[RFC PATCH 01/12] db: separate out straight buffer IO from map based IO.

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From: Dave Chinner <dchinner@xxxxxxxxxx>

First step in converting to libxfs based IO.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 db/init.c |   7 ++--
 db/io.c   | 125 +++++++++++++++++++++++++++++++++++++++++++++++++-------------
 db/io.h   |   5 +--
 3 files changed, 104 insertions(+), 33 deletions(-)

diff --git a/db/init.c b/db/init.c
index 2932e51..0e88b56 100644
--- a/db/init.c
+++ b/db/init.c
@@ -55,7 +55,7 @@ init(
 	char		**argv)
 {
 	xfs_sb_t	*sbp;
-	void		*bufp = NULL;
+	char		bufp[BBSIZE];
 	int		c;
 
 	setlocale(LC_ALL, "");
@@ -115,15 +115,14 @@ init(
 		exit(1);
 	}
 
-	if (read_bbs(XFS_SB_DADDR, 1, &bufp, NULL)) {
+	if (read_buf(XFS_SB_DADDR, 1, bufp)) {
 		fprintf(stderr, _("%s: %s is invalid (cannot read first 512 "
 			"bytes)\n"), progname, fsdevice);
 		exit(1);
 	}
 
 	/* copy SB from buffer to in-core, converting architecture as we go */
-	libxfs_sb_from_disk(&xmount.m_sb, bufp);
-	xfree(bufp);
+	libxfs_sb_from_disk(&xmount.m_sb, (struct xfs_dsb *)bufp);
 
 	sbp = &xmount.m_sb;
 	if (sbp->sb_magicnum != XFS_SB_MAGIC) {
diff --git a/db/io.c b/db/io.c
index 39a1827..fa11646 100644
--- a/db/io.c
+++ b/db/io.c
@@ -417,8 +417,61 @@ ring_add(void)
 	}
 }
 
-
 int
+read_buf(
+	xfs_daddr_t	bbno,
+	int		count,
+	void		*bufp)
+{
+	int		err;
+
+	err = pread64(x.dfd, bufp, BBTOB(count), BBTOB(bbno));
+	if (err < 0)
+		err = errno;
+	else if (err < count)
+		err = -1;
+	return err;
+}
+
+static int
+write_buf(
+	xfs_daddr_t	bbno,
+	int		count,
+	void		*bufp)
+{
+	int		err;
+
+	err = pwrite64(x.dfd, bufp, BBTOB(count), BBTOB(bbno));
+	if (err < 0)
+		err = errno;
+	else if (err < count)
+		err = -1;
+	return err;
+}
+
+static void
+write_cur_buf(void)
+{
+	int ret;
+
+	ret = write_buf(iocur_top->bb, iocur_top->blen, iocur_top->buf);
+
+	if (ret == -1)
+		dbprintf(_("incomplete write, block: %lld\n"),
+			 (iocur_base + iocur_sp)->bb);
+	else if (ret != 0)
+		dbprintf(_("write error: %s\n"), strerror(ret));
+
+	/* re-read buffer from disk */
+	ret = read_buf(iocur_top->bb, iocur_top->blen, iocur_top->buf);
+	if (ret == -1)
+		dbprintf(_("incomplete read, block: %lld\n"),
+			 (iocur_base + iocur_sp)->bb);
+	else if (ret != 0)
+		dbprintf(_("read error: %s\n"), strerror(ret));
+}
+
+static int
 write_bbs(
 	__int64_t       bbno,
 	int             count,
@@ -430,15 +483,14 @@ write_bbs(
 	int		j;
 	int		rval = EINVAL;	/* initialize for zero `count' case */
 
-	for (j = 0; j < count; j += bbmap ? 1 : count) {
-		if (bbmap)
-			bbno = bbmap->b[j];
+	for (j = 0; j < count; j++) {
+		bbno = bbmap->b[j];
 		if (lseek64(x.dfd, bbno << BBSHIFT, SEEK_SET) < 0) {
 			rval = errno;
 			dbprintf(_("can't seek in filesystem at bb %lld\n"), bbno);
 			return rval;
 		}
-		c = BBTOB(bbmap ? 1 : count);
+		c = BBTOB(1);
 		i = (int)write(x.dfd, (char *)bufp + BBTOB(j), c);
 		if (i < 0) {
 			rval = errno;
@@ -452,7 +504,7 @@ write_bbs(
 	return rval;
 }
 
