diff options
Diffstat (limited to 'fs/netfs/write_issue.c')
-rw-r--r-- | fs/netfs/write_issue.c | 683 |
1 files changed, 683 insertions, 0 deletions
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c new file mode 100644 index 000000000000..1b2e69934fbd --- /dev/null +++ b/fs/netfs/write_issue.c @@ -0,0 +1,683 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Network filesystem high-level (buffered) writeback. + * + * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * + * To support network filesystems with local caching, we manage a situation + * that can be envisioned like the following: + * + * +---+---+-----+-----+---+----------+ + * Folios: | | | | | | | + * +---+---+-----+-----+---+----------+ + * + * +------+------+ +----+----+ + * Upload: | | |.....| | | + * (Stream 0) +------+------+ +----+----+ + * + * +------+------+------+------+------+ + * Cache: | | | | | | + * (Stream 1) +------+------+------+------+------+ + * + * Where we have a sequence of folios of varying sizes that we need to overlay + * with multiple parallel streams of I/O requests, where the I/O requests in a + * stream may also be of various sizes (in cifs, for example, the sizes are + * negotiated with the server; in something like ceph, they may represent the + * sizes of storage objects). + * + * The sequence in each stream may contain gaps and noncontiguous subrequests + * may be glued together into single vectored write RPCs. + */ + +#include <linux/export.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include "internal.h" + +/* + * Kill all dirty folios in the event of an unrecoverable error, starting with + * a locked folio we've already obtained from writeback_iter(). + */ +static void netfs_kill_dirty_pages(struct address_space *mapping, + struct writeback_control *wbc, + struct folio *folio) +{ + int error = 0; + + do { + enum netfs_folio_trace why = netfs_folio_trace_kill; + struct netfs_group *group = NULL; + struct netfs_folio *finfo = NULL; + void *priv; + + priv = folio_detach_private(folio); + if (priv) { + finfo = __netfs_folio_info(priv); + if (finfo) { + /* Kill folio from streaming write. */ + group = finfo->netfs_group; + why = netfs_folio_trace_kill_s; + } else { + group = priv; + if (group == NETFS_FOLIO_COPY_TO_CACHE) { + /* Kill copy-to-cache folio */ + why = netfs_folio_trace_kill_cc; + group = NULL; + } else { + /* Kill folio with group */ + why = netfs_folio_trace_kill_g; + } + } + } + + trace_netfs_folio(folio, why); + + folio_start_writeback(folio); + folio_unlock(folio); + folio_end_writeback(folio); + + netfs_put_group(group); + kfree(finfo); + + } while ((folio = writeback_iter(mapping, wbc, folio, &error))); +} + +/* + * Create a write request and set it up appropriately for the origin type. + */ +struct netfs_io_request *netfs_create_write_req(struct address_space *mapping, + struct file *file, + loff_t start, + enum netfs_io_origin origin) +{ + struct netfs_io_request *wreq; + struct netfs_inode *ictx; + + wreq = netfs_alloc_request(mapping, file, start, 0, origin); + if (IS_ERR(wreq)) + return wreq; + + _enter("R=%x", wreq->debug_id); + + ictx = netfs_inode(wreq->inode); + if (test_bit(NETFS_RREQ_WRITE_TO_CACHE, &wreq->flags)) + fscache_begin_write_operation(&wreq->cache_resources, netfs_i_cookie(ictx)); + + wreq->contiguity = wreq->start; + wreq->cleaned_to = wreq->start; + INIT_WORK(&wreq->work, netfs_write_collection_worker); + + wreq->io_streams[0].stream_nr = 0; + wreq->io_streams[0].source = NETFS_UPLOAD_TO_SERVER; + wreq->io_streams[0].prepare_write = ictx->ops->prepare_write; + wreq->io_streams[0].issue_write = ictx->ops->issue_write; + wreq->io_streams[0].collected_to = start; + wreq->io_streams[0].transferred = LONG_MAX; + + wreq->io_streams[1].stream_nr = 1; + wreq->io_streams[1].source = NETFS_WRITE_TO_CACHE; + wreq->io_streams[1].collected_to = start; + wreq->io_streams[1].transferred = LONG_MAX; + if (fscache_resources_valid(&wreq->cache_resources)) { + wreq->io_streams[1].avail = true; + wreq->io_streams[1].prepare_write = wreq->cache_resources.ops->prepare_write_subreq; + wreq->io_streams[1].issue_write = wreq->cache_resources.ops->issue_write; + } + + return wreq; +} + +/** + * netfs_prepare_write_failed - Note write preparation failed + * @subreq: The subrequest to mark + * + * Mark a subrequest to note that preparation for write failed. + */ +void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq) +{ + __set_bit(NETFS_SREQ_FAILED, &subreq->flags); + trace_netfs_sreq(subreq, netfs_sreq_trace_prep_failed); +} +EXPORT_SYMBOL(netfs_prepare_write_failed); + +/* + * Prepare a write subrequest. We need to allocate a new subrequest + * if we don't have one. + */ +static void netfs_prepare_write(struct netfs_io_request *wreq, + struct netfs_io_stream *stream, + loff_t start) +{ + struct netfs_io_subrequest *subreq; + + subreq = netfs_alloc_subrequest(wreq); + subreq->source = stream->source; + subreq->start = start; + subreq->max_len = ULONG_MAX; + subreq->max_nr_segs = INT_MAX; + subreq->stream_nr = stream->stream_nr; + + _enter("R=%x[%x]", wreq->debug_id, subreq->debug_index); + + trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index, + refcount_read(&subreq->ref), + netfs_sreq_trace_new); + + trace_netfs_sreq(subreq, netfs_sreq_trace_prepare); + + switch (stream->source) { + case NETFS_UPLOAD_TO_SERVER: + netfs_stat(&netfs_n_wh_upload); + subreq->max_len = wreq->wsize; + break; + case NETFS_WRITE_TO_CACHE: + netfs_stat(&netfs_n_wh_write); + break; + default: + WARN_ON_ONCE(1); + break; + } + + if (stream->prepare_write) + stream->prepare_write(subreq); + + __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags); + + /* We add to the end of the list whilst the collector may be walking + * the list. The collector only goes nextwards and uses the lock to + * remove entries off of the front. + */ + spin_lock(&wreq->lock); + list_add_tail(&subreq->rreq_link, &stream->subrequests); + if (list_is_first(&subreq->rreq_link, &stream->subrequests)) { + stream->front = subreq; + if (!stream->active) { + stream->collected_to = stream->front->start; + /* Write list pointers before active flag */ + smp_store_release(&stream->active, true); + } + } + + spin_unlock(&wreq->lock); + + stream->construct = subreq; +} + +/* + * Set the I/O iterator for the filesystem/cache to use and dispatch the I/O + * operation. The operation may be asynchronous and should call + * netfs_write_subrequest_terminated() when complete. + */ +static void netfs_do_issue_write(struct netfs_io_stream *stream, + struct netfs_io_subrequest *subreq) +{ + struct netfs_io_request *wreq = subreq->rreq; + + _enter("R=%x[%x],%zx", wreq->debug_id, subreq->debug_index, subreq->len); + + if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) + return netfs_write_subrequest_terminated(subreq, subreq->error, false); + + // TODO: Use encrypted buffer + if (test_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags)) { + subreq->io_iter = wreq->io_iter; + iov_iter_advance(&subreq->io_iter, + subreq->start + subreq->transferred - wreq->start); + iov_iter_truncate(&subreq->io_iter, + subreq->len - subreq->transferred); + } else { + iov_iter_xarray(&subreq->io_iter, ITER_SOURCE, &wreq->mapping->i_pages, + subreq->start + subreq->transferred, + subreq->len - subreq->transferred); + } + + trace_netfs_sreq(subreq, netfs_sreq_trace_submit); + stream->issue_write(subreq); +} + +void netfs_reissue_write(struct netfs_io_stream *stream, + struct netfs_io_subrequest *subreq) +{ + __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags); + netfs_do_issue_write(stream, subreq); +} + +static void netfs_issue_write(struct netfs_io_request *wreq, + struct netfs_io_stream *stream) +{ + struct netfs_io_subrequest *subreq = stream->construct; + + if (!subreq) + return; + stream->construct = NULL; + + if (subreq->start + subreq->len > wreq->start + wreq->submitted) + wreq->len = wreq->submitted = subreq->start + subreq->len - wreq->start; + netfs_do_issue_write(stream, subreq); +} + +/* + * Add data to