diff options
Diffstat (limited to 'fs/ubifs/tnc_commit.c')
| -rw-r--r-- | fs/ubifs/tnc_commit.c | 1071 |
1 files changed, 1071 insertions, 0 deletions
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c new file mode 100644 index 000000000..b45345d70 --- /dev/null +++ b/fs/ubifs/tnc_commit.c @@ -0,0 +1,1071 @@ +/* + * 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: Adrian Hunter + * Artem Bityutskiy (Битюцкий Артём) + */ + +/* This file implements TNC functions for committing */ + +#include <linux/random.h> +#include "ubifs.h" + +/** + * make_idx_node - make an index node for fill-the-gaps method of TNC commit. + * @c: UBIFS file-system description object + * @idx: buffer in which to place new index node + * @znode: znode from which to make new index node + * @lnum: LEB number where new index node will be written + * @offs: offset where new index node will be written + * @len: length of new index node + */ +static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx, + struct ubifs_znode *znode, int lnum, int offs, int len) +{ + struct ubifs_znode *zp; + int i, err; + + /* Make index node */ + idx->ch.node_type = UBIFS_IDX_NODE; + idx->child_cnt = cpu_to_le16(znode->child_cnt); + idx->level = cpu_to_le16(znode->level); + for (i = 0; i < znode->child_cnt; i++) { + struct ubifs_branch *br = ubifs_idx_branch(c, idx, i); + struct ubifs_zbranch *zbr = &znode->zbranch[i]; + + key_write_idx(c, &zbr->key, &br->key); + br->lnum = cpu_to_le32(zbr->lnum); + br->offs = cpu_to_le32(zbr->offs); + br->len = cpu_to_le32(zbr->len); + if (!zbr->lnum || !zbr->len) { + ubifs_err(c, "bad ref in znode"); + ubifs_dump_znode(c, znode); + if (zbr->znode) + ubifs_dump_znode(c, zbr->znode); + } + } + ubifs_prepare_node(c, idx, len, 0); + + znode->lnum = lnum; + znode->offs = offs; + znode->len = len; + + err = insert_old_idx_znode(c, znode); + + /* Update the parent */ + zp = znode->parent; + if (zp) { + struct ubifs_zbranch *zbr; + + zbr = &zp->zbranch[znode->iip]; + zbr->lnum = lnum; + zbr->offs = offs; + zbr->len = len; + } else { + c->zroot.lnum = lnum; + c->zroot.offs = offs; + c->zroot.len = len; + } + c->calc_idx_sz += ALIGN(len, 8); + + atomic_long_dec(&c->dirty_zn_cnt); + + ubifs_assert(ubifs_zn_dirty(znode)); + ubifs_assert(ubifs_zn_cow(znode)); + + /* + * Note, unlike 'write_index()' we do not add memory barriers here + * because this function is called with @c->tnc_mutex locked. + */ + __clear_bit(DIRTY_ZNODE, &znode->flags); + __clear_bit(COW_ZNODE, &znode->flags); + + return err; +} + +/** + * fill_gap - make index nodes in gaps in dirty index LEBs. + * @c: UBIFS file-system description object + * @lnum: LEB number that gap appears in + * @gap_start: offset of start of gap + * @gap_end: offset of end of gap + * @dirt: adds dirty space to this + * + * This function returns the number of index nodes written into the gap. + */ +static int fill_gap(struct ubifs_info *c, int lnum, int gap_start, int gap_end, + int *dirt) +{ + int len, gap_remains, gap_pos, written, pad_len; + + ubifs_assert((gap_start & 7) == 0); + ubifs_assert((gap_end & 7) == 0); + ubifs_assert(gap_end >= gap_start); + + gap_remains = gap_end - gap_start; + if (!gap_remains) + return 0; + gap_pos = gap_start; + written = 0; + while (c->enext) { + len = ubifs_idx_node_sz(c, c->enext->child_cnt); + if (len < gap_remains) { + struct ubifs_znode *znode = c->enext; + const int alen = ALIGN(len, 8); + int err; + + ubifs_assert(alen <= gap_remains); + err = make_idx_node(c, c->ileb_buf + gap_pos, znode, + lnum, gap_pos, len); + if (err) + return err; + gap_remains -= alen; + gap_pos += alen; + c->enext = znode->cnext; + if (c->enext == c->cnext) + c->enext = NULL; + written += 1; + } else + break; + } + if (gap_end == c->leb_size) { + c->ileb_len = ALIGN(gap_pos, c->min_io_size); + /* Pad to end of min_io_size */ + pad_len = c->ileb_len - gap_pos; + } else + /* Pad to end of gap */ + pad_len = gap_remains; + dbg_gc("LEB %d:%d to %d len %d nodes written %d wasted bytes %d", + lnum, gap_start, gap_end, gap_end - gap_start, written, pad_len); + ubifs_pad(c, c->ileb_buf + gap_pos, pad_len); + *dirt += pad_len; + return written; +} + +/** + * find_old_idx - find an index node obsoleted since the last commit start. + * @c: UBIFS file-system description object + * @lnum: LEB number of obsoleted index node + * @offs: offset of obsoleted index node + * + * Returns %1 if found and %0 otherwise. + */ +static int find_old_idx(struct ubifs_info *c, int lnum, int offs) +{ + struct ubifs_old_idx *o; + struct rb_node *p; + + p = c->old_idx.rb_node; + while (p) { + o = rb_entry(p, struct ubifs_old_idx, rb); + if (lnum < o->lnum) + p = p->rb_left; + else if (lnum > o->lnum) + p = p->rb_right; + else if (offs < o->offs) + p = p->rb_left; + else if (offs > o->offs) + p = p->rb_right; + else + return 1; + } + return 0; +} + +/** + * is_idx_node_in_use - determine if an index node can be overwritten. + * @c: UBIFS file-system description object + * @key: key of index node + * @level: index node level + * @lnum: LEB number of index node + * @offs: offset of index node + * + * If @key / @lnum / @offs identify an index node that was not part of the old + * index, then this function returns %0 (obsolete). Else if the index node was + * part of the old index but is now dirty %1 is returned, else if it is clean %2 + * is returned. A negative error code is returned on failure. + */ +static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key, + int level, int lnum, int offs) +{ + int ret; + + ret = is_idx_node_in_tnc(c, key, level, lnum, offs); + if (ret < 0) + return ret; /* Error code */ + if (ret == 0) + if (find_old_idx(c, lnum, offs)) + return 1; + return ret; +} + +/** + * layout_leb_in_gaps - layout index nodes using in-the-gaps method. + * @c: UBIFS file-system description object + * @p: return LEB number here + * + * This function lays out new index nodes for dirty znodes using in-the-gaps + * method of TNC commit. + * This function merely puts the next znode into the next gap, making no attempt + * to try to maximise the number of znodes that fit. + * This function returns the number of index nodes written into the gaps, or a + * negative error code on failure. + */ +static int layout_leb_in_gaps(struct ubifs_info *c, int *p) +{ + struct ubifs_scan_leb *sleb; + struct ubifs_scan_node *snod; + int lnum, dirt = 0, gap_start, gap_end, err, written, tot_written; + + tot_written = 0; + /* Get an index LEB with lots of obsolete index nodes */ + lnum = ubifs_find_dirty_idx_leb(c); + if (lnum < 0) + /* + * There also may be dirt in the index head that could be + * filled, however we do not check there at present. + */ + return lnum; /* Error code */ + *p = lnum; + dbg_gc("LEB %d", lnum); + /* + * Scan the index LEB. We use the generic scan