format_text: Use explicit alignment in wrapping calc.

Expand out the metadata wrapping calculations to prepare
to support a larger alignment.

The current alignment is 512 bytes so
(mdac_area_start + rlocn->offset) % alignment is zero.

diff --git a/lib/format_text/format-text.c b/lib/format_text/format-text.c
index 09ce69336dfdca10f6be106134cc09d0fa83eb4d..c96fad910a0282262bb876f88ab4aa54c8e817dc 100644 (file)
--- a/lib/format_text/format-text.c
+++ b/lib/format_text/format-text.c
@@ -472,19 +472,24 @@ static struct raw_locn *_find_vg_rlocn(struct device_area *dev_area,
 /*
  * Determine offset for uncommitted metadata
  */
-static uint64_t _next_rlocn_offset(struct raw_locn *rlocn,
-                                  struct mda_header *mdah)
+static uint64_t _next_rlocn_offset(struct raw_locn *rlocn, struct mda_header *mdah, uint64_t mdac_area_start, uint64_t alignment)
 {
+       uint64_t new_start_offset;
+
        if (!rlocn)
                /* Find an empty slot */
                /* FIXME Assume only one VG per mdah for now */
-               return MDA_HEADER_SIZE;
+               return alignment;
+
+       /* Calculate new start position within buffer rounded up to absolute alignment */
+       new_start_offset = rlocn->offset + rlocn->size +
+                          (alignment - (mdac_area_start + rlocn->offset + rlocn->size) % alignment);
 
-       /* Start of free space - round up to next sector; circular */
-       return ((rlocn->offset + rlocn->size +
-               (SECTOR_SIZE - rlocn->size % SECTOR_SIZE) -
-               MDA_HEADER_SIZE) % (mdah->size - MDA_HEADER_SIZE))
-              + MDA_HEADER_SIZE;
+       /* If new location is beyond the end of the buffer, wrap around back to start of circular buffer */
+       if (new_start_offset > mdah->size - MDA_HEADER_SIZE)
+               new_start_offset -= (mdah->size - MDA_HEADER_SIZE);
+
+       return new_start_offset;
 }
 
 static int _raw_holds_vgname(struct format_instance *fid,
@@ -643,9 +648,6 @@ static int _vg_write_raw(struct format_instance *fid, struct volume_group *vg,
        if (!(mdah = raw_read_mda_header(fid->fmt, &mdac->area, mda_is_primary(mda))))
                goto_out;
 
-       rlocn = _find_vg_rlocn(&mdac->area, mdah, mda_is_primary(mda), old_vg_name ? : vg->name, &noprecommit);
-       mdac->rlocn.offset = _next_rlocn_offset(rlocn, mdah);
-
        if (!fidtc->raw_metadata_buf &&
            !(fidtc->raw_metadata_buf_size =
                        text_vg_export_raw(vg, "", &fidtc->raw_metadata_buf))) {
@@ -653,6 +655,9 @@ static int _vg_write_raw(struct format_instance *fid, struct volume_group *vg,
                goto out;
        }
 
+       rlocn = _find_vg_rlocn(&mdac->area, mdah, mda_is_primary(mda), old_vg_name ? : vg->name, &noprecommit);
+
+       mdac->rlocn.offset = _next_rlocn_offset(rlocn, mdah, mdac->area.start, MDA_ORIGINAL_ALIGNMENT);
        mdac->rlocn.size = fidtc->raw_metadata_buf_size;
 
        if (mdac->rlocn.offset + mdac->rlocn.size > mdah->size)
@@ -683,7 +688,7 @@ static int _vg_write_raw(struct format_instance *fid, struct volume_group *vg,
                goto_out;
 
        if (new_wrap) {
-               log_debug_metadata("Writing metadata to %s at %" PRIu64 " len %" PRIu64,
+               log_debug_metadata("Writing wrapped metadata to %s at %" PRIu64 " len %" PRIu64,
                                  dev_name(mdac->area.dev), mdac->area.start +
                                  MDA_HEADER_SIZE, new_wrap);
 

diff --git a/lib/format_text/layout.h b/lib/format_text/layout.h
index c88812f3ad22c3e161211411e2e2c83e547f8e7c..1746b9ccdf4aea58577038e88de4fac522b8a54d 100644 (file)
--- a/lib/format_text/layout.h
+++ b/lib/format_text/layout.h
@@ -102,6 +102,7 @@ struct mda_context {
 #define MDA_HEADER_SIZE 512
 #define LVM2_LABEL "LVM2 001"
 #define MDA_SIZE_MIN (8 * (unsigned) lvm_getpagesize())
+#define MDA_ORIGINAL_ALIGNMENT 512     /* Original alignment used for start of VG metadata content */
 
 int vgname_from_mda(const struct format_type *fmt, struct mda_header *mdah, int primary_mda, 
                    struct device_area *dev_area, struct lvmcache_vgsummary *vgsummary,