--- /dev/null
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff