| /* |
| * linux/fs/jbd2/checkpoint.c |
| * |
| * Written by Stephen C. Tweedie <sct@redhat.com>, 1999 |
| * |
| * Copyright 1999 Red Hat Software --- All Rights Reserved |
| * |
| * This file is part of the Linux kernel and is made available under |
| * the terms of the GNU General Public License, version 2, or at your |
| * option, any later version, incorporated herein by reference. |
| * |
| * Checkpoint routines for the generic filesystem journaling code. |
| * Part of the ext2fs journaling system. |
| * |
| * Checkpointing is the process of ensuring that a section of the log is |
| * committed fully to disk, so that that portion of the log can be |
| * reused. |
| */ |
| |
| #include <linux/time.h> |
| #include <linux/fs.h> |
| #include <linux/jbd2.h> |
| #include <linux/errno.h> |
| #include <linux/slab.h> |
| #include <linux/blkdev.h> |
| #include <trace/events/jbd2.h> |
| |
| /* |
| * Unlink a buffer from a transaction checkpoint list. |
| * |
| * Called with j_list_lock held. |
| */ |
| static inline void __buffer_unlink_first(struct journal_head *jh) |
| { |
| transaction_t *transaction = jh->b_cp_transaction; |
| |
| jh->b_cpnext->b_cpprev = jh->b_cpprev; |
| jh->b_cpprev->b_cpnext = jh->b_cpnext; |
| if (transaction->t_checkpoint_list == jh) { |
| transaction->t_checkpoint_list = jh->b_cpnext; |
| if (transaction->t_checkpoint_list == jh) |
| transaction->t_checkpoint_list = NULL; |
| } |
| } |
| |
| /* |
| * Unlink a buffer from a transaction checkpoint(io) list. |
| * |
| * Called with j_list_lock held. |
| */ |
| static inline void __buffer_unlink(struct journal_head *jh) |
| { |
| transaction_t *transaction = jh->b_cp_transaction; |
| |
| __buffer_unlink_first(jh); |
| if (transaction->t_checkpoint_io_list == jh) { |
| transaction->t_checkpoint_io_list = jh->b_cpnext; |
| if (transaction->t_checkpoint_io_list == jh) |
| transaction->t_checkpoint_io_list = NULL; |
| } |
| } |
| |
| /* |
| * Move a buffer from the checkpoint list to the checkpoint io list |
| * |
| * Called with j_list_lock held |
| */ |
| static inline void __buffer_relink_io(struct journal_head *jh) |
| { |
| transaction_t *transaction = jh->b_cp_transaction; |
| |
| __buffer_unlink_first(jh); |
| |
| if (!transaction->t_checkpoint_io_list) { |
| jh->b_cpnext = jh->b_cpprev = jh; |
| } else { |
| jh->b_cpnext = transaction->t_checkpoint_io_list; |
| jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev; |
| jh->b_cpprev->b_cpnext = jh; |
| jh->b_cpnext->b_cpprev = jh; |
| } |
| transaction->t_checkpoint_io_list = jh; |
| } |
| |
| /* |
| * Try to release a checkpointed buffer from its transaction. |
| * Returns 1 if we released it and 2 if we also released the |
| * whole transaction. |
| * |
| * Requires j_list_lock |
| */ |
| static int __try_to_free_cp_buf(struct journal_head *jh) |
| { |
| int ret = 0; |
| struct buffer_head *bh = jh2bh(jh); |
| |
| if (jh->b_transaction == NULL && !buffer_locked(bh) && |
| !buffer_dirty(bh) && !buffer_write_io_error(bh)) { |
| /* |
| * Get our reference so that bh cannot be freed before |
| * we unlock it |
| */ |
| get_bh(bh); |
| JBUFFER_TRACE(jh, "remove from checkpoint list"); |
| ret = __jbd2_journal_remove_checkpoint(jh) + 1; |
| BUFFER_TRACE(bh, "release"); |
| __brelse(bh); |
| } |
| return ret; |
| } |
| |
| /* |
| * __jbd2_log_wait_for_space: wait until there is space in the journal. |
| * |
| * Called under j-state_lock *only*. It will be unlocked if we have to wait |
| * for a checkpoint to free up some space in the log. |
| */ |
| void __jbd2_log_wait_for_space(journal_t *journal) |
| { |
| int nblocks, space_left; |
