u-boot/fs/ubifs/orphan.c

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/*
* 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;
}