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![Serge E. Hallyn](/assets/img/avatar_default.png)
Implement file posix capabilities. This allows programs to be given a subset of root's powers regardless of who runs them, without having to use setuid and giving the binary all of root's powers. This version works with Kaigai Kohei's userspace tools, found at http://www.kaigai.gr.jp/index.php. For more information on how to use this patch, Chris Friedhoff has posted a nice page at http://www.friedhoff.org/fscaps.html. Changelog: Nov 27: Incorporate fixes from Andrew Morton (security-introduce-file-caps-tweaks and security-introduce-file-caps-warning-fix) Fix Kconfig dependency. Fix change signaling behavior when file caps are not compiled in. Nov 13: Integrate comments from Alexey: Remove CONFIG_ ifdef from capability.h, and use %zd for printing a size_t. Nov 13: Fix endianness warnings by sparse as suggested by Alexey Dobriyan. Nov 09: Address warnings of unused variables at cap_bprm_set_security when file capabilities are disabled, and simultaneously clean up the code a little, by pulling the new code into a helper function. Nov 08: For pointers to required userspace tools and how to use them, see http://www.friedhoff.org/fscaps.html. Nov 07: Fix the calculation of the highest bit checked in check_cap_sanity(). Nov 07: Allow file caps to be enabled without CONFIG_SECURITY, since capabilities are the default. Hook cap_task_setscheduler when !CONFIG_SECURITY. Move capable(TASK_KILL) to end of cap_task_kill to reduce audit messages. Nov 05: Add secondary calls in selinux/hooks.c to task_setioprio and task_setscheduler so that selinux and capabilities with file cap support can be stacked. Sep 05: As Seth Arnold points out, uid checks are out of place for capability code. Sep 01: Define task_setscheduler, task_setioprio, cap_task_kill, and task_setnice to make sure a user cannot affect a process in which they called a program with some fscaps. One remaining question is the note under task_setscheduler: are we ok with CAP_SYS_NICE being sufficient to confine a process to a cpuset? It is a semantic change, as without fsccaps, attach_task doesn't allow CAP_SYS_NICE to override the uid equivalence check. But since it uses security_task_setscheduler, which elsewhere is used where CAP_SYS_NICE can be used to override the uid equivalence check, fixing it might be tough. task_setscheduler note: this also controls cpuset:attach_task. Are we ok with CAP_SYS_NICE being used to confine to a cpuset? task_setioprio task_setnice sys_setpriority uses this (through set_one_prio) for another process. Need same checks as setrlimit Aug 21: Updated secureexec implementation to reflect the fact that euid and uid might be the same and nonzero, but the process might still have elevated caps. Aug 15: Handle endianness of xattrs. Enforce capability version match between kernel and disk. Enforce that no bits beyond the known max capability are set, else return -EPERM. With this extra processing, it may be worth reconsidering doing all the work at bprm_set_security rather than d_instantiate. Aug 10: Always call getxattr at bprm_set_security, rather than caching it at d_instantiate. [morgan@kernel.org: file-caps clean up for linux/capability.h] [bunk@kernel.org: unexport cap_inode_killpriv] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Andrew Morgan <morgan@kernel.org> Signed-off-by: Andrew Morgan <morgan@kernel.org> Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1744 lines
40 KiB
C
1744 lines
40 KiB
C
/*
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* "splice": joining two ropes together by interweaving their strands.
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*
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* This is the "extended pipe" functionality, where a pipe is used as
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* an arbitrary in-memory buffer. Think of a pipe as a small kernel
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* buffer that you can use to transfer data from one end to the other.
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*
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* The traditional unix read/write is extended with a "splice()" operation
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* that transfers data buffers to or from a pipe buffer.
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*
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* Named by Larry McVoy, original implementation from Linus, extended by
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* Jens to support splicing to files, network, direct splicing, etc and
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* fixing lots of bugs.
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*
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* Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
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* Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
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* Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
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*
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*/
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/splice.h>
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#include <linux/mm_inline.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/buffer_head.h>
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#include <linux/module.h>
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#include <linux/syscalls.h>
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#include <linux/uio.h>
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#include <linux/security.h>
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/*
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* Attempt to steal a page from a pipe buffer. This should perhaps go into
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* a vm helper function, it's already simplified quite a bit by the
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* addition of remove_mapping(). If success is returned, the caller may
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* attempt to reuse this page for another destination.
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*/
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static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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struct page *page = buf->page;
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struct address_space *mapping;
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lock_page(page);
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mapping = page_mapping(page);
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if (mapping) {
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WARN_ON(!PageUptodate(page));
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/*
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* At least for ext2 with nobh option, we need to wait on
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* writeback completing on this page, since we'll remove it
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* from the pagecache. Otherwise truncate wont wait on the
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* page, allowing the disk blocks to be reused by someone else
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* before we actually wrote our data to them. fs corruption
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* ensues.
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*/
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wait_on_page_writeback(page);
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if (PagePrivate(page))
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try_to_release_page(page, GFP_KERNEL);
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/*
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* If we succeeded in removing the mapping, set LRU flag
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* and return good.
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*/
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if (remove_mapping(mapping, page)) {
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buf->flags |= PIPE_BUF_FLAG_LRU;
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return 0;
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}
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}
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/*
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* Raced with truncate or failed to remove page from current
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* address space, unlock and return failure.
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*/
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unlock_page(page);
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return 1;
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}
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static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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page_cache_release(buf->page);
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buf->flags &= ~PIPE_BUF_FLAG_LRU;
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}
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/*
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* Check whether the contents of buf is OK to access. Since the content
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* is a page cache page, IO may be in flight.
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*/
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static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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struct page *page = buf->page;
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int err;
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if (!PageUptodate(page)) {
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lock_page(page);
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/*
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* Page got truncated/unhashed. This will cause a 0-byte
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* splice, if this is the first page.
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*/
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if (!page->mapping) {
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err = -ENODATA;
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goto error;
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}
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/*
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* Uh oh, read-error from disk.
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*/
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if (!PageUptodate(page)) {
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err = -EIO;
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goto error;
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}
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/*
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* Page is ok afterall, we are done.
