netfs: Split fs/netfs/read_helper.c
Split fs/netfs/read_helper.c into two pieces, one to deal with buffered writes and one to deal with the I/O mechanism. Changes ======= ver #2) - Add kdoc reference to new file. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164623005586.3564931.6149556072728481767.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/164678217075.1200972.5101072043126828757.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/164692919953.2099075.7156989585513833046.stgit@warthog.procyon.org.uk/ # v3
This commit is contained in:
David Howells
parent
3be01750d7
commit
16211268fc
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@ -1,6 +1,7 @@
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# SPDX-License-Identifier: GPL-2.0
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netfs-y := \
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buffered_read.o \
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io.o \
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objects.o
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@ -0,0 +1,428 @@
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// SPDX-License-Identifier: GPL-2.0-or-later
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/* Network filesystem high-level buffered read support.
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*
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* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/export.h>
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#include <linux/task_io_accounting_ops.h>
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#include "internal.h"
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/*
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* Unlock the folios in a read operation. We need to set PG_fscache on any
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* folios we're going to write back before we unlock them.
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*/
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void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
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{
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struct netfs_io_subrequest *subreq;
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struct folio *folio;
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unsigned int iopos, account = 0;
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pgoff_t start_page = rreq->start / PAGE_SIZE;
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pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
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bool subreq_failed = false;
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XA_STATE(xas, &rreq->mapping->i_pages, start_page);
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if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) {
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__clear_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
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list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
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__clear_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
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}
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}
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/* Walk through the pagecache and the I/O request lists simultaneously.
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* We may have a mixture of cached and uncached sections and we only
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* really want to write out the uncached sections. This is slightly
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* complicated by the possibility that we might have huge pages with a
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* mixture inside.
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*/
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subreq = list_first_entry(&rreq->subrequests,
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struct netfs_io_subrequest, rreq_link);
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iopos = 0;
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subreq_failed = (subreq->error < 0);
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trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
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rcu_read_lock();
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xas_for_each(&xas, folio, last_page) {
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unsigned int pgpos = (folio_index(folio) - start_page) * PAGE_SIZE;
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unsigned int pgend = pgpos + folio_size(folio);
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bool pg_failed = false;
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for (;;) {
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if (!subreq) {
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pg_failed = true;
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break;
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}
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if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
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folio_start_fscache(folio);
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pg_failed |= subreq_failed;
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if (pgend < iopos + subreq->len)
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break;
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account += subreq->transferred;
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iopos += subreq->len;
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if (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
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subreq = list_next_entry(subreq, rreq_link);
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subreq_failed = (subreq->error < 0);
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} else {
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subreq = NULL;
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subreq_failed = false;
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}
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if (pgend == iopos)
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break;
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}
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if (!pg_failed) {
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flush_dcache_folio(folio);
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folio_mark_uptodate(folio);
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}
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if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
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if (folio_index(folio) == rreq->no_unlock_folio &&
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test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
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_debug("no unlock");
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else
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folio_unlock(folio);
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}
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}
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rcu_read_unlock();
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task_io_account_read(account);
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if (rreq->netfs_ops->done)
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rreq->netfs_ops->done(rreq);
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}
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static void netfs_cache_expand_readahead(struct netfs_io_request *rreq,
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loff_t *_start, size_t *_len, loff_t i_size)
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{
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struct netfs_cache_resources *cres = &rreq->cache_resources;
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if (cres->ops && cres->ops->expand_readahead)
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cres->ops->expand_readahead(cres, _start, _len, i_size);
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}
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static void netfs_rreq_expand(struct netfs_io_request *rreq,
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struct readahead_control *ractl)
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{
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/* Give the cache a chance to change the request parameters. The
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* resultant request must contain the original region.
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*/
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netfs_cache_expand_readahead(rreq, &rreq->start, &rreq->len, rreq->i_size);
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/* Give the netfs a chance to change the request parameters. The
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* resultant request must contain the original region.
