REPO: https://github.com/smipi1/linux-tinification.git BRANCH: tiny/config-syscall-splice BACKGROUND: This patch-set forms part of the Linux Kernel Tinification effort ( https://tiny.wiki.kernel.org/). GOAL: Support compiling out the splice family of syscalls (splice, vmsplice, tee and sendfile) along with all supporting infrastructure if not needed. Many embedded systems will not need the splice-family syscalls. Omitting them saves space. HISTORY: PATCH v6: - Removed unnecessary addition of __maybe_unused in fs/fuse PATCH v5: - Fix up commit log still referring to dropped __splice_p() PATCH v4: - Drops __splice_p() - Let nfsd fall back to non-splice support when splice is compiled out - Style fixes PATCH v3: - Fixup commit logs so that they are consistent with patch strategy - Style fixes PATCH v2: - Avoid the ifdef mess introduced in PATCH v1 by mocking out exported splice functions. STRATEGY: a. With the goal of eventually compiling out fs/splice.c, several functions that are only used in support of the the splice family of syscalls are moved into fs/splice.c from fs/read_write.c. The kernel_write function that is not used to support the splice syscalls is moved to fs/read_write.c. b. Introduce an EXPERT kernel configuration option; CONFIG_SYSCALL_SPLICE; to compile out the splice family of syscalls. This removes all userspace uses of the splice infrastructure. c. Splice exports an operations struct, nosteal_pipe_buf_ops. Eliminate the uses of this struct when CONFIG_SYSCALL_SPLICE is undefined, so that splice can later be compiled out. d. Let nfsd fall back to non-splice support when splice is compiled out. e. Compile out fs/splice.c. Functions exported by fs/splice are mocked out with failing static inlines. This is done so as to all but eliminate the maintenance burden on file-system drivers. RESULTS: A tinyconfig bloat-o-meter score for the entire patch-set: add/remove: 0/41 grow/shrink: 5/7 up/down: 23/-8422 (-8399) function old new delta sys_pwritev 115 122 +7 sys_preadv 115 122 +7 fdput_pos 29 36 +7 sys_pwrite64 115 116 +1 sys_pread64 115 116 +1 pipe_to_null 4 - -4 generic_pipe_buf_nosteal 6 - -6 spd_release_page 10 - -10 fdput 11 - -11 PageUptodate 22 11 -11 lock_page 36 24 -12 signal_pending 39 26 -13 fdget 56 42 -14 page_cache_pipe_buf_release 16 - -16 user_page_pipe_buf_ops 20 - -20 splice_write_null 24 4 -20 page_cache_pipe_buf_ops 20 - -20 nosteal_pipe_buf_ops 20 - -20 default_pipe_buf_ops 20 - -20 generic_splice_sendpage 24 - -24 user_page_pipe_buf_steal 25 - -25 splice_shrink_spd 27 - -27 pipe_to_user 43 - -43 direct_splice_actor 47 - -47 default_file_splice_write 49 - -49 wakeup_pipe_writers 54 - -54 wakeup_pipe_readers 54 - -54 write_pipe_buf 71 - -71 page_cache_pipe_buf_confirm 80 - -80 splice_grow_spd 87 - -87 do_splice_to 87 - -87 ipipe_prep.part 92 - -92 splice_from_pipe 93 - -93 splice_from_pipe_next 107 - -107 pipe_to_sendpage 109 - -109 page_cache_pipe_buf_steal 114 - -114 opipe_prep.part 119 - -119 sys_sendfile 122 - -122 generic_file_splice_read 131 8 -123 sys_sendfile64 126 - -126 sys_vmsplice 137 - -137 do_splice_direct 148 - -148 vmsplice_to_user 205 - -205 __splice_from_pipe 246 - -246 splice_direct_to_actor 348 - -348 splice_to_pipe 371 - -371 do_sendfile 492 - -492 sys_tee 497 - -497 vmsplice_to_pipe 558 - -558 default_file_splice_read 688 - -688 iter_file_splice_write 702 4 -698 sys_splice 1075 - -1075 __generic_file_splice_read 1109 - -1109 Pieter Smith (7): fs: move sendfile syscall into fs/splice fs: moved kernel_write to fs/read_write fs/splice: support compiling out splice-family syscalls fs/fuse: support compiling out splice net/core: support compiling out splice fs/nfsd: support compiling out splice fs/splice: full support for compiling out splice fs/Makefile | 3 +- fs/fuse/dev.c | 4 + fs/read_write.c | 181 +++------------------------------------------ fs/splice.c | 194 +++++++++++++++++++++++++++++++++++++++++++++---- include/linux/fs.h | 26 +++++++ include/linux/skbuff.h | 10 +++ include/linux/splice.h | 42 +++++++++++ init/Kconfig | 10 +++ kernel/sys_ni.c | 8 ++ net/core/skbuff.c | 11 ++- net/sunrpc/svc.c | 2 +- 11 files changed, 299 insertions(+), 192 deletions(-) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
