1/* 2 * gcinode.c - dummy inodes to buffer blocks for garbage collection 3 * 4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 19 * 20 * Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>, 21 * and Ryusuke Konishi <ryusuke@osrg.net>. 22 * Revised by Ryusuke Konishi <ryusuke@osrg.net>. 23 * 24 */ 25/* 26 * This file adds the cache of on-disk blocks to be moved in garbage 27 * collection. The disk blocks are held with dummy inodes (called 28 * gcinodes), and this file provides lookup function of the dummy 29 * inodes and their buffer read function. 30 * 31 * Since NILFS2 keeps up multiple checkpoints/snapshots across GC, it 32 * has to treat blocks that belong to a same file but have different 33 * checkpoint numbers. To avoid interference among generations, dummy 34 * inodes are managed separately from actual inodes, and their lookup 35 * function (nilfs_gc_iget) is designed to be specified with a 36 * checkpoint number argument as well as an inode number. 37 * 38 * Buffers and pages held by the dummy inodes will be released each 39 * time after they are copied to a new log. Dirty blocks made on the 40 * current generation and the blocks to be moved by GC never overlap 41 * because the dirty blocks make a new generation; they rather must be 42 * written individually. 43 */ 44 45#include <linux/buffer_head.h> 46#include <linux/mpage.h> 47#include <linux/hash.h> 48#include <linux/slab.h> 49#include <linux/swap.h> 50#include "nilfs.h" 51#include "btree.h" 52#include "btnode.h" 53#include "page.h" 54#include "mdt.h" 55#include "dat.h" 56#include "ifile.h" 57 58static const struct address_space_operations def_gcinode_aops = { 59 .sync_page = block_sync_page, 60}; 61 62/* 63 * nilfs_gccache_submit_read_data() - add data buffer and submit read request 64 * @inode - gc inode 65 * @blkoff - dummy offset treated as the key for the page cache 66 * @pbn - physical block number of the block 67 * @vbn - virtual block number of the block, 0 for non-virtual block 68 * @out_bh - indirect pointer to a buffer_head struct to receive the results 69 * 70 * Description: nilfs_gccache_submit_read_data() registers the data buffer 71 * specified by @pbn to the GC pagecache with the key @blkoff. 72 * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer. 73 * 74 * Return Value: On success, 0 is returned. On Error, one of the following 75 * negative error code is returned. 76 * 77 * %-EIO - I/O error. 78 * 79 * %-ENOMEM - Insufficient amount of memory available. 80 * 81 * %-ENOENT - The block specified with @pbn does not exist. 82 */ 83int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff, 84 sector_t pbn, __u64 vbn, 85 struct buffer_head **out_bh) 86{ 87 struct buffer_head *bh; 88 int err; 89 90 bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0); 91 if (unlikely(!bh)) 92 return -ENOMEM; 93 94 if (buffer_uptodate(bh)) 95 goto out; 96 97 if (pbn == 0) { 98 struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat; 99 /* use original dat, not gc dat. */ 100 err = nilfs_dat_translate(dat_inode, vbn, &pbn); 101 if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */ 102 brelse(bh); 103 goto failed; 104 } 105 } 106 107 lock_buffer(bh); 108 if (buffer_uptodate(bh)) { 109 unlock_buffer(bh); 110 goto out; 111 } 112 113 if (!buffer_mapped(bh)) { 114 bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev; 115 set_buffer_mapped(bh); 116 } 117 bh->b_blocknr = pbn; 118 bh->b_end_io = end_buffer_read_sync; 119 get_bh(bh); 120 submit_bh(READ, bh); 121 if (vbn) 122 bh->b_blocknr = vbn; 123 out: 124 err = 0; 125 *out_bh = bh; 126 127 failed: 128 unlock_page(bh->b_page); 129 page_cache_release(bh->b_page); 130 return err; 131} 132 133/* 134 * nilfs_gccache_submit_read_node() - add node buffer and submit read request 135 * @inode - gc inode 136 * @pbn - physical block number for the block 137 * @vbn - virtual block number for the block 138 * @out_bh - indirect pointer to a buffer_head struct to receive the results 139 * 140 * Description: nilfs_gccache_submit_read_node() registers the node buffer 141 * specified by @vbn to the GC pagecache. @pbn can be supplied by the 142 * caller to avoid translation of the disk block address. 