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*/
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if (rreq->netfs_ops->expand_readahead)
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rreq->netfs_ops->expand_readahead(rreq);
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/* Expand the request if the cache wants it to start earlier. Note
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* that the expansion may get further extended if the VM wishes to
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* insert THPs and the preferred start and/or end wind up in the middle
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* of THPs.
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*
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* If this is the case, however, the THP size should be an integer
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* multiple of the cache granule size, so we get a whole number of
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* granules to deal with.
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*/
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if (rreq->start != readahead_pos(ractl) ||
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rreq->len != readahead_length(ractl)) {
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readahead_expand(ractl, rreq->start, rreq->len);
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rreq->start = readahead_pos(ractl);
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rreq->len = readahead_length(ractl);
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trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
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netfs_read_trace_expanded);
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}
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}
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/**
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* netfs_readahead - Helper to manage a read request
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* @ractl: The description of the readahead request
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*
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* Fulfil a readahead request by drawing data from the cache if possible, or
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* the netfs if not. Space beyond the EOF is zero-filled. Multiple I/O
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* requests from different sources will get munged together. If necessary, the
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* readahead window can be expanded in either direction to a more convenient
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* alighment for RPC efficiency or to make storage in the cache feasible.
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*
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* The calling netfs must initialise a netfs context contiguous to the vfs
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* inode before calling this.
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*
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* This is usable whether or not caching is enabled.
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*/
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void netfs_readahead(struct readahead_control *ractl)
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{
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struct netfs_io_request *rreq;
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struct netfs_i_context *ctx = netfs_i_context(ractl->mapping->host);
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int ret;
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_enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
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if (readahead_count(ractl) == 0)
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return;
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rreq = netfs_alloc_request(ractl->mapping, ractl->file,
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readahead_pos(ractl),
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readahead_length(ractl),
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NETFS_READAHEAD);
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if (IS_ERR(rreq))
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return;
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if (ctx->ops->begin_cache_operation) {
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ret = ctx->ops->begin_cache_operation(rreq);
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if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
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goto cleanup_free;
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}
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netfs_stat(&netfs_n_rh_readahead);
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trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
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netfs_read_trace_readahead);
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netfs_rreq_expand(rreq, ractl);
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/* Drop the refs on the folios here rather than in the cache or
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* filesystem. The locks will be dropped in netfs_rreq_unlock().
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*/
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while (readahead_folio(ractl))
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;
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netfs_begin_read(rreq, false);
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return;
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cleanup_free:
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netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
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return;
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}
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EXPORT_SYMBOL(netfs_readahead);
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/**
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* netfs_readpage - Helper to manage a readpage request
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* @file: The file to read from
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* @subpage: A subpage of the folio to read
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*
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* Fulfil a readpage request by drawing data from the cache if possible, or the
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* netfs if not. Space beyond the EOF is zero-filled. Multiple I/O requests
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* from different sources will get munged together.
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*
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* The calling netfs must initialise a netfs context contiguous to the vfs
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* inode before calling this.
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*
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* This is usable whether or not caching is enabled.
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*/
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int netfs_readpage(struct file *file, struct page *subpage)
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{
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struct folio *folio = page_folio(subpage);
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struct address_space *mapping = folio_file_mapping(folio);
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struct netfs_io_request *rreq;
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struct netfs_i_context *ctx = netfs_i_context(mapping->host);
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int ret;
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_enter("%lx", folio_index(folio));
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rreq = netfs_alloc_request(mapping, file,
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folio_file_pos(folio), folio_size(folio),
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NETFS_READPAGE);
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if (IS_ERR(rreq)) {
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ret = PTR_ERR(rreq);
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goto alloc_error;
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}
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if (ctx->ops->begin_cache_operation) {
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ret = ctx->ops->begin_cache_operation(rreq);
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if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
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goto discard;
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}
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netfs_stat(&netfs_n_rh_readpage);
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trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
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return netfs_begin_read(rreq, true);
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discard:
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netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
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alloc_error:
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folio_unlock(folio);
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return ret;
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}
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EXPORT_SYMBOL(netfs_readpage);
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/*
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* Prepare a folio for writing without reading first
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* @folio: The folio being prepared
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* @pos: starting position for the write
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* @len: length of write
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* @always_fill: T if the folio should always be completely filled/cleared
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*
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* In some cases, write_begin doesn't need to read at all:
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* - full folio write
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* - write that lies in a folio that is completely beyond EOF
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* - write that covers the folio from start to EOF or beyond it
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*
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* If any of these criteria are met, then zero out the unwritten parts
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* of the folio and return true. Otherwise, return false.
