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-rw-r--r--fs/netfs/misc.c327
1 files changed, 327 insertions, 0 deletions
diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c
new file mode 100644
index 000000000000..78fe5796b2b2
--- /dev/null
+++ b/fs/netfs/misc.c
@@ -0,0 +1,327 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Miscellaneous routines.
+ *
+ * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/swap.h>
+#include "internal.h"
+
+/*
+ * Make sure there's space in the rolling queue.
+ */
+struct folio_queue *netfs_buffer_make_space(struct netfs_io_request *rreq)
+{
+ struct folio_queue *tail = rreq->buffer_tail, *prev;
+ unsigned int prev_nr_slots = 0;
+
+ if (WARN_ON_ONCE(!rreq->buffer && tail) ||
+ WARN_ON_ONCE(rreq->buffer && !tail))
+ return ERR_PTR(-EIO);
+
+ prev = tail;
+ if (prev) {
+ if (!folioq_full(tail))
+ return tail;
+ prev_nr_slots = folioq_nr_slots(tail);
+ }
+
+ tail = kmalloc(sizeof(*tail), GFP_NOFS);
+ if (!tail)
+ return ERR_PTR(-ENOMEM);
+ netfs_stat(&netfs_n_folioq);
+ folioq_init(tail);
+ tail->prev = prev;
+ if (prev)
+ /* [!] NOTE: After we set prev->next, the consumer is entirely
+ * at liberty to delete prev.
+ */
+ WRITE_ONCE(prev->next, tail);
+
+ rreq->buffer_tail = tail;
+ if (!rreq->buffer) {
+ rreq->buffer = tail;
+ iov_iter_folio_queue(&rreq->io_iter, ITER_SOURCE, tail, 0, 0, 0);
+ } else {
+ /* Make sure we don't leave the master iterator pointing to a
+ * block that might get immediately consumed.
+ */
+ if (rreq->io_iter.folioq == prev &&
+ rreq->io_iter.folioq_slot == prev_nr_slots) {
+ rreq->io_iter.folioq = tail;
+ rreq->io_iter.folioq_slot = 0;
+ }
+ }
+ rreq->buffer_tail_slot = 0;
+ return tail;
+}
+
+/*
+ * Append a folio to the rolling queue.
+ */
+int netfs_buffer_append_folio(struct netfs_io_request *rreq, struct folio *folio,
+ bool needs_put)
+{
+ struct folio_queue *tail;
+ unsigned int slot, order = folio_order(folio);
+
+ tail = netfs_buffer_make_space(rreq);
+ if (IS_ERR(tail))
+ return PTR_ERR(tail);
+
+ rreq->io_iter.count += PAGE_SIZE << order;
+
+ slot = folioq_append(tail, folio);
+ /* Store the counter after setting the slot. */
+ smp_store_release(&rreq->buffer_tail_slot, slot);
+ return 0;
+}
+
+/*
+ * Delete the head of a rolling queue.
+ */
+struct folio_queue *netfs_delete_buffer_head(struct netfs_io_request *wreq)
+{
+ struct folio_queue *head = wreq->buffer, *next = head->next;
+
+ if (next)
+ next->prev = NULL;
+ netfs_stat_d(&netfs_n_folioq);
+ kfree(head);
+ wreq->buffer = next;
+ return next;
+}
+
+/*
+ * Clear out a rolling queue.
+ */
+void netfs_clear_buffer(struct netfs_io_request *rreq)
+{
+ struct folio_queue *p;
+
+ while ((p = rreq->buffer)) {
+ rreq->buffer = p->next;
+ for (int slot = 0; slot < folioq_count(p); slot++) {
+ struct folio *folio = folioq_folio(p, slot);
+ if (!folio)
+ continue;
+ if (folioq_is_marked(p, slot)) {
+ trace_netfs_folio(folio, netfs_folio_trace_put);
+ folio_put(folio);
+ }
+ }
+ netfs_stat_d(&netfs_n_folioq);
+ kfree(p);
+ }
+}
+
+/*
+ * Reset the subrequest iterator to refer just to the region remaining to be
+ * read. The iterator may or may not have been advanced by socket ops or
+ * extraction ops to an extent that may or may not match the amount actually
+ * read.
+ */
+void netfs_reset_iter(struct netfs_io_subrequest *subreq)
+{
+ struct iov_iter *io_iter = &subreq->io_iter;
+ size_t remain = subreq->len - subreq->transferred;
+
+ if (io_iter->count > remain)
+ iov_iter_advance(io_iter, io_iter->count - remain);
+ else if (io_iter->count < remain)
+ iov_iter_revert(io_iter, remain - io_iter->count);
+ iov_iter_truncate(&subreq->io_iter, remain);
+}
+
+/**
+ * netfs_dirty_folio - Mark folio dirty and pin a cache object for writeback
+ * @mapping: The mapping the folio belongs to.
+ * @folio: The folio being dirtied.
+ *
+ * Set the dirty flag on a folio and pin an in-use cache object in memory so
+ * that writeback can later write to it. This is intended to be called from
+ * the filesystem's ->dirty_folio() method.
+ *
+ * Return: true if the dirty flag was set on the folio, false otherwise.
