[PATCH v3 15/18] xfs_copy: genericize write helper to facilitate separate log buf

[Brian Foster <bfoster@xxxxxxxxxx>]

xfs_copy uses a fixed write buffer throughout the code for the various
targets. This is a global buffer and is assumed to be the write source
in the do_write() helper used by the log clearing code.

v5 superblock log formatting will require a larger, independent buffer
to format the log. Therefore, update do_write() to accept a write buffer
parameter to optionally override the global write buffer. This patch
does not change current behavior.

Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
 copy/xfs_copy.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
index f3e5288..0481ece 100644
--- a/copy/xfs_copy.c
+++ b/copy/xfs_copy.c
@@ -170,20 +170,26 @@ check_errors(void)
  * are taken care of when the buffer's read in
  */
 int
-do_write(thread_args *args)
+do_write(
+       thread_args     *args,
+       wbuf            *buf)
 {
-       int     res, error = 0;
+       int             res;
+       int             error = 0;
 
-       if (target[args->id].position != w_buf.position)  {
-               if (lseek64(args->fd, w_buf.position, SEEK_SET) < 0)  {
+       if (!buf)
+               buf = &w_buf;
+
+       if (target[args->id].position != buf->position)  {
+               if (lseek64(args->fd, buf->position, SEEK_SET) < 0)  {
                        error = target[args->id].err_type = 1;
                } else  {
-                       target[args->id].position = w_buf.position;
+                       target[args->id].position = buf->position;
                }
        }
 
-       if ((res = write(target[args->id].fd, w_buf.data,
-                               w_buf.length)) == w_buf.length)  {
+       if ((res = write(target[args->id].fd, buf->data,
+                               buf->length)) == buf->length)  {
                target[args->id].position += res;
        } else  {
                error = 2;
@@ -191,7 +197,7 @@ do_write(thread_args *args)
 
        if (error) {
                target[args->id].error = errno;
-               target[args->id].position = w_buf.position;
+               target[args->id].position = buf->position;
        }
        return error;
 }
@@ -203,7 +209,7 @@ begin_reader(void *arg)
 
        for (;;) {
                pthread_mutex_lock(&args->wait);
-               if (do_write(args))
+               if (do_write(args, NULL))
                        goto handle_error;
                pthread_mutex_lock(&glob_masks.mutex);
                if (--glob_masks.num_working == 0)
@@ -1168,7 +1174,7 @@ main(int argc, char **argv)
                                memset(w_buf.data, 0, w_buf.length);
 
                                while (w_buf.position < end_pos)  {
-                                       do_write(tcarg);
+                                       do_write(tcarg, NULL);
                                        w_buf.position += w_buf.length;
                                }
                                tcarg++;
@@ -1190,7 +1196,7 @@ main(int argc, char **argv)
 
                        for (j = 0, tcarg = targ; j < num_targets; j++)  {
                                sb_update_uuid(sb, &ag_hdr, tcarg);
-                               do_write(tcarg);
+                               do_write(tcarg, NULL);
                                tcarg++;
                        }
                }
@@ -1212,7 +1218,7 @@ next_log_chunk(char *p, int offset, void *private)
        if (buf->length < (int)(p - buf->data) + offset) {
                /* need to flush this one, then start afresh */
 
-               do_write(buf->owner);
+               do_write(buf->owner, NULL);
                memset(buf->data, 0, buf->length);
                return buf->data;
        }
@@ -1247,7 +1253,7 @@ write_log_header(int fd, wbuf *buf, xfs_mount_t *mp)
                        xfs_sb_version_haslogv2(&mp->m_sb) ? 2 : 1,
                        mp->m_sb.sb_logsunit, XLOG_FMT, NULLCOMMITLSN,
                        NULLCOMMITLSN, next_log_chunk, buf);
-       do_write(buf->owner);
+       do_write(buf->owner, NULL);
 
        return roundup(logstart + offset, buf->length);
 }
@@ -1272,7 +1278,7 @@ write_log_trailer(int fd, wbuf *buf, xfs_mount_t *mp)
                read_wbuf(fd, buf, mp);
                offset = (int)(logend - buf->position);
                memset(buf->data, 0, offset);
-               do_write(buf->owner);
+               do_write(buf->owner, NULL);
        }
 
        return buf->position;
-- 
2.1.0