- 根目录:
- fs
- ubifs
- find.c
/*
* 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
*
* Authors: Artem Bityutskiy (Битюцкий Артём)
* Adrian Hunter
*/
/*
* This file contains functions for finding LEBs for various purposes e.g.
* garbage collection. In general, lprops category heaps and lists are used
* for fast access, falling back on scanning the LPT as a last resort.
*/
#include <linux/sort.h>
#include "ubifs.h"
/**
* struct scan_data - data provided to scan callback functions
* @min_space: minimum number of bytes for which to scan
* @pick_free: whether it is OK to scan for empty LEBs
* @lnum: LEB number found is returned here
* @exclude_index: whether to exclude index LEBs
*/
struct scan_data {
int min_space;
int pick_free;
int lnum;
int exclude_index;
};
/**
* valuable - determine whether LEB properties are valuable.
* @c: the UBIFS file-system description object
* @lprops: LEB properties
*
* This function return %1 if the LEB properties should be added to the LEB
* properties tree in memory. Otherwise %0 is returned.
*/
static int valuable(struct ubifs_info *c, const struct ubifs_lprops *lprops)
{
int n, cat = lprops->flags & LPROPS_CAT_MASK;
struct ubifs_lpt_heap *heap;
switch (cat) {
case LPROPS_DIRTY:
case LPROPS_DIRTY_IDX:
case LPROPS_FREE:
heap = &c->lpt_heap[cat - 1];
if (heap->cnt < heap->max_cnt)
return 1;
if (lprops->free + lprops->dirty >= c->dark_wm)
return 1;
return 0;
case LPROPS_EMPTY:
n = c->lst.empty_lebs + c->freeable_cnt -
c->lst.taken_empty_lebs;
if (n < c->lsave_cnt)
return 1;
return 0;
case LPROPS_FREEABLE:
return 1;
case LPROPS_FRDI_IDX:
return 1;
}
return 0;
}
/**
* scan_for_dirty_cb - dirty space scan callback.
* @c: the UBIFS file-system description object
* @lprops: LEB properties to scan
* @in_tree: whether the LEB properties are in main memory
* @data: information passed to and from the caller of the scan
*
* This function returns a code that indicates whether the scan should continue
* (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
* in main memory (%LPT_SCAN_ADD), or whether the scan should stop
* (%LPT_SCAN_STOP).
*/
static int scan_for_dirty_cb(struct ubifs_info *c,
const struct ubifs_lprops *lprops, int in_tree,
struct scan_data *data)
{
int ret = LPT_SCAN_CONTINUE;
/* Exclude LEBs that are currently in use */
if (lprops->flags & LPROPS_TAKEN)
return LPT_SCAN_CONTINUE;
/* Determine whether to add these LEB properties to the tree */
if (!in_tree && valuable(c, lprops))
ret |= LPT_SCAN_ADD;
/* Exclude LEBs with too little space */
if (lprops->free + lprops->dirty < data->min_space)
return ret;
/* If specified, exclude index LEBs */
if (data->exclude_index && lprops->flags & LPROPS_INDEX)
return ret;
/* If specified, exclude empty or freeable LEBs */
if (lprops->free + lprops->dirty == c->leb_size) {
if (!data->pick_free)
return ret;
/* Exclude LEBs with too little dirty space (unless it is empty) */
} else if (lprops->dirty < c->dead_wm)
return ret;
/* Finally we found space */
data->lnum = lprops->lnum;
return LPT_SCAN_ADD | LPT_SCAN_STOP;
}
/**
* scan_for_dirty - find a data LEB with free space.
* @c: the UBIFS file-system description object
* @min_space: minimum amount free plus dirty space the returned LEB has to
* have
* @pick_free: if it is OK to return a free or freeable LEB
* @exclude_index: whether to exclude index LEBs
*
* This function returns a pointer to the LEB properties found or a negative
* error code.
