fdisk: use more elegant way to count and check alignment

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

diff --git a/fdisk/fdisk.c b/fdisk/fdisk.c
index c1868c0107d6e9b2835f532a36f10c805937a490..affea090c74bb49417a827de96dff106d9f5497e 100644 (file)
--- a/fdisk/fdisk.c
+++ b/fdisk/fdisk.c
@@ -215,7 +215,6 @@ unsigned long long sector_offset = 1, extended_offset = 0, sectors;
 
 unsigned int   heads,
        cylinders,
-       phy_sector_size = DEFAULT_SECTOR_SIZE,
        sector_size = DEFAULT_SECTOR_SIZE,
        sector_factor = 1,
        user_set_sector_size = 0,
@@ -226,6 +225,7 @@ unsigned long long total_number_of_sectors; /* (!) 512-byte sectors */
 unsigned long grain = DEFAULT_SECTOR_SIZE,
              io_size = DEFAULT_SECTOR_SIZE,
              min_io_size = DEFAULT_SECTOR_SIZE,
+             phy_sector_size = DEFAULT_SECTOR_SIZE,
              alignment_offset;
 int has_topology;
 
@@ -647,12 +647,10 @@ test_c(char **m, char *mesg) {
 static int
 lba_is_aligned(unsigned long long lba)
 {
-       unsigned long long bytes, phy_sectors;
+       unsigned int granularity = max(phy_sector_size, min_io_size);
+       unsigned long long offset = (lba << 9) & (granularity - 1);
 
-       bytes = lba * sector_size;
-       phy_sectors = bytes / phy_sector_size;
-
-       return (alignment_offset + (phy_sectors * phy_sector_size) == bytes);
+       return !((granularity + alignment_offset - offset) & (granularity - 1));
 }
 
 #define ALIGN_UP       1
@@ -662,41 +660,44 @@ lba_is_aligned(unsigned long long lba)
 static unsigned long long
 align_lba(unsigned long long lba, int direction)
 {
-       unsigned long long sects_in_phy, res;
-
-       sects_in_phy = grain / sector_size;
-
-       if (lba == sector_offset)
-               res = lba;                      /* the offset should be aligned */
+       unsigned long long res;
 
-       else if (lba < sects_in_phy)
-               res = sects_in_phy;             /* align to the first physical sector */
+       if (lba_is_aligned(lba))
+               res = lba;
+       else {
+               unsigned long long sects_in_phy = grain / sector_size;
 
-       else if (lba % sects_in_phy == 0)
-               res = lba;                      /* already aligned to the grain */
+               if (lba < sector_offset)
+                       res = sector_offset;
 
-       else if (direction == ALIGN_UP)
-               res = ((lba + sects_in_phy) / sects_in_phy) * sects_in_phy;
+               else if (direction == ALIGN_UP)
+                       res = ((lba + sects_in_phy) / sects_in_phy) * sects_in_phy;
 
-       else if (direction == ALIGN_DOWN)
-               res = (lba / sects_in_phy) * sects_in_phy;
+               else if (direction == ALIGN_DOWN)
+                       res = (lba / sects_in_phy) * sects_in_phy;
 
-       else /* ALIGN_NEAREST */
-               res = ((lba + sects_in_phy/2) / sects_in_phy) * sects_in_phy;
+               else /* ALIGN_NEAREST */
+                       res = ((lba + sects_in_phy / 2) / sects_in_phy) * sects_in_phy;
 
-       if (alignment_offset && res > alignment_offset / sector_size)
-               /*
-                * apply alignment_offset
-                *
-                * On disk with alignment compensation physical blocks start
-                * at LBA < 0 (usually LBA -1). It means we have to move LBA
-                * according the offset to be on the physical boundary.
-                */
-               res -= (phy_sector_size - alignment_offset) / sector_size;
+               if (alignment_offset && !lba_is_aligned(res) &&
+                   res > alignment_offset / 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(phy_sector_size, min_io_size) -
+                                       alignment_offset) / sector_size;
+               }
+       }
 
        /***
-        fprintf(stderr, "LBA %llu --align-(%s)--> %llu (%s)\n",
+        fprintf(stderr, "LBA %llu (%s) --align-(%s)--> %llu (%s)\n",
                                lba,
+                               lba_is_aligned(lba) ? "OK" : "FALSE",
                                direction == ALIGN_UP ?   "UP     " :
                                direction == ALIGN_DOWN ? "DOWN   " : "NEAREST",
                                res,
@@ -1861,7 +1862,7 @@ list_disk_geometry(void) {
               str_units(PLURAL),
               units_per_sector, sector_size, units_per_sector * sector_size);
 
-       printf(_("Sector size (logical/physical): %u bytes / %u bytes\n"),
+       printf(_("Sector size (logical/physical): %u bytes / %lu bytes\n"),
                                sector_size, phy_sector_size);
        printf(_("I/O size (minimum/optimal): %lu bytes / %lu bytes\n"),
                                min_io_size, io_size);