diff options
Diffstat (limited to 'fs/jbd/checkpoint.c')
| -rw-r--r-- | fs/jbd/checkpoint.c | 782 |
1 files changed, 0 insertions, 782 deletions
diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c deleted file mode 100644 index 08c03044abdd..000000000000 --- a/fs/jbd/checkpoint.c +++ /dev/null @@ -1,782 +0,0 @@ -/* - * linux/fs/jbd/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/jbd.h> -#include <linux/errno.h> -#include <linux/slab.h> -#include <linux/blkdev.h> -#include <trace/events/jbd.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 - * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it - */ -static int __try_to_free_cp_buf(struct journal_head *jh) -{ - int ret = 0; - struct buffer_head *bh = jh2bh(jh); - - if (jh->b_jlist == BJ_None && !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 = __journal_remove_checkpoint(jh) + 1; - jbd_unlock_bh_state(bh); - BUFFER_TRACE(bh, "release"); - __brelse(bh); - } else { - jbd_unlock_bh_state(bh); - } - return ret; -} - -/* - * __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 __log_wait_for_space(journal_t *journal) -{ - int nblocks, space_left; - assert_spin_locked(&journal->j_state_lock); - - nblocks = jbd_space_needed(journal); - while (__log_space_left(journal) < nblocks) { - if (journal->j_flags & JFS_ABORT) - return; - spin_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. - */ - spin_lock(&journal->j_state_lock); - spin_lock(&journal->j_list_lock); - nblocks = jbd_space_needed(journal); - space_left = __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); - spin_unlock(&journal->j_state_lock); - if (chkpt) { - log_do_checkpoint(journal); - } else if (cleanup_journal_tail(journal) == 0) { - /* We were able to recover space; yay! */ - ; - } else if (tid) { - 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\n", __func__); - WARN_ON(1); - journal_abort(journal, 0); - } - spin_lock(&journal->j_state_lock); - } else { - spin_unlock(&journal->j_list_lock); - } - mutex_unlock(&journal->j_checkpoint_mutex); - } -} - -/* - * We were unable to perform jbd_trylock_bh_state() inside j_list_lock. - * The caller must restart a list walk. Wait for someone else to run - * jbd_unlock_bh_state(). - */ -static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh) - __releases(journal->j_list_lock) -{ - get_bh(bh); - spin_unlock(&journal->j_list_lock); - jbd_lock_bh_state(bh); - jbd_unlock_bh_state(bh); - put_bh(bh); -} - -/* - * 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); - if (!jbd_trylock_bh_state(bh)) { - jbd_sync_bh(journal, bh); - spin_lock(&journal->j_list_lock); - goto restart; - } - get_bh(bh); - if (buffer_locked(bh)) { - spin_unlock(&journal->j_list_lock); - jbd_unlock_bh_state(bh); - 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 = __journal_remove_checkpoint(jh); - jbd_unlock_bh_state(bh); - __brelse(bh); - } - - return ret; -} - -#define NR_BATCH 64 - -static void -__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) -{ - int i; - struct blk_plug plug; - - blk_start_plug(&plug); - for (i = 0; i < *batch_count; i++) - write_dirty_buffer(bhs[i], WRITE_SYNC); - blk_finish_plug(&plug); - - for (i = 0; i < *batch_count; i++) { - struct buffer_head *bh = bhs[i]; - clear_buffer_jwrite(bh); - 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 - * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it - */ -static int __process_buffer(journal_t *journal, struct journal_head *jh, - struct buffer_head **bhs, int *batch_count) -{ - struct buffer_head *bh = jh2bh(jh); - int ret = 0; - - if (buffer_locked(bh)) { - get_bh(bh); - spin_unlock(&journal->j_list_lock); - jbd_unlock_bh_state(bh); - 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; - - spin_unlock(&journal->j_list_lock); - jbd_unlock_bh_state(bh); - log_start_commit(journal, tid); - 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); - J_ASSERT_JH(jh, !buffer_jbddirty(bh)); - BUFFER_TRACE(bh, "remove from checkpoint"); - __journal_remove_checkpoint(jh); - spin_unlock(&journal->j_list_lock); - jbd_unlock_bh_state(bh); - __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)); - set_buffer_jwrite(bh); - bhs[*batch_count] = bh; - __buffer_relink_io(jh); - jbd_unlock_bh_state(bh); - (*batch_count)++; - if (*batch_count == NR_BATCH) { - spin_unlock(&journal->j_list_lock); - __flush_batch(journal, bhs, 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 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 = cleanup_journal_tail(journal); - trace_jbd_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; - 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 buffer_head *bhs[NR_BATCH]; - struct journal_head *jh; - int retry = 0, err; - - while (!retry && transaction->t_checkpoint_list) { - struct buffer_head *bh; - - jh = transaction->t_checkpoint_list; - bh = jh2bh(jh); - if (!jbd_trylock_bh_state(bh)) { - jbd_sync_bh(journal, bh); - retry = 1; - break; - } - retry = __process_buffer(journal, jh, bhs,&batch_count); - 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, bhs, &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) - journal_abort(journal, result); - else - result = 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. - * - * 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 cleanup_journal_tail(journal_t *journal) -{ - transaction_t * transaction; - tid_t first_tid; - unsigned int blocknr, freed; - - if (is_journal_aborted(journal)) - return 1; - - /* - * OK, work out the oldest transaction remaining in the log, and - * the log block it starts at. - * - * If the log is now empty, we need to work out which is the - * next transaction ID we will write, and where it will - * start. - */ - spin_lock(&journal->j_state_lock); - spin_lock(&journal->j_list_lock); - transaction = journal->j_checkpoint_transactions; - if (transaction) { - first_tid = transaction->t_tid; - blocknr = transaction->t_log_start; - } else if ((transaction = journal->j_committing_transaction) != NULL) { - first_tid = transaction->t_tid; - blocknr = transaction->t_log_start; - } else if ((transaction = journal->j_running_transaction) != NULL) { - first_tid = transaction->t_tid; - blocknr = journal->j_head; - } else { - first_tid = journal->j_transaction_sequence; - blocknr = journal->j_head; - } - spin_unlock(&journal->j_list_lock); - J_ASSERT(blocknr != 0); - - /* If the oldest pinned transaction is at the tail of the log - already then there's not much we can do right now. */ - if (journal->j_tail_sequence == first_tid) { - spin_unlock(&journal->j_state_lock); - return 1; - } - spin_unlock(&journal->j_state_lock); - - /* - * We need to make sure that any blocks that were recently written out - * --- perhaps by log_do_checkpoint() --- are flushed out before we - * drop the transactions from the journal. Similarly we need to be sure - * superblock makes it to disk before next transaction starts reusing - * freed space (otherwise we could replay some blocks of the new - * transaction thinking they belong to the old one). So we use - * WRITE_FLUSH_FUA. It's unlikely this will be necessary, especially - * with an appropriately sized journal, but we need this to guarantee - * correctness. Fortunately cleanup_journal_tail() doesn't get called - * all that often. - */ - journal_update_sb_log_tail(journal, first_tid, blocknr, - WRITE_FLUSH_FUA); - - spin_lock(&journal->j_state_lock); - /* OK, update the superblock to recover the freed space. - * Physical blocks come first: have we wrapped beyond the end of - * the log? */ - freed = blocknr - journal->j_tail; - if (blocknr < journal->j_tail) - freed = freed + journal->j_last - journal->j_first; - - trace_jbd_cleanup_journal_tail(journal, first_tid, blocknr, freed); - jbd_debug(1, - "Cleaning journal tail from %d to %d (offset %u), " - "freeing %u\n", - journal->j_tail_sequence, first_tid, blocknr, freed); - - journal->j_free += freed; - journal->j_tail_sequence = first_tid; - journal->j_tail = blocknr; - spin_unlock(&journal->j_state_lock); - 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 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; - /* Use trylock because of the ranking */ - if (jbd_trylock_bh_state(jh2bh(jh))) { - 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 __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. - * This function is called with jbd_lock_bh_state(jh2bh(jh)) - */ - -int __journal_remove_checkpoint(struct journal_head *jh) -{ - 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; - 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 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 */ - - __journal_drop_transaction(journal, transaction); - - /* Just in case anybody was waiting for more transactions to be - checkpointed... */ - wake_up(&journal->j_wait_logspace); - 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 __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 */ - 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 __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_sync_datalist == NULL); - J_ASSERT(transaction->t_forget == NULL); - J_ASSERT(transaction->t_iobuf_list == NULL); - J_ASSERT(transaction->t_shadow_list == NULL); - J_ASSERT(transaction->t_log_list == NULL); - J_ASSERT(transaction->t_checkpoint_list == NULL); - J_ASSERT(transaction->t_checkpoint_io_list == NULL); - J_ASSERT(transaction->t_updates == 0); - J_ASSERT(journal->j_committing_transaction != transaction); - J_ASSERT(journal->j_running_transaction != transaction); - - trace_jbd_drop_transaction(journal, transaction); - jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); - kfree(transaction); -} |