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*/
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unlock_page(page);
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}
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return 0;
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error:
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unlock_page(page);
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return err;
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}
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static const struct pipe_buf_operations page_cache_pipe_buf_ops = {
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.can_merge = 0,
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.map = generic_pipe_buf_map,
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.unmap = generic_pipe_buf_unmap,
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.confirm = page_cache_pipe_buf_confirm,
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.release = page_cache_pipe_buf_release,
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.steal = page_cache_pipe_buf_steal,
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.get = generic_pipe_buf_get,
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};
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static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
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return 1;
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buf->flags |= PIPE_BUF_FLAG_LRU;
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return generic_pipe_buf_steal(pipe, buf);
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}
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static const struct pipe_buf_operations user_page_pipe_buf_ops = {
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.can_merge = 0,
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.map = generic_pipe_buf_map,
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.unmap = generic_pipe_buf_unmap,
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.confirm = generic_pipe_buf_confirm,
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.release = page_cache_pipe_buf_release,
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.steal = user_page_pipe_buf_steal,
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.get = generic_pipe_buf_get,
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};
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/**
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* splice_to_pipe - fill passed data into a pipe
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* @pipe: pipe to fill
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* @spd: data to fill
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*
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* Description:
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* @spd contains a map of pages and len/offset tuples, along with
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* the struct pipe_buf_operations associated with these pages. This
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* function will link that data to the pipe.
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*
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*/
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ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
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struct splice_pipe_desc *spd)
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{
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unsigned int spd_pages = spd->nr_pages;
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int ret, do_wakeup, page_nr;
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ret = 0;
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do_wakeup = 0;
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page_nr = 0;
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if (pipe->inode)
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mutex_lock(&pipe->inode->i_mutex);
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for (;;) {
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if (!pipe->readers) {
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send_sig(SIGPIPE, current, 0);
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if (!ret)
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ret = -EPIPE;
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break;
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}
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if (pipe->nrbufs < PIPE_BUFFERS) {
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int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
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struct pipe_buffer *buf = pipe->bufs + newbuf;
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buf->page = spd->pages[page_nr];
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buf->offset = spd->partial[page_nr].offset;
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buf->len = spd->partial[page_nr].len;
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buf->private = spd->partial[page_nr].private;
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buf->ops = spd->ops;
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if (spd->flags & SPLICE_F_GIFT)
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buf->flags |= PIPE_BUF_FLAG_GIFT;
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pipe->nrbufs++;
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page_nr++;
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ret += buf->len;
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if (pipe->inode)
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do_wakeup = 1;
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if (!--spd->nr_pages)
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break;
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if (pipe->nrbufs < PIPE_BUFFERS)
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continue;
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break;
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}
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if (spd->flags & SPLICE_F_NONBLOCK) {
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if (!ret)
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ret = -EAGAIN;
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break;
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}
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if (signal_pending(current)) {
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if (!ret)
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ret = -ERESTARTSYS;
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break;
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}
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if (do_wakeup) {
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smp_mb();
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if (waitqueue_active(&pipe->wait))
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wake_up_interruptible_sync(&pipe->wait);
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kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
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do_wakeup = 0;
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}
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pipe->waiting_writers++;
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pipe_wait(pipe);
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pipe->waiting_writers--;
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}
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if (pipe->inode) {
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mutex_unlock(&pipe->inode->i_mutex);
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if (do_wakeup) {
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smp_mb();
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if (waitqueue_active(&pipe->wait))
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wake_up_interruptible(&pipe->wait);
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kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
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}
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}
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while (page_nr < spd_pages)
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page_cache_release(spd->pages[page_nr++]);
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return ret;
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}
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static int
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__generic_file_splice_read(struct file *in, loff_t *ppos,
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struct pipe_inode_info *pipe, size_t len,
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unsigned int flags)
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{
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struct address_space *mapping = in->f_mapping;
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unsigned int loff, nr_pages, req_pages;
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struct page *pages[PIPE_BUFFERS];
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struct partial_page partial[PIPE_BUFFERS];
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struct page *page;
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pgoff_t index, end_index;
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loff_t isize;
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int error, page_nr;
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struct splice_pipe_desc spd = {
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.pages = pages,
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.partial = partial,
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.flags = flags,
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.ops = &page_cache_pipe_buf_ops,
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};
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index = *ppos >> PAGE_CACHE_SHIFT;
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loff = *ppos & ~PAGE_CACHE_MASK;
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req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS);
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/*
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* Lookup the (hopefully) full range of pages we need.
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*/
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spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
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index += spd.nr_pages;
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/*
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* If find_get_pages_contig() returned fewer pages than we needed,
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* readahead/allocate the rest and fill in the holes.
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*/
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if (spd.nr_pages < nr_pages)
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page_cache_sync_readahead(mapping, &in->f_ra, in,
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index, req_pages - spd.nr_pages);
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error = 0;
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while (spd.nr_pages < nr_pages) {
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/*
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* Page could be there, find_get_pages_contig() breaks on
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* the first hole.
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*/
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page = find_get_page(mapping, index);
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if (!page) {
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/*
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* page didn't exist, allocate one.
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*/
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page = page_cache_alloc_cold(mapping);
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if (!page)
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break;
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error = add_to_page_cache_lru(page, mapping, index,
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GFP_KERNEL);
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if (unlikely(error)) {
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page_cache_release(page);
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if (error == -EEXIST)
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continue;
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break;
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}
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/*
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* add_to_page_cache() locks the page, unlock it
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* to avoid convoluting the logic below even more.
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*/
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unlock_page(page);
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}
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pages[spd.nr_pages++] = page;
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index++;
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}
|
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/*
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* Now loop over the map and see if we need to start IO on any
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* pages, fill in the partial map, etc.