-int
+static int
 read_bbs(
 	__int64_t	bbno,
 	int		count,
@@ -473,9 +525,8 @@ read_bbs(
 		buf = xmalloc(c);
 	else
 		buf = *bufp;
-	for (j = 0; j < count; j += bbmap ? 1 : count) {
-		if (bbmap)
-			bbno = bbmap->b[j];
+	for (j = 0; j < count; j++) {
+		bbno = bbmap->b[j];
 		if (lseek64(x.dfd, bbno << BBSHIFT, SEEK_SET) < 0) {
 			rval = errno;
 			dbprintf(_("can't seek in filesystem at bb %lld\n"), bbno);
@@ -483,7 +534,7 @@ read_bbs(
 				xfree(buf);
 			buf = NULL;
 		} else {
-			c = BBTOB(bbmap ? 1 : count);
+			c = BBTOB(1);
 			i = (int)read(x.dfd, (char *)buf + BBTOB(j), c);
 			if (i < 0) {
 				rval = errno;
@@ -506,22 +557,19 @@ read_bbs(
 	return rval;
 }
 
-void
-write_cur(void)
+static void
+write_cur_bbs(void)
 {
 	int ret;
 
-	if (iocur_sp < 0) {
-		dbprintf(_("nothing to write\n"));
-		return;
-	}
 	ret = write_bbs(iocur_top->bb, iocur_top->blen, iocur_top->buf,
-		iocur_top->use_bbmap ? &iocur_top->bbmap : NULL);
+			&iocur_top->bbmap);
 	if (ret == -1)
 		dbprintf(_("incomplete write, block: %lld\n"),
 			 (iocur_base + iocur_sp)->bb);
 	else if (ret != 0)
 		dbprintf(_("write error: %s\n"), strerror(ret));
+
 	/* re-read buffer from disk */
 	ret = read_bbs(iocur_top->bb, iocur_top->blen, &iocur_top->buf,
 		iocur_top->use_bbmap ? &iocur_top->bbmap : NULL);
@@ -533,6 +581,20 @@ write_cur(void)
 }
 
 void
+write_cur(void)
+{
+	if (iocur_sp < 0) {
+		dbprintf(_("nothing to write\n"));
+		return;
+	}
+
+	if (iocur_top->use_bbmap)
+		write_cur_bbs();
+	else
+		write_cur_buf();
+}
+
+void
 set_cur(
 	const typ_t	*t,
 	__int64_t	d,
@@ -549,17 +611,32 @@ set_cur(
 		return;
 	}
 
-#ifdef DEBUG
-	if (bbmap)
-		printf(_("xfs_db got a bbmap for %lld\n"), (long long)d);
-#endif
 	ino = iocur_top->ino;
 	dirino = iocur_top->dirino;
 	mode = iocur_top->mode;
 	pop_cur();
 	push_cur();
-	if (read_bbs(d, c, &iocur_top->buf, bbmap))
-		return;
+
+	if (bbmap) {
+#ifdef DEBUG
+		printf(_("xfs_db got a bbmap for %lld\n"), (long long)d);
+#endif
+
+		if (read_bbs(d, c, &iocur_top->buf, bbmap))
+			return;
+		iocur_top->bbmap = *bbmap;
+		iocur_top->use_bbmap = 1;
+	} else {
+		if (!iocur_top->buf) {
+			iocur_top->buf = malloc(BBTOB(c));
+			if (!iocur_top->buf)
+				return;
+		}
+		if (read_buf(d, c, iocur_top->buf))
+			return;
+		iocur_top->use_bbmap = 0;
+	}
+
 	iocur_top->bb = d;
 	iocur_top->blen = c;
 	iocur_top->boff = 0;
@@ -570,8 +647,6 @@ set_cur(
 	iocur_top->ino = ino;
 	iocur_top->dirino = dirino;
 	iocur_top->mode = mode;
-	if ((iocur_top->use_bbmap = (bbmap != NULL)))
-		iocur_top->bbmap = *bbmap;
 
 	/* store location in ring */
 	if (ring_flag)
diff --git a/db/io.h b/db/io.h
index 549aad9..9ea6223 100644
--- a/db/io.h
+++ b/db/io.h
@@ -52,10 +52,7 @@ extern void	off_cur(int off, int len);
 extern void	pop_cur(void);
 extern void	print_iocur(char *tag, iocur_t *ioc);
 extern void	push_cur(void);
-extern int	read_bbs(__int64_t daddr, int count, void **bufp,
-			 bbmap_t *bbmap);
-extern int	write_bbs(__int64_t daddr, int count, void *bufp,
-			  bbmap_t *bbmap);
+extern int	read_buf(__int64_t daddr, int count, void *bufp);
 extern void     write_cur(void);
 extern void	set_cur(const struct typ *t, __int64_t d, int c, int ring_add,
 			bbmap_t *bbmap);
-- 
1.8.3.2

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