1 /* 2 * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved. 3 * 4 * This software may be freely redistributed under the terms of the 5 * GNU General Public License. 6 * 7 * You should have received a copy of the GNU General Public License 8 * along with this program; if not, write to the Free Software 9 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 10 * 11 * Authors: David Woodhouse <dwmw2@infradead.org> 12 * David Howells <dhowells@redhat.com> 13 * 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/init.h> 19 #include <linux/circ_buf.h> 20 #include <linux/sched.h> 21 #include "internal.h" 22 23 /* 24 * Handle invalidation of an mmap'd file. We invalidate all the PTEs referring 25 * to the pages in this file's pagecache, forcing the kernel to go through 26 * ->fault() or ->page_mkwrite() - at which point we can handle invalidation 27 * more fully. 28 */ 29 void afs_invalidate_mmap_work(struct work_struct *work) 30 { 31 struct afs_vnode *vnode = container_of(work, struct afs_vnode, cb_work); 32 33 unmap_mapping_pages(vnode->vfs_inode.i_mapping, 0, 0, false); 34 } 35 36 void afs_server_init_callback_work(struct work_struct *work) 37 { 38 struct afs_server *server = container_of(work, struct afs_server, initcb_work); 39 struct afs_vnode *vnode; 40 struct afs_cell *cell = server->cell; 41 42 down_read(&cell->fs_open_mmaps_lock); 43 44 list_for_each_entry(vnode, &cell->fs_open_mmaps, cb_mmap_link) { 45 if (vnode->cb_server == server) { 46 clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags); 47 queue_work(system_unbound_wq, &vnode->cb_work); 48 } 49 } 50 51 up_read(&cell->fs_open_mmaps_lock); 52 } 53 54 /* 55 * Allow the fileserver to request callback state (re-)initialisation. 56 * Unfortunately, UUIDs are not guaranteed unique. 57 */ 58 void afs_init_callback_state(struct afs_server *server) 59 { 60 rcu_read_lock(); 61 do { 62 server->cb_s_break++; 63 atomic_inc(&server->cell->fs_s_break); 64 if (!list_empty(&server->cell->fs_open_mmaps)) 65 queue_work(system_unbound_wq, &server->initcb_work); 66 67 } while ((server = rcu_dereference(server->uuid_next))); 68 rcu_read_unlock(); 69 } 70 71 /* 72 * actually break a callback 73 */ 74 void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason) 75 { 76 _enter(""); 77 78 clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags); 79 if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) { 80 vnode->cb_break++; 81 vnode->cb_v_break = vnode->volume->cb_v_break; 82 afs_clear_permits(vnode); 83 84 if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB) 85 afs_lock_may_be_available(vnode); 86 87 if (reason != afs_cb_break_for_deleted && 88 vnode->status.type == AFS_FTYPE_FILE && 89 atomic_read(&vnode->cb_nr_mmap)) 90 queue_work(system_unbound_wq, &vnode->cb_work); 91 92 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, true); 93 } else { 94 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, false); 95 } 96 } 97 98 void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason) 99 { 100 write_seqlock(&vnode->cb_lock); 101 __afs_break_callback(vnode, reason); 102 write_sequnlock(&vnode->cb_lock); 103 } 104 105 /* 106 * Look up a volume by volume ID under RCU conditions. 107 */ 108 static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell, 109 afs_volid_t vid) 110 { 111 struct afs_volume *volume = NULL; 112 struct rb_node *p; 113 int seq = 0; 114 115 do { 116 /* Unfortunately, rbtree walking doesn't give reliable results 117 * under just the RCU read lock, so we have to check for 118 * changes. 119 */ 120 read_seqbegin_or_lock(&cell->volume_lock, &seq); 121 122 p = rcu_dereference_raw(cell->volumes.rb_node); 123 while (p) { 124 volume = rb_entry(p, struct afs_volume, cell_node); 125 126 if (volume->vid < vid) 127 p = rcu_dereference_raw(p->rb_left); 128 else if (volume->vid > vid) 129 p = rcu_dereference_raw(p->rb_right); 130 else 131 break; 132 volume = NULL; 133 } 134 135 } while (need_seqretry(&cell->volume_lock, seq)); 136 137 done_seqretry(&cell->volume_lock, seq); 138 return volume; 139 } 140 141 /* 142 * allow the fileserver to explicitly break one callback 143 * - happens when 144 * - the backing file is changed 145 * - a lock is released 146 */ 147 static void afs_break_one_callback(struct afs_volume *volume, 148 struct afs_fid *fid) 149 { 150 struct super_block *sb; 151 struct afs_vnode *vnode; 152 struct inode *inode; 153 154 if (fid->vnode == 0 && fid->unique == 0) { 155 /* The callback break applies to an entire volume. */ 156 write_lock(&volume->cb_v_break_lock); 157 volume->cb_v_break++; 158 trace_afs_cb_break(fid, volume->cb_v_break, 159 afs_cb_break_for_volume_callback, false); 160 write_unlock(&volume->cb_v_break_lock); 161 return; 162 } 163 164 /* See if we can find a matching inode - even an I_NEW inode needs to 165 * be marked as it can have its callback broken before we finish 166 * setting up the local inode. 167 */ 168 sb = rcu_dereference(volume->sb); 169 if (!sb) 170 return; 171 172 inode = find_inode_rcu(sb, fid->vnode, afs_ilookup5_test_by_fid, fid); 173 if (inode) { 174 vnode = AFS_FS_I(inode); 175 afs_break_callback(vnode, afs_cb_break_for_callback); 176 } else { 177 trace_afs_cb_miss(fid, afs_cb_break_for_callback); 178 } 179 } 180 181 static void afs_break_some_callbacks(struct afs_server *server, 182 struct afs_callback_break *cbb, 183 size_t *_count) 184 { 185 struct afs_callback_break *residue = cbb; 186 struct afs_volume *volume; 187 afs_volid_t vid = cbb->fid.vid; 188 size_t i; 189 190 volume = afs_lookup_volume_rcu(server->cell, vid); 191 192 /* TODO: Find all matching volumes if we couldn't match the server and 193 * break them anyway. 194 */ 195 196 for (i = *_count; i > 0; cbb++, i--) { 197 if (cbb->fid.vid == vid) { 198 _debug("- Fid { vl=%08llx n=%llu u=%u }", 199 cbb->fid.vid, 200 cbb->fid.vnode, 201 cbb->fid.unique); 202 --*_count; 203 if (volume) 204 afs_break_one_callback(volume, &cbb->fid); 205 } else { 206 *residue++ = *cbb; 207 } 208 } 209 } 210 211 /* 212 * allow the fileserver to break callback promises 213 */ 214 void afs_break_callbacks(struct afs_server *server, size_t count, 215 struct afs_callback_break *callbacks) 216 { 217 _enter("%p,%zu,", server, count); 218 219 ASSERT(server != NULL); 220 221 rcu_read_lock(); 222 223 while (count > 0) 224 afs_break_some_callbacks(server, callbacks, &count); 225 226 rcu_read_unlock(); 227 return; 228 } 229