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*/
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static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,
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bool always_fill)
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{
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struct inode *inode = folio_inode(folio);
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loff_t i_size = i_size_read(inode);
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size_t offset = offset_in_folio(folio, pos);
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size_t plen = folio_size(folio);
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if (unlikely(always_fill)) {
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if (pos - offset + len <= i_size)
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return false; /* Page entirely before EOF */
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zero_user_segment(&folio->page, 0, plen);
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folio_mark_uptodate(folio);
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return true;
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}
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/* Full folio write */
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if (offset == 0 && len >= plen)
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return true;
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/* Page entirely beyond the end of the file */
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if (pos - offset >= i_size)
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goto zero_out;
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/* Write that covers from the start of the folio to EOF or beyond */
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if (offset == 0 && (pos + len) >= i_size)
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goto zero_out;
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return false;
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zero_out:
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zero_user_segments(&folio->page, 0, offset, offset + len, plen);
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return true;
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}
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/**
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* netfs_write_begin - Helper to prepare for writing
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* @file: The file to read from
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* @mapping: The mapping to read from
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* @pos: File position at which the write will begin
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* @len: The length of the write (may extend beyond the end of the folio chosen)
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* @aop_flags: AOP_* flags
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* @_folio: Where to put the resultant folio
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* @_fsdata: Place for the netfs to store a cookie
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*
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* Pre-read data for a write-begin request by drawing data from the cache if
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* possible, or the netfs if not. Space beyond the EOF is zero-filled.
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* Multiple I/O requests from different sources will get munged together. If
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* necessary, the readahead window can be expanded in either direction to a
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* more convenient alighment for RPC efficiency or to make storage in the cache
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* feasible.
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*
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* The calling netfs must provide a table of operations, only one of which,
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* issue_op, is mandatory.
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*
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* The check_write_begin() operation can be provided to check for and flush
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* conflicting writes once the folio is grabbed and locked. It is passed a
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* pointer to the fsdata cookie that gets returned to the VM to be passed to
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* write_end. It is permitted to sleep. It should return 0 if the request
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* should go ahead; unlock the folio and return -EAGAIN to cause the folio to
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* be regot; or return an error.
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*
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* The calling netfs must initialise a netfs context contiguous to the vfs
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* inode before calling this.
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*
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* This is usable whether or not caching is enabled.
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*/
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int netfs_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned int len, unsigned int aop_flags,
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struct folio **_folio, void **_fsdata)
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{
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struct netfs_io_request *rreq;
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struct netfs_i_context *ctx = netfs_i_context(file_inode(file ));
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struct folio *folio;
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unsigned int fgp_flags;
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pgoff_t index = pos >> PAGE_SHIFT;
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int ret;
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DEFINE_READAHEAD(ractl, file, NULL, mapping, index);
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retry:
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fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;
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if (aop_flags & AOP_FLAG_NOFS)
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fgp_flags |= FGP_NOFS;
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folio = __filemap_get_folio(mapping, index, fgp_flags,
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mapping_gfp_mask(mapping));
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if (!folio)
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return -ENOMEM;
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if (ctx->ops->check_write_begin) {
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/* Allow the netfs (eg. ceph) to flush conflicts. */
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ret = ctx->ops->check_write_begin(file, pos, len, folio, _fsdata);
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if (ret < 0) {
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trace_netfs_failure(NULL, NULL, ret, netfs_fail_check_write_begin);
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if (ret == -EAGAIN)
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goto retry;
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goto error;
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}
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}
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if (folio_test_uptodate(folio))
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goto have_folio;
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/* If the page is beyond the EOF, we want to clear it - unless it's
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* within the cache granule containing the EOF, in which case we need
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* to preload the granule.
