diff options
Diffstat (limited to 'fs/netfs/misc.c')
-rw-r--r-- | fs/netfs/misc.c | 327 |
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); |