*/
static const struct ubifs_lprops *scan_for_dirty(struct ubifs_info *c,
int min_space, int pick_free,
int exclude_index)
{
const struct ubifs_lprops *lprops;
struct ubifs_lpt_heap *heap;
struct scan_data data;
int err, i;
/* There may be an LEB with enough dirty space on the free heap */
heap = &c->lpt_heap[LPROPS_FREE - 1];
for (i = 0; i < heap->cnt; i++) {
lprops = heap->arr[i];
if (lprops->free + lprops->dirty < min_space)
continue;
if (lprops->dirty < c->dead_wm)
continue;
return lprops;
}
/*
* A LEB may have fallen off of the bottom of the dirty heap, and ended
* up as uncategorized even though it has enough dirty space for us now,
* so check the uncategorized list. N.B. neither empty nor freeable LEBs
* can end up as uncategorized because they are kept on lists not
* finite-sized heaps.
*/
list_for_each_entry(lprops, &c->uncat_list, list) {
if (lprops->flags & LPROPS_TAKEN)
continue;
if (lprops->free + lprops->dirty < min_space)
continue;
if (exclude_index && (lprops->flags & LPROPS_INDEX))
continue;
if (lprops->dirty < c->dead_wm)
continue;
return lprops;
}
/* We have looked everywhere in main memory, now scan the flash */
if (c->pnodes_have >= c->pnode_cnt)
/* All pnodes are in memory, so skip scan */
return ERR_PTR(-ENOSPC);
data.min_space = min_space;
data.pick_free = pick_free;
data.lnum = -1;
data.exclude_index = exclude_index;
err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
(ubifs_lpt_scan_callback)scan_for_dirty_cb,
&data);
if (err)
return ERR_PTR(err);
ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
c->lscan_lnum = data.lnum;
lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
if (IS_ERR(lprops))
return lprops;
ubifs_assert(lprops->lnum == data.lnum);
ubifs_assert(lprops->free + lprops->dirty >= min_space);
ubifs_assert(lprops->dirty >= c->dead_wm ||
(pick_free &&
lprops->free + lprops->dirty == c->leb_size));
ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
ubifs_assert(!exclude_index || !(lprops->flags & LPROPS_INDEX));
return lprops;
}
/**
* ubifs_find_dirty_leb - find a dirty LEB for the Garbage Collector.
* @c: the UBIFS file-system description object
* @ret_lp: LEB properties are returned here on exit
* @min_space: minimum amount free plus dirty space the returned LEB has to
* have
* @pick_free: controls whether it is OK to pick empty or index LEBs
*
* This function tries to find a dirty logical eraseblock which has at least
* @min_space free and dirty space. It prefers to take an LEB from the dirty or
* dirty index heap, and it falls-back to LPT scanning if the heaps are empty
* or do not have an LEB which satisfies the @min_space criteria.
*
* Note, LEBs which have less than dead watermark of free + dirty space are
* never picked by this function.
*
* The additional @pick_free argument controls if this function has to return a
* free or freeable LEB if one is present. For example, GC must to set it to %1,
* when called from the journal space reservation function, because the
* appearance of free space may coincide with the loss of enough dirty space
* for GC to succeed anyway.
*
* In contrast, if the Garbage Collector is called from budgeting, it should
* just make free space, not return LEBs which are already free or freeable.
*
* In addition @pick_free is set to %2 by the recovery process in order to
* recover gc_lnum in which case an index LEB must not be returned.
*
* This function returns zero and the LEB properties of found dirty LEB in case
* of success, %-ENOSPC if no dirty LEB was found and a negative error code in
* case of other failures. The returned LEB is marked as "taken".
*/
int ubifs_find_dirty_leb(struct ubifs_info *c, struct ubifs_lprops *ret_lp,
int min_space, int pick_free)
{
int err = 0, sum, exclude_index = pick_free == 2 ? 1 : 0;
const struct ubifs_lprops *lp = NULL, *idx_lp = NULL;
struct ubifs_lpt_heap *heap, *idx_heap;
ubifs_get_lprops(c);
if (pick_free) {
int lebs, rsvd_idx_lebs = 0;
spin_lock(&c->space_lock);
lebs = c->lst.empty_lebs + c->idx_gc_cnt;
lebs += c->freeable_cnt - c->lst.taken_empty_lebs;
/*
* Note, the index may consume more LEBs than have been reserved
* for it. It is OK because it might be consolidated by GC.