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*/
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index = *ppos >> PAGE_CACHE_SHIFT;
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nr_pages = spd.nr_pages;
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spd.nr_pages = 0;
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for (page_nr = 0; page_nr < nr_pages; page_nr++) {
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unsigned int this_len;
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if (!len)
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break;
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/*
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* this_len is the max we'll use from this page
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*/
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this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
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page = pages[page_nr];
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if (PageReadahead(page))
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page_cache_async_readahead(mapping, &in->f_ra, in,
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page, index, req_pages - page_nr);
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|
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/*
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* If the page isn't uptodate, we may need to start io on it
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*/
|
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if (!PageUptodate(page)) {
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/*
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* If in nonblock mode then dont block on waiting
|
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* for an in-flight io page
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*/
|
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if (flags & SPLICE_F_NONBLOCK) {
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if (TestSetPageLocked(page))
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break;
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} else
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lock_page(page);
|
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|
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/*
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* page was truncated, stop here. if this isn't the
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* first page, we'll just complete what we already
|
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* added
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*/
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if (!page->mapping) {
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unlock_page(page);
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break;
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}
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/*
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* page was already under io and is now done, great
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*/
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if (PageUptodate(page)) {
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unlock_page(page);
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goto fill_it;
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}
|
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|
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/*
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* need to read in the page
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*/
|
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error = mapping->a_ops->readpage(in, page);
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if (unlikely(error)) {
|
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/*
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* We really should re-lookup the page here,
|
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* but it complicates things a lot. Instead
|
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* lets just do what we already stored, and
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* we'll get it the next time we are called.
|
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*/
|
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if (error == AOP_TRUNCATED_PAGE)
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error = 0;
|
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|
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break;
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}
|
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}
|
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fill_it:
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/*
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* i_size must be checked after PageUptodate.
|
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*/
|
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isize = i_size_read(mapping->host);
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end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
|
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if (unlikely(!isize || index > end_index))
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break;
|
|
|
|
/*
|
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* if this is the last page, see if we need to shrink
|
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* the length and stop
|
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*/
|
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if (end_index == index) {
|
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unsigned int plen;
|
|
|
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/*
|
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* max good bytes in this page
|
|
*/
|
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plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
|
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if (plen <= loff)
|
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break;
|
|
|
|
/*
|
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* force quit after adding this page
|
|
*/
|
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this_len = min(this_len, plen - loff);
|
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len = this_len;
|
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}
|
|
|
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partial[page_nr].offset = loff;
|
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partial[page_nr].len = this_len;
|
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len -= this_len;
|
|
loff = 0;
|
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spd.nr_pages++;
|
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index++;
|
|
}
|
|
|
|
/*
|
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* Release any pages at the end, if we quit early. 'page_nr' is how far
|
|
* we got, 'nr_pages' is how many pages are in the map.
|
|
*/
|
|
while (page_nr < nr_pages)
|
|
page_cache_release(pages[page_nr++]);
|
|
in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
|
|
|
|
if (spd.nr_pages)
|
|
return splice_to_pipe(pipe, &spd);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* generic_file_splice_read - splice data from file to a pipe
|
|
* @in: file to splice from
|
|
* @ppos: position in @in
|
|
* @pipe: pipe to splice to
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will read pages from given file and fill them into a pipe. Can be
|
|
* used as long as the address_space operations for the source implements
|
|
* a readpage() hook.
|
|
*
|
|
*/
|
|
ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
|
|
struct pipe_inode_info *pipe, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
ssize_t spliced;
|
|
int ret;
|
|
loff_t isize, left;
|
|
|
|
isize = i_size_read(in->f_mapping->host);
|
|
if (unlikely(*ppos >= isize))
|
|
return 0;
|
|
|
|
left = isize - *ppos;
|
|
if (unlikely(left < len))
|
|
len = left;
|
|
|
|
ret = 0;
|
|
spliced = 0;
|
|
while (len && !spliced) {
|
|
ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
|
|
|
|
if (ret < 0)
|
|
break;
|
|
else if (!ret) {
|
|
if (spliced)
|
|
break;
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
}
|
|
|
|
*ppos += ret;
|
|
len -= ret;
|
|
spliced += ret;
|
|
}
|
|
|
|
if (spliced)
|
|
return spliced;
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_splice_read);
|
|
|
|
/*
|
|
* Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
|
|
* using sendpage(). Return the number of bytes sent.
|
|
*/
|
|
static int pipe_to_sendpage(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf, struct splice_desc *sd)
|
|
{
|
|
struct file *file = sd->u.file;
|
|
loff_t pos = sd->pos;
|
|
int ret, more;
|
|
|
|
ret = buf->ops->confirm(pipe, buf);
|
|
if (!ret) {
|
|
more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
|
|
|
|
ret = file->f_op->sendpage(file, buf->page, buf->offset,
|
|
sd->len, &pos, more);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This is a little more tricky than the file -> pipe splicing. There are
|
|
* basically three cases:
|
|
*
|
|
* - Destination page already exists in the address space and there
|
|
* are users of it. For that case we have no other option that
|
|
* copying the data. Tough luck.
|
|
* - Destination page already exists in the address space, but there
|
|
* are no users of it. Make sure it's uptodate, then drop it. Fall
|
|
* through to last case.
|
|
* - Destination page does not exist, we can add the pipe page to
|
|
* the page cache and avoid the copy.
|
|
*
|
|
* If asked to move pages to the output file (SPLICE_F_MOVE is set in
|
|
* sd->flags), we attempt to migrate pages from the pipe to the output
|
|
* file address space page cache. This is possible if no one else has
|
|
* the pipe page referenced outside of the pipe and page cache. If
|
|
* SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
|
|
* a new page in the output file page cache and fill/dirty that.
|
|
*/
|
|
static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
|
|
struct splice_desc *sd)
|
|
{
|
|
struct file *file = sd->u.file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
unsigned int offset, this_len;
|
|
struct page *page;
|
|
void *fsdata;
|
|
int ret;
|
|
|
|
/*
|
|
* make sure the data in this buffer is uptodate
|
|
*/
|
|
ret = buf->ops->confirm(pipe, buf);
|
|
if (unlikely(ret))
|
|
return ret;
|
|
|
|
offset = sd->pos & ~PAGE_CACHE_MASK;
|
|
|
|
this_len = sd->len;
|
|
if (this_len + offset > PAGE_CACHE_SIZE)
|
|
this_len = PAGE_CACHE_SIZE - offset;
|
|
|
|
ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
|
|
AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
|
|
if (unlikely(ret))
|
|
goto out;
|
|
|
|
if (buf->page != page) {
|
|
/*
|
|
* Careful, ->map() uses KM_USER0!
