DDF: make "null_aligned" a static buffer

Use a static buffer for this "zero page". This makes it easier
to factor out the header writing code.

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

diff --git a/super-ddf.c b/super-ddf.c
index e5007b94a63441225a00e8ddf29a0a9da2e40050..efdba6d07578b78b942022475a8785b799eeb2d7 100644 (file)
--- a/super-ddf.c
+++ b/super-ddf.c
@@ -2756,14 +2756,21 @@ static int remove_from_super_ddf(struct supertype *st, mdu_disk_info_t *dk)
  */
 #define NULL_CONF_SZ   4096
 
-static int __write_ddf_structure(struct dl *d, struct ddf_super *ddf, __u8 type,
-                                char *null_aligned)
+static char *null_aligned;
+static int __write_ddf_structure(struct dl *d, struct ddf_super *ddf, __u8 type)
 {
        unsigned long long sector;
        struct ddf_header *header;
        int fd, i, n_config, conf_size;
        int ret = 0;
 
+       if (null_aligned == NULL) {
+               if (posix_memalign((void **)&null_aligned, 4096, NULL_CONF_SZ)
+                   != 0)
+                       return 0;
+               memset(null_aligned, 0xff, NULL_CONF_SZ);
+       }
+
        fd = d->fd;
 
        switch (type) {
@@ -2864,14 +2871,9 @@ static int __write_init_super_ddf(struct supertype *st)
        int attempts = 0;
        int successes = 0;
        unsigned long long size;
-       char *null_aligned;
        __u32 seq;
 
        pr_state(ddf, __func__);
-       if (posix_memalign((void**)&null_aligned, 4096, NULL_CONF_SZ) != 0) {
-               return -ENOMEM;
-       }
-       memset(null_aligned, 0xff, NULL_CONF_SZ);
 
        seq = ddf->active->seq;
 
@@ -2916,12 +2918,10 @@ static int __write_init_super_ddf(struct supertype *st)
                ddf->anchor.seq = 0xFFFFFFFF; /* no sequencing in anchor */
                ddf->anchor.crc = calc_crc(&ddf->anchor, 512);
 
-               if (!__write_ddf_structure(d, ddf, DDF_HEADER_PRIMARY,
-                                          null_aligned))
+               if (!__write_ddf_structure(d, ddf, DDF_HEADER_PRIMARY))
                        continue;
 
-               if (!__write_ddf_structure(d, ddf, DDF_HEADER_SECONDARY,
-                                          null_aligned))
+               if (!__write_ddf_structure(d, ddf, DDF_HEADER_SECONDARY))
                        continue;
 
                lseek64(fd, (size-1)*512, SEEK_SET);
@@ -2929,7 +2929,6 @@ static int __write_init_super_ddf(struct supertype *st)
                        continue;
                successes++;
        }
-       free(null_aligned);
 
        return attempts != successes;
 }