* But if the index takes fewer LEBs than it is reserved for it,
* this function must avoid picking those reserved LEBs.
*/
if (c->bi.min_idx_lebs >= c->lst.idx_lebs) {
rsvd_idx_lebs = c->bi.min_idx_lebs - c->lst.idx_lebs;
exclude_index = 1;
}
spin_unlock(&c->space_lock);
/* Check if there are enough free LEBs for the index */
if (rsvd_idx_lebs < lebs) {
/* OK, try to find an empty LEB */
lp = ubifs_fast_find_empty(c);
if (lp)
goto found;
/* Or a freeable LEB */
lp = ubifs_fast_find_freeable(c);
if (lp)
goto found;
} else
/*
* We cannot pick free/freeable LEBs in the below code.
*/
pick_free = 0;
} else {
spin_lock(&c->space_lock);
exclude_index = (c->bi.min_idx_lebs >= c->lst.idx_lebs);
spin_unlock(&c->space_lock);
}
/* Look on the dirty and dirty index heaps */
heap = &c->lpt_heap[LPROPS_DIRTY - 1];
idx_heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
if (idx_heap->cnt && !exclude_index) {
idx_lp = idx_heap->arr[0];
sum = idx_lp->free + idx_lp->dirty;
/*
* Since we reserve thrice as much space for the index than it
* actually takes, it does not make sense to pick indexing LEBs
* with less than, say, half LEB of dirty space. May be half is
* not the optimal boundary - this should be tested and
* checked. This boundary should determine how much we use
* in-the-gaps to consolidate the index comparing to how much
* we use garbage collector to consolidate it. The "half"
* criteria just feels to be fine.
*/
if (sum < min_space || sum < c->half_leb_size)
idx_lp = NULL;
}
if (heap->cnt) {
lp = heap->arr[0];
if (lp->dirty + lp->free < min_space)
lp = NULL;
}
/* Pick the LEB with most space */
if (idx_lp && lp) {
if (idx_lp->free + idx_lp->dirty >= lp->free + lp->dirty)
lp = idx_lp;
} else if (idx_lp && !lp)
lp = idx_lp;
if (lp) {
ubifs_assert(lp->free + lp->dirty >= c->dead_wm);
goto found;
}
/* Did not find a dirty LEB on the dirty heaps, have to scan */
dbg_find("scanning LPT for a dirty LEB");
lp = scan_for_dirty(c, min_space, pick_free, exclude_index);
if (IS_ERR(lp)) {
err = PTR_ERR(lp);
goto out;
}
ubifs_assert(lp->dirty >= c->dead_wm ||
(pick_free && lp->free + lp->dirty == c->leb_size));
found:
dbg_find("found LEB %d, free %d, dirty %d, flags %#x",
lp->lnum, lp->free, lp->dirty, lp->flags);
lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
lp->flags | LPROPS_TAKEN, 0);
if (IS_ERR(lp)) {
err = PTR_ERR(lp);
goto out;
}
memcpy(ret_lp, lp, sizeof(struct ubifs_lprops));
out:
ubifs_release_lprops(c);
return err;
}
/**
* scan_for_free_cb - free space scan callback.
* @c: the UBIFS file-system description object
* @lprops: LEB properties to scan
* @in_tree: whether the LEB properties are in main memory
* @data: information passed to and from the caller of the scan
*
* This function returns a code that indicates whether the scan should continue
* (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
* in main memory (%LPT_SCAN_ADD), or whether the scan should stop
* (%LPT_SCAN_STOP).
*/
static int scan_for_free_cb(struct ubifs_info *c,
const struct ubifs_lprops *lprops, int in_tree,
struct scan_data *data)
{
int ret = LPT_SCAN_CONTINUE;
/* Exclude LEBs that are currently in use */
if (lprops->flags & LPROPS_TAKEN)
return LPT_SCAN_CONTINUE;
/* Determine whether to add these LEB properties to the tree */
if (!in_tree && valuable(c, lprops))
ret |= LPT_SCAN_ADD;
/* Exclude index LEBs */
if (lprops->flags & LPROPS_INDEX)
return ret;
/* Exclude LEBs with too little space */
if (lprops->free < data->min_space)
return ret;
/* If specified, exclude empty LEBs */
if (!data->pick_free && lprops->free == c->leb_size)
return ret;
/*
* LEBs that have only free and dirty space must not be allocated
* because they may have been unmapped already or they may have data
* that is obsolete only because of nodes that are still sitting in a
* wbuf.