|
|
*/
|
|
char *src = buf->ops->map(pipe, buf, 1);
|
|
char *dst = kmap_atomic(page, KM_USER1);
|
|
|
|
memcpy(dst + offset, src + buf->offset, this_len);
|
|
flush_dcache_page(page);
|
|
kunmap_atomic(dst, KM_USER1);
|
|
buf->ops->unmap(pipe, buf, src);
|
|
}
|
|
ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
|
|
page, fsdata);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* __splice_from_pipe - splice data from a pipe to given actor
|
|
* @pipe: pipe to splice from
|
|
* @sd: information to @actor
|
|
* @actor: handler that splices the data
|
|
*
|
|
* Description:
|
|
* This function does little more than loop over the pipe and call
|
|
* @actor to do the actual moving of a single struct pipe_buffer to
|
|
* the desired destination. See pipe_to_file, pipe_to_sendpage, or
|
|
* pipe_to_user.
|
|
*
|
|
*/
|
|
ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
|
|
splice_actor *actor)
|
|
{
|
|
int ret, do_wakeup, err;
|
|
|
|
ret = 0;
|
|
do_wakeup = 0;
|
|
|
|
for (;;) {
|
|
if (pipe->nrbufs) {
|
|
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
|
|
const struct pipe_buf_operations *ops = buf->ops;
|
|
|
|
sd->len = buf->len;
|
|
if (sd->len > sd->total_len)
|
|
sd->len = sd->total_len;
|
|
|
|
err = actor(pipe, buf, sd);
|
|
if (err <= 0) {
|
|
if (!ret && err != -ENODATA)
|
|
ret = err;
|
|
|
|
break;
|
|
}
|
|
|
|
ret += err;
|
|
buf->offset += err;
|
|
buf->len -= err;
|
|
|
|
sd->len -= err;
|
|
sd->pos += err;
|
|
sd->total_len -= err;
|
|
if (sd->len)
|
|
continue;
|
|
|
|
if (!buf->len) {
|
|
buf->ops = NULL;
|
|
ops->release(pipe, buf);
|
|
pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
|
|
pipe->nrbufs--;
|
|
if (pipe->inode)
|
|
do_wakeup = 1;
|
|
}
|
|
|
|
if (!sd->total_len)
|
|
break;
|
|
}
|
|
|
|
if (pipe->nrbufs)
|
|
continue;
|
|
if (!pipe->writers)
|
|
break;
|
|
if (!pipe->waiting_writers) {
|
|
if (ret)
|
|
break;
|
|
}
|
|
|
|
if (sd->flags & SPLICE_F_NONBLOCK) {
|
|
if (!ret)
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
|
|
if (signal_pending(current)) {
|
|
if (!ret)
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
|
|
if (do_wakeup) {
|
|
smp_mb();
|
|
if (waitqueue_active(&pipe->wait))
|
|
wake_up_interruptible_sync(&pipe->wait);
|
|
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
|
|
do_wakeup = 0;
|
|
}
|
|
|
|
pipe_wait(pipe);
|
|
}
|
|
|
|
if (do_wakeup) {
|
|
smp_mb();
|
|
if (waitqueue_active(&pipe->wait))
|
|
wake_up_interruptible(&pipe->wait);
|
|
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__splice_from_pipe);
|
|
|
|
/**
|
|
* splice_from_pipe - splice data from a pipe to a file
|
|
* @pipe: pipe to splice from
|
|
* @out: file to splice to
|
|
* @ppos: position in @out
|
|
* @len: how many bytes to splice
|
|
* @flags: splice modifier flags
|
|
* @actor: handler that splices the data
|
|
*
|
|
* Description:
|
|
* See __splice_from_pipe. This function locks the input and output inodes,
|
|
* otherwise it's identical to __splice_from_pipe().
|
|
*
|
|
*/
|
|
ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags,
|
|
splice_actor *actor)
|
|
{
|
|
ssize_t ret;
|
|
struct inode *inode = out->f_mapping->host;
|
|
struct splice_desc sd = {
|
|
.total_len = len,
|
|
.flags = flags,
|
|
.pos = *ppos,
|
|
.u.file = out,
|
|
};
|
|
|
|
/*
|
|
* The actor worker might be calling ->prepare_write and
|
|
* ->commit_write. Most of the time, these expect i_mutex to
|
|
* be held. Since this may result in an ABBA deadlock with
|
|
* pipe->inode, we have to order lock acquiry here.
|
|
*/
|
|
inode_double_lock(inode, pipe->inode);
|
|
ret = __splice_from_pipe(pipe, &sd, actor);
|
|
inode_double_unlock(inode, pipe->inode);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* generic_file_splice_write_nolock - generic_file_splice_write without mutexes
|
|
* @pipe: pipe info
|
|
* @out: file to write to
|
|
* @ppos: position in @out
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will either move or copy pages (determined by @flags options) from
|
|
* the given pipe inode to the given file. The caller is responsible
|
|
* for acquiring i_mutex on both inodes.
|
|
*
|
|
*/
|
|
ssize_t
|
|
generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
struct address_space *mapping = out->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
struct splice_desc sd = {
|
|
.total_len = len,
|
|
.flags = flags,
|
|
.pos = *ppos,
|
|
.u.file = out,
|
|
};
|
|
ssize_t ret;
|
|
int err;
|
|
|
|
err = remove_suid(out->f_path.dentry);
|
|
if (unlikely(err))
|
|
return err;
|
|
|
|
ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
|
|
if (ret > 0) {
|
|
unsigned long nr_pages;
|
|
|
|
*ppos += ret;
|
|
nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
|
|
/*
|
|
* If file or inode is SYNC and we actually wrote some data,
|
|
* sync it.
|
|
*/
|
|
if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
err = generic_osync_inode(inode, mapping,
|
|
OSYNC_METADATA|OSYNC_DATA);
|
|
|
|
if (err)
|
|
ret = err;
|
|
}
|
|
balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_splice_write_nolock);
|
|
|
|
/**
|
|
* generic_file_splice_write - splice data from a pipe to a file
|
|
* @pipe: pipe info
|
|
* @out: file to write to
|
|
* @ppos: position in @out
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will either move or copy pages (determined by @flags options) from
|
|
* the given pipe inode to the given file.
