summaryrefslogtreecommitdiff
path: root/fs/netfs/misc.c
blob: 172808e83ca81c01db5d99716f987fd6a82932f5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
// 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"

/**
 * 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;

	kenter("");

	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;
	size_t flen = folio_size(folio);

	kenter("{%lx},%zx,%zx", folio->index, offset, length);

	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 end = offset + length;

		if (offset >= fend)
			return;
		if (end <= fstart)
			return;
		if (offset <= fstart && end >= fend)
			goto erase_completely;
		if (offset <= fstart && end > fstart)
			goto reduce_len;
		if (offset > fstart && end >= fend)
			goto move_start;
		/* 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;
reduce_len:
	finfo->dirty_len = offset + length - finfo->dirty_offset;
	return;
move_start:
	finfo->dirty_len -= offset - finfo->dirty_offset;
	finfo->dirty_offset = offset;
}
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;

	end = folio_pos(folio) + folio_size(folio);
	if (end > ctx->zero_point)
		ctx->zero_point = end;

	if (folio_test_private(folio))
		return false;
	fscache_note_page_release(netfs_i_cookie(ctx));
	return true;
}
EXPORT_SYMBOL(netfs_release_folio);