for this even though + * it is more comprehensive and less efficient than is needed for this + * purpose. + */ + sleb = ubifs_scan(c, lnum, 0, c->ileb_buf, 0); + c->ileb_len = 0; + if (IS_ERR(sleb)) + return PTR_ERR(sleb); + gap_start = 0; + list_for_each_entry(snod, &sleb->nodes, list) { + struct ubifs_idx_node *idx; + int in_use, level; + + ubifs_assert(snod->type == UBIFS_IDX_NODE); + idx = snod->node; + key_read(c, ubifs_idx_key(c, idx), &snod->key); + level = le16_to_cpu(idx->level); + /* Determine if the index node is in use (not obsolete) */ + in_use = is_idx_node_in_use(c, &snod->key, level, lnum, + snod->offs); + if (in_use < 0) { + ubifs_scan_destroy(sleb); + return in_use; /* Error code */ + } + if (in_use) { + if (in_use == 1) + dirt += ALIGN(snod->len, 8); + /* + * The obsolete index nodes form gaps that can be + * overwritten. This gap has ended because we have + * found an index node that is still in use + * i.e. not obsolete + */ + gap_end = snod->offs; + /* Try to fill gap */ + written = fill_gap(c, lnum, gap_start, gap_end, &dirt); + if (written < 0) { + ubifs_scan_destroy(sleb); + return written; /* Error code */ + } + tot_written += written; + gap_start = ALIGN(snod->offs + snod->len, 8); + } + } + ubifs_scan_destroy(sleb); + c->ileb_len = c->leb_size; + gap_end = c->leb_size; + /* Try to fill gap */ + written = fill_gap(c, lnum, gap_start, gap_end, &dirt); + if (written < 0) + return written; /* Error code */ + tot_written += written; + if (tot_written == 0) { + struct ubifs_lprops lp; + + dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written); + err = ubifs_read_one_lp(c, lnum, &lp); + if (err) + return err; + if (lp.free == c->leb_size) { + /* + * We must have snatched this LEB from the idx_gc list + * so we need to correct the free and dirty space. + */ + err = ubifs_change_one_lp(c, lnum, + c->leb_size - c->ileb_len, + dirt, 0, 0, 0); + if (err) + return err; + } + return 0; + } + err = ubifs_change_one_lp(c, lnum, c->leb_size - c->ileb_len, dirt, + 0, 0, 0); + if (err) + return err; + err = ubifs_leb_change(c, lnum, c->ileb_buf, c->ileb_len); + if (err) + return err; + dbg_gc("LEB %d wrote %d index nodes", lnum, tot_written); + return tot_written; +} + +/** + * get_leb_cnt - calculate the number of empty LEBs needed to commit. + * @c: UBIFS file-system description object + * @cnt: number of znodes to commit + * + * This function returns the number of empty LEBs needed to commit @cnt znodes + * to the current index head. The number is not exact and may be more than + * needed. + */ +static int get_leb_cnt(struct ubifs_info *c, int cnt) +{ + int d; + + /* Assume maximum index node size (i.e. overestimate space needed) */ + cnt -= (c->leb_size - c->ihead_offs) / c->max_idx_node_sz; + if (cnt < 0) + cnt = 0; + d = c->leb_size / c->max_idx_node_sz; + return DIV_ROUND_UP(cnt, d); +} + +/** + * layout_in_gaps - in-the-gaps method of committing TNC. + * @c: UBIFS file-system description object + * @cnt: number of dirty znodes to commit. + * + * This function lays out new index nodes for dirty znodes using in-the-gaps + * method of TNC commit. + * + * This function returns %0 on success and a negative error code on failure. + */ +static int layout_in_gaps(struct ubifs_info *c, int cnt) +{ + int err, leb_needed_cnt, written, *p; + + dbg_gc("%d znodes to write", cnt); + + c->gap_lebs = kmalloc(sizeof(int) * (c->lst.idx_lebs + 1), GFP_NOFS); + if (!c->gap_lebs) + return -ENOMEM; + + p = c->gap_lebs; + do { + ubifs_assert(p < c->gap_lebs + sizeof(int) * c->lst.idx_lebs); + written = layout_leb_in_gaps(c, p); + if (written < 0) { + err = written; + if (err != -ENOSPC) { + kfree(c->gap_lebs); + c->gap_lebs = NULL; + return err; + } + if (!dbg_is_chk_index(c)) { + /* + * Do not print scary warnings if the debugging + * option which forces in-the-gaps is enabled. + */ + ubifs_warn(c, "out of space"); + ubifs_dump_budg(c, &c->bi); + ubifs_dump_lprops(c); + } + /* Try to commit anyway */ + break; + } + p++; + cnt -= written; + leb_needed_cnt = get_leb_cnt(c, cnt); + dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt, + leb_needed_cnt, c->ileb_cnt); + } while (leb_needed_cnt > c->ileb_cnt); + + *p = -1; + return 0; +} + +/** + * layout_in_empty_space - layout index nodes in empty space. + * @c: UBIFS file-system description object + * + * This function lays out new index nodes for dirty znodes using empty LEBs. + * + * This function returns %0 on success and a negative error code on failure. + */ +static int layout_in_empty_space(struct ubifs_info *c) +{ + struct ubifs_znode *znode, *cnext, *zp; + int lnum, offs, len, next_len, buf_len, buf_offs, used, avail; + int wlen, blen, err; + + cnext = c->enext; + if (!cnext) + return 0; + + lnum = c->ihead_lnum; + buf_offs = c->ihead_offs; + + buf_len = ubifs_idx_node_sz(c, c->fanout); + buf_len = ALIGN(buf_len, c->min_io_size); + used = 0; + avail = buf_len; + + /* Ensure there is enough room for first write */ + next_len = ubifs_idx_node_sz(c, cnext->child_cnt); + if (buf_offs + next_len > c->leb_size) + lnum = -1; + + while (1) { + znode = cnext; + + len = ubifs_idx_node_sz(c, znode->child_cnt); + + /* Determine the index node position */ + if (lnum == -1) { + if (c->ileb_nxt >= c->ileb_cnt) { + ubifs_err(c, "out of space"); + return -ENOSPC; + } + lnum = c->ilebs[c->ileb_nxt++]; + buf_offs = 0; + used = 0; + avail = buf_len; + } + + offs = buf_offs + used; + + znode->lnum = lnum; + znode->offs = offs; + znode->len = len; + + /* Update the parent */ + zp = znode->parent; + if (zp) { + struct ubifs_zbranch *zbr; + int i; + + i = znode->iip; + zbr = &zp->zbranch[i]; + zbr->lnum = lnum; + zbr->offs = offs; + zbr->len = len; + } else { + c->zroot.lnum = lnum; + c->zroot.offs = offs; + c->zroot.len = len; + } + c->calc_idx_sz += ALIGN(len, 8); + + /* + * Once lprops is updated, we can decrease the dirty znode count + * but it is easier to just do it here. + */ + atomic_long_dec(&c->dirty_zn_cnt); + + /* + * Calculate the next index node length to see if there is + * enough room for it + */ + cnext = znode->cnext; + if (cnext == c->cnext) + next_len = 0; + else + next_len = ubifs_idx_node_sz(c, cnext->child_cnt); + + /* Update buffer positions */ + wlen = used + len; + used += ALIGN(len, 8); + avail -= ALIGN(len, 8); + + if (next_len != 0 && + buf_offs + used + next_len <= c->leb_size && + avail > 0) + continue; + + if (avail <= 0 && next_len && + buf_offs + used + next_len <= c->leb_size) + blen = buf_len; + else + blen = ALIGN(wlen, c->min_io_size); + + /* The buffer is full or there are no more znodes to do */ + buf_offs += blen; + if (next_len) { + if (buf_offs + next_len > c->leb_size) { + err = ubifs_update_one_lp(c, lnum, + c->leb_size - buf_offs, blen - used, + 0, 0); + if (err) + return err; + lnum = -1; + } + used -= blen; + if (used < 0) + used = 0; + avail = buf_len - used; + continue; + } + err = ubifs_update_one_lp(c, lnum, c->leb_size - buf_offs, + blen - used, 0, 0); + if (err) + return err; + break; + } + + c->dbg->new_ihead_lnum = lnum; + c->dbg->new_ihead_offs = buf_offs; + + return 0; +} + +/** + * layout_commit - determine positions of index nodes to commit. + * @c: UBIFS file-system description object + * @no_space: indicates that insufficient empty LEBs were allocated + * @cnt: number of znodes to commit + * + * Calculate and update the positions of index nodes to commit. If there were + * an insufficient number of empty LEBs allocated, then index nodes are placed + * into the gaps created by obsolete index nodes in non-empty index LEBs. For + * this purpose, an obsolete index node is one that was not in the index as at + * the end of the last commit. To write "in-the-gaps" requires that those index + * LEBs are updated atomically in-place. + */ +static int layout_commit(struct ubifs_info *c, int no_space, int cnt) +{ + int err; + + if (no_space) { + err = layout_in_gaps(c, cnt); + if (err) + return err; + } + err = layout_in_empty_space(c); + return err; +} + +/** + * find_first_dirty - find first dirty znode. + * @znode: znode to begin searching from + */ +static struct ubifs_znode *find_first_dirty(struct ubifs_znode *znode) +{ + int i, cont; + + if (!znode) + return NULL; + + while (1) { + if (znode->level == 0) { + if (ubifs_zn_dirty(znode)) + return znode; + return NULL; + } + cont = 0; + for (i = 0; i < znode->child_cnt; i++) { + struct ubifs_zbranch *zbr = &znode->zbranch[i]; + + if (zbr->znode && ubifs_zn_dirty(zbr->znode)) { + znode = zbr->znode; + cont = 1; + break; + } + } + if (!cont) { + if (ubifs_zn_dirty(znode)) + return znode; + return NULL; + } + } +} + +/** + * find_next_dirty - find next dirty znode. + * @znode: znode to begin searching from + */ +static struct ubifs_znode *find_next_dirty(struct ubifs_znode *znode) +{ + int n = znode->iip + 1; + + znode = znode->parent; + if (!znode) + return NULL; + for (; n < znode->child_cnt; n++) { + struct ubifs_zbranch *zbr = &znode->zbranch[n]; + + if (zbr->znode && ubifs_zn_dirty(zbr->znode)) + return find_first_dirty(zbr->znode); + } + return znode; +} + +/** + * get_znodes_to_commit - create list of dirty znodes to commit. + * @c: UBIFS file-system description object + * + * This function returns the number of znodes to commit. + */ +static int get_znodes_to_commit(struct ubifs_info *c) +{ + struct ubifs_znode *znode, *cnext; + int cnt = 0; + + c->cnext = find_first_dirty(c->zroot.znode); + znode = c->enext = c->cnext; + if (!znode) { + dbg_cmt("no znodes to commit"); + return 0; + } + cnt += 1; + while (1) { + ubifs_assert(!ubifs_zn_cow(znode)); + __set_bit(COW_ZNODE, &znode->flags); + znode->alt = 0; + cnext = find_next_dirty(znode); + if (!cnext) { + znode->cnext = c->cnext; + break; + } + znode->cnext = cnext; + znode = cnext; + cnt += 1; + } + dbg_cmt("committing %d znodes", cnt); + ubifs_assert(cnt == atomic_long_read(&c->dirty_zn_cnt)); + return cnt; +} + +/** + * alloc_idx_lebs - allocate empty LEBs to be used to commit. + * @c: UBIFS file-system description object + * @cnt: number of znodes to commit + * + * This function returns %-ENOSPC if it cannot allocate a sufficient number of + * empty LEBs. %0 is returned on success, otherwise a negative