|
|
*
|
|
*/
|
|
ssize_t
|
|
generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
struct address_space *mapping = out->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
int killsuid, killpriv;
|
|
ssize_t ret;
|
|
int err = 0;
|
|
|
|
killpriv = security_inode_need_killpriv(out->f_path.dentry);
|
|
killsuid = should_remove_suid(out->f_path.dentry);
|
|
if (unlikely(killsuid || killpriv)) {
|
|
mutex_lock(&inode->i_mutex);
|
|
if (killpriv)
|
|
err = security_inode_killpriv(out->f_path.dentry);
|
|
if (!err && killsuid)
|
|
err = __remove_suid(out->f_path.dentry, killsuid);
|
|
mutex_unlock(&inode->i_mutex);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
|
|
if (ret > 0) {
|
|
unsigned long nr_pages;
|
|
|
|
*ppos += ret;
|
|
nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
|
|
/*
|
|
* If file or inode is SYNC and we actually wrote some data,
|
|
* sync it.
|
|
*/
|
|
if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
mutex_lock(&inode->i_mutex);
|
|
err = generic_osync_inode(inode, mapping,
|
|
OSYNC_METADATA|OSYNC_DATA);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
if (err)
|
|
ret = err;
|
|
}
|
|
balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_splice_write);
|
|
|
|
/**
|
|
* generic_splice_sendpage - splice data from a pipe to a socket
|
|
* @pipe: pipe to splice from
|
|
* @out: socket to write to
|
|
* @ppos: position in @out
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will send @len bytes from the pipe to a network socket. No data copying
|
|
* is involved.
|
|
*
|
|
*/
|
|
ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_splice_sendpage);
|
|
|
|
/*
|
|
* Attempt to initiate a splice from pipe to file.
|
|
*/
|
|
static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
if (unlikely(!out->f_op || !out->f_op->splice_write))
|
|
return -EINVAL;
|
|
|
|
if (unlikely(!(out->f_mode & FMODE_WRITE)))
|
|
return -EBADF;
|
|
|
|
ret = rw_verify_area(WRITE, out, ppos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
ret = security_file_permission(out, MAY_WRITE);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
return out->f_op->splice_write(pipe, out, ppos, len, flags);
|
|
}
|
|
|
|
/*
|
|
* Attempt to initiate a splice from a file to a pipe.
|
|
*/
|
|
static long do_splice_to(struct file *in, loff_t *ppos,
|
|
struct pipe_inode_info *pipe, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
if (unlikely(!in->f_op || !in->f_op->splice_read))
|
|
return -EINVAL;
|
|
|
|
if (unlikely(!(in->f_mode & FMODE_READ)))
|
|
return -EBADF;
|
|
|
|
ret = rw_verify_area(READ, in, ppos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
ret = security_file_permission(in, MAY_READ);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
return in->f_op->splice_read(in, ppos, pipe, len, flags);
|
|
}
|
|
|
|
/**
|
|
* splice_direct_to_actor - splices data directly between two non-pipes
|
|
* @in: file to splice from
|
|
* @sd: actor information on where to splice to
|
|
* @actor: handles the data splicing
|
|
*
|
|
* Description:
|
|
* This is a special case helper to splice directly between two
|
|
* points, without requiring an explicit pipe. Internally an allocated
|
|
* pipe is cached in the process, and reused during the lifetime of
|
|
* that process.
|
|
*
|
|
*/
|
|
ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
|
|
splice_direct_actor *actor)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
long ret, bytes;
|
|
umode_t i_mode;
|
|
size_t len;
|
|
int i, flags;
|
|
|
|
/*
|
|
* We require the input being a regular file, as we don't want to
|
|
* randomly drop data for eg socket -> socket splicing. Use the
|
|
* piped splicing for that!
|
|
*/
|
|
i_mode = in->f_path.dentry->d_inode->i_mode;
|
|
if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* neither in nor out is a pipe, setup an internal pipe attached to
|
|
* 'out' and transfer the wanted data from 'in' to 'out' through that
|
|
*/
|
|
pipe = current->splice_pipe;
|
|
if (unlikely(!pipe)) {
|
|
pipe = alloc_pipe_info(NULL);
|
|
if (!pipe)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* We don't have an immediate reader, but we'll read the stuff
|
|
* out of the pipe right after the splice_to_pipe(). So set
|
|
* PIPE_READERS appropriately.
|
|
*/
|
|
pipe->readers = 1;
|
|
|
|
current->splice_pipe = pipe;
|
|
}
|
|
|
|
/*
|
|
* Do the splice.
|
|
*/
|
|
ret = 0;
|
|
bytes = 0;
|
|
len = sd->total_len;
|
|
flags = sd->flags;
|
|
|
|
/*
|
|
* Don't block on output, we have to drain the direct pipe.
|
|
*/
|
|
sd->flags &= ~SPLICE_F_NONBLOCK;
|
|
|
|
while (len) {
|
|
size_t read_len;
|
|
loff_t pos = sd->pos;
|
|
|
|
ret = do_splice_to(in, &pos, pipe, len, flags);
|
|
if (unlikely(ret <= 0))
|
|
goto out_release;
|
|
|
|
read_len = ret;
|
|
sd->total_len = read_len;
|
|
|
|
/*
|
|
* NOTE: nonblocking mode only applies to the input. We
|
|
* must not do the output in nonblocking mode as then we
|
|
* could get stuck data in the internal pipe:
|
|
*/
|
|
ret = actor(pipe, sd);
|
|
if (unlikely(ret <= 0))
|
|
goto out_release;
|
|
|
|
bytes += ret;
|
|
len -= ret;
|
|
sd->pos = pos;
|
|
|
|
if (ret < read_len)
|
|
goto out_release;
|
|
}
|
|
|
|
pipe->nrbufs = pipe->curbuf = 0;
|
|
return bytes;
|
|
|
|
out_release:
|
|
/*
|
|
* If we did an incomplete transfer we must release
|
|
* the pipe buffers in question:
|
|
*/
|
|
for (i = 0; i < PIPE_BUFFERS; i++) {
|
|
struct pipe_buffer *buf = pipe->bufs + i;
|
|
|
|
if (buf->ops) {
|
|
buf->ops->release(pipe, buf);
|
|
buf->ops = NULL;
|
|
}
|
|
}
|
|
pipe->nrbufs = pipe->curbuf = 0;
|
|
|
|
/*
|
|
* If we transferred some data, return the number of bytes:
|
|
*/
|
|
if (bytes > 0)
|
|
return bytes;
|
|
|
|
return ret;
|
|
|
|
}
|
|
EXPORT_SYMBOL(splice_direct_to_actor);
|
|
|
|
static int direct_splice_actor(struct pipe_inode_info *pipe,
|
|
struct splice_desc *sd)
|
|
{
|
|
struct file *file = sd->u.file;
|
|
|
|
return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
|
|
}
|
|
|
|
/**
|
|
* do_splice_direct - splices data directly between two files
|
|
* @in: file to splice from
|
|
* @ppos: input file offset
|
|
* @out: file to splice to
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* For use by do_sendfile(). splice can easily emulate sendfile, but
|
|
* doing it in the application would incur an extra system call
|
|
* (splice in + splice out, as compared to just sendfile()). So this helper
|
|
* can splice directly through a process-private pipe.