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*/
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if (!netfs_is_cache_enabled(ctx) &&
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netfs_skip_folio_read(folio, pos, len, false)) {
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netfs_stat(&netfs_n_rh_write_zskip);
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goto have_folio_no_wait;
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}
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rreq = netfs_alloc_request(mapping, file,
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folio_file_pos(folio), folio_size(folio),
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NETFS_READ_FOR_WRITE);
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if (IS_ERR(rreq)) {
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ret = PTR_ERR(rreq);
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goto error;
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}
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rreq->no_unlock_folio = folio_index(folio);
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__set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags);
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if (ctx->ops->begin_cache_operation) {
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ret = ctx->ops->begin_cache_operation(rreq);
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if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
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goto error_put;
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}
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netfs_stat(&netfs_n_rh_write_begin);
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trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
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/* Expand the request to meet caching requirements and download
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* preferences.
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*/
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ractl._nr_pages = folio_nr_pages(folio);
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netfs_rreq_expand(rreq, &ractl);
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/* We hold the folio locks, so we can drop the references */
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folio_get(folio);
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while (readahead_folio(&ractl))
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;
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ret = netfs_begin_read(rreq, true);
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if (ret < 0)
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goto error;
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have_folio:
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ret = folio_wait_fscache_killable(folio);
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if (ret < 0)
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goto error;
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have_folio_no_wait:
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*_folio = folio;
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_leave(" = 0");
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return 0;
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error_put:
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netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
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error:
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folio_unlock(folio);
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folio_put(folio);
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_leave(" = %d", ret);
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return ret;
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||||
}
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EXPORT_SYMBOL(netfs_write_begin);
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418
fs/netfs/io.c
418
fs/netfs/io.c
|
|
@ -246,91 +246,6 @@ static void netfs_rreq_write_to_cache(struct netfs_io_request *rreq)
|
|||
BUG();
|
||||
}
|
||||
|
||||
/*
|
||||
* Unlock the folios in a read operation. We need to set PG_fscache on any
|
||||
* folios we're going to write back before we unlock them.
|
||||
*/
|
||||
void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
|
||||
{
|
||||
struct netfs_io_subrequest *subreq;
|
||||
struct folio *folio;
|
||||
unsigned int iopos, account = 0;
|
||||
pgoff_t start_page = rreq->start / PAGE_SIZE;
|
||||
pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
|
||||
bool subreq_failed = false;
|
||||
|
||||
XA_STATE(xas, &rreq->mapping->i_pages, start_page);
|
||||
|
||||
if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) {
|
||||
__clear_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags);
|
||||
list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
|
||||
__clear_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
|
||||
}
|
||||
}
|
||||
|
||||
/* Walk through the pagecache and the I/O request lists simultaneously.
|
||||
* We may have a mixture of cached and uncached sections and we only
|
||||
* really want to write out the uncached sections. This is slightly
|
||||
* complicated by the possibility that we might have huge pages with a
|
||||
* mixture inside.
