linux-kernel - [PATCH v1 1/2] romfs: use s_blocksize(_bits) if CONFIG

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Date:   Mon, 22 Jun 2020 20:45:19 -0400
From:   Sven Van Asbroeck <thesven73@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        David Howells <dhowells@...hat.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Janos Farkas <chexum+dev@...il.com>,
        Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v1 1/2] romfs: use s_blocksize(_bits) if CONFIG_BLOCK

The super_block fields s_blocksize and s_blocksize_bits always
reflect the actual configured blocksize for a filesystem.

Use these in all calculations where blocksize is required.
This allows us to easily change the blocksize in a later patch.

Note that I cannot determine what happens if !CONFIG_BLOCK, as
I have no access to such a system. Out of an abundance of caution,
I have left all !CONFIG_BLOCK codepaths in their original state.

Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Deepa Dinamani <deepa.kernel@...il.com>
Cc: David Howells <dhowells@...hat.com>
Cc: "Darrick J. Wong" <darrick.wong@...cle.com>
Cc: Janos Farkas <chexum+dev@...il.com>
Cc: Jeff Layton <jlayton@...nel.org>
To: linux-kernel@...r.kernel.org
Signed-off-by: Sven Van Asbroeck <TheSven73@...il.com>
---
 fs/romfs/storage.c | 25 +++++++++++++------------
 fs/romfs/super.c   |  9 ++++++++-
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/fs/romfs/storage.c b/fs/romfs/storage.c
index 6b2b4362089e..5e84efadac3f 100644
--- a/fs/romfs/storage.c
+++ b/fs/romfs/storage.c
@@ -109,9 +109,9 @@ static int romfs_blk_read(struct super_block *sb, unsigned long pos,
 
 	/* copy the string up to blocksize bytes at a time */
 	while (buflen > 0) {
-		offset = pos & (ROMBSIZE - 1);
-		segment = min_t(size_t, buflen, ROMBSIZE - offset);
-		bh = sb_bread(sb, pos >> ROMBSBITS);
+		offset = pos & (sb->s_blocksize - 1);
+		segment = min_t(size_t, buflen, sb->s_blocksize - offset);
+		bh = sb_bread(sb, pos >> sb->s_blocksize_bits);
 		if (!bh)
 			return -EIO;
 		memcpy(buf, bh->b_data + offset, segment);
@@ -138,9 +138,9 @@ static ssize_t romfs_blk_strnlen(struct super_block *sb,
 
 	/* scan the string up to blocksize bytes at a time */
 	while (limit > 0) {
-		offset = pos & (ROMBSIZE - 1);
-		segment = min_t(size_t, limit, ROMBSIZE - offset);
-		bh = sb_bread(sb, pos >> ROMBSBITS);
+		offset = pos & (sb->s_blocksize - 1);
+		segment = min_t(size_t, limit, sb->s_blocksize - offset);
+		bh = sb_bread(sb, pos >> sb->s_blocksize_bits);
 		if (!bh)
 			return -EIO;
 		buf = bh->b_data + offset;
@@ -170,9 +170,9 @@ static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
 
 	/* compare string up to a block at a time */
 	while (size > 0) {
-		offset = pos & (ROMBSIZE - 1);
-		segment = min_t(size_t, size, ROMBSIZE - offset);
-		bh = sb_bread(sb, pos >> ROMBSBITS);
+		offset = pos & (sb->s_blocksize - 1);
+		segment = min_t(size_t, size, sb->s_blocksize - offset);
+		bh = sb_bread(sb, pos >> sb->s_blocksize_bits);
 		if (!bh)
 			return -EIO;
 		matched = (memcmp(bh->b_data + offset, str, segment) == 0);
@@ -180,7 +180,8 @@ static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
 		size -= segment;
 		pos += segment;
 		str += segment;
-		if (matched && size == 0 && offset + segment < ROMBSIZE) {
+		if (matched && size == 0 &&
+				offset + segment < sb->s_blocksize) {
 			if (!bh->b_data[offset + segment])
 				terminated = true;
 			else
@@ -194,8 +195,8 @@ static int romfs_blk_strcmp(struct super_block *sb, unsigned long pos,
 	if (!terminated) {
 		/* the terminating NUL must be on the first byte of the next
 		 * block */
-		BUG_ON((pos & (ROMBSIZE - 1)) != 0);
-		bh = sb_bread(sb, pos >> ROMBSBITS);
+		BUG_ON((pos & (sb->s_blocksize - 1)) != 0);
+		bh = sb_bread(sb, pos >> sb->s_blocksize_bits);
 		if (!bh)
 			return -EIO;
 		matched = !bh->b_data[0];
diff --git a/fs/romfs/super.c b/fs/romfs/super.c
index e582d001f792..6fecdea791f1 100644
--- a/fs/romfs/super.c
+++ b/fs/romfs/super.c
@@ -411,10 +411,17 @@ static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 
 	buf->f_type = ROMFS_MAGIC;
 	buf->f_namelen = ROMFS_MAXFN;
-	buf->f_bsize = ROMBSIZE;
 	buf->f_bfree = buf->f_bavail = buf->f_ffree;
+#ifdef CONFIG_BLOCK
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_blocks =
+		(romfs_maxsize(dentry->d_sb) + sb->s_blocksize - 1) >>
+		sb->s_blocksize_bits;
+#else
+	buf->f_bsize = ROMBSIZE;
 	buf->f_blocks =
 		(romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
+#endif
 	buf->f_fsid.val[0] = (u32)id;
 	buf->f_fsid.val[1] = (u32)(id >> 32);
 	return 0;
-- 
2.17.1