*/
if (lprops->free + lprops->dirty == c->leb_size && lprops->dirty > 0)
return ret;
/* Finally we found space */
data->lnum = lprops->lnum;
return LPT_SCAN_ADD | LPT_SCAN_STOP;
}
/**
* do_find_free_space - find a data LEB with free space.
* @c: the UBIFS file-system description object
* @min_space: minimum amount of free space required
* @pick_free: whether it is OK to scan for empty LEBs
* @squeeze: whether to try to find space in a non-empty LEB first
*
* This function returns a pointer to the LEB properties found or a negative
* error code.
*/
static
const struct ubifs_lprops *do_find_free_space(struct ubifs_info *c,
int min_space, int pick_free,
int squeeze)
{
const struct ubifs_lprops *lprops;
struct ubifs_lpt_heap *heap;
struct scan_data data;
int err, i;
if (squeeze) {
lprops = ubifs_fast_find_free(c);
if (lprops && lprops->free >= min_space)
return lprops;
}
if (pick_free) {
lprops = ubifs_fast_find_empty(c);
if (lprops)
return lprops;
}
if (!squeeze) {
lprops = ubifs_fast_find_free(c);
if (lprops && lprops->free >= min_space)
return lprops;
}
/* There may be an LEB with enough free space on the dirty heap */
heap = &c->lpt_heap[LPROPS_DIRTY - 1];
for (i = 0; i < heap->cnt; i++) {
lprops = heap->arr[i];
if (lprops->free >= min_space)
return lprops;
}
/*
* A LEB may have fallen off of the bottom of the free heap, and ended
* up as uncategorized even though it has enough free space for us now,
* so check the uncategorized list. N.B. neither empty nor freeable LEBs
* can end up as uncategorized because they are kept on lists not
* finite-sized heaps.
*/
list_for_each_entry(lprops, &c->uncat_list, list) {
if (lprops->flags & LPROPS_TAKEN)
continue;
if (lprops->flags & LPROPS_INDEX)
continue;
if (lprops->free >= min_space)
return lprops;
}
/* We have looked everywhere in main memory, now scan the flash */
if (c->pnodes_have >= c->pnode_cnt)
/* All pnodes are in memory, so skip scan */
return ERR_PTR(-ENOSPC);
data.min_space = min_space;
data.pick_free = pick_free;
data.lnum = -1;
err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
(ubifs_lpt_scan_callback)scan_for_free_cb,
&data);
if (err)
return ERR_PTR(err);
ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
c->lscan_lnum = data.lnum;
lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
if (IS_ERR(lprops))
return lprops;
ubifs_assert(lprops->lnum == data.lnum);
ubifs_assert(lprops->free >= min_space);
ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
ubifs_assert(!(lprops->flags & LPROPS_INDEX));
return lprops;
}
/**
* ubifs_find_free_space - find a data LEB with free space.
* @c: the UBIFS file-system description object
* @min_space: minimum amount of required free space
* @offs: contains offset of where free space starts on exit
* @squeeze: whether to try to find space in a non-empty LEB first
*
* This function looks for an LEB with at least @min_space bytes of free space.
* It tries to find an empty LEB if possible. If no empty LEBs are available,
* this function searches for a non-empty data LEB. The returned LEB is marked
* as "taken".
*
* This function returns found LEB number in case of success, %-ENOSPC if it
* failed to find a LEB with @min_space bytes of free space and other a negative
* error codes in case of failure.