|
||||
*/
|
||||
subreq = list_first_entry(&rreq->subrequests,
|
||||
struct netfs_io_subrequest, rreq_link);
|
||||
iopos = 0;
|
||||
subreq_failed = (subreq->error < 0);
|
||||
|
||||
trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
|
||||
|
||||
rcu_read_lock();
|
||||
xas_for_each(&xas, folio, last_page) {
|
||||
unsigned int pgpos = (folio_index(folio) - start_page) * PAGE_SIZE;
|
||||
unsigned int pgend = pgpos + folio_size(folio);
|
||||
bool pg_failed = false;
|
||||
|
||||
for (;;) {
|
||||
if (!subreq) {
|
||||
pg_failed = true;
|
||||
break;
|
||||
}
|
||||
if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
|
||||
folio_start_fscache(folio);
|
||||
pg_failed |= subreq_failed;
|
||||
if (pgend < iopos + subreq->len)
|
||||
break;
|
||||
|
||||
account += subreq->transferred;
|
||||
iopos += subreq->len;
|
||||
if (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
|
||||
subreq = list_next_entry(subreq, rreq_link);
|
||||
subreq_failed = (subreq->error < 0);
|
||||
} else {
|
||||
subreq = NULL;
|
||||
subreq_failed = false;
|
||||
}
|
||||
if (pgend == iopos)
|
||||
break;
|
||||
}
|
||||
|
||||
if (!pg_failed) {
|
||||
flush_dcache_folio(folio);
|
||||
folio_mark_uptodate(folio);
|
||||
}
|
||||
|
||||
if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
|
||||
if (folio_index(folio) == rreq->no_unlock_folio &&
|
||||
test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
|
||||
_debug("no unlock");
|
||||
else
|
||||
folio_unlock(folio);
|
||||
}
|
||||
}
|
||||
rcu_read_unlock();
|
||||
|
||||
task_io_account_read(account);
|
||||
if (rreq->netfs_ops->done)
|
||||
rreq->netfs_ops->done(rreq);
|
||||
}
|
||||
|
||||
/*
|
||||
* Handle a short read.
|
||||
*/
|
||||
|
|
@ -750,336 +665,3 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
|
|||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
static void netfs_cache_expand_readahead(struct netfs_io_request *rreq,
|
||||
loff_t *_start, size_t *_len, loff_t i_size)
|
||||
{
|
||||
struct netfs_cache_resources *cres = &rreq->cache_resources;
|
||||
|
||||
if (cres->ops && cres->ops->expand_readahead)
|
||||
cres->ops->expand_readahead(cres, _start, _len, i_size);
|
||||
}
|
||||
|
||||
static void netfs_rreq_expand(struct netfs_io_request *rreq,
|
||||
struct readahead_control *ractl)
|
||||
{
|
||||
/* Give the cache a chance to change the request parameters. The
|
||||
* resultant request must contain the original region.
|
||||
*/
|
||||
netfs_cache_expand_readahead(rreq, &rreq->start, &rreq->len, rreq->i_size);
|
||||
|
||||
/* Give the netfs a chance to change the request parameters. The
|
||||
* resultant request must contain the original region.
|
||||
*/
|
||||
if (rreq->netfs_ops->expand_readahead)
|
||||
rreq->netfs_ops->expand_readahead(rreq);
|
||||
|
||||
/* Expand the request if the cache wants it to start earlier. Note
|
||||
* that the expansion may get further extended if the VM wishes to
|
||||
* insert THPs and the preferred start and/or end wind up in the middle
|
||||
* of THPs.
|
||||
*
|
||||
* If this is the case, however, the THP size should be an integer
|
||||
* multiple of the cache granule size, so we get a whole number of
|
||||
* granules to deal with.
|
||||
*/
|
||||
if (rreq->start != readahead_pos(ractl) ||
|
||||
rreq->len != readahead_length(ractl)) {
|
||||
readahead_expand(ractl, rreq->start, rreq->len);
|
||||
rreq->start = readahead_pos(ractl);
|
||||
rreq->len = readahead_length(ractl);
|
||||
|
||||
trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
|
||||
netfs_read_trace_expanded);
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* netfs_readahead - Helper to manage a read request
|
||||
* @ractl: The description of the readahead request
|
||||
*
|
||||
* Fulfil a readahead request by drawing data from the cache if possible, or
|
||||
* the netfs if not. Space beyond the EOF is zero-filled. Multiple I/O
|
||||
* requests from different sources will get munged together. If necessary, the
|
||||
* readahead window can be expanded in either direction to a more convenient
|
||||
* alighment for RPC efficiency or to make storage in the cache feasible.