| /* assert_spin_locked(&journal->j_state_lock); */ |
| |
| nblocks = jbd2_space_needed(journal); |
| while (jbd2_log_space_left(journal) < nblocks) { |
| if (journal->j_flags & JBD2_ABORT) |
| return; |
| write_unlock(&journal->j_state_lock); |
| mutex_lock(&journal->j_checkpoint_mutex); |
| |
| /* |
| * Test again, another process may have checkpointed while we |
| * were waiting for the checkpoint lock. If there are no |
| * transactions ready to be checkpointed, try to recover |
| * journal space by calling cleanup_journal_tail(), and if |
| * that doesn't work, by waiting for the currently committing |
| * transaction to complete. If there is absolutely no way |
| * to make progress, this is either a BUG or corrupted |
| * filesystem, so abort the journal and leave a stack |
| * trace for forensic evidence. |
| */ |
| write_lock(&journal->j_state_lock); |
| spin_lock(&journal->j_list_lock); |
| nblocks = jbd2_space_needed(journal); |
| space_left = jbd2_log_space_left(journal); |
| if (space_left < nblocks) { |
| int chkpt = journal->j_checkpoint_transactions != NULL; |
| tid_t tid = 0; |
| |
| if (journal->j_committing_transaction) |
| tid = journal->j_committing_transaction->t_tid; |
| spin_unlock(&journal->j_list_lock); |
| write_unlock(&journal->j_state_lock); |
| if (chkpt) { |
| jbd2_log_do_checkpoint(journal); |
| } else if (jbd2_cleanup_journal_tail(journal) == 0) { |
| /* We were able to recover space; yay! */ |
| ; |
| } else if (tid) { |
| jbd2_log_wait_commit(journal, tid); |
| } else { |
| printk(KERN_ERR "%s: needed %d blocks and " |
| "only had %d space available\n", |
| __func__, nblocks, space_left); |
| printk(KERN_ERR "%s: no way to get more " |
| "journal space in %s\n", __func__, |
| journal->j_devname); |
| WARN_ON(1); |
| jbd2_journal_abort(journal, 0); |
| } |
| write_lock(&journal->j_state_lock); |
| } else { |
| spin_unlock(&journal->j_list_lock); |
| } |
| mutex_unlock(&journal->j_checkpoint_mutex); |
| } |
| } |
| |
| /* |
| * Clean up transaction's list of buffers submitted for io. |
| * We wait for any pending IO to complete and remove any clean |
| * buffers. Note that we take the buffers in the opposite ordering |
| * from the one in which they were submitted for IO. |
| * |
| * Return 0 on success, and return <0 if some buffers have failed |
| * to be written out. |
| * |
| * Called with j_list_lock held. |
| */ |
| static int __wait_cp_io(journal_t *journal, transaction_t *transaction) |
| { |
| struct journal_head *jh; |
| struct buffer_head *bh; |
| tid_t this_tid; |
| int released = 0; |
| int ret = 0; |
| |
| this_tid = transaction->t_tid; |
| restart: |
| /* Did somebody clean up the transaction in the meanwhile? */ |
| if (journal->j_checkpoint_transactions != transaction || |
| transaction->t_tid != this_tid) |
| return ret; |
| while (!released && transaction->t_checkpoint_io_list) { |
| jh = transaction->t_checkpoint_io_list; |
| bh = jh2bh(jh); |
| get_bh(bh); |
| if (buffer_locked(bh)) { |
| spin_unlock(&journal->j_list_lock); |
| wait_on_buffer(bh); |
| /* the journal_head may have gone by now */ |
| BUFFER_TRACE(bh, "brelse"); |
| __brelse(bh); |
| spin_lock(&journal->j_list_lock); |
| goto restart; |
| } |
| if (unlikely(buffer_write_io_error(bh))) |
| ret = -EIO; |
| |
| /* |
| * Now in whatever state the buffer currently is, we know that |
| * it has been written out and so we can drop it from the list |
| */ |
| released = __jbd2_journal_remove_checkpoint(jh); |
| __brelse(bh); |
| } |
| |
| return ret; |
| } |
| |
| static void |
| __flush_batch(journal_t *journal, int *batch_count) |
| { |
| int i; |
