linux-kernel - [PATCH 4.5 163/200] f2fs: slightly reorganize read_raw_super

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Message-Id: <20160503000559.936780286@linuxfoundation.org>
Date:	Mon,  2 May 2016 17:12:42 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Shawn Lin <shawn.lin@...k-chips.com>,
	Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 4.5 163/200] f2fs: slightly reorganize read_raw_super_block

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Shawn Lin <shawn.lin@...k-chips.com>

commit 2b39e9072d79ab2525100413f3f7a0b8a3e15873 upstream.

read_raw_super_block was introduced to help find the
first valid superblock. Commit da554e48caab ("f2fs:
recovering broken superblock during mount") changed the
behaviour to read both of them and check whether need
the recovery flag or not. So the comment before this
function isn't consistent with what it actually does.
Also, the origin code use two tags to round the err
cases, which isn't so readable. So this patch amend
the comment and slightly reorganize it.

Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/f2fs/super.c |   77 +++++++++++++++++++++++++++-----------------------------
 1 file changed, 38 insertions(+), 39 deletions(-)

--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1134,14 +1134,15 @@ static void init_sb_info(struct f2fs_sb_
 
 /*
  * Read f2fs raw super block.
- * Because we have two copies of super block, so read the first one at first,
- * if the first one is invalid, move to read the second one.
+ * Because we have two copies of super block, so read both of them
+ * to get the first valid one. If any one of them is broken, we pass
+ * them recovery flag back to the caller.
  */
 static int read_raw_super_block(struct super_block *sb,
 			struct f2fs_super_block **raw_super,
 			int *valid_super_block, int *recovery)
 {
-	int block = 0;
+	int block;
 	struct buffer_head *bh;
 	struct f2fs_super_block *super, *buf;
 	int err = 0;
@@ -1149,50 +1150,48 @@ static int read_raw_super_block(struct s
 	super = kzalloc(sizeof(struct f2fs_super_block), GFP_KERNEL);
 	if (!super)
 		return -ENOMEM;
-retry:
-	bh = sb_bread(sb, block);
-	if (!bh) {
-		*recovery = 1;
-		f2fs_msg(sb, KERN_ERR, "Unable to read %dth superblock",
-				block + 1);
-		err = -EIO;
-		goto next;
-	}
 
-	buf = (struct f2fs_super_block *)(bh->b_data + F2FS_SUPER_OFFSET);
-
-	/* sanity checking of raw super */
-	if (sanity_check_raw_super(sb, buf)) {
+	for (block = 0; block < 2; block++) {
+		bh = sb_bread(sb, block);
+		if (!bh) {
+			f2fs_msg(sb, KERN_ERR, "Unable to read %dth superblock",
+				block + 1);
+			err = -EIO;
+			continue;
+		}
+
+		buf = (struct f2fs_super_block *)
+				(bh->b_data + F2FS_SUPER_OFFSET);
+
+		/* sanity checking of raw super */
+		if (sanity_check_raw_super(sb, buf)) {
+			f2fs_msg(sb, KERN_ERR,
+				"Can't find valid F2FS filesystem in %dth superblock",
+				block + 1);
+			err = -EINVAL;
+			brelse(bh);
+			continue;
+		}
+
+		if (!*raw_super) {
+			memcpy(super, buf, sizeof(*super));
+			*valid_super_block = block;
+			*raw_super = super;
+		}
 		brelse(bh);
-		*recovery = 1;
-		f2fs_msg(sb, KERN_ERR,
-			"Can't find valid F2FS filesystem in %dth superblock",
-								block + 1);
-		err = -EINVAL;
-		goto next;
-	}
-
-	if (!*raw_super) {
-		memcpy(super, buf, sizeof(*super));
-		*valid_super_block = block;
-		*raw_super = super;
 	}
-	brelse(bh);
 
-next:
-	/* check the validity of the second superblock */
-	if (block == 0) {
-		block++;
-		goto retry;
-	}
+	/* Fail to read any one of the superblocks*/
+	if (err < 0)
+		*recovery = 1;
 
 	/* No valid superblock */
-	if (!*raw_super) {
+	if (!*raw_super)
 		kfree(super);
-		return err;
-	}
+	else
+		err = 0;
 
-	return 0;
+	return err;
 }
 
 static int __f2fs_commit_super(struct f2fs_sb_info *sbi, int block)