LOOP_CONFIGURE is added to Linux 5.8 This allows userspace to completely setup a loop device with a single ioctl, removing the in-between state where the device can be partially configured - eg the loop device has a backing file associated with it, but is reading from the wrong offset.
https://lwn.net/Articles/820408/ https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3448914e8cc5 patch 1-8: To facilitate the addition of new functions, the code of set_loop() is micro-refactored. function old new delta set_loop 760 716 -44 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-44) Total: -44 bytes patch 9: add LOOP_CONFIGURE Builders can use config to choose which algorithm to build into their busybox binary --- v4: Fine-tuned based on review comments patch2: add assert(dev_size >= LOOP_NAMESIZE) in get_next_free_loop(). patch6,8,9: The const modifier is added to the "bb_loop_info *loopinfo" parameter. v3: http://lists.busybox.net/pipermail/busybox/2022-November/090009.html Fine-tuned based on review comments patch2: Rename local variables, use "loopdevno" instead of "i" in get_next_free_loop(). patch7: Reduce indentation using guard statements in do_stat_and_mknod(). patch9: Rename set_loop_configure_old() to set_loop_fd_and_status() v2: http://lists.busybox.net/pipermail/busybox/2022-November/089990.html changes in patch9: add config for builder to select v1: http://lists.busybox.net/pipermail/busybox/2022-November/089969.html --- Xiaoming Ni (9): loop:refactor: extract subfunction open_file() loop:refactor: extract subfunction get_next_free_loop() loop:refactor: del close_and_try_next_loopN loop:refactor: extract subfunction set_loop_info() loop:refactor: extract subfunction set_loop_configure() loop:refactor: Use a structure to reduce parameters loop:refactor: Extract subfunction do_stat_and_mknod() loop:refactor: extract subfunction set_loop_dev() loop: Add LOOP_CONFIGURE ioctl libbb/Config.src | 22 ++++ libbb/loop.c | 295 ++++++++++++++++++++++++++++++----------------- 2 files changed, 214 insertions(+), 103 deletions(-) -- 2.27.0 _______________________________________________ busybox mailing list busybox@busybox.net http://lists.busybox.net/mailman/listinfo/busybox