*/
int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *offs,
int squeeze)
{
const struct ubifs_lprops *lprops;
int lebs, rsvd_idx_lebs, pick_free = 0, err, lnum, flags;
dbg_find("min_space %d", min_space);
ubifs_get_lprops(c);
/* Check if there are enough empty LEBs for commit */
spin_lock(&c->space_lock);
if (c->bi.min_idx_lebs > c->lst.idx_lebs)
rsvd_idx_lebs = c->bi.min_idx_lebs - c->lst.idx_lebs;
else
rsvd_idx_lebs = 0;
lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
c->lst.taken_empty_lebs;
if (rsvd_idx_lebs < lebs)
/*
* OK to allocate an empty LEB, but we still don't want to go
* looking for one if there aren't any.
*/
if (c->lst.empty_lebs - c->lst.taken_empty_lebs > 0) {
pick_free = 1;
/*
* Because we release the space lock, we must account
* for this allocation here. After the LEB properties
* flags have been updated, we subtract one. Note, the
* result of this is that lprops also decreases
* @taken_empty_lebs in 'ubifs_change_lp()', so it is
* off by one for a short period of time which may
* introduce a small disturbance to budgeting
* calculations, but this is harmless because at the
* worst case this would make the budgeting subsystem
* be more pessimistic than needed.
*
* Fundamentally, this is about serialization of the
* budgeting and lprops subsystems. We could make the
* @space_lock a mutex and avoid dropping it before
* calling 'ubifs_change_lp()', but mutex is more
* heavy-weight, and we want budgeting to be as fast as
* possible.
*/
c->lst.taken_empty_lebs += 1;
}
spin_unlock(&c->space_lock);
lprops = do_find_free_space(c, min_space, pick_free, squeeze);
if (IS_ERR(lprops)) {
err = PTR_ERR(lprops);
goto out;
}
lnum = lprops->lnum;
flags = lprops->flags | LPROPS_TAKEN;
lprops = ubifs_change_lp(c, lprops, LPROPS_NC, LPROPS_NC, flags, 0);
if (IS_ERR(lprops)) {
err = PTR_ERR(lprops);
goto out;
}
if (pick_free) {
spin_lock(&c->space_lock);
c->lst.taken_empty_lebs -= 1;
spin_unlock(&c->space_lock);
}
*offs = c->leb_size - lprops->free;
ubifs_release_lprops(c);
if (*offs == 0) {
/*
* Ensure that empty LEBs have been unmapped. They may not have
* been, for example, because of an unclean unmount. Also
* LEBs that were freeable LEBs (free + dirty == leb_size) will
* not have been unmapped.
*/
err = ubifs_leb_unmap(c, lnum);
if (err)
return err;
}
dbg_find("found LEB %d, free %d", lnum, c->leb_size - *offs);
ubifs_assert(*offs <= c->leb_size - min_space);
return lnum;
out:
if (pick_free) {
spin_lock(&c->space_lock);
c->lst.taken_empty_lebs -= 1;
spin_unlock(&c->space_lock);
}
ubifs_release_lprops(c);
return err;
}
/**
* scan_for_idx_cb - callback used by the scan for a free LEB for the index.
* @c: the UBIFS file-system description object
* @lprops: LEB properties to scan
* @in_tree: whether the LEB properties are in main memory
* @data: information passed to and from the caller of the scan
*
* This function returns a code that indicates whether the scan should continue
* (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
* in main memory (%LPT_SCAN_ADD), or whether the scan should stop
* (%LPT_SCAN_STOP).
*/
static int scan_for_idx_cb(struct ubifs_info *c,
const struct ubifs_lprops *lprops, int in_tree,
struct scan_data *data)
{
int ret = LPT_SCAN_CONTINUE;
/* Exclude LEBs that are currently in use */
if (lprops->flags & LPROPS_TAKEN)
return LPT_SCAN_CONTINUE;
/* Determine whether to add these LEB properties to the tree */
if (!in_tree && valuable(c, lprops))
ret |= LPT_SCAN_ADD;
/* Exclude index LEBS */
if (lprops->flags & LPROPS_INDEX)
return ret;
/* Exclude LEBs that cannot be made empty */
if (lprops->free + lprops->dirty != c->leb_size)
return ret;
/*
* We are allocating for the index so it is safe to allocate LEBs with
* only free and dirty space, because write buffers are sync'd at commit
* start.
