super0: Do all metadata IO with 4096byte alignment

.. because some devices (dasd) have 4096 byte sector size.

As the superblock is 4096 bytes and the bitmap is in a
60K region, this is safe from any possible corruption.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/super0.c b/super0.c
index 2221617b0f4b63deb3e64e10dfb8ec64e7643b72..18e1d45eed5e5c4b651b44bc9a5b5f60a3f66af8 100644 (file)
--- a/super0.c
+++ b/super0.c
@@ -545,7 +545,8 @@ static int init_super0(struct supertype *st, mdu_array_info_t *info,
        mdp_super_t *sb;
        int spares;
 
-       if (posix_memalign((void**)&sb, 512, MD_SB_BYTES + sizeof(bitmap_super_t)) != 0) {
+       if (posix_memalign((void**)&sb, 4096,
+                          MD_SB_BYTES + ROUND_UP(sizeof(bitmap_super_t), 4096)) != 0) {
                fprintf(stderr, Name ": %s could not allocate superblock\n", __func__);
                return 0;
        }
@@ -682,8 +683,8 @@ static int store_super0(struct supertype *st, int fd)
        if (super->state & (1<<MD_SB_BITMAP_PRESENT)) {
                struct bitmap_super_s * bm = (struct bitmap_super_s*)(super+1);
                if (__le32_to_cpu(bm->magic) == BITMAP_MAGIC)
-                       if (write(fd, bm, ROUND_UP(sizeof(*bm),512)) != 
-                           ROUND_UP(sizeof(*bm),512))
+                       if (write(fd, bm, ROUND_UP(sizeof(*bm),4096)) != 
+                           ROUND_UP(sizeof(*bm),4096))
                            return 5;
        }
 
@@ -743,8 +744,9 @@ static int compare_super0(struct supertype *st, struct supertype *tst)
        if (second->md_magic != MD_SB_MAGIC)
                return 1;
        if (!first) {
-               if (posix_memalign((void**)&first, 512, 
-                              MD_SB_BYTES + sizeof(struct bitmap_super_s)) != 0) {
+               if (posix_memalign((void**)&first, 4096,
+                            MD_SB_BYTES + 
+                            ROUND_UP(sizeof(struct bitmap_super_s), 4096)) != 0) {
                        fprintf(stderr, Name
                                ": %s could not allocate superblock\n", __func__);
                        return 1;
@@ -817,8 +819,9 @@ static int load_super0(struct supertype *st, int fd, char *devname)
                return 1;
        }
 
-       if (posix_memalign((void**)&super, 512,
-                          MD_SB_BYTES + sizeof(bitmap_super_t)+512) != 0) {
+       if (posix_memalign((void**)&super, 4096,
+                          MD_SB_BYTES +
+                          ROUND_UP(sizeof(bitmap_super_t), 4096)) != 0) {
                fprintf(stderr, Name
                        ": %s could not allocate superblock\n", __func__);
                return 1;
@@ -866,8 +869,8 @@ static int load_super0(struct supertype *st, int fd, char *devname)
         * valid.  If it doesn't clear the bit.  An --assemble --force
         * should get that written out.
         */
-       if (read(fd, super+1, ROUND_UP(sizeof(struct bitmap_super_s),512))
-           != ROUND_UP(sizeof(struct bitmap_super_s),512))
+       if (read(fd, super+1, ROUND_UP(sizeof(struct bitmap_super_s),4096))
+           != ROUND_UP(sizeof(struct bitmap_super_s),4096))
                goto no_bitmap;
 
        uuid_from_super0(st, uuid);
@@ -998,8 +1001,8 @@ static int write_bitmap0(struct supertype *st, int fd)
        int rv = 0;
 
        int towrite, n;
-       char abuf[4096+512];
-       char *buf = (char*)(((long)(abuf+512))&~511UL);
+       char abuf[4096+4096];
+       char *buf = (char*)(((long)(abuf+4096))&~4095L);
 
        if (!get_dev_size(fd, NULL, &dsize))
                return 1;