+ */
+bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio)
+{
+ struct inode *inode = mapping->host;
+ struct netfs_inode *ictx = netfs_inode(inode);
+ struct fscache_cookie *cookie = netfs_i_cookie(ictx);
+ bool need_use = false;
+
+ _enter("");
+
+ if (!filemap_dirty_folio(mapping, folio))
+ return false;
+ if (!fscache_cookie_valid(cookie))
+ return true;
+
+ if (!(inode->i_state & I_PINNING_NETFS_WB)) {
+ spin_lock(&inode->i_lock);
+ if (!(inode->i_state & I_PINNING_NETFS_WB)) {
+ inode->i_state |= I_PINNING_NETFS_WB;
+ need_use = true;
+ }
+ spin_unlock(&inode->i_lock);
+
+ if (need_use)
+ fscache_use_cookie(cookie, true);
+ }
+ return true;
+}
+EXPORT_SYMBOL(netfs_dirty_folio);
+
+/**
+ * netfs_unpin_writeback - Unpin writeback resources
+ * @inode: The inode on which the cookie resides
+ * @wbc: The writeback control
+ *
+ * Unpin the writeback resources pinned by netfs_dirty_folio(). This is
+ * intended to be called as/by the netfs's ->write_inode() method.
+ */
+int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc)
+{
+ struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
+
+ if (wbc->unpinned_netfs_wb)
+ fscache_unuse_cookie(cookie, NULL, NULL);
+ return 0;
+}
+EXPORT_SYMBOL(netfs_unpin_writeback);
+
+/**
+ * netfs_clear_inode_writeback - Clear writeback resources pinned by an inode
+ * @inode: The inode to clean up
+ * @aux: Auxiliary data to apply to the inode
+ *
+ * Clear any writeback resources held by an inode when the inode is evicted.
+ * This must be called before clear_inode() is called.
+ */
+void netfs_clear_inode_writeback(struct inode *inode, const void *aux)
+{
+ struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
+
+ if (inode->i_state & I_PINNING_NETFS_WB) {
+ loff_t i_size = i_size_read(inode);
+ fscache_unuse_cookie(cookie, aux, &i_size);
+ }
+}
+EXPORT_SYMBOL(netfs_clear_inode_writeback);
+
+/**
+ * netfs_invalidate_folio - Invalidate or partially invalidate a folio
+ * @folio: Folio proposed for release
+ * @offset: Offset of the invalidated region
+ * @length: Length of the invalidated region
+ *
+ * Invalidate part or all of a folio for a network filesystem. The folio will
+ * be removed afterwards if the invalidated region covers the entire folio.
+ */
+void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length)
+{
+ struct netfs_folio *finfo;
+ struct netfs_inode *ctx = netfs_inode(folio_inode(folio));
+ size_t flen = folio_size(folio);
+
+ _enter("{%lx},%zx,%zx", folio->index, offset, length);
+
+ if (offset == 0 && length == flen) {
+ unsigned long long i_size = i_size_read(&ctx->inode);
+ unsigned long long fpos = folio_pos(folio), end;
+
+ end = umin(fpos + flen, i_size);
+ if (fpos < i_size && end > ctx->zero_point)
+ ctx->zero_point = end;
+ }
+
+ folio_wait_private_2(folio); /* [DEPRECATED] */
+
+ if (!folio_test_private(folio))
+ return;
+
+ finfo = netfs_folio_info(folio);
+
+ if (offset == 0 && length >= flen)
+ goto erase_completely;
+
+ if (finfo) {
+ /* We have a partially uptodate page from a streaming write. */
+ unsigned int fstart = finfo->dirty_offset;
+ unsigned int fend = fstart + finfo->dirty_len;
+ unsigned int iend = offset + length;
+
+ if (offset >= fend)
+ return;
+ if (iend <= fstart)
+ return;
+
+ /* The invalidation region overlaps the data. If the region
+ * covers the start of the data, we either move along the start
+ * or just erase the data entirely.
+ */
+ if (offset <= fstart) {
+ if (iend >= fend)
+ goto erase_completely;
+ /* Move the start of the data. */
+ finfo->dirty_len = fend - iend;
+ finfo->dirty_offset = offset;
+ return;
+ }
+
+ /* Reduce the length of the data if the invalidation region
+ * covers the tail part.
+ */
+ if (iend >= fend) {
+ finfo->dirty_len = offset - fstart;
+ return;
+ }
+
+ /* A partial write was split. The caller has already zeroed
+ * it, so just absorb the hole.
+ */
+ }
+ return;
+
+erase_completely:
+ netfs_put_group(netfs_folio_group(folio));
+ folio_detach_private(folio);
+ folio_clear_uptodate(folio);
+ kfree(finfo);
+ return;
+}
+EXPORT_SYMBOL(netfs_invalidate_folio);
+
+/**
+ * netfs_release_folio - Try to release a folio
+ * @folio: Folio proposed for release
+ * @gfp: Flags qualifying the release
+ *
+ * Request release of a folio and clean up its private state if it's not busy.
+ * Returns true if the folio can now be released, false if not
+ */
+bool netfs_release_folio(struct folio *folio, gfp_t gfp)
+{
+ struct netfs_inode *ctx = netfs_inode(folio_inode(folio));
+ unsigned long long end;
+
+ if (folio_test_dirty(folio))
+ return false;
+
+ end = umin(folio_pos(folio) + folio_size(folio), i_size_read(&ctx->inode));
+ if (end > ctx->zero_point)
+ ctx->zero_point = end;
+
+ if (folio_test_private(folio))
+ return false;
+ if (unlikely(folio_test_private_2(folio))) { /* [DEPRECATED] */
+ if (current_is_kswapd() || !(gfp & __GFP_FS))
+ return false;
+ folio_wait_private_2(folio);
+ }
+ fscache_note_page_release(netfs_i_cookie(ctx));
+ return true;
+}
+EXPORT_SYMBOL(netfs_release_folio);