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Diffstat (limited to 'fs/ubifs/orphan.c')
| -rw-r--r-- | fs/ubifs/orphan.c | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c new file mode 100644 index 0000000..d091031 --- /dev/null +++ b/fs/ubifs/orphan.c @@ -0,0 +1,316 @@ +/* + * This file is part of UBIFS. + * + * Copyright (C) 2006-2008 Nokia Corporation. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program; if not, write to the Free Software Foundation, Inc., 51 + * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + * + * Author: Adrian Hunter + */ + +#include "ubifs.h" + +/* + * An orphan is an inode number whose inode node has been committed to the index + * with a link count of zero. That happens when an open file is deleted + * (unlinked) and then a commit is run. In the normal course of events the inode + * would be deleted when the file is closed. However in the case of an unclean + * unmount, orphans need to be accounted for. After an unclean unmount, the + * orphans' inodes must be deleted which means either scanning the entire index + * looking for them, or keeping a list on flash somewhere. This unit implements + * the latter approach. + * + * The orphan area is a fixed number of LEBs situated between the LPT area and + * the main area. The number of orphan area LEBs is specified when the file + * system is created. The minimum number is 1. The size of the orphan area + * should be so that it can hold the maximum number of orphans that are expected + * to ever exist at one time. + * + * The number of orphans that can fit in a LEB is: + * + * (c->leb_size - UBIFS_ORPH_NODE_SZ) / sizeof(__le64) + * + * For example: a 15872 byte LEB can fit 1980 orphans so 1 LEB may be enough. + * + * Orphans are accumulated in a rb-tree. When an inode's link count drops to + * zero, the inode number is added to the rb-tree. It is removed from the tree + * when the inode is deleted. Any new orphans that are in the orphan tree when + * the commit is run, are written to the orphan area in 1 or more orphan nodes. + * If the orphan area is full, it is consolidated to make space. There is + * always enough space because validation prevents the user from creating more + * than the maximum number of orphans allowed. + */ + +/** + * tot_avail_orphs - calculate total space. + * @c: UBIFS file-system description object + * + * This function returns the number of orphans that can be written in half + * the total space. That leaves half the space for adding new orphans. + */ +static int tot_avail_orphs(struct ubifs_info *c) +{ + int avail_lebs, avail; + + avail_lebs = c->orph_lebs; + avail = avail_lebs * + ((c->leb_size - UBIFS_ORPH_NODE_SZ) / sizeof(__le64)); + return avail / 2; +} + +/** + * ubifs_clear_orphans - erase all LEBs used for orphans. + * @c: UBIFS file-system description object + * + * If recovery is not required, then the orphans from the previous session + * are not needed. This function locates the LEBs used to record + * orphans, and un-maps them. + */ +int ubifs_clear_orphans(struct ubifs_info *c) +{ + int lnum, err; + + for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) { + err = ubifs_leb_unmap(c, lnum); + if (err) + return err; + } + c->ohead_lnum = c->orph_first; + c->ohead_offs = 0; + return 0; +} + +/** + * insert_dead_orphan - insert an orphan. + * @c: UBIFS file-system description object + * @inum: orphan inode number + * + * This function is a helper to the 'do_kill_orphans()' function. The orphan + * must be kept until the next commit, so it is added to the rb-tree and the + * deletion list. + */ +static int insert_dead_orphan(struct ubifs_info *c, ino_t inum) +{ + struct ubifs_orphan *orphan, *o; + struct rb_node **p, *parent = NULL; + + orphan = kzalloc(sizeof(struct ubifs_orphan), GFP_KERNEL); + if (!orphan) + return -ENOMEM; + orphan->inum = inum; + + p = &c->orph_tree.rb_node; + while (*p) { + parent = *p; + o = rb_entry(parent, struct ubifs_orphan, rb); + if (inum < o->inum) + p = &(*p)->rb_left; + else if (inum > o->inum) + p = &(*p)->rb_right; + else { + /* Already added - no problem */ + kfree(orphan); + return 0; + } + } + c->tot_orphans += 1; + rb_link_node(&orphan->rb, parent, p); + rb_insert_color(&orphan->rb, &c->orph_tree); + list_add_tail(&orphan->list, &c->orph_list); + orphan->dnext = c->orph_dnext; + c->orph_dnext = orphan; + dbg_mnt("ino %lu, new %d, tot %d", (unsigned long)inum, + c->new_orphans, c->tot_orphans); + return 0; +} + +/** + * do_kill_orphans - remove orphan inodes from the index. + * @c: UBIFS file-system description object + * @sleb: scanned LEB + * @last_cmt_no: cmt_no of last orphan node read is passed and returned here + * @outofdate: whether the LEB is out of date is returned here + * @last_flagged: whether the end orphan node is encountered + * + * This function is a helper to the 'kill_orphans()' function. It goes through + * every orphan node in a LEB and for every inode number recorded, removes + * all keys for that inode from the TNC. + */ +static int do_kill_orphans(struct ubifs_info *c, struct ubifs_scan_leb *sleb, + unsigned long long *last_cmt_no, int *outofdate, + int *last_flagged) +{ + struct ubifs_scan_node *snod; + struct ubifs_orph_node *orph; + unsigned long long cmt_no; + ino_t inum; + int i, n, err, first = 1; + + list_for_each_entry(snod, &sleb->nodes, list) { + if (snod->type != UBIFS_ORPH_NODE) { + ubifs_err("invalid node type %d in orphan area at " + "%d:%d", snod->type, sleb->lnum, snod->offs); + dbg_dump_node(c, snod->node); + return -EINVAL; + } + + orph = snod->node; + + /* Check commit number */ + cmt_no = le64_to_cpu(orph->cmt_no) & LLONG_MAX; + /* + * The commit number on the master node may be less, because + * of a failed commit. If there are several failed commits in a + * row, the commit number written on orphan nodes will continue + * to increase (because the commit number is adjusted here) even + * though the commit number on the master node stays the same + * because the master node has not been re-written. + */ + if (cmt_no > c->cmt_no) + c->cmt_no = cmt_no; + if (cmt_no < *last_cmt_no && *last_flagged) { + /* + * The last orphan node had a higher commit number and + * was flagged as the last written for that commit + * number. That makes this orphan node, out of date. + */ + if (!first) { + ubifs_err("out of order commit number %llu in " + "orphan node at %d:%d", + cmt_no, sleb->lnum, snod->offs); + dbg_dump_node(c, snod->node); + return -EINVAL; + } + dbg_rcvry("out of date LEB %d", sleb->lnum); + *outofdate = 1; + return 0; + } + + if (first) + first = 0; + + n = (le32_to_cpu(orph->ch.len) - UBIFS_ORPH_NODE_SZ) >> 3; + for (i = 0; i < n; i++) { + inum = le64_to_cpu(orph->inos[i]); + dbg_rcvry("deleting orphaned inode %lu", + (unsigned long)inum); + err = ubifs_tnc_remove_ino(c, inum); + if (err) + return err; + err = insert_dead_orphan(c, inum); + if (err) + return err; + } + + *last_cmt_no = cmt_no; + if (le64_to_cpu(orph->cmt_no) & (1ULL << 63)) { + dbg_rcvry("last orph node for commit %llu at %d:%d", + cmt_no, sleb->lnum, snod->offs); + *last_flagged = 1; + } else + *last_flagged = 0; + } + + return 0; +} + +/** + * kill_orphans - remove all orphan inodes from the index. + * @c: UBIFS file-system description object + * + * If recovery is required, then orphan inodes recorded during the previous + * session (which ended with an unclean unmount) must be deleted from the index. + * This is done by updating the TNC, but since the index is not updated until + * the next commit, the LEBs where the orphan information is recorded are not + * erased until the next commit. + */ +static int kill_orphans(struct ubifs_info *c) +{ + unsigned long long last_cmt_no = 0; + int lnum, err = 0, outofdate = 0, last_flagged = 0; + + c->ohead_lnum = c->orph_first; + c->ohead_offs = 0; + /* Check no-orphans flag and skip this if no orphans */ + if (c->no_orphs) { + dbg_rcvry("no orphans"); + return 0; + } + /* + * Orph nodes always start at c->orph_first and are written to each + * successive LEB in turn. Generally unused LEBs will have been unmapped + * but may contain out of date orphan nodes if the unmap didn't go + * through. In addition, the last orphan node written for each commit is + * marked (top bit of orph->cmt_no is set to 1). It is possible that + * there are orphan nodes from the next commit (i.e. the commit did not + * complete successfully). In that case, no orphans will have been lost + * due to the way that orphans are written, and any orphans added will + * be valid orphans anyway and so can be deleted. + */ + for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) { + struct ubifs_scan_leb *sleb; + + dbg_rcvry("LEB %d", lnum); + sleb = ubifs_scan(c, lnum, 0, c->sbuf); + if (IS_ERR(sleb)) { + sleb = ubifs_recover_leb(c, lnum, 0, c->sbuf, 0); + if (IS_ERR(sleb)) { + err = PTR_ERR(sleb); + break; + } + } + err = do_kill_orphans(c, sleb, &last_cmt_no, &outofdate, + &last_flagged); + if (err || outofdate) { + ubifs_scan_destroy(sleb); + break; + } + if (sleb->endpt) { + c->ohead_lnum = lnum; + c->ohead_offs = sleb->endpt; + } + ubifs_scan_destroy(sleb); + } + return err; +} + +/** + * ubifs_mount_orphans - delete orphan inodes and erase LEBs that recorded them. + * @c: UBIFS file-system description object + * @unclean: indicates recovery from unclean unmount + * @read_only: indicates read only mount + * + * This function is called when mounting to erase orphans from the previous + * session. If UBIFS was not unmounted cleanly, then the inodes recorded as + * orphans are deleted. + */ +int ubifs_mount_orphans(struct ubifs_info *c, int unclean, int read_only) +{ + int err = 0; + + c->max_orphans = tot_avail_orphs(c); + + if (!read_only) { + c->orph_buf = vmalloc(c->leb_size); + if (!c->orph_buf) + return -ENOMEM; + } + + if (unclean) + err = kill_orphans(c); + else if (!read_only) + err = ubifs_clear_orphans(c); + + return err; +} |