diff options
| -rw-r--r-- | kernel/relay.c | 144 |
1 files changed, 115 insertions, 29 deletions
diff --git a/kernel/relay.c b/kernel/relay.c index 9358e8eb8476..fefe2b2a7277 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -95,15 +95,16 @@ int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) * @buf: the buffer struct * @size: total size of the buffer * - * Returns a pointer to the resulting buffer, NULL if unsuccessful + * Returns a pointer to the resulting buffer, NULL if unsuccessful. The + * passed in size will get page aligned, if it isn't already. */ -static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size) +static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size) { void *mem; unsigned int i, j, n_pages; - size = PAGE_ALIGN(size); - n_pages = size >> PAGE_SHIFT; + *size = PAGE_ALIGN(*size); + n_pages = *size >> PAGE_SHIFT; buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); if (!buf->page_array) @@ -118,7 +119,7 @@ static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size) if (!mem) goto depopulate; - memset(mem, 0, size); + memset(mem, 0, *size); buf->page_count = n_pages; return mem; @@ -146,7 +147,7 @@ struct rchan_buf *relay_create_buf(struct rchan *chan) if (!buf->padding) goto free_buf; - buf->start = relay_alloc_buf(buf, chan->alloc_size); + buf->start = relay_alloc_buf(buf, &chan->alloc_size); if (!buf->start) goto free_buf; @@ -543,6 +544,9 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; buf->padding[old_subbuf] = buf->prev_padding; buf->subbufs_produced++; + buf->dentry->d_inode->i_size += buf->chan->subbuf_size - + buf->padding[old_subbuf]; + smp_mb(); if (waitqueue_active(&buf->read_wait)) { PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); schedule_delayed_work(&buf->wake_readers, 1); @@ -757,37 +761,33 @@ static void relay_file_read_consume(struct rchan_buf *buf, */ static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) { - size_t bytes_produced, bytes_consumed, write_offset; size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; - size_t produced = buf->subbufs_produced % n_subbufs; - size_t consumed = buf->subbufs_consumed % n_subbufs; + size_t produced = buf->subbufs_produced; + size_t consumed = buf->subbufs_consumed; - write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset; + relay_file_read_consume(buf, read_pos, 0); - if (consumed > produced) { - if ((produced > n_subbufs) && - (produced + n_subbufs - consumed <= n_subbufs)) - produced += n_subbufs; - } else if (consumed == produced) { - if (buf->offset > subbuf_size) { - produced += n_subbufs; - if (buf->subbufs_produced == buf->subbufs_consumed) - consumed += n_subbufs; - } + if (unlikely(buf->offset > subbuf_size)) { + if (produced == consumed) + return 0; + return 1; } - if (buf->offset > subbuf_size) - bytes_produced = (produced - 1) * subbuf_size + write_offset; - else - bytes_produced = produced * subbuf_size + write_offset; - bytes_consumed = consumed * subbuf_size + buf->bytes_consumed; - - if (bytes_produced == bytes_consumed) + if (unlikely(produced - consumed >= n_subbufs)) { + consumed = (produced / n_subbufs) * n_subbufs; + buf->subbufs_consumed = consumed; + } + + produced = (produced % n_subbufs) * subbuf_size + buf->offset; + consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed; + + if (consumed > produced) + produced += n_subbufs * subbuf_size; + + if (consumed == produced) return 0; - relay_file_read_consume(buf, read_pos, 0); - return 1; } @@ -908,6 +908,91 @@ out: return ret; } +static ssize_t relay_file_sendsubbuf(struct file *filp, loff_t *ppos, + size_t count, read_actor_t actor, + void *target) +{ + struct rchan_buf *buf = filp->private_data; + read_descriptor_t desc; + size_t read_start, avail; + unsigned long pidx, poff; + unsigned int subbuf_pages; + ssize_t ret = 0; + + if (!relay_file_read_avail(buf, *ppos)) + return 0; + + read_start = relay_file_read_start_pos(*ppos, buf); + avail = relay_file_read_subbuf_avail(read_start, buf); + if (!avail) + return 0; + + count = min(count, avail); + + desc.written = 0; + desc.count = count; + desc.arg.data = target; + desc.error = 0; + + subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT; + pidx = (read_start / PAGE_SIZE) % subbuf_pages; + poff = read_start & ~PAGE_MASK; + while (count) { + struct page *p = buf->page_array[pidx]; + unsigned int len; + + len = PAGE_SIZE - poff; + if (len > count) + len = count; + + len = actor(&desc, p, poff, len); + + if (desc.error) { + if (!ret) + ret = desc.error; + break; + } + + count -= len; + ret += len; + poff = 0; + pidx = (pidx + 1) % subbuf_pages; + } + + if (ret > 0) { + relay_file_read_consume(buf, read_start, ret); + *ppos = relay_file_read_end_pos(buf, read_start, ret); + } + + return ret; +} + +static ssize_t relay_file_sendfile(struct file *filp, loff_t *ppos, + size_t count, read_actor_t actor, + void *target) +{ + ssize_t sent = 0, ret = 0; + + if (!count) + return 0; + + mutex_lock(&filp->f_dentry->d_inode->i_mutex); + + do { + ret = relay_file_sendsubbuf(filp, ppos, count, actor, target); + if (ret < 0) { + if (!sent) + sent = ret; + break; + } + count -= ret; + sent += ret; + } while (count && ret); + + mutex_unlock(&filp->f_dentry->d_inode->i_mutex); + return sent; +} + struct file_operations relay_file_operations = { .open = relay_file_open, .poll = relay_file_poll, @@ -915,5 +1000,6 @@ struct file_operations relay_file_operations = { .read = relay_file_read, .llseek = no_llseek, .release = relay_file_release, + .sendfile = relay_file_sendfile, }; EXPORT_SYMBOL_GPL(relay_file_operations); |