| struct blk_plug plug; |
| |
| blk_start_plug(&plug); |
| for (i = 0; i < *batch_count; i++) |
| write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC); |
| blk_finish_plug(&plug); |
| |
| for (i = 0; i < *batch_count; i++) { |
| struct buffer_head *bh = journal->j_chkpt_bhs[i]; |
| BUFFER_TRACE(bh, "brelse"); |
| __brelse(bh); |
| } |
| *batch_count = 0; |
| } |
| |
| /* |
| * Try to flush one buffer from the checkpoint list to disk. |
| * |
| * Return 1 if something happened which requires us to abort the current |
| * scan of the checkpoint list. Return <0 if the buffer has failed to |
| * be written out. |
| * |
| * Called with j_list_lock held and drops it if 1 is returned |
| */ |
| static int __process_buffer(journal_t *journal, struct journal_head *jh, |
| int *batch_count, transaction_t *transaction) |
| { |
| struct buffer_head *bh = jh2bh(jh); |
| int ret = 0; |
| |
| if (buffer_locked(bh)) { |
| get_bh(bh); |
| spin_unlock(&journal->j_list_lock); |
| wait_on_buffer(bh); |
| /* the journal_head may have gone by now */ |
| BUFFER_TRACE(bh, "brelse"); |
| __brelse(bh); |
| ret = 1; |
| } else if (jh->b_transaction != NULL) { |
| transaction_t *t = jh->b_transaction; |
| tid_t tid = t->t_tid; |
| |
| transaction->t_chp_stats.cs_forced_to_close++; |
| spin_unlock(&journal->j_list_lock); |
| if (unlikely(journal->j_flags & JBD2_UNMOUNT)) |
| /* |
| * The journal thread is dead; so starting and |
| * waiting for a commit to finish will cause |
| * us to wait for a _very_ long time. |
| */ |
| printk(KERN_ERR "JBD2: %s: " |
| "Waiting for Godot: block %llu\n", |
| journal->j_devname, |
| (unsigned long long) bh->b_blocknr); |
| jbd2_log_start_commit(journal, tid); |
| jbd2_log_wait_commit(journal, tid); |
| ret = 1; |
| } else if (!buffer_dirty(bh)) { |
| ret = 1; |
| if (unlikely(buffer_write_io_error(bh))) |
| ret = -EIO; |
| get_bh(bh); |
| BUFFER_TRACE(bh, "remove from checkpoint"); |
| __jbd2_journal_remove_checkpoint(jh); |
| spin_unlock(&journal->j_list_lock); |
| __brelse(bh); |
| } else { |
| /* |
| * Important: we are about to write the buffer, and |
| * possibly block, while still holding the journal lock. |
| * We cannot afford to let the transaction logic start |
| * messing around with this buffer before we write it to |
| * disk, as that would break recoverability. |
| */ |
| BUFFER_TRACE(bh, "queue"); |
| get_bh(bh); |
| J_ASSERT_BH(bh, !buffer_jwrite(bh)); |
| journal->j_chkpt_bhs[*batch_count] = bh; |
| __buffer_relink_io(jh); |
| transaction->t_chp_stats.cs_written++; |
| (*batch_count)++; |
| if (*batch_count == JBD2_NR_BATCH) { |
| spin_unlock(&journal->j_list_lock); |
| __flush_batch(journal, batch_count); |
| ret = 1; |
| } |
| } |
| return ret; |
| } |
| |
| /* |
| * Perform an actual checkpoint. We take the first transaction on the |
| * list of transactions to be checkpointed and send all its buffers |
| * to disk. We submit larger chunks of data at once. |
| * |
| * The journal should be locked before calling this function. |
| * Called with j_checkpoint_mutex held. |
| */ |
| int jbd2_log_do_checkpoint(journal_t *journal) |
| { |
| transaction_t *transaction; |
| tid_t this_tid; |
| int result; |
| |
| jbd_debug(1, "Start checkpoint\n"); |
| |
| /* |
| * First thing: if there are any transactions in the log which |
| * don't need checkpointing, just eliminate them from the |
| * journal straight away. |
| */ |
| result = jbd2_cleanup_journal_tail(journal); |
| trace_jbd2_checkpoint(journal, result); |
| jbd_debug(1, "cleanup_journal_tail returned %d\n", result); |
| if (result <= 0) |
| return result; |
| |
| /* |
