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Diffstat (limited to 'ubifs-utils/libubifs/commit.c')
| -rw-r--r-- | ubifs-utils/libubifs/commit.c | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/ubifs-utils/libubifs/commit.c b/ubifs-utils/libubifs/commit.c new file mode 100644 index 0000000..f3b6113 --- /dev/null +++ b/ubifs-utils/libubifs/commit.c @@ -0,0 +1,383 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * This file is part of UBIFS. + * + * Copyright (C) 2006-2008 Nokia Corporation. + * + * Authors: Adrian Hunter + * Artem Bityutskiy (Битюцкий Артём) + */ + +/* + * This file implements functions that manage the running of the commit process. + * Each affected module has its own functions to accomplish their part in the + * commit and those functions are called here. + * + * The commit is the process whereby all updates to the index and LEB properties + * are written out together and the journal becomes empty. This keeps the + * file system consistent - at all times the state can be recreated by reading + * the index and LEB properties and then replaying the journal. + * + * The commit is split into two parts named "commit start" and "commit end". + * During commit start, the commit process has exclusive access to the journal + * by holding the commit semaphore down for writing. As few I/O operations as + * possible are performed during commit start, instead the nodes that are to be + * written are merely identified. During commit end, the commit semaphore is no + * longer held and the journal is again in operation, allowing users to continue + * to use the file system while the bulk of the commit I/O is performed. The + * purpose of this two-step approach is to prevent the commit from causing any + * latency blips. Note that in any case, the commit does not prevent lookups + * (as permitted by the TNC mutex), or access to VFS data structures e.g. page + * cache. + */ + +#include "linux_err.h" +#include "bitops.h" +#include "kmem.h" +#include "ubifs.h" +#include "debug.h" +#include "defs.h" +#include "misc.h" + +/* + * nothing_to_commit - check if there is nothing to commit. + * @c: UBIFS file-system description object + * + * This is a helper function which checks if there is anything to commit. It is + * used as an optimization to avoid starting the commit if it is not really + * necessary. Indeed, the commit operation always assumes flash I/O (e.g., + * writing the commit start node to the log), and it is better to avoid doing + * this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is + * nothing to commit, it is more optimal to avoid any flash I/O. + * + * This function has to be called with @c->commit_sem locked for writing - + * this function does not take LPT/TNC locks because the @c->commit_sem + * guarantees that we have exclusive access to the TNC and LPT data structures. + * + * This function returns %1 if there is nothing to commit and %0 otherwise. + */ +static int nothing_to_commit(struct ubifs_info *c) +{ + /* + * During mounting or remounting from R/O mode to R/W mode we may + * commit for various recovery-related reasons. + */ + if (c->mounting || c->remounting_rw) + return 0; + + /* + * If the root TNC node is dirty, we definitely have something to + * commit. + */ + if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode)) + return 0; + + /* + * Increasing @c->dirty_pn_cnt/@c->dirty_nn_cnt and marking + * nnodes/pnodes as dirty in run_gc() could race with following + * checking, which leads inconsistent states between @c->nroot + * and @c->dirty_pn_cnt/@c->dirty_nn_cnt, holding @c->lp_mutex + * to avoid that. + */ + mutex_lock(&c->lp_mutex); + /* + * Even though the TNC is clean, the LPT tree may have dirty nodes. For + * example, this may happen if the budgeting subsystem invoked GC to + * make some free space, and the GC found an LEB with only dirty and + * free space. In this case GC would just change the lprops of this + * LEB (by turning all space