diff options
Diffstat (limited to 'fs/netfs/direct_read.c')
| -rw-r--r-- | fs/netfs/direct_read.c | 147 |
1 files changed, 141 insertions, 6 deletions
diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c index 10a1e4da6bda..b1a66a6e6bc2 100644 --- a/fs/netfs/direct_read.c +++ b/fs/netfs/direct_read.c @@ -16,6 +16,143 @@ #include <linux/netfs.h> #include "internal.h" +static void netfs_prepare_dio_read_iterator(struct netfs_io_subrequest *subreq) +{ + struct netfs_io_request *rreq = subreq->rreq; + size_t rsize; + + rsize = umin(subreq->len, rreq->io_streams[0].sreq_max_len); + subreq->len = rsize; + + if (unlikely(rreq->io_streams[0].sreq_max_segs)) { + size_t limit = netfs_limit_iter(&rreq->iter, 0, rsize, + rreq->io_streams[0].sreq_max_segs); + + if (limit < rsize) { + subreq->len = limit; + trace_netfs_sreq(subreq, netfs_sreq_trace_limited); + } + } + + trace_netfs_sreq(subreq, netfs_sreq_trace_prepare); + + subreq->io_iter = rreq->iter; + iov_iter_truncate(&subreq->io_iter, subreq->len); + iov_iter_advance(&rreq->iter, subreq->len); +} + +/* + * Perform a read to a buffer from the server, slicing up the region to be read + * according to the network rsize. + */ +static int netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq) +{ + unsigned long long start = rreq->start; + ssize_t size = rreq->len; + int ret = 0; + + atomic_set(&rreq->nr_outstanding, 1); + + do { + struct netfs_io_subrequest *subreq; + ssize_t slice; + + subreq = netfs_alloc_subrequest(rreq); + if (!subreq) { + ret = -ENOMEM; + break; + } + + subreq->source = NETFS_DOWNLOAD_FROM_SERVER; + subreq->start = start; + subreq->len = size; + + atomic_inc(&rreq->nr_outstanding); + spin_lock_bh(&rreq->lock); + list_add_tail(&subreq->rreq_link, &rreq->subrequests); + subreq->prev_donated = rreq->prev_donated; + rreq->prev_donated = 0; + trace_netfs_sreq(subreq, netfs_sreq_trace_added); + spin_unlock_bh(&rreq->lock); + + netfs_stat(&netfs_n_rh_download); + if (rreq->netfs_ops->prepare_read) { + ret = rreq->netfs_ops->prepare_read(subreq); + if (ret < 0) { + atomic_dec(&rreq->nr_outstanding); + netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel); + break; + } + } + + netfs_prepare_dio_read_iterator(subreq); + slice = subreq->len; + rreq->netfs_ops->issue_read(subreq); + + size -= slice; + start += slice; + rreq->submitted += slice; + + if (test_bit(NETFS_RREQ_BLOCKED, &rreq->flags) && + test_bit(NETFS_RREQ_NONBLOCK, &rreq->flags)) + break; + cond_resched(); + } while (size > 0); + + if (atomic_dec_and_test(&rreq->nr_outstanding)) + netfs_rreq_terminated(rreq, false); + return ret; +} + +/* + * Perform a read to an application buffer, bypassing the pagecache and the + * local disk cache. + */ +static int netfs_unbuffered_read(struct netfs_io_request *rreq, bool sync) +{ + int ret; + + _enter("R=%x %llx-%llx", + rreq->debug_id, rreq->start, rreq->start + rreq->len - 1); + + if (rreq->len == 0) { + pr_err("Zero-sized read [R=%x]\n", rreq->debug_id); + return -EIO; + } + + // TODO: Use bounce buffer if requested + + inode_dio_begin(rreq->inode); + + ret = netfs_dispatch_unbuffered_reads(rreq); + + if (!rreq->submitted) { + netfs_put_request(rreq, false, netfs_rreq_trace_put_no_submit); + inode_dio_end(rreq->inode); + ret = 0; + goto out; + } + + if (sync) { + trace_netfs_rreq(rreq, netfs_rreq_trace_wait_ip); + wait_on_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS, + TASK_UNINTERRUPTIBLE); + + ret = rreq->error; + if (ret == 0 && rreq->submitted < rreq->len && + rreq->origin != NETFS_DIO_READ) { + trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read); + ret = -EIO; + } + } else { + ret = -EIOCBQUEUED; + } + +out: + _leave(" = %d", ret); + return ret; +} + /** * netfs_unbuffered_read_iter_locked - Perform an unbuffered or direct I/O read * @iocb: The I/O control descriptor describing the read @@ -31,7 +168,7 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i struct netfs_io_request *rreq; ssize_t ret; size_t orig_count = iov_iter_count(iter); - bool async = !is_sync_kiocb(iocb); + bool sync = is_sync_kiocb(iocb); _enter(""); @@ -78,13 +215,13 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i // TODO: Set up bounce buffer if needed - if (async) + if (!sync) rreq->iocb = iocb; - ret = netfs_begin_read(rreq, is_sync_kiocb(iocb)); + ret = netfs_unbuffered_read(rreq, sync); if (ret < 0) goto out; /* May be -EIOCBQUEUED */ - if (!async) { + if (sync) { // TODO: Copy from bounce buffer iocb->ki_pos += rreq->transferred; ret = rreq->transferred; @@ -94,8 +231,6 @@ out: netfs_put_request(rreq, false, netfs_rreq_trace_put_return); if (ret > 0) orig_count -= ret; - if (ret != -EIOCBQUEUED) - iov_iter_revert(iter, orig_count - iov_iter_count(iter)); return ret; } EXPORT_SYMBOL(netfs_unbuffered_read_iter_locked); |