error code + * is returned. + */ +static int alloc_idx_lebs(struct ubifs_info *c, int cnt) +{ + int i, leb_cnt, lnum; + + c->ileb_cnt = 0; + c->ileb_nxt = 0; + leb_cnt = get_leb_cnt(c, cnt); + dbg_cmt("need about %d empty LEBS for TNC commit", leb_cnt); + if (!leb_cnt) + return 0; + c->ilebs = kmalloc(leb_cnt * sizeof(int), GFP_NOFS); + if (!c->ilebs) + return -ENOMEM; + for (i = 0; i < leb_cnt; i++) { + lnum = ubifs_find_free_leb_for_idx(c); + if (lnum < 0) + return lnum; + c->ilebs[c->ileb_cnt++] = lnum; + dbg_cmt("LEB %d", lnum); + } + if (dbg_is_chk_index(c) && !(prandom_u32() & 7)) + return -ENOSPC; + return 0; +} + +/** + * free_unused_idx_lebs - free unused LEBs that were allocated for the commit. + * @c: UBIFS file-system description object + * + * It is possible that we allocate more empty LEBs for the commit than we need. + * This functions frees the surplus. + * + * This function returns %0 on success and a negative error code on failure. + */ +static int free_unused_idx_lebs(struct ubifs_info *c) +{ + int i, err = 0, lnum, er; + + for (i = c->ileb_nxt; i < c->ileb_cnt; i++) { + lnum = c->ilebs[i]; + dbg_cmt("LEB %d", lnum); + er = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0, + LPROPS_INDEX | LPROPS_TAKEN, 0); + if (!err) + err = er; + } + return err; +} + +/** + * free_idx_lebs - free unused LEBs after commit end. + * @c: UBIFS file-system description object + * + * This function returns %0 on success and a negative error code on failure. + */ +static int free_idx_lebs(struct ubifs_info *c) +{ + int err; + + err = free_unused_idx_lebs(c); + kfree(c->ilebs); + c->ilebs = NULL; + return err; +} + +/** + * ubifs_tnc_start_commit - start TNC commit. + * @c: UBIFS file-system description object + * @zroot: new index root position is returned here + * + * This function prepares the list of indexing nodes to commit and lays out + * their positions on flash. If there is not enough free space it uses the + * in-gap commit method. Returns zero in case of success and a negative error + * code in case of failure. + */ +int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot) +{ + int err = 0, cnt; + + mutex_lock(&c->tnc_mutex); + err = dbg_check_tnc(c, 1); + if (err) + goto out; + cnt = get_znodes_to_commit(c); + if (cnt != 0) { + int no_space = 0; + + err = alloc_idx_lebs(c, cnt); + if (err == -ENOSPC) + no_space = 1; + else if (err) + goto out_free; + err = layout_commit(c, no_space, cnt); + if (err) + goto out_free; + ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0); + err = free_unused_idx_lebs(c); + if (err) + goto out; + } + destroy_old_idx(c); + memcpy(zroot, &c->zroot, sizeof(struct ubifs_zbranch)); + + err = ubifs_save_dirty_idx_lnums(c); + if (err) + goto out; + + spin_lock(&c->space_lock); + /* + * Although we have not finished committing yet, update size of the + * committed index ('c->bi.old_idx_sz') and zero out the index growth + * budget. It is OK to do this now, because we've reserved all the + * space which is needed to commit the index, and it is save for the + * budgeting subsystem to assume the index is already committed, + * even though it is not. + */ + ubifs_assert(c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c)); + c->bi.old_idx_sz = c->calc_idx_sz; + c->bi.uncommitted_idx = 0; + c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c); + spin_unlock(&c->space_lock); + mutex_unlock(&c->tnc_mutex); + + dbg_cmt("number