|
|
*
|
|
*/
|
|
long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct splice_desc sd = {
|
|
.len = len,
|
|
.total_len = len,
|
|
.flags = flags,
|
|
.pos = *ppos,
|
|
.u.file = out,
|
|
};
|
|
long ret;
|
|
|
|
ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
|
|
if (ret > 0)
|
|
*ppos += ret;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
|
|
* location, so checking ->i_pipe is not enough to verify that this is a
|
|
* pipe.
|
|
*/
|
|
static inline struct pipe_inode_info *pipe_info(struct inode *inode)
|
|
{
|
|
if (S_ISFIFO(inode->i_mode))
|
|
return inode->i_pipe;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Determine where to splice to/from.
|
|
*/
|
|
static long do_splice(struct file *in, loff_t __user *off_in,
|
|
struct file *out, loff_t __user *off_out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
loff_t offset, *off;
|
|
long ret;
|
|
|
|
pipe = pipe_info(in->f_path.dentry->d_inode);
|
|
if (pipe) {
|
|
if (off_in)
|
|
return -ESPIPE;
|
|
if (off_out) {
|
|
if (out->f_op->llseek == no_llseek)
|
|
return -EINVAL;
|
|
if (copy_from_user(&offset, off_out, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
off = &offset;
|
|
} else
|
|
off = &out->f_pos;
|
|
|
|
ret = do_splice_from(pipe, out, off, len, flags);
|
|
|
|
if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
|
|
ret = -EFAULT;
|
|
|
|
return ret;
|
|
}
|
|
|
|
pipe = pipe_info(out->f_path.dentry->d_inode);
|
|
if (pipe) {
|
|
if (off_out)
|
|
return -ESPIPE;
|
|
if (off_in) {
|
|
if (in->f_op->llseek == no_llseek)
|
|
return -EINVAL;
|
|
if (copy_from_user(&offset, off_in, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
off = &offset;
|
|
} else
|
|
off = &in->f_pos;
|
|
|
|
ret = do_splice_to(in, off, pipe, len, flags);
|
|
|
|
if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
|
|
ret = -EFAULT;
|
|
|
|
return ret;
|
|
}
|
|
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Do a copy-from-user while holding the mmap_semaphore for reading, in a
|
|
* manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem
|
|
* for writing) and page faulting on the user memory pointed to by src.
|
|
* This assumes that we will very rarely hit the partial != 0 path, or this
|
|
* will not be a win.
|
|
*/
|
|
static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n)
|
|
{
|
|
int partial;
|
|
|
|
pagefault_disable();
|
|
partial = __copy_from_user_inatomic(dst, src, n);
|
|
pagefault_enable();
|
|
|
|
/*
|
|
* Didn't copy everything, drop the mmap_sem and do a faulting copy
|
|
*/
|
|
if (unlikely(partial)) {
|
|
up_read(¤t->mm->mmap_sem);
|
|
partial = copy_from_user(dst, src, n);
|
|
down_read(¤t->mm->mmap_sem);
|
|
}
|
|
|
|
return partial;
|
|
}
|
|
|
|
/*
|
|
* Map an iov into an array of pages and offset/length tupples. With the
|
|
* partial_page structure, we can map several non-contiguous ranges into
|
|
* our ones pages[] map instead of splitting that operation into pieces.
|
|
* Could easily be exported as a generic helper for other users, in which
|
|
* case one would probably want to add a 'max_nr_pages' parameter as well.
|
|
*/
|
|
static int get_iovec_page_array(const struct iovec __user *iov,
|
|
unsigned int nr_vecs, struct page **pages,
|
|
struct partial_page *partial, int aligned)
|
|
{
|
|
int buffers = 0, error = 0;
|
|
|
|
down_read(¤t->mm->mmap_sem);
|
|
|
|
while (nr_vecs) {
|
|
unsigned long off, npages;
|
|
struct iovec entry;
|
|
void __user *base;
|
|
size_t len;
|
|
int i;
|
|
|
|
error = -EFAULT;
|
|
if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry)))
|
|
break;
|
|
|
|
base = entry.iov_base;
|
|
len = entry.iov_len;
|
|
|
|
/*
|
|
* Sanity check this iovec. 0 read succeeds.
|
|
*/
|
|
error = 0;
|
|
if (unlikely(!len))
|
|
break;
|
|
error = -EFAULT;
|
|
if (unlikely(!base))
|
|
break;
|
|
|
|
/*
|
|
* Get this base offset and number of pages, then map
|
|
* in the user pages.
|
|
*/
|
|
off = (unsigned long) base & ~PAGE_MASK;
|
|
|
|
/*
|
|
* If asked for alignment, the offset must be zero and the
|
|
* length a multiple of the PAGE_SIZE.
|
|
*/
|
|
error = -EINVAL;
|
|
if (aligned && (off || len & ~PAGE_MASK))
|
|
break;
|
|
|
|
npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (npages > PIPE_BUFFERS - buffers)
|
|
npages = PIPE_BUFFERS - buffers;
|
|
|
|
error = get_user_pages(current, current->mm,
|
|
(unsigned long) base, npages, 0, 0,
|
|
&pages[buffers], NULL);
|
|
|
|
if (unlikely(error <= 0))
|
|
break;
|
|
|
|
/*
|
|
* Fill this contiguous range into the partial page map.
