linux-kernel - [PATCH 5/5] ubi: Allow to use read-only UBI volume with not enough PEBs

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Message-Id: <1496418222-23483-6-git-send-email-pali.rohar@gmail.com>
Date:   Fri,  2 Jun 2017 17:43:42 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Joern Engel <joern@...ybastard.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        Artem Bityutskiy <dedekind1@...il.com>
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Pali Rohár <pali.rohar@...il.com>
Subject: [PATCH 5/5] ubi: Allow to use read-only UBI volume with not enough PEBs

In read-only mode is skipped auto-resize. For pre-build images ready for
auto-resize there can be reserved more PEBs as whole size of pre-build
image. In read-only we do not do any write operation therefore this would
allow to use read-only UBI volume which is not auto-resized yet.

Signed-off-by: Pali Rohár <pali.rohar@...il.com>
---
 drivers/mtd/ubi/vtbl.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index 263743e..1d708c5 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -240,8 +240,10 @@ static int vtbl_check(const struct ubi_device *ubi,
 		if (reserved_pebs > ubi->good_peb_count) {
 			ubi_err(ubi, "too large reserved_pebs %d, good PEBs %d",
 				reserved_pebs, ubi->good_peb_count);
-			err = 9;
-			goto bad;
+			if (!ubi->ro_mode) {
+				err = 9;
+				goto bad;
+			}
 		}
 
 		if (name_len > UBI_VOL_NAME_MAX) {
@@ -652,10 +654,12 @@ static int init_volumes(struct ubi_device *ubi,
 		if (ubi->corr_peb_count)
 			ubi_err(ubi, "%d PEBs are corrupted and not used",
 				ubi->corr_peb_count);
-		return -ENOSPC;
+		if (!ubi->ro_mode)
+			return -ENOSPC;
+	} else {
+		ubi->rsvd_pebs += reserved_pebs;
+		ubi->avail_pebs -= reserved_pebs;
 	}
-	ubi->rsvd_pebs += reserved_pebs;
-	ubi->avail_pebs -= reserved_pebs;
 
 	return 0;
 }
-- 
1.7.9.5