the write subrequest, dispatching each as we fill it up or if it + * is discontiguous with the previous. We only fill one part at a time so that + * we can avoid overrunning the credits obtained (cifs) and try to parallelise + * content-crypto preparation with network writes. + */ +int netfs_advance_write(struct netfs_io_request *wreq, + struct netfs_io_stream *stream, + loff_t start, size_t len, bool to_eof) +{ + struct netfs_io_subrequest *subreq = stream->construct; + size_t part; + + if (!stream->avail) { + _leave("no write"); + return len; + } + + _enter("R=%x[%x]", wreq->debug_id, subreq ? subreq->debug_index : 0); + + if (subreq && start != subreq->start + subreq->len) { + netfs_issue_write(wreq, stream); + subreq = NULL; + } + + if (!stream->construct) + netfs_prepare_write(wreq, stream, start); + subreq = stream->construct; + + part = min(subreq->max_len - subreq->len, len); + _debug("part %zx/%zx %zx/%zx", subreq->len, subreq->max_len, part, len); + subreq->len += part; + subreq->nr_segs++; + + if (subreq->len >= subreq->max_len || + subreq->nr_segs >= subreq->max_nr_segs || + to_eof) { + netfs_issue_write(wreq, stream); + subreq = NULL; + } + + return part; +} + +/* + * Write some of a pending folio data back to the server. + */ +static int netfs_write_folio(struct netfs_io_request *wreq, + struct writeback_control *wbc, + struct folio *folio) +{ + struct netfs_io_stream *upload = &wreq->io_streams[0]; + struct netfs_io_stream *cache = &wreq->io_streams[1]; + struct netfs_io_stream *stream; + struct netfs_group *fgroup; /* TODO: Use this with ceph */ + struct netfs_folio *finfo; + size_t fsize = folio_size(folio), flen = fsize, foff = 0; + loff_t fpos = folio_pos(folio), i_size; + bool to_eof = false, streamw = false; + bool debug = false; + + _enter(""); + + /* netfs_perform_write() may shift i_size around the page or from out + * of the page to beyond it, but cannot move i_size into or through the + * page since we have it locked. + */ + i_size = i_size_read(wreq->inode); + + if (fpos >= i_size) { + /* mmap beyond eof. */ + _debug("beyond eof"); + folio_start_writeback(folio); + folio_unlock(folio); + wreq->nr_group_rel += netfs_folio_written_back(folio); + netfs_put_group_many(wreq->group, wreq->nr_group_rel); + wreq->nr_group_rel = 0; + return 0; + } + + if (fpos + fsize > wreq->i_size) + wreq->i_size = i_size; + + fgroup = netfs_folio_group(folio); + finfo = netfs_folio_info(folio); + if (finfo) { + foff = finfo->dirty_offset; + flen = foff + finfo->dirty_len; + streamw = true; + } + + if (wreq->origin == NETFS_WRITETHROUGH) { + to_eof = false; + if (flen > i_size - fpos) + flen = i_size - fpos; + } else if (flen > i_size - fpos) { + flen = i_size - fpos; + if (!streamw) + folio_zero_segment(folio, flen, fsize); + to_eof = true; + } else if (flen == i_size - fpos) { + to_eof = true; + } + flen -= foff; + + _debug("folio %zx %zx %zx", foff, flen, fsize); + + /* Deal with discontinuities in the stream of dirty pages. These can + * arise from a number of sources: + * + * (1) Intervening non-dirty pages from random-access writes, multiple + * flushers writing back different parts simultaneously and manual + * syncing. + * + * (2) Partially-written pages from write-streaming. + * + * (3) Pages that belong to a different write-back group (eg. Ceph + * snapshots). + * + * (4) Actually-clean pages that were marked for write to the cache + * when they were read. Note that these appear as a special + * write-back group. + */ + if (fgroup == NETFS_FOLIO_COPY_TO_CACHE) { + netfs_issue_write(wreq, upload); + } else if (fgroup != wreq->group) { + /* We can't write this page to the server yet. */ + kdebug("wrong group"); + folio_redirty_for_writepage(wbc, folio); + folio_unlock(folio); + netfs_issue_write(wreq, upload); + netfs_issue_write(wreq, cache); + return 0; + } + + if (foff > 0) + netfs_issue_write(wreq, upload); + if (streamw) + netfs_issue_write(wreq, cache); + + /* Flip the page to the writeback state and unlock. If we're called + * from write-through, then the page has already been put into the wb + * state. + */ + if (wreq->origin == NETFS_WRITEBACK) + folio_start_writeback(folio); + folio_unlock(folio); + + if (fgroup == NETFS_FOLIO_COPY_TO_CACHE) { + if (!fscache_resources_valid(&wreq->cache_resources)) { + trace_netfs_folio(folio, netfs_folio_trace_cancel_copy); + netfs_issue_write(wreq, upload); + netfs_folio_written_back(folio); + return 0; + } + trace_netfs_folio(folio, netfs_folio_trace_store_copy); + } else if (!upload->construct) { + trace_netfs_folio(folio, netfs_folio_trace_store); + } else { + trace_netfs_folio(folio, netfs_folio_trace_store_plus); + } + + /* Move the submission point forward to allow for write-streaming data + * not starting at the front of the page. We don't do write-streaming + * with the cache as the cache requires DIO alignment. + * + * Also skip uploading for data that's been read and just needs copying + * to the cache. + */ + for (int s = 0; s < NR_IO_STREAMS; s++) { + stream = &wreq->io_streams[s]; + stream->submit_max_len = fsize; + stream->submit_off = foff; + stream->submit_len = flen; + if ((stream->source == NETFS_WRITE_TO_CACHE && streamw) || + (stream->source == NETFS_UPLOAD_TO_SERVER && + fgroup == NETFS_FOLIO_COPY_TO_CACHE)) { + stream->submit_off = UINT_MAX; + stream->submit_len = 0; + stream->submit_max_len = 0; + } + } + + /* Attach the folio to one or more subrequests. For a big folio, we + * could end up with thousands of subrequests if the wsize is small - + * but we might need to wait during the creation of subrequests for + * network resources (eg. SMB credits). + */ + for (;;) { + ssize_t part; + size_t lowest_off = ULONG_MAX; + int choose_s = -1; + + /* Always add to the lowest-submitted stream first. */ + for (int s = 0; s < NR_IO_STREAMS; s++) { + stream = &wreq->io_streams[s]; + if (stream->submit_len > 0 && + stream->submit_off < lowest_off) { + lowest_off = stream->submit_off; + choose_s = s; + } + } + + if (choose_s < 0) + break; + stream = &wreq->io_streams[choose_s]; + + part = netfs_advance_write(wreq, stream, fpos + stream->submit_off, + stream->submit_len, to_eof); + atomic64_set(&wreq->issued_to, fpos + stream->submit_off); + stream->submit_off += part; + stream->submit_max_len -= part; + if (part > stream->submit_len) + stream->submit_len = 0; + else + stream->submit_len -= part; + if (part > 0) + debug = true; + } + + atomic64_set(&wreq->issued_to, fpos + fsize); + + if (!debug) + kdebug("R=%x: No submit", wreq->debug_id); + + if (flen < fsize) + for (int s = 0; s < NR_IO_STREAMS; s++) + netfs_issue_write(wreq, &wreq->io_streams[s]); + + _leave(" = 0"); + return 0; +} + +/* + * Write some of the pending data back to the server + */ +int new_netfs_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct netfs_inode *ictx = netfs_inode(mapping->host); + struct netfs_io_request *wreq = NULL; + struct folio *folio; + int error = 0; + + if (wbc->sync_mode == WB_SYNC_ALL) + mutex_lock(&ictx->wb_lock); + else if (!mutex_trylock(&ictx->wb_lock)) + return 0; + + /* Need the first folio to be able to set up the op. */ + folio = writeback_iter(mapping, wbc, NULL, &error); + if (!folio) + goto out; + + wreq = netfs_create_write_req(mapping, NULL, folio_pos(folio), NETFS_WRITEBACK); + if (IS_ERR(wreq)) { + error = PTR_ERR(wreq); + goto couldnt_start; + } + + trace_netfs_write(wreq, netfs_write_trace_writeback); + + do { + _debug("wbiter %lx %llx", folio->index, wreq->start + wreq->submitted); + + /* It appears we don't have to handle cyclic writeback wrapping. */ + WARN_ON_ONCE(wreq && folio_pos(folio) < wreq->start + wreq->submitted); + + if (netfs_folio_group(folio) != NETFS_FOLIO_COPY_TO_CACHE && + unlikely(!test_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags))) { + set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); + wreq->netfs_ops->begin_writeback(wreq); + } + + error = netfs_write_folio(wreq, wbc, folio); + if (error < 0) + break; + } while ((folio = writeback_iter(mapping, wbc, folio, &error))); + + for (int s = 0; s < NR_IO_STREAMS; s++) + netfs_issue_write(wreq, &wreq->io_streams[s]); + smp_wmb(); /* Write lists before ALL_QUEUED. */ + set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags); + + mutex_unlock(&ictx->wb_lock); + + netfs_put_request(wreq, false, netfs_rreq_trace_put_return); + _leave(" = %d", error); + return error; + +couldnt_start: + netfs_kill_dirty_pages(mapping, wbc, folio); +out: + mutex_unlock(&ictx->wb_lock); + _leave(" = %d", error); + return error; +} +EXPORT_SYMBOL(new_netfs_writepages); + +/* + * Begin a write operation for writing through the pagecache. + */ +struct netfs_io_request *new_netfs_begin_writethrough(struct kiocb *iocb, size_t len) +{ + struct netfs_io_request *wreq = NULL; + struct netfs_inode *ictx = netfs_inode(file_inode(iocb->ki_filp)); + + mutex_lock(&ictx->wb_lock); + + wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, + iocb->ki_pos, NETFS_WRITETHROUGH); + if (IS_ERR(wreq)) { + mutex_unlock(&ictx->wb_lock); + return wreq; + } + + wreq->io_streams[0].avail = true; + trace_netfs_write(wreq, netfs_write_trace_writethrough); + return wreq; +} + +/* + * Advance the state of the write operation used when writing through the + * pagecache. Data has been copied into the pagecache that we need to append + * to the request. If we've added more than wsize then we need to create a new + * subrequest. + */ +int new_netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc, + struct folio *folio, size_t copied, bool to_page_end, + struct folio **writethrough_cache) +{ + _enter("R=%x ic=%zu ws=%u cp=%zu tp=%u", + wreq->debug_id, wreq->iter.count, wreq->wsize, copied, to_page_end); + + if (!*writethrough_cache) { + if (folio_test_dirty(folio)) + /* Sigh. mmap. */ + folio_clear_dirty_for_io(folio); + + /* We can make multiple writes to the folio... */ + folio_start_writeback(folio); + if (wreq->len == 0) + trace_netfs_folio(folio, netfs_folio_trace_wthru); + else + trace_netfs_folio(folio, netfs_folio_trace_wthru_plus); + *writethrough_cache = folio; + } + + wreq->len += copied; + if (!to_page_end) + return 0; + + *writethrough_cache = NULL; + return netfs_write_folio(wreq, wbc, folio); +} + +/* + * End a write operation used when writing through the pagecache. + */ +int new_netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc, + struct folio *writethrough_cache) +{ + struct netfs_inode *ictx = netfs_inode(wreq->inode); + int ret; + + _enter("R=%x", wreq->debug_id); + + if (writethrough_cache) + netfs_write_folio(wreq, wbc, writethrough_cache); + + netfs_issue_write(wreq, &wreq->io_streams[0]); + netfs_issue_write(wreq, &wreq->io_streams[1]); + smp_wmb(); /* Write lists before ALL_QUEUED. */ + set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags); + + mutex_unlock(&ictx->wb_lock); + + ret = wreq->error; + netfs_put_request(wreq, false, netfs_rreq_trace_put_return); + return ret; +} + +/* + * Write data to the server without going through the pagecache and without + * writing it to the local cache. + */ +int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t len) +{ + struct netfs_io_stream *upload = &wreq->io_streams[0]; + ssize_t part; + loff_t start = wreq->start; + int error = 0; + + _enter("%zx", len); + + if (wreq->origin == NETFS_DIO_WRITE) + inode_dio_begin(wreq->inode); + + while (len) { + // TODO: Prepare content encryption + + _debug("unbuffered %zx", len); + part = netfs_advance_write(wreq, upload, start, len, false); + start += part; + len -= part; + if (test_bit(NETFS_RREQ_PAUSE, &wreq->flags)) { + trace_netfs_rreq(wreq, netfs_rreq_trace_wait_pause); + wait_on_bit(&wreq->flags, NETFS_RREQ_PAUSE, TASK_UNINTERRUPTIBLE); + } + if (test_bit(NETFS_RREQ_FAILED, &wreq->flags)) + break; + } + + netfs_issue_write(wreq, upload); + + smp_wmb(); /* Write lists before ALL_QUEUED. */ + set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags); + if (list_empty(&upload->subrequests)) + netfs_wake_write_collector(wreq, false); + + _leave(" = %d", error); + return error; +} |