On Sun, Jan 07, 2018 at 01:54:21PM -0800, Rosen Penev wrote: > As btrfs is specific to Linux, %m can be used instead of strerror(errno) > in format strings. This has some size reduction benefits for embedded > systems. Makes sense. > glibc, musl, and uclibc-ng all support %m as a modifier to printf. > A quick glance at the BIONIC libc source indicates that it has > support for %m as well. BSDs and Windows do not but I do believe > them to be beyond the scope of btrfs-progs. Thanks for checking the compatibility. The %m can be substituted by a wrapper if this becomes a problem in the future. > Compiled sizes on Ubuntu 16.04: > > Before: > 3916512 btrfs > After: > 3908744 btrfs the delta is about 7KiB, that's not much but still counts. I would not object further optimizations towards size reduction as long as the code remains maintainable. > 233256 libbtrfs.so.0.1 > 4899 bcp > 2366560 btrfs-convert > 2207432 btrfs-corrupt-block > 13302 btrfs-debugfs > 2151104 btrfs-debug-tree > 2134968 btrfs-find-root > 2281864 btrfs-image > 2143536 btrfs-map-logical > 2129704 btrfs-select-super > 2151552 btrfstune > 2130696 btrfs-zero-log > 2276272 mkfs.btrfs Some of the utilities are typically installed by default, the binaries share a lot of code as they get built from the same object files. I had once an idea of a compound binary that would switch the function by the name of the executable. Similar to what busybox does. https://github.com/kdave/btrfs-progs/commit/8fc697a7f763f39f3afe0abaa68ac13a49ac8a86 --- * btrfs * mkfs.btrfs * btrfstun * btrfs-image * btrfs-convert * btrfs-debug-tree * btrfs-show-super * btrfs-find-root The static target is also supported. The name of resulting boxed binaries is btrfs.box and btrfs.box.static . text data bss dec hex filename 550988 19120 15444 585552 8ef50 btrfs 1562099 25316 42256 1629671 18dde7 btrfs.static 659504 21104 16492 697100 aa30c btrfs.box 1817274 27988 44088 1889350 1cd446 btrfs.box.static --- I was not sure if this is was just another good idea waiting for a usecase (or not), so I haven't continued past the prototype. Please let me know if you'd be interested in this functionality, the patch is fairly trivial to update. > @@ -815,7 +815,7 @@ static const char * const cmd_filesystem_sync_usage[] = { > > static int cmd_filesystem_sync(int argc, char **argv) > { > - int fd, res, e; > + int fd, res; > char *path; > DIR *dirstream = NULL; > > @@ -831,10 +831,9 @@ static int cmd_filesystem_sync(int argc, char **argv) > return 1; > > res = ioctl(fd, BTRFS_IOC_SYNC); > - e = errno; > close_file_or_dir(fd, dirstream); > if( res < 0 ){ > - error("sync ioctl failed on '%s': %s", path, strerror(e)); > + error("sync ioctl failed on '%s': %m", path); Let me use that one as example, there are a few more similar updates. There's potentially lost errno from the ioctl if something inside close_file_or_dir() overwrites it, as there are closedir and close. This is highly unlikely and I'll deal with that separately, so I'm going to apply the patch without further changes. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