of index LEBs %d", c->lst.idx_lebs); + dbg_cmt("size of index %llu", c->calc_idx_sz); + return err; + +out_free: + free_idx_lebs(c); +out: + mutex_unlock(&c->tnc_mutex); + return err; +} + +/** + * write_index - write index nodes. + * @c: UBIFS file-system description object + * + * This function writes the index nodes whose positions were laid out in the + * layout_in_empty_space function. + */ +static int write_index(struct ubifs_info *c) +{ + struct ubifs_idx_node *idx; + struct ubifs_znode *znode, *cnext; + int i, lnum, offs, len, next_len, buf_len, buf_offs, used; + int avail, wlen, err, lnum_pos = 0, blen, nxt_offs; + + cnext = c->enext; + if (!cnext) + return 0; + + /* + * Always write index nodes to the index head so that index nodes and + * other types of nodes are never mixed in the same erase block. + */ + lnum = c->ihead_lnum; + buf_offs = c->ihead_offs; + + /* Allocate commit buffer */ + buf_len = ALIGN(c->max_idx_node_sz, c->min_io_size); + used = 0; + avail = buf_len; + + /* Ensure there is enough room for first write */ + next_len = ubifs_idx_node_sz(c, cnext->child_cnt); + if (buf_offs + next_len > c->leb_size) { + err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, 0, + LPROPS_TAKEN); + if (err) + return err; + lnum = -1; + } + + while (1) { + cond_resched(); + + znode = cnext; + idx = c->cbuf + used; + + /* Make index node */ + idx->ch.node_type = UBIFS_IDX_NODE; + idx->child_cnt = cpu_to_le16(znode->child_cnt); + idx->level = cpu_to_le16(znode->level); + for (i = 0; i < znode->child_cnt; i++) { + struct ubifs_branch *br = ubifs_idx_branch(c, idx, i); + struct ubifs_zbranch *zbr = &znode->zbranch[i]; + + key_write_idx(c, &zbr->key, &br->key); + br->lnum = cpu_to_le32(zbr->lnum); + br->offs = cpu_to_le32(zbr->offs); + br->len = cpu_to_le32(zbr->len); + if (!zbr->lnum || !zbr->len) { + ubifs_err(c, "bad ref in znode"); + ubifs_dump_znode(c, znode); + if (zbr->znode) + ubifs_dump_znode(c, zbr->znode); + } + } + len = ubifs_idx_node_sz(c, znode->child_cnt); + ubifs_prepare_node(c, idx, len, 0); + + /* Determine the index node position */ + if (lnum == -1) { + lnum = c->ilebs[lnum_pos++]; + buf_offs = 0; + used = 0; + avail = buf_len; + } + offs = buf_offs + used; + + if (lnum != znode->lnum || offs != znode->offs || + len != znode->len) { + ubifs_err(c, "inconsistent znode posn"); + return -EINVAL; + } + + /* Grab some stuff from znode while we still can */ + cnext = znode->cnext; + + ubifs_assert(ubifs_zn_dirty(znode)); + ubifs_assert(ubifs_zn_cow(znode)); + + /* + * It is important that other threads should see %DIRTY_ZNODE + * flag cleared before %COW_ZNODE. Specifically, it matters in + * the 'dirty_cow_znode()' function. This is the reason for the + * first barrier. Also, we want the bit changes to be seen to + * other threads ASAP, to avoid unnecesarry copying, which is + * the reason for the second barrier. + */ + clear_bit(DIRTY_ZNODE, &znode->flags); + smp_mb__before_atomic(); + clear_bit(COW_ZNODE, &znode->flags); + smp_mb__after_atomic(); + + /* + * We have marked the znode as clean but have not updated the + * @c->clean_zn_cnt counter. If this znode becomes dirty again + * before 'free_obsolete_znodes()' is called, then + * @c->clean_zn_cnt will be decremented before it gets + * incremented (resulting in 2 decrements for the same znode). + * This means that @c->clean_zn_cnt