|
||||
*
|
||||
* The calling netfs must initialise a netfs context contiguous to the vfs
|
||||
* inode before calling this.
|
||||
*
|
||||
* This is usable whether or not caching is enabled.
|
||||
*/
|
||||
void netfs_readahead(struct readahead_control *ractl)
|
||||
{
|
||||
struct netfs_io_request *rreq;
|
||||
struct netfs_i_context *ctx = netfs_i_context(ractl->mapping->host);
|
||||
int ret;
|
||||
|
||||
_enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
|
||||
|
||||
if (readahead_count(ractl) == 0)
|
||||
return;
|
||||
|
||||
rreq = netfs_alloc_request(ractl->mapping, ractl->file,
|
||||
readahead_pos(ractl),
|
||||
readahead_length(ractl),
|
||||
NETFS_READAHEAD);
|
||||
if (IS_ERR(rreq))
|
||||
return;
|
||||
|
||||
if (ctx->ops->begin_cache_operation) {
|
||||
ret = ctx->ops->begin_cache_operation(rreq);
|
||||
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
|
||||
goto cleanup_free;
|
||||
}
|
||||
|
||||
netfs_stat(&netfs_n_rh_readahead);
|
||||
trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
|
||||
netfs_read_trace_readahead);
|
||||
|
||||
netfs_rreq_expand(rreq, ractl);
|
||||
|
||||
/* Drop the refs on the folios here rather than in the cache or
|
||||
* filesystem. The locks will be dropped in netfs_rreq_unlock().
|
||||
*/
|
||||
while (readahead_folio(ractl))
|
||||
;
|
||||
|
||||
netfs_begin_read(rreq, false);
|
||||
return;
|
||||
|
||||
cleanup_free:
|
||||
netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
|
||||
return;
|
||||
}
|
||||
EXPORT_SYMBOL(netfs_readahead);
|
||||
|
||||
/**
|
||||
* netfs_readpage - Helper to manage a readpage request
|
||||
* @file: The file to read from
|
||||
* @subpage: A subpage of the folio to read
|
||||
*
|
||||
* Fulfil a readpage request by drawing data from the cache if possible, or the
|
||||
* netfs if not. Space beyond the EOF is zero-filled. Multiple I/O requests
|
||||
* from different sources will get munged together.
|
||||
*
|
||||
* The calling netfs must initialise a netfs context contiguous to the vfs
|
||||
* inode before calling this.
|
||||
*
|
||||
* This is usable whether or not caching is enabled.
|
||||
*/
|
||||
int netfs_readpage(struct file *file, struct page *subpage)
|
||||
{
|
||||
struct folio *folio = page_folio(subpage);
|
||||
struct address_space *mapping = folio->mapping;
|
||||
struct netfs_io_request *rreq;
|
||||
struct netfs_i_context *ctx = netfs_i_context(mapping->host);
|
||||
int ret;
|
||||
|
||||
_enter("%lx", folio_index(folio));
|
||||
|
||||
rreq = netfs_alloc_request(mapping, file,
|
||||
folio_file_pos(folio), folio_size(folio),
|
||||
NETFS_READPAGE);
|
||||
if (IS_ERR(rreq)) {
|
||||
ret = PTR_ERR(rreq);
|
||||
goto alloc_error;
|
||||
}
|
||||
|
||||
if (ctx->ops->begin_cache_operation) {
|
||||
ret = ctx->ops->begin_cache_operation(rreq);
|
||||
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
|
||||
goto discard;
|
||||
}
|
||||
|
||||
netfs_stat(&netfs_n_rh_readpage);
|
||||
trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
|
||||
return netfs_begin_read(rreq, true);
|
||||
|
||||
discard:
|
||||
netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
|
||||
alloc_error:
|
||||
folio_unlock(folio);
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL(netfs_readpage);
|
||||
|
||||
/*
|
||||
* Prepare a folio for writing without reading first
|
||||
* @folio: The folio being prepared
|
||||
* @pos: starting position for the write
|
||||
* @len: length of write
|
||||
* @always_fill: T if the folio should always be completely filled/cleared
|
||||
*
|
||||
* In some cases, write_begin doesn't need to read at all:
|
||||
* - full folio write
|
||||
* - write that lies in a folio that is completely beyond EOF
|
||||
* - write that covers the folio from start to EOF or beyond it
|
||||
*
|
||||
* If any of these criteria are met, then zero out the unwritten parts
|
||||
* of the folio and return true. Otherwise, return false.