|
|
*/
|
|
for (i = 0; i < error; i++) {
|
|
const int plen = min_t(size_t, len, PAGE_SIZE - off);
|
|
|
|
partial[buffers].offset = off;
|
|
partial[buffers].len = plen;
|
|
|
|
off = 0;
|
|
len -= plen;
|
|
buffers++;
|
|
}
|
|
|
|
/*
|
|
* We didn't complete this iov, stop here since it probably
|
|
* means we have to move some of this into a pipe to
|
|
* be able to continue.
|
|
*/
|
|
if (len)
|
|
break;
|
|
|
|
/*
|
|
* Don't continue if we mapped fewer pages than we asked for,
|
|
* or if we mapped the max number of pages that we have
|
|
* room for.
|
|
*/
|
|
if (error < npages || buffers == PIPE_BUFFERS)
|
|
break;
|
|
|
|
nr_vecs--;
|
|
iov++;
|
|
}
|
|
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
if (buffers)
|
|
return buffers;
|
|
|
|
return error;
|
|
}
|
|
|
|
static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
|
|
struct splice_desc *sd)
|
|
{
|
|
char *src;
|
|
int ret;
|
|
|
|
ret = buf->ops->confirm(pipe, buf);
|
|
if (unlikely(ret))
|
|
return ret;
|
|
|
|
/*
|
|
* See if we can use the atomic maps, by prefaulting in the
|
|
* pages and doing an atomic copy
|
|
*/
|
|
if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) {
|
|
src = buf->ops->map(pipe, buf, 1);
|
|
ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset,
|
|
sd->len);
|
|
buf->ops->unmap(pipe, buf, src);
|
|
if (!ret) {
|
|
ret = sd->len;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* No dice, use slow non-atomic map and copy
|
|
*/
|
|
src = buf->ops->map(pipe, buf, 0);
|
|
|
|
ret = sd->len;
|
|
if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len))
|
|
ret = -EFAULT;
|
|
|
|
buf->ops->unmap(pipe, buf, src);
|
|
out:
|
|
if (ret > 0)
|
|
sd->u.userptr += ret;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* For lack of a better implementation, implement vmsplice() to userspace
|
|
* as a simple copy of the pipes pages to the user iov.
|
|
*/
|
|
static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
struct splice_desc sd;
|
|
ssize_t size;
|
|
int error;
|
|
long ret;
|
|
|
|
pipe = pipe_info(file->f_path.dentry->d_inode);
|
|
if (!pipe)
|
|
return -EBADF;
|
|
|
|
if (pipe->inode)
|
|
mutex_lock(&pipe->inode->i_mutex);
|
|
|
|
error = ret = 0;
|
|
while (nr_segs) {
|
|
void __user *base;
|
|
size_t len;
|
|
|
|
/*
|
|
* Get user address base and length for this iovec.
|
|
*/
|
|
error = get_user(base, &iov->iov_base);
|
|
if (unlikely(error))
|
|
break;
|
|
error = get_user(len, &iov->iov_len);
|
|
if (unlikely(error))
|
|
break;
|
|
|
|
/*
|
|
* Sanity check this iovec. 0 read succeeds.
|
|
*/
|
|
if (unlikely(!len))
|
|
break;
|
|
if (unlikely(!base)) {
|
|
error = -EFAULT;
|
|
break;
|
|
}
|
|
|
|
sd.len = 0;
|
|
sd.total_len = len;
|
|
sd.flags = flags;
|
|
sd.u.userptr = base;
|
|
sd.pos = 0;
|
|
|
|
size = __splice_from_pipe(pipe, &sd, pipe_to_user);
|
|
if (size < 0) {
|
|
if (!ret)
|
|
ret = size;
|
|
|
|
break;
|
|
}
|
|
|
|
ret += size;
|
|
|
|
if (size < len)
|
|
break;
|
|
|
|
nr_segs--;
|
|
iov++;
|
|
}
|
|
|
|
if (pipe->inode)
|
|
mutex_unlock(&pipe->inode->i_mutex);
|
|
|
|
if (!ret)
|
|
ret = error;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* vmsplice splices a user address range into a pipe. It can be thought of
|
|
* as splice-from-memory, where the regular splice is splice-from-file (or
|
|
* to file). In both cases the output is a pipe, naturally.
|
|
*/
|
|
static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
struct page *pages[PIPE_BUFFERS];
|
|
struct partial_page partial[PIPE_BUFFERS];
|
|
struct splice_pipe_desc spd = {
|
|
.pages = pages,
|
|
.partial = partial,
|
|
.flags = flags,
|
|
.ops = &user_page_pipe_buf_ops,
|
|
};
|
|
|
|
pipe = pipe_info(file->f_path.dentry->d_inode);
|
|
if (!pipe)
|
|
return -EBADF;
|
|
|
|
spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
|
|
flags & SPLICE_F_GIFT);
|
|
if (spd.nr_pages <= 0)
|
|
return spd.nr_pages;
|
|
|
|
return splice_to_pipe(pipe, &spd);
|
|
}
|
|
|
|
/*
|
|
* Note that vmsplice only really supports true splicing _from_ user memory
|
|
* to a pipe, not the other way around. Splicing from user memory is a simple
|
|
* operation that can be supported without any funky alignment restrictions
|
|
* or nasty vm tricks. We simply map in the user memory and fill them into
|
|
* a pipe. The reverse isn't quite as easy, though. There are two possible
|
|
* solutions for that:
|
|
*
|
|
* - memcpy() the data internally, at which point we might as well just
|
|
* do a regular read() on the buffer anyway.
|
|
* - Lots of nasty vm tricks, that are neither fast nor flexible (it
|
|
* has restriction limitations on both ends of the pipe).
|
|
*
|
|
* Currently we punt and implement it as a normal copy, see pipe_to_user().
