libfdisk: add alignment code

Signed-off-by: Karel Zak <kzak@redhat.com>

3 files changed, 120 insertions, 0 deletions

diff --git a/libfdisk/src/Makemodule.am b/libfdisk/src/Makemodule.am
index 66cbe872c..3159432f5 100644
--- a/libfdisk/src/Makemodule.am
+++ b/libfdisk/src/Makemodule.am
@@ -9,6 +9,7 @@ libfdisk_la_SOURCES = \
 	libfdisk/src/libfdisk.h \
 	\
 	libfdisk/src/init.c \
+	libfdisk/src/alignment.c \
 	libfdisk/src/parttype.c
 
 
diff --git a/libfdisk/src/alignment.c b/libfdisk/src/alignment.c
new file mode 100644
index 000000000..b0d38ae23
--- /dev/null
+++ b/libfdisk/src/alignment.c
@@ -0,0 +1,101 @@
+
+#include "fdiskP.h"
+
+/*
+ * Alignment according to logical granulity (usually 1MiB)
+ */
+static int lba_is_aligned(struct fdisk_context *cxt, sector_t lba)
+{
+	unsigned long granularity = max(cxt->phy_sector_size, cxt->min_io_size);
+	uintmax_t offset;
+
+	if (cxt->grain > granularity)
+		granularity = cxt->grain;
+	offset = (lba * cxt->sector_size) & (granularity - 1);
+
+	return !((granularity + cxt->alignment_offset - offset) & (granularity - 1));
+}
+
+/*
+ * Alignment according to physical device topology (usually minimal i/o size)
+ */
+static int lba_is_phy_aligned(struct fdisk_context *cxt, sector_t lba)
+{
+	unsigned long granularity = max(cxt->phy_sector_size, cxt->min_io_size);
+	uintmax_t offset = (lba * cxt->sector_size) & (granularity - 1);
+
+	return !((granularity + cxt->alignment_offset - offset) & (granularity - 1));
+}
+
+/*
+ * Align @lba in @direction FDISK_ALIGN_{UP,DOWN,NEAREST}
+ */
+sector_t fdisk_align_lba(struct fdisk_context *cxt, sector_t lba, int direction)
+{
+	sector_t res;
+
+	if (lba_is_aligned(cxt, lba))
+		res = lba;
+	else {
+		sector_t sects_in_phy = cxt->grain / cxt->sector_size;
+
+		if (lba < cxt->first_lba)
+			res = cxt->first_lba;
+
+		else if (direction == FDISK_ALIGN_UP)
+			res = ((lba + sects_in_phy) / sects_in_phy) * sects_in_phy;
+
+		else if (direction == FDISK_ALIGN_DOWN)
+			res = (lba / sects_in_phy) * sects_in_phy;
+
+		else /* FDISK_ALIGN_NEAREST */
+			res = ((lba + sects_in_phy / 2) / sects_in_phy) * sects_in_phy;
+
+		if (cxt->alignment_offset && !lba_is_aligned(cxt, res) &&
+		    res > cxt->alignment_offset / cxt->sector_size) {
+			/*
+			 * apply alignment_offset
+			 *
+			 * On disk with alignment compensation physical blocks starts
+			 * at LBA < 0 (usually LBA -1). It means we have to move LBA
+			 * according the offset to be on the physical boundary.
+			 */
+			/* fprintf(stderr, "LBA: %llu apply alignment_offset\n", res); */
+			res -= (max(cxt->phy_sector_size, cxt->min_io_size) -
+					cxt->alignment_offset) / cxt->sector_size;
+
+			if (direction == FDISK_ALIGN_UP && res < lba)
+				res += sects_in_phy;
+		}
+	}
+
+	return res;
+}
+
+/*
+ * Align @lba, the result has to be between @start and @stop
+ */
+sector_t fdisk_align_lba_in_range(struct fdisk_context *cxt,
+				  sector_t lba, sector_t start, sector_t stop)
+{
+	start = fdisk_align_lba(cxt, start, FDISK_ALIGN_UP);
+	stop = fdisk_align_lba(cxt, stop, FDISK_ALIGN_DOWN);
+	lba = fdisk_align_lba(cxt, lba, FDISK_ALIGN_NEAREST);
+
+	if (lba < start)
+		return start;
+	else if (lba > stop)
+		return stop;
+	return lba;
+}
+
+/*
+ * Print warning if the partition @lba (start of the @partition) is not
+ * aligned to physical sector boundary.
+ */
+void fdisk_warn_alignment(struct fdisk_context *cxt, sector_t lba, int partition)
+{
+	if (!lba_is_phy_aligned(cxt, lba))
+		printf(_("Partition %i does not start on physical sector boundary.\n"),
+			partition + 1);
+}
diff --git a/libfdisk/src/fdiskP.h b/libfdisk/src/fdiskP.h
index 82443453a..9ae258e13 100644
--- a/libfdisk/src/fdiskP.h
+++ b/libfdisk/src/fdiskP.h
@@ -20,6 +20,8 @@
 #include "c.h"
 #include "libfdisk.h"
 
+#include "nls.h"		/* temporary before dialog API will be implamented */
+
 /* features */
 #define CONFIG_LIBFDISK_ASSERT
 #define CONFIG_LIBFDISK_DEBUG
@@ -189,4 +191,20 @@ struct fdisk_label {
 	int (*reset_alignment)(struct fdisk_context *cxt);
 };
 
+/* alignment.c */
+extern sector_t fdisk_topology_get_first_lba(struct fdisk_context *cxt);
+extern unsigned long fdisk_topology_get_grain(struct fdisk_context *cxt);
+
+extern void fdisk_warn_alignment(struct fdisk_context *cxt,
+				 sector_t lba, int partition);
+
+
+#define FDISK_ALIGN_UP		1
+#define FDISK_ALIGN_DOWN	2
+#define FDISK_ALIGN_NEAREST	3
+
+extern sector_t fdisk_align_lba(struct fdisk_context *cxt, sector_t lba, int direction);
+extern sector_t fdisk_align_lba_in_range(struct fdisk_context *cxt, sector_t lba,
+					 sector_t start, sector_t stop);
+
 #endif /* _LIBFDISK_PRIVATE_H */