|
||||
*/
|
||||
static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,
|
||||
bool always_fill)
|
||||
{
|
||||
struct inode *inode = folio_inode(folio);
|
||||
loff_t i_size = i_size_read(inode);
|
||||
size_t offset = offset_in_folio(folio, pos);
|
||||
size_t plen = folio_size(folio);
|
||||
|
||||
if (unlikely(always_fill)) {
|
||||
if (pos - offset + len <= i_size)
|
||||
return false; /* Page entirely before EOF */
|
||||
zero_user_segment(&folio->page, 0, plen);
|
||||
folio_mark_uptodate(folio);
|
||||
return true;
|
||||
}
|
||||
|
||||
/* Full folio write */
|
||||
if (offset == 0 && len >= plen)
|
||||
return true;
|
||||
|
||||
/* Page entirely beyond the end of the file */
|
||||
if (pos - offset >= i_size)
|
||||
goto zero_out;
|
||||
|
||||
/* Write that covers from the start of the folio to EOF or beyond */
|
||||
if (offset == 0 && (pos + len) >= i_size)
|
||||
goto zero_out;
|
||||
|
||||
return false;
|
||||
zero_out:
|
||||
zero_user_segments(&folio->page, 0, offset, offset + len, plen);
|
||||
return true;
|
||||
}
|
||||
|
||||
/**
|
||||
* netfs_write_begin - Helper to prepare for writing
|
||||
* @file: The file to read from
|
||||
* @mapping: The mapping to read from
|
||||
* @pos: File position at which the write will begin
|
||||
* @len: The length of the write (may extend beyond the end of the folio chosen)
|
||||
* @aop_flags: AOP_* flags
|
||||
* @_folio: Where to put the resultant folio
|
||||
* @_fsdata: Place for the netfs to store a cookie
|
||||
*
|
||||
* Pre-read data for a write-begin request by drawing data from the cache if
|
||||
* possible, or the netfs if not. Space beyond the EOF is zero-filled.
|
||||
* Multiple I/O requests from different sources will get munged together. If
|
||||
* necessary, the readahead window can be expanded in either direction to a
|
||||
* more convenient alighment for RPC efficiency or to make storage in the cache
|
||||
* feasible.
|
||||
*
|
||||
* The calling netfs must provide a table of operations, only one of which,
|
||||
* issue_op, is mandatory.
|
||||
*
|
||||
* The check_write_begin() operation can be provided to check for and flush
|
||||
* conflicting writes once the folio is grabbed and locked. It is passed a
|
||||
* pointer to the fsdata cookie that gets returned to the VM to be passed to
|
||||
* write_end. It is permitted to sleep. It should return 0 if the request
|
||||
* should go ahead; unlock the folio and return -EAGAIN to cause the folio to
|
||||
* be regot; or return an error.
|
||||
*
|
||||
* The calling netfs must initialise a netfs context contiguous to the vfs
|
||||
* inode before calling this.
|
||||
*
|
||||
* This is usable whether or not caching is enabled.
