From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- fs/netfs/direct_write.c | 387 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 387 insertions(+) create mode 100644 fs/netfs/direct_write.c (limited to 'fs/netfs/direct_write.c') diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c new file mode 100644 index 000000000..c16fbad28 --- /dev/null +++ b/fs/netfs/direct_write.c @@ -0,0 +1,387 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Unbuffered and direct write support. + * + * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include "internal.h" + +/* + * Perform the cleanup rituals after an unbuffered write is complete. + */ +static void netfs_unbuffered_write_done(struct netfs_io_request *wreq) +{ + struct netfs_inode *ictx = netfs_inode(wreq->inode); + + _enter("R=%x", wreq->debug_id); + + /* Okay, declare that all I/O is complete. */ + trace_netfs_rreq(wreq, netfs_rreq_trace_write_done); + + if (!wreq->error) + netfs_update_i_size(ictx, &ictx->inode, wreq->start, wreq->transferred); + + if (wreq->origin == NETFS_DIO_WRITE && + wreq->mapping->nrpages) { + /* mmap may have got underfoot and we may now have folios + * locally covering the region we just wrote. Attempt to + * discard the folios, but leave in place any modified locally. + * ->write_iter() is prevented from interfering by the DIO + * counter. + */ + pgoff_t first = wreq->start >> PAGE_SHIFT; + pgoff_t last = (wreq->start + wreq->transferred - 1) >> PAGE_SHIFT; + + invalidate_inode_pages2_range(wreq->mapping, first, last); + } + + if (wreq->origin == NETFS_DIO_WRITE) + inode_dio_end(wreq->inode); + + _debug("finished"); + netfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip); + /* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */ + + if (wreq->iocb) { + size_t written = umin(wreq->transferred, wreq->len); + + wreq->iocb->ki_pos += written; + if (wreq->iocb->ki_complete) { + trace_netfs_rreq(wreq, netfs_rreq_trace_ki_complete); + wreq->iocb->ki_complete(wreq->iocb, wreq->error ?: written); + } + wreq->iocb = VFS_PTR_POISON; + } + + netfs_clear_subrequests(wreq); +} + +/* + * Collect the subrequest results of unbuffered write subrequests. + */ +static void netfs_unbuffered_write_collect(struct netfs_io_request *wreq, + struct netfs_io_stream *stream, + struct netfs_io_subrequest *subreq) +{ + trace_netfs_collect_sreq(wreq, subreq); + + spin_lock(&wreq->lock); + list_del_init(&subreq->rreq_link); + spin_unlock(&wreq->lock); + + wreq->transferred += subreq->transferred; + iov_iter_advance(&wreq->buffer.iter, subreq->transferred); + + stream->collected_to = subreq->start + subreq->transferred; + wreq->collected_to = stream->collected_to; + netfs_put_subrequest(subreq, netfs_sreq_trace_put_done); + + trace_netfs_collect_stream(wreq, stream); + trace_netfs_collect_state(wreq, wreq->collected_to, 0); +} + +/* + * Write data to the server without going through the pagecache and without + * writing it to the local cache. We dispatch the subrequests serially and + * wait for each to complete before dispatching the next, lest we leave a gap + * in the data written due to a failure such as ENOSPC. We could, however + * attempt to do preparation such as content encryption for the next subreq + * whilst the current is in progress. + */ +static int netfs_unbuffered_write(struct netfs_io_request *wreq) +{ + struct netfs_io_subrequest *subreq = NULL; + struct netfs_io_stream *stream = &wreq->io_streams[0]; + int ret; + + _enter("%llx", wreq->len); + + if (wreq->origin == NETFS_DIO_WRITE) + inode_dio_begin(wreq->inode); + + stream->collected_to = wreq->start; + + for (;;) { + bool retry = false; + + if (!subreq) { + netfs_prepare_write(wreq, stream, wreq->start + wreq->transferred); + subreq = stream->construct; + stream->construct = NULL; + } + + /* Check if (re-)preparation failed. */ + if (unlikely(test_bit(NETFS_SREQ_FAILED, &subreq->flags))) { + netfs_write_subrequest_terminated(subreq, subreq->error); + wreq->error = subreq->error; + break; + } + + iov_iter_truncate(&subreq->io_iter, wreq->len - wreq->transferred); + if (!iov_iter_count(&subreq->io_iter)) + break; + + subreq->len = netfs_limit_iter(&subreq->io_iter, 0, + stream->sreq_max_len, + stream->sreq_max_segs); + iov_iter_truncate(&subreq->io_iter, subreq->len); + stream->submit_extendable_to = subreq->len; + + trace_netfs_sreq(subreq, netfs_sreq_trace_submit); + stream->issue_write(subreq); + + /* Async, need to wait. */ + netfs_wait_for_in_progress_stream(wreq, stream); + + if (test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) { + retry = true; + } else if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) { + ret = subreq->error; + wreq->error = ret; + netfs_see_subrequest(subreq, netfs_sreq_trace_see_failed); + subreq = NULL; + break; + } + ret = 0; + + if (!retry) { + netfs_unbuffered_write_collect(wreq, stream, subreq); + subreq = NULL; + if (wreq->transferred >= wreq->len) + break; + if (!wreq->iocb && signal_pending(current)) { + ret = wreq->transferred ? -EINTR : -ERESTARTSYS; + trace_netfs_rreq(wreq, netfs_rreq_trace_intr); + break; + } + continue; + } + + /* We need to retry the last subrequest, so first reset the + * iterator, taking into account what, if anything, we managed + * to transfer. + */ + subreq->error = -EAGAIN; + trace_netfs_sreq(subreq, netfs_sreq_trace_retry); + if (subreq->transferred > 0) { + iov_iter_advance(&wreq->buffer.iter, subreq->transferred); + wreq->transferred += subreq->transferred; + } + + if (stream->source == NETFS_UPLOAD_TO_SERVER && + wreq->netfs_ops->retry_request) + wreq->netfs_ops->retry_request(wreq, stream); + + __clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags); + __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags); + __clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags); + __clear_bit(NETFS_SREQ_FAILED, &subreq->flags); + subreq->io_iter = wreq->buffer.iter; + subreq->start = wreq->start + wreq->transferred; + subreq->len = wreq->len - wreq->transferred; + subreq->transferred = 0; + subreq->retry_count += 1; + stream->sreq_max_len = UINT_MAX; + stream->sreq_max_segs = INT_MAX; + + netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); + + if (stream->prepare_write) + stream->prepare_write(subreq); + __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags); + netfs_stat(&netfs_n_wh_retry_write_subreq); + } + + netfs_unbuffered_write_done(wreq); + _leave(" = %d", ret); + return ret; +} + +static void netfs_unbuffered_write_async(struct work_struct *work) +{ + struct netfs_io_request *wreq = container_of(work, struct netfs_io_request, work); + + netfs_unbuffered_write(wreq); + netfs_put_request(wreq, netfs_rreq_trace_put_complete); +} + +/* + * Perform an unbuffered write where we may have to do an RMW operation on an + * encrypted file. This can also be used for direct I/O writes. + */ +ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter, + struct netfs_group *netfs_group) +{ + struct netfs_io_request *wreq; + unsigned long long start = iocb->ki_pos; + unsigned long long end = start + iov_iter_count(iter); + ssize_t ret, n; + size_t len = iov_iter_count(iter); + bool async = !is_sync_kiocb(iocb); + + _enter(""); + + /* We're going to need a bounce buffer if what we transmit is going to + * be different in some way to the source buffer, e.g. because it gets + * encrypted/compressed or because it needs expanding to a block size. + */ + // TODO + + _debug("uw %llx-%llx", start, end); + + wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start, + iocb->ki_flags & IOCB_DIRECT ? + NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE); + if (IS_ERR(wreq)) + return PTR_ERR(wreq); + + wreq->io_streams[0].avail = true; + trace_netfs_write(wreq, (iocb->ki_flags & IOCB_DIRECT ? + netfs_write_trace_dio_write : + netfs_write_trace_unbuffered_write)); + + { + /* If this is an async op and we're not using a bounce buffer, + * we have to save the source buffer as the iterator is