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Diffstat (limited to 'fs/ubifs/find.c')
| -rw-r--r-- | fs/ubifs/find.c | 975 |
1 files changed, 975 insertions, 0 deletions
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; +} |