|
||||
*/
|
||||
int netfs_write_begin(struct file *file, struct address_space *mapping,
|
||||
loff_t pos, unsigned int len, unsigned int aop_flags,
|
||||
struct folio **_folio, void **_fsdata)
|
||||
{
|
||||
struct netfs_io_request *rreq;
|
||||
struct netfs_i_context *ctx = netfs_i_context(file_inode(file ));
|
||||
struct folio *folio;
|
||||
unsigned int fgp_flags;
|
||||
pgoff_t index = pos >> PAGE_SHIFT;
|
||||
int ret;
|
||||
|
||||
DEFINE_READAHEAD(ractl, file, NULL, mapping, index);
|
||||
|
||||
retry:
|
||||
fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;
|
||||
if (aop_flags & AOP_FLAG_NOFS)
|
||||
fgp_flags |= FGP_NOFS;
|
||||
folio = __filemap_get_folio(mapping, index, fgp_flags,
|
||||
mapping_gfp_mask(mapping));
|
||||
if (!folio)
|
||||
return -ENOMEM;
|
||||
|
||||
if (ctx->ops->check_write_begin) {
|
||||
/* Allow the netfs (eg. ceph) to flush conflicts. */
|
||||
ret = ctx->ops->check_write_begin(file, pos, len, folio, _fsdata);
|
||||
if (ret < 0) {
|
||||
trace_netfs_failure(NULL, NULL, ret, netfs_fail_check_write_begin);
|
||||
if (ret == -EAGAIN)
|
||||
goto retry;
|
||||
goto error;
|
||||
}
|
||||
}
|
||||
|
||||
if (folio_test_uptodate(folio))
|
||||
goto have_folio;
|
||||
|
||||
/* If the page is beyond the EOF, we want to clear it - unless it's
|
||||
* within the cache granule containing the EOF, in which case we need
|
||||
* to preload the granule.
|
||||
*/
|
||||
if (!netfs_is_cache_enabled(ctx) &&
|
||||
netfs_skip_folio_read(folio, pos, len, false)) {
|
||||
netfs_stat(&netfs_n_rh_write_zskip);
|
||||
goto have_folio_no_wait;
|
||||
}
|
||||
|
||||
rreq = netfs_alloc_request(mapping, file,
|
||||
folio_file_pos(folio), folio_size(folio),
|
||||
NETFS_READ_FOR_WRITE);
|
||||
if (IS_ERR(rreq)) {
|
||||
ret = PTR_ERR(rreq);
|
||||
goto error;
|
||||
}
|
||||
rreq->no_unlock_folio = folio_index(folio);
|
||||
__set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags);
|
||||
|
||||
if (ctx->ops->begin_cache_operation) {
|
||||
ret = ctx->ops->begin_cache_operation(rreq);
|
||||
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
|
||||
goto error_put;
|
||||
}
|
||||
|
||||
netfs_stat(&netfs_n_rh_write_begin);
|
||||
trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
|
||||
|
||||
/* Expand the request to meet caching requirements and download
|
||||
* preferences.
|
||||
*/
|
||||
ractl._nr_pages = folio_nr_pages(folio);
|
||||
netfs_rreq_expand(rreq, &ractl);
|
||||
|
||||
/* We hold the folio locks, so we can drop the references */
|
||||
folio_get(folio);
|
||||
while (readahead_folio(&ractl))
|
||||
;
|
||||
|
||||
ret = netfs_begin_read(rreq, true);
|
||||
if (ret < 0)
|
||||
goto error;
|
||||
|
||||
have_folio:
|
||||
ret = folio_wait_fscache_killable(folio);
|
||||
if (ret < 0)
|
||||
goto error;
|
||||
have_folio_no_wait:
|
||||
*_folio = folio;
|
||||
_leave(" = 0");
|
||||
return 0;
|
||||
|
||||
error_put:
|
||||
netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
|
||||
error:
|
||||
folio_unlock(folio);
|
||||
folio_put(folio);
|
||||
_leave(" = %d", ret);
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL(netfs_write_begin);
|
||||
|
|
|
|||
Loading…
Reference in New Issue