| * OK, we need to start writing disk blocks. Take one transaction |
| * and write it. |
| */ |
| result = 0; |
| spin_lock(&journal->j_list_lock); |
| if (!journal->j_checkpoint_transactions) |
| goto out; |
| transaction = journal->j_checkpoint_transactions; |
| if (transaction->t_chp_stats.cs_chp_time == 0) |
| transaction->t_chp_stats.cs_chp_time = jiffies; |
| this_tid = transaction->t_tid; |
| restart: |
| /* |
| * If someone cleaned up this transaction while we slept, we're |
| * done (maybe it's a new transaction, but it fell at the same |
| * address). |
| */ |
| if (journal->j_checkpoint_transactions == transaction && |
| transaction->t_tid == this_tid) { |
| int batch_count = 0; |
| struct journal_head *jh; |
| int retry = 0, err; |
| |
| while (!retry && transaction->t_checkpoint_list) { |
| jh = transaction->t_checkpoint_list; |
| retry = __process_buffer(journal, jh, &batch_count, |
| transaction); |
| if (retry < 0 && !result) |
| result = retry; |
| if (!retry && (need_resched() || |
| spin_needbreak(&journal->j_list_lock))) { |
| spin_unlock(&journal->j_list_lock); |
| retry = 1; |
| break; |
| } |
| } |
| |
| if (batch_count) { |
| if (!retry) { |
| spin_unlock(&journal->j_list_lock); |
| retry = 1; |
| } |
| __flush_batch(journal, &batch_count); |
| } |
| |
| if (retry) { |
| spin_lock(&journal->j_list_lock); |
| goto restart; |
| } |
| /* |
| * Now we have cleaned up the first transaction's checkpoint |
| * list. Let's clean up the second one |
| */ |
| err = __wait_cp_io(journal, transaction); |
| if (!result) |
| result = err; |
| } |
| out: |
| spin_unlock(&journal->j_list_lock); |
| if (result < 0) |
| jbd2_journal_abort(journal, result); |
| else |
| result = jbd2_cleanup_journal_tail(journal); |
| |
| return (result < 0) ? result : 0; |
| } |
| |
| /* |
| * Check the list of checkpoint transactions for the journal to see if |
| * we have already got rid of any since the last update of the log tail |
| * in the journal superblock. If so, we can instantly roll the |
| * superblock forward to remove those transactions from the log. |
| * |
| * Return <0 on error, 0 on success, 1 if there was nothing to clean up. |
| * |
| * Called with the journal lock held. |
| * |
| * This is the only part of the journaling code which really needs to be |
| * aware of transaction aborts. Checkpointing involves writing to the |
| * main filesystem area rather than to the journal, so it can proceed |
| * even in abort state, but we must not update the super block if |
| * checkpointing may have failed. Otherwise, we would lose some metadata |
| * buffers which should be written-back to the filesystem. |
| */ |
| |
| int jbd2_cleanup_journal_tail(journal_t *journal) |
| { |
| tid_t first_tid; |
| unsigned long blocknr; |
| |
| if (is_journal_aborted(journal)) |
| return 1; |
| |
| if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr)) |
| return 1; |
| J_ASSERT(blocknr != 0); |
| |
| /* |
| * We need to make sure that any blocks that were recently written out |
| * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before |
| * we drop the transactions from the journal. It's unlikely this will |
| * be necessary, especially with an appropriately sized journal, but we |
| * need this to guarantee correctness. Fortunately |
| * jbd2_cleanup_journal_tail() doesn't get called all that often. |
| */ |
| if (journal->j_flags & JBD2_BARRIER) |
| blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL); |
| |
| __jbd2_update_log_tail(journal, first_tid, blocknr); |
| return 0; |
| } |
| |
| |
| /* Checkpoint list management */ |
| |
| /* |
| * journal_clean_one_cp_list |
| * |
