[PATCH 17/32] db: separate out straight buffer IO from map based IO.

Dave Chinner
2013-09-30T03:15:58Z

First step in converting to libxfs based IO.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
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);