*/
data->lnum = lprops->lnum;
return LPT_SCAN_ADD | LPT_SCAN_STOP;
}
/**
* scan_for_leb_for_idx - scan for a free LEB for the index.
* @c: the UBIFS file-system description object
*/
static const struct ubifs_lprops *scan_for_leb_for_idx(struct ubifs_info *c)
{
struct ubifs_lprops *lprops;
struct scan_data data;
int err;
data.lnum = -1;
err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
(ubifs_lpt_scan_callback)scan_for_idx_cb,
&data);
if (err)
return ERR_PTR(err);
ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
c->lscan_lnum = data.lnum;
lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
if (IS_ERR(lprops))
return lprops;
ubifs_assert(lprops->lnum == data.lnum);
ubifs_assert(lprops->free + lprops->dirty == c->leb_size);
ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
ubifs_assert(!(lprops->flags & LPROPS_INDEX));
return lprops;
}
/**
* ubifs_find_free_leb_for_idx - find a free LEB for the index.
* @c: the UBIFS file-system description object
*
* This function looks for a free LEB and returns that LEB number. The returned
* LEB is marked as "taken", "index".
*
* Only empty LEBs are allocated. This is for two reasons. First, the commit
* calculates the number of LEBs to allocate based on the assumption that they
* will be empty. Secondly, free space at the end of an index LEB is not
* guaranteed to be empty because it may have been used by the in-the-gaps
* method prior to an unclean unmount.
*
* If no LEB is found %-ENOSPC is returned. For other failures another negative
* error code is returned.
*/
int ubifs_find_free_leb_for_idx(struct ubifs_info *c)
{
const struct ubifs_lprops *lprops;
int lnum = -1, err, flags;
ubifs_get_lprops(c);
lprops = ubifs_fast_find_empty(c);
if (!lprops) {
lprops = ubifs_fast_find_freeable(c);
if (!lprops) {
/*
* The first condition means the following: go scan the
* LPT if there are uncategorized lprops, which means
* there may be freeable LEBs there (UBIFS does not
* store the information about freeable LEBs in the
* master node).
*/
if (c->in_a_category_cnt != c->main_lebs ||
c->lst.empty_lebs - c->lst.taken_empty_lebs > 0) {
ubifs_assert(c->freeable_cnt == 0);
lprops = scan_for_leb_for_idx(c);
if (IS_ERR(lprops)) {
err = PTR_ERR(lprops);
goto out;
}
}
}
}
if (!lprops) {
err = -ENOSPC;
goto out;
}
lnum = lprops->lnum;
dbg_find("found LEB %d, free %d, dirty %d, flags %#x",
lnum, lprops->free, lprops->dirty, lprops->flags);
flags = lprops->flags | LPROPS_TAKEN | LPROPS_INDEX;
lprops = ubifs_change_lp(c, lprops, c->leb_size, 0, flags, 0);
if (IS_ERR(lprops)) {
err = PTR_ERR(lprops);
goto out;
}
ubifs_release_lprops(c);
/*
* Ensure that empty LEBs have been unmapped. They may not have been,
* for example, because of an unclean unmount. Also LEBs that were
* freeable LEBs (free + dirty == leb_size) will not have been unmapped.
*/
err = ubifs_leb_unmap(c, lnum);
if (err) {
ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
LPROPS_TAKEN | LPROPS_INDEX, 0);
return err;
}
return lnum;
out:
ubifs_release_lprops(c);
return err;
}
static int cmp_dirty_idx(const struct ubifs_lprops **a,
const struct ubifs_lprops **b)
{
const struct ubifs_lprops *lpa = *a;
const struct ubifs_lprops *lpb = *b;
return lpa->dirty + lpa->free - lpb->dirty - lpb->free;
}
static void swap_dirty_idx(struct ubifs_lprops **a, struct ubifs_lprops **b,
int size)
{
struct ubifs_lprops *t = *a;
*a = *b;
*b = t;
}
/**
* ubifs_save_dirty_idx_lnums - save an array of the most dirty index LEB nos.