may become negative for a + * while. + * + * Q: why we cannot increment @c->clean_zn_cnt? + * A: because we do not have the @c->tnc_mutex locked, and the + * following code would be racy and buggy: + * + * if (!ubifs_zn_obsolete(znode)) { + * atomic_long_inc(&c->clean_zn_cnt); + * atomic_long_inc(&ubifs_clean_zn_cnt); + * } + * + * Thus, we just delay the @c->clean_zn_cnt update until we + * have the mutex locked. + */ + + /* Do not access znode from this point on */ + + /* Update buffer positions */ + wlen = used + len; + used += ALIGN(len, 8); + avail -= ALIGN(len, 8); + + /* + * Calculate the next index node length to see if there is + * enough room for it + */ + if (cnext == c->cnext) + next_len = 0; + else + next_len = ubifs_idx_node_sz(c, cnext->child_cnt); + + nxt_offs = buf_offs + used + next_len; + if (next_len && nxt_offs <= c->leb_size) { + if (avail > 0) + continue; + else + blen = buf_len; + } else { + wlen = ALIGN(wlen, 8); + blen = ALIGN(wlen, c->min_io_size); + ubifs_pad(c, c->cbuf + wlen, blen - wlen); + } + + /* The buffer is full or there are no more znodes to do */ + err = ubifs_leb_write(c, lnum, c->cbuf, buf_offs, blen); + if (err) + return err; + buf_offs += blen; + if (next_len) { + if (nxt_offs > c->leb_size) { + err = ubifs_update_one_lp(c, lnum, LPROPS_NC, 0, + 0, LPROPS_TAKEN); + if (err) + return err; + lnum = -1; + } + used -= blen; + if (used < 0) + used = 0; + avail = buf_len - used; + memmove(c->cbuf, c->cbuf + blen, used); + continue; + } + break; + } + + if (lnum != c->dbg->new_ihead_lnum || + buf_offs != c->dbg->new_ihead_offs) { + ubifs_err(c, "inconsistent ihead"); + return -EINVAL; + } + + c->ihead_lnum = lnum; + c->ihead_offs = buf_offs; + + return 0; +} + +/** + * free_obsolete_znodes - free obsolete znodes. + * @c: UBIFS file-system description object + * + * At the end of commit end, obsolete znodes are freed. + */ +static void free_obsolete_znodes(struct ubifs_info *c) +{ + struct ubifs_znode *znode, *cnext; + + cnext = c->cnext; + do { + znode = cnext; + cnext = znode->cnext; + if (ubifs_zn_obsolete(znode)) + kfree(znode); + else { + znode->cnext = NULL; + atomic_long_inc(&c->clean_zn_cnt); + atomic_long_inc(&ubifs_clean_zn_cnt); + } + } while (cnext != c->cnext); +} + +/** + * return_gap_lebs - return LEBs used by the in-gap commit method. + * @c: UBIFS file-system description object + * + * This function clears the "taken" flag for the LEBs which were used by the + * "commit in-the-gaps" method. + */ +static int return_gap_lebs(struct ubifs_info *c) +{ + int *p, err; + + if (!c->gap_lebs) + return 0; + + dbg_cmt(""); + for (p = c->gap_lebs; *p != -1; p++) { + err = ubifs_change_one_lp(c, *p, LPROPS_NC, LPROPS_NC, 0, + LPROPS_TAKEN, 0); + if (err) + return err; + } + + kfree(c->gap_lebs); + c->gap_lebs = NULL; + return 0; +} + +/** + * ubifs_tnc_end_commit - update the TNC for commit end. + * @c: UBIFS file-system description object + * + * Write the dirty znodes. + */ +int ubifs_tnc_end_commit(struct ubifs_info *c) +{ + int err; + + if (!c->cnext) + return 0; + + err = return_gap_lebs(c); + if (err) + return err; + + err = write_index(c); + if (err) + return err; + + mutex_lock(&c->tnc_mutex); + + dbg_cmt("TNC height is %d", c->zroot.znode->level + 1); + + free_obsolete_znodes(c); + + c->cnext = NULL; + kfree(c->ilebs); + c->ilebs = NULL; + + mutex_unlock(&c->tnc_mutex); + + return 0; +} |