| * Find all the written-back checkpoint buffers in the given list and |
| * release them. |
| * |
| * Called with the journal locked. |
| * Called with j_list_lock held. |
| * Returns number of buffers reaped (for debug) |
| */ |
| |
| static int journal_clean_one_cp_list(struct journal_head *jh, int *released) |
| { |
| struct journal_head *last_jh; |
| struct journal_head *next_jh = jh; |
| int ret, freed = 0; |
| |
| *released = 0; |
| if (!jh) |
| return 0; |
| |
| last_jh = jh->b_cpprev; |
| do { |
| jh = next_jh; |
| next_jh = jh->b_cpnext; |
| ret = __try_to_free_cp_buf(jh); |
| if (ret) { |
| freed++; |
| if (ret == 2) { |
| *released = 1; |
| return freed; |
| } |
| } |
| /* |
| * This function only frees up some memory |
| * if possible so we dont have an obligation |
| * to finish processing. Bail out if preemption |
| * requested: |
| */ |
| if (need_resched()) |
| return freed; |
| } while (jh != last_jh); |
| |
| return freed; |
| } |
| |
| /* |
| * journal_clean_checkpoint_list |
| * |
| * Find all the written-back checkpoint buffers in the journal and release them. |
| * |
| * Called with the journal locked. |
| * Called with j_list_lock held. |
| * Returns number of buffers reaped (for debug) |
| */ |
| |
| int __jbd2_journal_clean_checkpoint_list(journal_t *journal) |
| { |
| transaction_t *transaction, *last_transaction, *next_transaction; |
| int ret = 0; |
| int released; |
| |
| transaction = journal->j_checkpoint_transactions; |
| if (!transaction) |
| goto out; |
| |
| last_transaction = transaction->t_cpprev; |
| next_transaction = transaction; |
| do { |
| transaction = next_transaction; |
| next_transaction = transaction->t_cpnext; |
| ret += journal_clean_one_cp_list(transaction-> |
| t_checkpoint_list, &released); |
| /* |
| * This function only frees up some memory if possible so we |
| * dont have an obligation to finish processing. Bail out if |
| * preemption requested: |
| */ |
| if (need_resched()) |
| goto out; |
| if (released) |
| continue; |
| /* |
| * It is essential that we are as careful as in the case of |
| * t_checkpoint_list with removing the buffer from the list as |
| * we can possibly see not yet submitted buffers on io_list |
| */ |
| ret += journal_clean_one_cp_list(transaction-> |
| t_checkpoint_io_list, &released); |
| if (need_resched()) |
| goto out; |
| } while (transaction != last_transaction); |
| out: |
| return ret; |
| } |
| |
| /* |
| * journal_remove_checkpoint: called after a buffer has been committed |
| * to disk (either by being write-back flushed to disk, or being |
| * committed to the log). |
| * |
| * We cannot safely clean a transaction out of the log until all of the |
| * buffer updates committed in that transaction have safely been stored |
| * elsewhere on disk. To achieve this, all of the buffers in a |
| * transaction need to be maintained on the transaction's checkpoint |
| * lists until they have been rewritten, at which point this function is |
| * called to remove the buffer from the existing transaction's |
| * checkpoint lists. |
| * |
| * The function returns 1 if it frees the transaction, 0 otherwise. |
| * The function can free jh and bh. |
| * |
| * This function is called with j_list_lock held. |
| */ |
| int __jbd2_journal_remove_checkpoint(struct journal_head *jh) |
| { |
| struct transaction_chp_stats_s *stats; |
| transaction_t *transaction; |
| journal_t *journal; |
| int ret = 0; |
| |
| JBUFFER_TRACE(jh, "entry"); |
| |
| if ((transaction = jh->b_cp_transaction) == NULL) { |
| JBUFFER_TRACE(jh, "not on transaction"); |
| goto out; |
| } |
| journal = transaction->t_journal; |