* @c: the UBIFS file-system description object
*
* This function is called each commit to create an array of LEB numbers of
* dirty index LEBs sorted in order of dirty and free space. This is used by
* the in-the-gaps method of TNC commit.
*/
int ubifs_save_dirty_idx_lnums(struct ubifs_info *c)
{
int i;
ubifs_get_lprops(c);
/* Copy the LPROPS_DIRTY_IDX heap */
c->dirty_idx.cnt = c->lpt_heap[LPROPS_DIRTY_IDX - 1].cnt;
memcpy(c->dirty_idx.arr, c->lpt_heap[LPROPS_DIRTY_IDX - 1].arr,
sizeof(void *) * c->dirty_idx.cnt);
/* Sort it so that the dirtiest is now at the end */
sort(c->dirty_idx.arr, c->dirty_idx.cnt, sizeof(void *),
(int (*)(const void *, const void *))cmp_dirty_idx,
(void (*)(void *, void *, int))swap_dirty_idx);
dbg_find("found %d dirty index LEBs", c->dirty_idx.cnt);
if (c->dirty_idx.cnt)
dbg_find("dirtiest index LEB is %d with dirty %d and free %d",
c->dirty_idx.arr[c->dirty_idx.cnt - 1]->lnum,
c->dirty_idx.arr[c->dirty_idx.cnt - 1]->dirty,
c->dirty_idx.arr[c->dirty_idx.cnt - 1]->free);
/* Replace the lprops pointers with LEB numbers */
for (i = 0; i < c->dirty_idx.cnt; i++)
c->dirty_idx.arr[i] = (void *)(size_t)c->dirty_idx.arr[i]->lnum;
ubifs_release_lprops(c);
return 0;
}
/**
* scan_dirty_idx_cb - callback used by the scan for a dirty index LEB.
* @c: the UBIFS file-system description object
* @lprops: LEB properties to scan
* @in_tree: whether the LEB properties are in main memory
* @data: information passed to and from the caller of the scan
*
* This function returns a code that indicates whether the scan should continue
* (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
* in main memory (%LPT_SCAN_ADD), or whether the scan should stop
* (%LPT_SCAN_STOP).
*/
static int scan_dirty_idx_cb(struct ubifs_info *c,
const struct ubifs_lprops *lprops, int in_tree,
struct scan_data *data)
{
int ret = LPT_SCAN_CONTINUE;
/* Exclude LEBs that are currently in use */
if (lprops->flags & LPROPS_TAKEN)
return LPT_SCAN_CONTINUE;
/* Determine whether to add these LEB properties to the tree */
if (!in_tree && valuable(c, lprops))
ret |= LPT_SCAN_ADD;
/* Exclude non-index LEBs */
if (!(lprops->flags & LPROPS_INDEX))
return ret;
/* Exclude LEBs with too little space */
if (lprops->free + lprops->dirty < c->min_idx_node_sz)
return ret;
/* Finally we found space */
data->lnum = lprops->lnum;
return LPT_SCAN_ADD | LPT_SCAN_STOP;
}
/**
* find_dirty_idx_leb - find a dirty index LEB.
* @c: the UBIFS file-system description object
*
* This function returns LEB number upon success and a negative error code upon
* failure. In particular, -ENOSPC is returned if a dirty index LEB is not
* found.
*
* Note that this function scans the entire LPT but it is called very rarely.
