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Date: Sun, 23 Nov 2014 15:20:47 +0100 From: Pieter Smith <pieter@...sman.nl> To: pieter@...sman.nl Cc: Josh Triplett <josh@...htriplett.org>, Alexander Duyck <alexander.h.duyck@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, Alexei Starovoitov <ast@...mgrid.com>, Andrew Morton <akpm@...ux-foundation.org>, Bertrand Jacquin <beber@...eeweb.net>, Catalina Mocanu <catalina.mocanu@...il.com>, Daniel Borkmann <dborkman@...hat.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, Fabian Frederick <fabf@...net.be>, fuse-devel@...ts.sourceforge.net (open list:FUSE: FILESYSTEM...), Geert Uytterhoeven <geert@...ux-m68k.org>, Hugh Dickins <hughd@...gle.com>, Iulia Manda <iulia.manda21@...il.com>, Jan Beulich <JBeulich@...e.com>, "J. Bruce Fields" <bfields@...ldses.org>, Jeff Layton <jlayton@...chiereds.net>, linux-api@...r.kernel.org (open list:ABI/API), linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org (open list), "Luis R. Rodriguez" <mcgrof@...e.com>, Matt Turner <mattst88@...il.com>, Mel Gorman <mgorman@...e.de>, "Michael S. Tsirkin" <mst@...hat.com>, Miklos Szeredi <miklos@...redi.hu>, netdev@...r.kernel.org (open list:NETWORKING [GENERAL]), Oleg Nesterov <oleg@...hat.com>, Paul Durrant <Paul.Durrant@...rix.com>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Peter Foley <pefoley2@...oley.com>, Thomas Graf <tgraf@...g.ch>, Tom Herbert <therbert@...gle.com>, Willem de Bruijn <willemb@...gle.com>, Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>, 蔡正龙 <zhenglong.cai@...c.com.cn> Subject: [PATCH 3/6] fs/splice: support compiling out splice-family syscalls Many embedded systems will not need the splice-family syscalls (splice, vmsplice, tee and sendfile). Omitting them saves space. This adds a new EXPERT config option CONFIG_SYSCALL_SPLICE (default y) to support compiling them out. The goal is to completely compile out fs/splice. To achieve this, the remaining patch-set will deal with fs/splice exports. As far as possible, the impact on other device drivers will be minimized so as to reduce the maintenance burden of CONFIG_SYSCALL_SPLICE. The use of exported functions will be solved by transparently mocking them out with static inlines. Use of the exported pipe_buf_operations struct however require direct modification in fs/fuse and net/core. The next two patches will deal with this. Once all exports are solved, fs/splice can be compiled out. The bloat benefit of this patch given a tinyconfig is: add/remove: 0/16 grow/shrink: 2/5 up/down: 114/-3693 (-3579) function old new delta splice_direct_to_actor 348 416 +68 splice_to_pipe 371 417 +46 splice_from_pipe_next 107 106 -1 fdput 11 - -11 signal_pending 39 26 -13 fdget 56 42 -14 user_page_pipe_buf_ops 20 - -20 user_page_pipe_buf_steal 25 - -25 file_end_write 58 29 -29 file_start_write 68 34 -34 pipe_to_user 43 - -43 wakeup_pipe_readers 54 - -54 do_splice_to 87 - -87 ipipe_prep.part 92 - -92 opipe_prep.part 119 - -119 sys_sendfile 122 - -122 sys_sendfile64 126 - -126 sys_vmsplice 137 - -137 vmsplice_to_user 205 - -205 sys_tee 491 - -491 do_sendfile 492 - -492 vmsplice_to_pipe 558 - -558 sys_splice 1020 - -1020 Signed-off-by: Pieter Smith <pieter@...sman.nl> --- fs/splice.c | 2 ++ init/Kconfig | 10 ++++++++++ kernel/sys_ni.c | 8 ++++++++ 3 files changed, 20 insertions(+) diff --git a/fs/splice.c b/fs/splice.c index 44b201b..7c4c695 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -1316,6 +1316,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, return ret; } +#ifdef CONFIG_SYSCALL_SPLICE static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, struct pipe_inode_info *opipe, size_t len, unsigned int flags); @@ -2200,4 +2201,5 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, return do_sendfile(out_fd, in_fd, NULL, count, 0); } #endif +#endif diff --git a/init/Kconfig b/init/Kconfig index d811d5f..dec9819 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1571,6 +1571,16 @@ config NTP system clock to an NTP server, you can disable this option to save space. +config SYSCALL_SPLICE + bool "Enable splice/vmsplice/tee/sendfile syscalls" if EXPERT + default y + help + This option enables the splice, vmsplice, tee and sendfile syscalls. These + are used by applications to: move data between buffers and arbitrary file + descriptors; "copy" data between buffers; or copy data from userspace into + buffers. If building an embedded system where no applications use these + syscalls, you can disable this option to save space. + config PCI_QUIRKS default y bool "Enable PCI quirk workarounds" if EXPERT diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index d2f5b00..25d5551 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -170,6 +170,14 @@ cond_syscall(sys_fstat); cond_syscall(sys_stat); cond_syscall(sys_uname); cond_syscall(sys_olduname); +cond_syscall(sys_vmsplice); +cond_syscall(sys_splice); +cond_syscall(sys_tee); +cond_syscall(sys_sendfile); +cond_syscall(sys_sendfile64); +cond_syscall(compat_sys_vmsplice); +cond_syscall(compat_sys_sendfile); +cond_syscall(compat_sys_sendfile64); /* arch-specific weak syscall entries */ cond_syscall(sys_pciconfig_read); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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