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-rw-r--r--utils.c58
1 files changed, 20 insertions, 38 deletions
diff --git a/utils.c b/utils.c
index 87424fe4..b7e4f744 100644
--- a/utils.c
+++ b/utils.c
@@ -585,25 +585,23 @@ static int zero_blocks(int fd, off_t start, size_t len)
return ret;
}
-static int zero_dev_start(int fd)
+#define ZERO_DEV_BYTES (2 * 1024 * 1024)
+
+/* don't write outside the device by clamping the region to the device size */
+static int zero_dev_clamped(int fd, off_t start, ssize_t len, u64 dev_size)
{
- off_t start = 0;
- size_t len = 2 * 1024 * 1024;
+ off_t end = max(start, start + len);
#ifdef __sparc__
- /* don't overwrite the disk labels on sparc */
- start = 1024;
- len -= 1024;
+ /* and don't overwrite the disk labels on sparc */
+ start = max(start, 1024);
+ end = max(end, 1024);
#endif
- return zero_blocks(fd, start, len);
-}
-static int zero_dev_end(int fd, u64 dev_size)
-{
- size_t len = 2 * 1024 * 1024;
- off_t start = dev_size - len;
+ start = min_t(u64, start, dev_size);
+ end = min_t(u64, end, dev_size);
- return zero_blocks(fd, start, len);
+ return zero_blocks(fd, start, end - start);
}
int btrfs_add_to_fsid(struct btrfs_trans_handle *trans,
@@ -684,7 +682,6 @@ int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret,
u64 max_block_count, int *mixed, int discard)
{
u64 block_count;
- u64 bytenr;
struct stat st;
int i, ret;
@@ -720,36 +717,21 @@ int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret,
}
}
- ret = zero_dev_start(fd);
- if (ret)
- goto zero_dev_error;
-
- for (i = 0 ; i < BTRFS_SUPER_MIRROR_MAX; i++) {
- bytenr = btrfs_sb_offset(i);
- if (bytenr >= block_count)
- break;
- ret = zero_blocks(fd, bytenr, BTRFS_SUPER_INFO_SIZE);
- if (ret)
- goto zero_dev_error;
- }
+ ret = zero_dev_clamped(fd, 0, ZERO_DEV_BYTES, block_count);
+ for (i = 0 ; !ret && i < BTRFS_SUPER_MIRROR_MAX; i++)
+ ret = zero_dev_clamped(fd, btrfs_sb_offset(i),
+ BTRFS_SUPER_INFO_SIZE, block_count);
+ if (!ret && zero_end)
+ ret = zero_dev_clamped(fd, block_count - ZERO_DEV_BYTES,
+ ZERO_DEV_BYTES, block_count);
- if (zero_end) {
- ret = zero_dev_end(fd, block_count);
- if (ret)
- goto zero_dev_error;
- }
- *block_count_ret = block_count;
-
-zero_dev_error:
if (ret < 0) {
fprintf(stderr, "ERROR: failed to zero device '%s' - %s\n",
file, strerror(-ret));
return 1;
- } else if (ret > 0) {
- fprintf(stderr, "ERROR: failed to zero device '%s' - %d\n",
- file, ret);
- return 1;
}
+
+ *block_count_ret = block_count;
return 0;
}