From 35f3d14dbbc58447c61e38a162ea10add6b31dc7 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 20 May 2010 10:43:18 +0200 Subject: pipe: add support for shrinking and growing pipes This patch adds F_GETPIPE_SZ and F_SETPIPE_SZ fcntl() actions for growing and shrinking the size of a pipe and adjusts pipe.c and splice.c (and relay and network splice) usage to work with these larger (or smaller) pipes. Signed-off-by: Jens Axboe --- kernel/trace/trace.c | 60 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 36 insertions(+), 24 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 44f916a04065..7b155a0e6f31 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3269,12 +3269,12 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, size_t len, unsigned int flags) { - struct page *pages[PIPE_BUFFERS]; - struct partial_page partial[PIPE_BUFFERS]; + struct page *pages_def[PIPE_DEF_BUFFERS]; + struct partial_page partial_def[PIPE_DEF_BUFFERS]; struct trace_iterator *iter = filp->private_data; struct splice_pipe_desc spd = { - .pages = pages, - .partial = partial, + .pages = pages_def, + .partial = partial_def, .nr_pages = 0, /* This gets updated below. */ .flags = flags, .ops = &tracing_pipe_buf_ops, @@ -3285,6 +3285,9 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, size_t rem; unsigned int i; + if (splice_grow_spd(pipe, &spd)) + return -ENOMEM; + /* copy the tracer to avoid using a global lock all around */ mutex_lock(&trace_types_lock); if (unlikely(old_tracer != current_trace && current_trace)) { @@ -3315,23 +3318,23 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, trace_access_lock(iter->cpu_file); /* Fill as many pages as possible. */ - for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) { - pages[i] = alloc_page(GFP_KERNEL); - if (!pages[i]) + for (i = 0, rem = len; i < pipe->buffers && rem; i++) { + spd.pages[i] = alloc_page(GFP_KERNEL); + if (!spd.pages[i]) break; rem = tracing_fill_pipe_page(rem, iter); /* Copy the data into the page, so we can start over. */ ret = trace_seq_to_buffer(&iter->seq, - page_address(pages[i]), + page_address(spd.pages[i]), iter->seq.len); if (ret < 0) { - __free_page(pages[i]); + __free_page(spd.pages[i]); break; } - partial[i].offset = 0; - partial[i].len = iter->seq.len; + spd.partial[i].offset = 0; + spd.partial[i].len = iter->seq.len; trace_seq_init(&iter->seq); } @@ -3342,12 +3345,14 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, spd.nr_pages = i; - return splice_to_pipe(pipe, &spd); + ret = splice_to_pipe(pipe, &spd); +out: + splice_shrink_spd(pipe, &spd); + return ret; out_err: mutex_unlock(&iter->mutex); - - return ret; + goto out; } static ssize_t @@ -3746,11 +3751,11 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, unsigned int flags) { struct ftrace_buffer_info *info = file->private_data; - struct partial_page partial[PIPE_BUFFERS]; - struct page *pages[PIPE_BUFFERS]; + struct partial_page partial_def[PIPE_DEF_BUFFERS]; + struct page *pages_def[PIPE_DEF_BUFFERS]; struct splice_pipe_desc spd = { - .pages = pages, - .partial = partial, + .pages = pages_def, + .partial = partial_def, .flags = flags, .ops = &buffer_pipe_buf_ops, .spd_release = buffer_spd_release, @@ -3759,22 +3764,28 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, int entries, size, i; size_t ret; + if (splice_grow_spd(pipe, &spd)) + return -ENOMEM; + if (*ppos & (PAGE_SIZE - 1)) { WARN_ONCE(1, "Ftrace: previous read must page-align\n"); - return -EINVAL; + ret = -EINVAL; + goto out; } if (len & (PAGE_SIZE - 1)) { WARN_ONCE(1, "Ftrace: splice_read should page-align\n"); - if (len < PAGE_SIZE) - return -EINVAL; + if (len < PAGE_SIZE) { + ret = -EINVAL; + goto out; + } len &= PAGE_MASK; } trace_access_lock(info->cpu); entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu); - for (i = 0; i < PIPE_BUFFERS && len && entries; i++, len -= PAGE_SIZE) { + for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) { struct page *page; int r; @@ -3829,11 +3840,12 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, else ret = 0; /* TODO: block */ - return ret; + goto out; } ret = splice_to_pipe(pipe, &spd); - + splice_shrink_spd(pipe, &spd); +out: return ret; } -- cgit v1.2.3