1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Miscellaneous routines. 3 * 4 * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/swap.h> 9 #include "internal.h" 10 11 /** 12 * netfs_dirty_folio - Mark folio dirty and pin a cache object for writeback 13 * @mapping: The mapping the folio belongs to. 14 * @folio: The folio being dirtied. 15 * 16 * Set the dirty flag on a folio and pin an in-use cache object in memory so 17 * that writeback can later write to it. This is intended to be called from 18 * the filesystem's ->dirty_folio() method. 19 * 20 * Return: true if the dirty flag was set on the folio, false otherwise. 21 */ 22 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio) 23 { 24 struct inode *inode = mapping->host; 25 struct netfs_inode *ictx = netfs_inode(inode); 26 struct fscache_cookie *cookie = netfs_i_cookie(ictx); 27 bool need_use = false; 28 29 _enter(""); 30 31 if (!filemap_dirty_folio(mapping, folio)) 32 return false; 33 if (!fscache_cookie_valid(cookie)) 34 return true; 35 36 if (!(inode->i_state & I_PINNING_NETFS_WB)) { 37 spin_lock(&inode->i_lock); 38 if (!(inode->i_state & I_PINNING_NETFS_WB)) { 39 inode->i_state |= I_PINNING_NETFS_WB; 40 need_use = true; 41 } 42 spin_unlock(&inode->i_lock); 43 44 if (need_use) 45 fscache_use_cookie(cookie, true); 46 } 47 return true; 48 } 49 EXPORT_SYMBOL(netfs_dirty_folio); 50 51 /** 52 * netfs_unpin_writeback - Unpin writeback resources 53 * @inode: The inode on which the cookie resides 54 * @wbc: The writeback control 55 * 56 * Unpin the writeback resources pinned by netfs_dirty_folio(). This is 57 * intended to be called as/by the netfs's ->write_inode() method. 58 */ 59 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc) 60 { 61 struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode)); 62 63 if (wbc->unpinned_netfs_wb) 64 fscache_unuse_cookie(cookie, NULL, NULL); 65 return 0; 66 } 67 EXPORT_SYMBOL(netfs_unpin_writeback); 68 69 /** 70 * netfs_clear_inode_writeback - Clear writeback resources pinned by an inode 71 * @inode: The inode to clean up 72 * @aux: Auxiliary data to apply to the inode 73 * 74 * Clear any writeback resources held by an inode when the inode is evicted. 75 * This must be called before clear_inode() is called. 76 */ 77 void netfs_clear_inode_writeback(struct inode *inode, const void *aux) 78 { 79 struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode)); 80 81 if (inode->i_state & I_PINNING_NETFS_WB) { 82 loff_t i_size = i_size_read(inode); 83 fscache_unuse_cookie(cookie, aux, &i_size); 84 } 85 } 86 EXPORT_SYMBOL(netfs_clear_inode_writeback); 87 88 /** 89 * netfs_invalidate_folio - Invalidate or partially invalidate a folio 90 * @folio: Folio proposed for release 91 * @offset: Offset of the invalidated region 92 * @length: Length of the invalidated region 93 * 94 * Invalidate part or all of a folio for a network filesystem. The folio will 95 * be removed afterwards if the invalidated region covers the entire folio. 96 */ 97 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length) 98 { 99 struct netfs_folio *finfo; 100 size_t flen = folio_size(folio); 101 102 _enter("{%lx},%zx,%zx", folio->index, offset, length); 103 104 if (!folio_test_private(folio)) 105 return; 106 107 finfo = netfs_folio_info(folio); 108 109 if (offset == 0 && length >= flen) 110 goto erase_completely; 111 112 if (finfo) { 113 /* We have a partially uptodate page from a streaming write. */ 114 unsigned int fstart = finfo->dirty_offset; 115 unsigned int fend = fstart + finfo->dirty_len; 116 unsigned int end = offset + length; 117 118 if (offset >= fend) 119 return; 120 if (end <= fstart) 121 return; 122 if (offset <= fstart && end >= fend) 123 goto erase_completely; 124 if (offset <= fstart && end > fstart) 125 goto reduce_len; 126 if (offset > fstart && end >= fend) 127 goto move_start; 128 /* A partial write was split. The caller has already zeroed 129 * it, so just absorb the hole. 130 */ 131 } 132 return; 133 134 erase_completely: 135 netfs_put_group(netfs_folio_group(folio)); 136 folio_detach_private(folio); 137 folio_clear_uptodate(folio); 138 kfree(finfo); 139 return; 140 reduce_len: 141 finfo->dirty_len = offset + length - finfo->dirty_offset; 142 return; 143 move_start: 144 finfo->dirty_len -= offset - finfo->dirty_offset; 145 finfo->dirty_offset = offset; 146 } 147 EXPORT_SYMBOL(netfs_invalidate_folio); 148 149 /** 150 * netfs_release_folio - Try to release a folio 151 * @folio: Folio proposed for release 152 * @gfp: Flags qualifying the release 153 * 154 * Request release of a folio and clean up its private state if it's not busy. 155 * Returns true if the folio can now be released, false if not 156 */ 157 bool netfs_release_folio(struct folio *folio, gfp_t gfp) 158 { 159 struct netfs_inode *ctx = netfs_inode(folio_inode(folio)); 160 unsigned long long end; 161 162 end = folio_pos(folio) + folio_size(folio); 163 if (end > ctx->zero_point) 164 ctx->zero_point = end; 165 166 if (folio_test_private(folio)) 167 return false; 168 fscache_note_page_release(netfs_i_cookie(ctx)); 169 return true; 170 } 171 EXPORT_SYMBOL(netfs_release_folio); 172