into free space) and unmap it. + */ + if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags)) { + mutex_unlock(&c->lp_mutex); + return 0; + } + + ubifs_assert(c, atomic_long_read(&c->dirty_zn_cnt) == 0); + ubifs_assert(c, c->dirty_pn_cnt == 0); + ubifs_assert(c, c->dirty_nn_cnt == 0); + mutex_unlock(&c->lp_mutex); + + return 1; +} + +/** + * do_commit - commit the journal. + * @c: UBIFS file-system description object + * + * This function implements UBIFS commit. It has to be called with commit lock + * locked. Returns zero in case of success and a negative error code in case of + * failure. + */ +static int do_commit(struct ubifs_info *c) +{ + int err, new_ltail_lnum, old_ltail_lnum, i; + struct ubifs_zbranch zroot; + struct ubifs_lp_stats lst; + + dbg_cmt("start"); + ubifs_assert(c, !c->ro_media && !c->ro_mount); + + if (c->ro_error) { + err = -EROFS; + goto out_up; + } + + if (nothing_to_commit(c)) { + up_write(&c->commit_sem); + err = 0; + goto out_cancel; + } + + /* Sync all write buffers (necessary for recovery) */ + for (i = 0; i < c->jhead_cnt; i++) { + err = ubifs_wbuf_sync(&c->jheads[i].wbuf); + if (err) + goto out_up; + } + + c->cmt_no += 1; + err = ubifs_gc_start_commit(c); + if (err) + goto out_up; + err = dbg_check_lprops(c); + if (err) + goto out_up; + err = ubifs_log_start_commit(c, &new_ltail_lnum); + if (err) + goto out_up; + err = ubifs_tnc_start_commit(c, &zroot); + if (err) + goto out_up; + err = ubifs_lpt_start_commit(c); + if (err) + goto out_up; + err = ubifs_orphan_start_commit(c); + if (err) + goto out_up; + + ubifs_get_lp_stats(c, &lst); + + up_write(&c->commit_sem); + + err = ubifs_tnc_end_commit(c); + if (err) + goto out; + err = ubifs_lpt_end_commit(c); + if (err) + goto out; + err = ubifs_orphan_end_commit(c); + if (err) + goto out; + err = dbg_check_old_index(c, &zroot); + if (err) + goto out; + + c->mst_node->cmt_no = cpu_to_le64(c->cmt_no); + c->mst_node->log_lnum = cpu_to_le32(new_ltail_lnum); + c->mst_node->root_lnum = cpu_to_le32(zroot.lnum); + c->mst_node->root_offs = cpu_to_le32(zroot.offs); + c->mst_node->root_len = cpu_to_le32(zroot.len); + c->mst_node->ihead_lnum = cpu_to_le32(c->ihead_lnum); + c->mst_node->ihead_offs = cpu_to_le32(c->ihead_offs); + c->mst_node->index_size = cpu_to_le64(c->bi.old_idx_sz); + c->mst_node->lpt_lnum = cpu_to_le32(c->lpt_lnum); + c->mst_node->lpt_offs = cpu_to_le32(c->lpt_offs); + c->mst_node->nhead_lnum = cpu_to_le32(c->nhead_lnum); + c->mst_node->nhead_offs = cpu_to_le32(c->nhead_offs); + c->mst_node->ltab_lnum = cpu_to_le32(c->ltab_lnum); + c->mst_node->ltab_offs = cpu_to_le32(c->ltab_offs); + c->mst_node->lsave_lnum = cpu_to_le32(c->lsave_lnum); + c->mst_node->lsave_offs = cpu_to_le32(c->lsave_offs); + c->mst_node->lscan_lnum = cpu_to_le32(c->lscan_lnum); + c->mst_node->empty_lebs = cpu_to_le32(lst.empty_lebs); + c->mst_node->idx_lebs = cpu_to_le32(lst.idx_lebs); + c->mst_node->total_free = cpu_to_le64(lst.total_free); + c->mst_node->total_dirty = cpu_to_le64(lst.total_dirty); + c->mst_node->total_used = cpu_to_le64(lst.total_used); + c->mst_node->total_dead = cpu_to_le64(lst.total_dead); + c->mst_node->total_dark = cpu_to_le64(lst.total_dark); + if (c->no_orphs) + c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS); + else + c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_NO_ORPHS); + + old_ltail_lnum = c->ltail_lnum; + err = ubifs_log_end_commit(c, new_ltail_lnum); + if (err) + goto out; + + err = ubifs_log_post_commit(c, old_ltail_lnum); + if (err) + goto out; + err = ubifs_gc_end_commit(c); + if (err) + goto out; + err = ubifs_lpt_post_commit(c); + if (err) + goto out; + +out_cancel: + spin_lock(&c->cs_lock); + c->cmt_state = COMMIT_RESTING; + dbg_cmt("commit end"); + spin_unlock(&c->cs_lock); + return 0; + +out_up: + up_write(&c->commit_sem); +out: + ubifs_err(c, "commit failed, error %d", err); + spin_lock(&c->cs_lock); + c->cmt_state = COMMIT_BROKEN; + spin_unlock(&c->cs_lock); + ubifs_ro_mode(c, err); + return