| |
| JBUFFER_TRACE(jh, "removing from transaction"); |
| __buffer_unlink(jh); |
| jh->b_cp_transaction = NULL; |
| jbd2_journal_put_journal_head(jh); |
| |
| if (transaction->t_checkpoint_list != NULL || |
| transaction->t_checkpoint_io_list != NULL) |
| goto out; |
| |
| /* |
| * There is one special case to worry about: if we have just pulled the |
| * buffer off a running or committing transaction's checkpoing list, |
| * then even if the checkpoint list is empty, the transaction obviously |
| * cannot be dropped! |
| * |
| * The locking here around t_state is a bit sleazy. |
| * See the comment at the end of jbd2_journal_commit_transaction(). |
| */ |
| if (transaction->t_state != T_FINISHED) |
| goto out; |
| |
| /* OK, that was the last buffer for the transaction: we can now |
| safely remove this transaction from the log */ |
| stats = &transaction->t_chp_stats; |
| if (stats->cs_chp_time) |
| stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time, |
| jiffies); |
| trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev, |
| transaction->t_tid, stats); |
| |
| __jbd2_journal_drop_transaction(journal, transaction); |
| jbd2_journal_free_transaction(transaction); |
| ret = 1; |
| out: |
| return ret; |
| } |
| |
| /* |
| * journal_insert_checkpoint: put a committed buffer onto a checkpoint |
| * list so that we know when it is safe to clean the transaction out of |
| * the log. |
| * |
| * Called with the journal locked. |
| * Called with j_list_lock held. |
| */ |
| void __jbd2_journal_insert_checkpoint(struct journal_head *jh, |
| transaction_t *transaction) |
| { |
| JBUFFER_TRACE(jh, "entry"); |
| J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh))); |
| J_ASSERT_JH(jh, jh->b_cp_transaction == NULL); |
| |
| /* Get reference for checkpointing transaction */ |
| jbd2_journal_grab_journal_head(jh2bh(jh)); |
| jh->b_cp_transaction = transaction; |
| |
| if (!transaction->t_checkpoint_list) { |
| jh->b_cpnext = jh->b_cpprev = jh; |
| } else { |
| jh->b_cpnext = transaction->t_checkpoint_list; |
| jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev; |
| jh->b_cpprev->b_cpnext = jh; |
| jh->b_cpnext->b_cpprev = jh; |
| } |
| transaction->t_checkpoint_list = jh; |
| } |
| |
| /* |
| * We've finished with this transaction structure: adios... |
| * |
| * The transaction must have no links except for the checkpoint by this |
| * point. |
| * |
| * Called with the journal locked. |
| * Called with j_list_lock held. |
| */ |
| |
| void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction) |
| { |
| assert_spin_locked(&journal->j_list_lock); |
| if (transaction->t_cpnext) { |
| transaction->t_cpnext->t_cpprev = transaction->t_cpprev; |
| transaction->t_cpprev->t_cpnext = transaction->t_cpnext; |
| if (journal->j_checkpoint_transactions == transaction) |
| journal->j_checkpoint_transactions = |
| transaction->t_cpnext; |
| if (journal->j_checkpoint_transactions == transaction) |
| journal->j_checkpoint_transactions = NULL; |
| } |
| |
| J_ASSERT(transaction->t_state == T_FINISHED); |
| J_ASSERT(transaction->t_buffers == NULL); |
| J_ASSERT(transaction->t_forget == NULL); |
| J_ASSERT(transaction->t_shadow_list == NULL); |
| J_ASSERT(transaction->t_checkpoint_list == NULL); |
| J_ASSERT(transaction->t_checkpoint_io_list == NULL); |
| J_ASSERT(atomic_read(&transaction->t_updates) == 0); |
| J_ASSERT(journal->j_committing_transaction != transaction); |
| J_ASSERT(journal->j_running_transaction != transaction); |
| |
| trace_jbd2_drop_transaction(journal, transaction); |
| |
| jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); |
| } |