143 * 144 * Return Value: On success, 0 is returned. On Error, one of the following 145 * negative error code is returned. 146 * 147 * %-EIO - I/O error. 148 * 149 * %-ENOMEM - Insufficient amount of memory available. 150 */ 151int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn, 152 __u64 vbn, struct buffer_head **out_bh) 153{ 154 int ret; 155 156 ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache, 157 vbn ? : pbn, pbn, READ, out_bh, &pbn); 158 if (ret == -EEXIST) /* internal code (cache hit) */ 159 ret = 0; 160 return ret; 161} 162 163int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh) 164{ 165 wait_on_buffer(bh); 166 if (!buffer_uptodate(bh)) 167 return -EIO; 168 if (buffer_dirty(bh)) 169 return -EEXIST; 170 171 if (buffer_nilfs_node(bh)) { 172 if (nilfs_btree_broken_node_block(bh)) { 173 clear_buffer_uptodate(bh); 174 return -EIO; 175 } 176 nilfs_btnode_mark_dirty(bh); 177 } else { 178 nilfs_mdt_mark_buffer_dirty(bh); 179 } 180 return 0; 181} 182 183/* 184 * nilfs_init_gccache() - allocate and initialize gc_inode hash table 185 * @nilfs - the_nilfs 186 * 187 * Return Value: On success, 0. 188 * On error, a negative error code is returned. 189 */ 190int nilfs_init_gccache(struct the_nilfs *nilfs) 191{ 192 int loop; 193 194 BUG_ON(nilfs->ns_gc_inodes_h); 195 196 INIT_LIST_HEAD(&nilfs->ns_gc_inodes); 197 198 nilfs->ns_gc_inodes_h = 199 kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE, 200 GFP_NOFS); 201 if (nilfs->ns_gc_inodes_h == NULL) 202 return -ENOMEM; 203 204 for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++) 205 INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]); 206 return 0; 207} 208 209/* 210 * nilfs_destroy_gccache() - free gc_inode hash table 211 * @nilfs - the nilfs 212 */ 213void nilfs_destroy_gccache(struct the_nilfs *nilfs) 214{ 215 if (nilfs->ns_gc_inodes_h) { 216 nilfs_remove_all_gcinode(nilfs); 217 kfree(nilfs->ns_gc_inodes_h); 218 nilfs->ns_gc_inodes_h = NULL; 219 } 220} 221 222static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino, 223 __u64 cno) 224{ 225 struct inode *inode; 226 struct nilfs_inode_info *ii; 227 228 inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS, 0); 229 if (!inode) 230 return NULL; 231 232 inode->i_op = NULL; 233 inode->i_fop = NULL; 234 inode->i_mapping->a_ops = &def_gcinode_aops; 235 236 ii = NILFS_I(inode); 237 ii->i_cno = cno; 238 ii->i_flags = 0; 239 ii->i_state = 1 << NILFS_I_GCINODE; 240 ii->i_bh = NULL; 241 nilfs_bmap_init_gc(ii->i_bmap); 242 243 return inode; 244} 245 246static unsigned long ihash(ino_t ino, __u64 cno) 247{ 248 return hash_long((unsigned long)((ino << 2) + cno), 249 NILFS_GCINODE_HASH_BITS); 250} 251 252/* 253 * nilfs_gc_iget() - find or create gc inode with specified (ino,cno) 254 */ 255struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno) 256{ 257 struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno); 258 struct hlist_node *node; 259 struct inode *inode; 260 261 hlist_for_each_entry(inode, node, head, i_hash) { 262 if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno) 263 return inode; 264 } 265 266 inode = alloc_gcinode(nilfs, ino, cno); 267 if (likely(inode)) { 268 hlist_add_head(&inode->i_hash, head); 269 list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes); 270 } 271 return inode; 272} 273 274/* 275 * nilfs_clear_gcinode() - clear and free a gc inode 276 */ 277void nilfs_clear_gcinode(struct inode *inode) 278{ 279 nilfs_mdt_destroy(inode); 280} 281 282/* 283 * nilfs_remove_all_gcinode() - remove all inodes from the_nilfs 284 */ 285void nilfs_remove_all_gcinode(struct the_nilfs *nilfs) 286{ 287 struct hlist_head *head = nilfs->ns_gc_inodes_h; 288 struct hlist_node *node, *n; 289 struct inode *inode; 290 int loop; 291 292 for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) { 293 hlist_for_each_entry_safe(inode, node, n, head, i_hash) { 294 hlist_del_init(&inode->i_hash); 295 list_del_init(&NILFS_I(inode)->i_dirty); 296 nilfs_clear_gcinode(inode); /* might sleep */ 297 } 298 } 299} 300