err; +} + +/** + * ubifs_commit_required - set commit state to "required". + * @c: UBIFS file-system description object + * + * This function is called if a commit is required but cannot be done from the + * calling function, so it is just flagged instead. + */ +void ubifs_commit_required(struct ubifs_info *c) +{ + spin_lock(&c->cs_lock); + switch (c->cmt_state) { + case COMMIT_RESTING: + case COMMIT_BACKGROUND: + dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state), + dbg_cstate(COMMIT_REQUIRED)); + c->cmt_state = COMMIT_REQUIRED; + break; + case COMMIT_RUNNING_BACKGROUND: + dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state), + dbg_cstate(COMMIT_RUNNING_REQUIRED)); + c->cmt_state = COMMIT_RUNNING_REQUIRED; + break; + case COMMIT_REQUIRED: + case COMMIT_RUNNING_REQUIRED: + case COMMIT_BROKEN: + break; + } + spin_unlock(&c->cs_lock); +} + +/** + * ubifs_request_bg_commit - notify the background thread to do a commit. + * @c: UBIFS file-system description object + * + * This function is called if the journal is full enough to make a commit + * worthwhile, so background thread is kicked to start it. + */ +void ubifs_request_bg_commit(__unused struct ubifs_info *c) +{ +} + +/** + * wait_for_commit - wait for commit. + * @c: UBIFS file-system description object + * + * This function sleeps until the commit operation is no longer running. + */ +static int wait_for_commit(struct ubifs_info *c) +{ + /* + * All commit operations are executed in synchronization context, + * so it is impossible that more than one threads doing commit. + */ + ubifs_assert(c, 0); + return 0; +} + +/** + * ubifs_run_commit - run or wait for commit. + * @c: UBIFS file-system description object + * + * This function runs commit and returns zero in case of success and a negative + * error code in case of failure. + */ +int ubifs_run_commit(struct ubifs_info *c) +{ + int err = 0; + + spin_lock(&c->cs_lock); + if (c->cmt_state == COMMIT_BROKEN) { + err = -EROFS; + goto out; + } + + if (c->cmt_state == COMMIT_RUNNING_BACKGROUND) + /* + * We set the commit state to 'running required' to indicate + * that we want it to complete as quickly as possible. + */ + c->cmt_state = COMMIT_RUNNING_REQUIRED; + + if (c->cmt_state == COMMIT_RUNNING_REQUIRED) { + spin_unlock(&c->cs_lock); + return wait_for_commit(c); + } + spin_unlock(&c->cs_lock); + + /* Ok, the commit is indeed needed */ + + down_write(&c->commit_sem); + spin_lock(&c->cs_lock); + /* + * Since we unlocked 'c->cs_lock', the state may have changed, so + * re-check it. + */ + if (c->cmt_state == COMMIT_BROKEN) { + err = -EROFS; + goto out_cmt_unlock; + } + + if (c->cmt_state == COMMIT_RUNNING_BACKGROUND) + c->cmt_state = COMMIT_RUNNING_REQUIRED; + + if (c->cmt_state == COMMIT_RUNNING_REQUIRED) { + up_write(&c->commit_sem); + spin_unlock(&c->cs_lock); + return wait_for_commit(c); + } + c->cmt_state = COMMIT_RUNNING_REQUIRED; + spin_unlock(&c->cs_lock); + + err = do_commit(c); + return err; + +out_cmt_unlock: + up_write(&c->commit_sem); +out: + spin_unlock(&c->cs_lock); + return err; +} + +/** + * ubifs_gc_should_commit - determine if it is time for GC to run commit. + * @c: UBIFS file-system description object + * + * This function is called by garbage collection to determine if commit should + * be run. If commit state is @COMMIT_BACKGROUND, which means that the journal + * is full enough to start commit, this function returns true. It is not + * absolutely necessary to commit yet, but it feels like this should be better + * then to keep doing GC. This function returns %1 if GC has to initiate commit + * and %0 if not. + */ +int ubifs_gc_should_commit(struct ubifs_info *c) +{ + int ret = 0; + + spin_lock(&c->cs_lock); + if (c->cmt_state == COMMIT_BACKGROUND) { + dbg_cmt("commit required now"); + c->cmt_state = COMMIT_REQUIRED; + } else + dbg_cmt("commit not requested"); + if (c->cmt_state == COMMIT_REQUIRED) + ret = 1; + spin_unlock(&c->cs_lock); + return ret; +} |