only + * good until we return. In such a case, extract an iterator + * to represent as much of the the output buffer as we can + * manage. Note that the extraction might not be able to + * allocate a sufficiently large bvec array and may shorten the + * request. + */ + if (user_backed_iter(iter)) { + n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0); + if (n < 0) { + ret = n; + goto error_put; + } + wreq->direct_bv = (struct bio_vec *)wreq->buffer.iter.bvec; + wreq->direct_bv_count = n; + wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter); + } else { + /* If this is a kernel-generated async DIO request, + * assume that any resources the iterator points to + * (eg. a bio_vec array) will persist till the end of + * the op. + */ + wreq->buffer.iter = *iter; + } + + wreq->len = iov_iter_count(&wreq->buffer.iter); + } + + __set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags); + + /* Copy the data into the bounce buffer and encrypt it. */ + // TODO + + /* Dispatch the write. */ + __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); + + if (async) { + INIT_WORK(&wreq->work, netfs_unbuffered_write_async); + wreq->iocb = iocb; + queue_work(system_dfl_wq, &wreq->work); + ret = -EIOCBQUEUED; + } else { + ret = netfs_unbuffered_write(wreq); + if (ret < 0) { + _debug("begin = %zd", ret); + } else { + iocb->ki_pos += wreq->transferred; + ret = wreq->transferred ?: wreq->error; + } + + netfs_put_request(wreq, netfs_rreq_trace_put_complete); + } + + netfs_put_request(wreq, netfs_rreq_trace_put_return); + return ret; + +error_put: + netfs_put_failed_request(wreq); + return ret; +} +EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked); + +/** + * netfs_unbuffered_write_iter - Unbuffered write to a file + * @iocb: IO state structure + * @from: iov_iter with data to write + * + * Do an unbuffered write to a file, writing the data directly to the server + * and not lodging the data in the pagecache. + * + * Return: + * * Negative error code if no data has been written at all of + * vfs_fsync_range() failed for a synchronous write + * * Number of bytes written, even for truncated writes + */ +ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from) +{ + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct netfs_inode *ictx = netfs_inode(inode); + ssize_t ret; + loff_t pos = iocb->ki_pos; + unsigned long long end = pos + iov_iter_count(from) - 1; + + _enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode)); + + if (!iov_iter_count(from)) + return 0; + + trace_netfs_write_iter(iocb, from); + netfs_stat(&netfs_n_wh_dio_write); + + ret = netfs_start_io_direct(inode); + if (ret < 0) + return ret; + ret = generic_write_checks(iocb, from); + if (ret <= 0) + goto out; + ret = file_remove_privs(file); + if (ret < 0) + goto out; + ret = file_update_time(file); + if (ret < 0) + goto out; + if (iocb->ki_flags & IOCB_NOWAIT) { + /* We could block if there are any pages in the range. */ + ret = -EAGAIN; + if (filemap_range_has_page(mapping, pos, end)) + if (filemap_invalidate_inode(inode, true, pos, end)) + goto out; + } else { + ret = filemap_write_and_wait_range(mapping, pos, end); + if (ret < 0) + goto out; + } + + /* + * After a write we want buffered reads to be sure to go to disk to get + * the new data. We invalidate clean cached page from the region we're + * about to write. We do this *before* the write so that we can return + * without clobbering -EIOCBQUEUED from ->direct_IO(). + */ + ret = filemap_invalidate_inode(inode, true, pos, end); + if (ret < 0) + goto out; + end = iocb->ki_pos + iov_iter_count(from); + spin_lock(&inode->i_lock); + if (end > ictx->_zero_point) + netfs_write_zero_point(inode, end); + spin_unlock(&inode->i_lock); + + fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode), + FSCACHE_INVAL_DIO_WRITE); + ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL); +out: + netfs_end_io_direct(inode); + return ret; +} +EXPORT_SYMBOL(netfs_unbuffered_write_iter); -- cgit v1.3.1