UBIFS: add new flash file system
This is a new flash file system. See
http://www.linux-mtd.infradead.org/doc/ubifs.html
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
diff --git a/fs/ubifs/find.c b/fs/ubifs/find.c
new file mode 100644
index 0000000..10394c5
--- /dev/null
+++ b/fs/ubifs/find.c
@@ -0,0 +1,975 @@
+/*
+ * 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:
+ * o LEBs which have less than dead watermark of dirty space are never picked
+ * by 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".
+ *
+ * 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.
+ */
+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;
+ 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->min_idx_lebs >= c->lst.idx_lebs) {
+ rsvd_idx_lebs = c->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->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 twice as more space for the index than it
+ * actually takes, it does not make sense to pick indexing LEBs
+ * with less than half LEB of dirty space.
+ */
+ 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->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
+ * @free: contains amount of free space in the LEB 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 *free,
+ 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->min_idx_lebs > c->lst.idx_lebs)
+ rsvd_idx_lebs = c->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;
+ ubifs_assert(lebs + c->lst.idx_lebs >= c->min_idx_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);
+ }
+
+ *free = lprops->free;
+ ubifs_release_lprops(c);
+
+ if (*free == c->leb_size) {
+ /*
+ * 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, *free);
+ ubifs_assert(*free >= 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) {
+ ubifs_assert(c->freeable_cnt == 0);
+ if (c->lst.empty_lebs - c->lst.taken_empty_lebs > 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 (unlikely(IS_ERR(lp)))
+ return PTR_ERR(lp);
+ lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
+ lp->flags | LPROPS_INDEX, -1);
+ if (unlikely(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;
+}