diff options
| -rw-r--r-- | make-bcache.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/make-bcache.c b/make-bcache.c index 6ffe89e..9c038a8 100644 --- a/make-bcache.c +++ b/make-bcache.c @@ -269,6 +269,37 @@ static unsigned get_blocksize(const char *path) exit(EXIT_FAILURE); } + if (S_ISBLK(statbuf.st_mode)) { + /* check IO limits: + * BLKALIGNOFF: alignment_offset + * BLKPBSZGET: physical_block_size + * BLKSSZGET: logical_block_size + * BLKIOMIN: minimum_io_size + * BLKIOOPT: optimal_io_size + * + * It may be tempting to use physical_block_size, + * or even minimum_io_size. + * But to be as transparent as possible, + * we want to use logical_block_size. + */ + unsigned int logical_block_size; + int fd = open(path, O_RDONLY); + + if (fd < 0) { + fprintf(stderr, "open(%s) failed: %m\n", path); + exit(EXIT_FAILURE); + } + if (ioctl(fd, BLKSSZGET, &logical_block_size)) { + fprintf(stderr, "ioctl(%s, BLKSSZGET) failed: %m\n", path); + exit(EXIT_FAILURE); + } + close(fd); + return logical_block_size / 512; + + } + /* else: not a block device. + * Why would we even want to write a bcache super block there? */ + return statbuf.st_blksize / 512; } |