix makes no sens anymore - kill it */
 	err = ubi_wl_init_scan(ubi, si);
 	if (err) {
 		ubi_err("ubi_wl_init_scan failed!");
@@ -1022,7 +1030,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	err = attach_by_fastmap(ubi);
 	if (err) {
 		if (err != -ENOENT)
-			ubi_msg("falling back to attach by scanning mode!");
+			ubi_msg("falling back to attach by scanning");
 
 		ubi->attached_by_scanning = true;
 		err = attach_by_scanning(ubi);
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 2ea1682..7c5f1f7 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -582,7 +582,12 @@ struct ubi_scan_info *ubi_read_fastmap(struct ubi_device *ubi,
 		goto out;
 	}
 
+	/* TODO: Before checking version - check the CRC.
+	 * I think you need to add a separate helper function in io.c, similar
+	 * to ubi_io_read_vid_hdr(). */
 	if (fmsb->version != UBI_FM_FMT_VERSION) {
+		/* TODO: we can fall back to scanning instead of saying good
+		 * bye! */
 		ubi_err("Unknown fastmap format version!");
 		si = ERR_PTR(-EINVAL);
 		kfree(fmsb);
@@ -606,6 +611,7 @@ struct ubi_scan_info *ubi_read_fastmap(struct ubi_device *ubi,
 	if (!fm_raw) {
 		si = ERR_PTR(-ENOMEM);
 		kfree(fmsb);
+		/* TODO: goto? */
 	}
 
 	vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
@@ -617,6 +623,9 @@ struct ubi_scan_info *ubi_read_fastmap(struct ubi_device *ubi,
 	}
 
 	for (i = 0; i < nblocks; i++) {
+		/* TODO: you basically perform the scanning here - you should
+		 * share the same code as we use in scan.c: use process_peb().
+		 */
 		ret = ubi_io_read_vid_hdr(ubi, be32_to_cpu(fmsb->block_loc[i]),
 			vh, 0);
 		if (ret) {
@@ -653,6 +662,7 @@ struct ubi_scan_info *ubi_read_fastmap(struct ubi_device *ubi,
 				i, be32_to_cpu(fmsb->block_loc[i]));
 			si = ERR_PTR(ret);
 
+			/* TODO: fsmb is not freed? */
 			goto free_vhdr;
 		}
 	}


-- 
Best Regards,
Artem Bityutskiy

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