|
|
*
|
|
*/
|
|
asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct file *file;
|
|
long error;
|
|
int fput;
|
|
|
|
if (unlikely(nr_segs > UIO_MAXIOV))
|
|
return -EINVAL;
|
|
else if (unlikely(!nr_segs))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
file = fget_light(fd, &fput);
|
|
if (file) {
|
|
if (file->f_mode & FMODE_WRITE)
|
|
error = vmsplice_to_pipe(file, iov, nr_segs, flags);
|
|
else if (file->f_mode & FMODE_READ)
|
|
error = vmsplice_to_user(file, iov, nr_segs, flags);
|
|
|
|
fput_light(file, fput);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
|
|
int fd_out, loff_t __user *off_out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
long error;
|
|
struct file *in, *out;
|
|
int fput_in, fput_out;
|
|
|
|
if (unlikely(!len))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
in = fget_light(fd_in, &fput_in);
|
|
if (in) {
|
|
if (in->f_mode & FMODE_READ) {
|
|
out = fget_light(fd_out, &fput_out);
|
|
if (out) {
|
|
if (out->f_mode & FMODE_WRITE)
|
|
error = do_splice(in, off_in,
|
|
out, off_out,
|
|
len, flags);
|
|
fput_light(out, fput_out);
|
|
}
|
|
}
|
|
|
|
fput_light(in, fput_in);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Make sure there's data to read. Wait for input if we can, otherwise
|
|
* return an appropriate error.
|
|
*/
|
|
static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Check ->nrbufs without the inode lock first. This function
|
|
* is speculative anyways, so missing one is ok.
|
|
*/
|
|
if (pipe->nrbufs)
|
|
return 0;
|
|
|
|
ret = 0;
|
|
mutex_lock(&pipe->inode->i_mutex);
|
|
|
|
while (!pipe->nrbufs) {
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
if (!pipe->writers)
|
|
break;
|
|
if (!pipe->waiting_writers) {
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
}
|
|
pipe_wait(pipe);
|
|
}
|
|
|
|
mutex_unlock(&pipe->inode->i_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Make sure there's writeable room. Wait for room if we can, otherwise
|
|
* return an appropriate error.
|
|
*/
|
|
static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Check ->nrbufs without the inode lock first. This function
|
|
* is speculative anyways, so missing one is ok.
|
|
*/
|
|
if (pipe->nrbufs < PIPE_BUFFERS)
|
|
return 0;
|
|
|
|
ret = 0;
|
|
mutex_lock(&pipe->inode->i_mutex);
|
|
|
|
while (pipe->nrbufs >= PIPE_BUFFERS) {
|
|
if (!pipe->readers) {
|
|
send_sig(SIGPIPE, current, 0);
|
|
ret = -EPIPE;
|
|
break;
|
|
}
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
pipe->waiting_writers++;
|
|
pipe_wait(pipe);
|
|
pipe->waiting_writers--;
|
|
}
|
|
|
|
mutex_unlock(&pipe->inode->i_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Link contents of ipipe to opipe.
|
|
*/
|
|
static int link_pipe(struct pipe_inode_info *ipipe,
|
|
struct pipe_inode_info *opipe,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct pipe_buffer *ibuf, *obuf;
|
|
int ret = 0, i = 0, nbuf;
|
|
|
|
/*
|
|
* Potential ABBA deadlock, work around it by ordering lock
|
|
* grabbing by inode address. Otherwise two different processes
|
|
* could deadlock (one doing tee from A -> B, the other from B -> A).
|
|
*/
|
|
inode_double_lock(ipipe->inode, opipe->inode);
|
|
|
|
do {
|
|
if (!opipe->readers) {
|
|
send_sig(SIGPIPE, current, 0);
|
|
if (!ret)
|
|
ret = -EPIPE;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If we have iterated all input buffers or ran out of
|
|
* output room, break.
|
|
*/
|
|
if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
|
|
break;
|
|
|
|
ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
|
|
nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
|
|
|
|
/*
|
|
* Get a reference to this pipe buffer,
|
|
* so we can copy the contents over.
|
|
*/
|
|
ibuf->ops->get(ipipe, ibuf);
|
|
|
|
obuf = opipe->bufs + nbuf;
|
|
*obuf = *ibuf;
|
|
|
|
/*
|
|
* Don't inherit the gift flag, we need to
|
|
* prevent multiple steals of this page.
|
|
*/
|
|
obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
|
|
|
|
if (obuf->len > len)
|
|
obuf->len = len;
|
|
|
|
opipe->nrbufs++;
|
|
ret += obuf->len;
|
|
len -= obuf->len;
|
|
i++;
|
|
} while (len);
|
|
|
|
inode_double_unlock(ipipe->inode, opipe->inode);
|
|
|
|
/*
|
|
* If we put data in the output pipe, wakeup any potential readers.
|
|
*/
|
|
if (ret > 0) {
|
|
smp_mb();
|
|
if (waitqueue_active(&opipe->wait))
|
|
wake_up_interruptible(&opipe->wait);
|
|
kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This is a tee(1) implementation that works on pipes. It doesn't copy
|
|
* any data, it simply references the 'in' pages on the 'out' pipe.
|
|
* The 'flags' used are the SPLICE_F_* variants, currently the only
|
|
* applicable one is SPLICE_F_NONBLOCK.
|
|
*/
|
|
static long do_tee(struct file *in, struct file *out, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode);
|
|
struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode);
|
|
int ret = -EINVAL;
|
|
|
|
/*
|
|
* Duplicate the contents of ipipe to opipe without actually
|
|
* copying the data.
|
|
*/
|
|
if (ipipe && opipe && ipipe != opipe) {
|
|
/*
|
|
* Keep going, unless we encounter an error. The ipipe/opipe
|
|
* ordering doesn't really matter.
|
|
*/
|
|
ret = link_ipipe_prep(ipipe, flags);
|
|
if (!ret) {
|
|
ret = link_opipe_prep(opipe, flags);
|
|
if (!ret) {
|
|
ret = link_pipe(ipipe, opipe, len, flags);
|
|
if (!ret && (flags & SPLICE_F_NONBLOCK))
|
|
ret = -EAGAIN;
|
|
}
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
|
|
{
|
|
struct file *in;
|
|
int error, fput_in;
|
|
|
|
if (unlikely(!len))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
in = fget_light(fdin, &fput_in);
|
|
if (in) {
|
|
if (in->f_mode & FMODE_READ) {
|
|
int fput_out;
|
|
struct file *out = fget_light(fdout, &fput_out);
|
|
|
|
if (out) {
|
|
if (out->f_mode & FMODE_WRITE)
|
|
error = do_tee(in, out, len, flags);
|
|
fput_light(out, fput_out);
|
|
}
|
|
}
|
|
fput_light(in, fput_in);
|
|
}
|
|
|
|
return error;
|
|
}
|