// SPDX-License-Identifier: GPL-2.0-only
/* Miscellaneous routines.
*
* Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*/
#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);
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