*/
static int find_dirty_idx_leb(struct ubifs_info *c)
{
const struct ubifs_lprops *lprops;
struct ubifs_lpt_heap *heap;
struct scan_data data;
int err, i, ret;
/* Check all structures in memory first */
data.lnum = -1;
heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
for (i = 0; i < heap->cnt; i++) {
lprops = heap->arr[i];
ret = scan_dirty_idx_cb(c, lprops, 1, &data);
if (ret & LPT_SCAN_STOP)
goto found;
}
list_for_each_entry(lprops, &c->frdi_idx_list, list) {
ret = scan_dirty_idx_cb(c, lprops, 1, &data);
if (ret & LPT_SCAN_STOP)
goto found;
}
list_for_each_entry(lprops, &c->uncat_list, list) {
ret = scan_dirty_idx_cb(c, lprops, 1, &data);
if (ret & LPT_SCAN_STOP)
goto found;
}
if (c->pnodes_have >= c->pnode_cnt)
/* All pnodes are in memory, so skip scan */
return -ENOSPC;
err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
(ubifs_lpt_scan_callback)scan_dirty_idx_cb,
&data);
if (err)
return err;
found:
ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
c->lscan_lnum = data.lnum;
lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
if (IS_ERR(lprops))
return PTR_ERR(lprops);
ubifs_assert(lprops->lnum == data.lnum);
ubifs_assert(lprops->free + lprops->dirty >= c->min_idx_node_sz);
ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
ubifs_assert((lprops->flags & LPROPS_INDEX));
dbg_find("found dirty LEB %d, free %d, dirty %d, flags %#x",
lprops->lnum, lprops->free, lprops->dirty, lprops->flags);
lprops = ubifs_change_lp(c, lprops, LPROPS_NC, LPROPS_NC,
lprops->flags | LPROPS_TAKEN, 0);
if (IS_ERR(lprops))
return PTR_ERR(lprops);
return lprops->lnum;
}
/**
* get_idx_gc_leb - try to get a LEB number from trivial GC.
* @c: the UBIFS file-system description object
*/
static int get_idx_gc_leb(struct ubifs_info *c)
{
const struct ubifs_lprops *lp;
int err, lnum;
err = ubifs_get_idx_gc_leb(c);
if (err < 0)
return err;
lnum = err;
/*
* The LEB was due to be unmapped after the commit but
* it is needed now for this commit.
*/
lp = ubifs_lpt_lookup_dirty(c, lnum);
if (IS_ERR(lp))
return PTR_ERR(lp);
lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
lp->flags | LPROPS_INDEX, -1);
if (IS_ERR(lp))
return PTR_ERR(lp);
dbg_find("LEB %d, dirty %d and free %d flags %#x",
lp->lnum, lp->dirty, lp->free, lp->flags);
return lnum;
}
/**
* find_dirtiest_idx_leb - find dirtiest index LEB from dirtiest array.
* @c: the UBIFS file-system description object
*/
static int find_dirtiest_idx_leb(struct ubifs_info *c)
{
const struct ubifs_lprops *lp;
int lnum;
while (1) {
if (!c->dirty_idx.cnt)
return -ENOSPC;
/* The lprops pointers were replaced by LEB numbers */
lnum = (size_t)c->dirty_idx.arr[--c->dirty_idx.cnt];
lp = ubifs_lpt_lookup(c, lnum);
if (IS_ERR(lp))
return PTR_ERR(lp);
if ((lp->flags & LPROPS_TAKEN) || !(lp->flags & LPROPS_INDEX))
continue;
lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
lp->flags | LPROPS_TAKEN, 0);
if (IS_ERR(lp))
return PTR_ERR(lp);
break;
}
dbg_find("LEB %d, dirty %d and free %d flags %#x", lp->lnum, lp->dirty,
lp->free, lp->flags);
ubifs_assert(lp->flags & LPROPS_TAKEN);
ubifs_assert(lp->flags & LPROPS_INDEX);
return lnum;
}
/**
* ubifs_find_dirty_idx_leb - try to find dirtiest index LEB as at last commit.
* @c: the UBIFS file-system description object
*
* This function attempts to find an untaken index LEB with the most free and
* dirty space that can be used without overwriting index nodes that were in the
* last index committed.
*/
int ubifs_find_dirty_idx_leb(struct ubifs_info *c)
{
int err;
ubifs_get_lprops(c);
/*
* We made an array of the dirtiest index LEB numbers as at the start of
* last commit. Try that array first.
*/
err = find_dirtiest_idx_leb(c);
/* Next try scanning the entire LPT */
if (err == -ENOSPC)
err = find_dirty_idx_leb(c);
/* Finally take any index LEBs awaiting trivial GC */
if (err == -ENOSPC)
err = get_idx_gc_leb(c);
ubifs_release_lprops(c);
return err;
}