cregit-Linux how code gets into the kernel

Release 4.10 fs/jbd2/checkpoint.c

Directory: fs/jbd2
 * linux/fs/jbd2/checkpoint.c
 * Written by Stephen C. Tweedie <>, 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; } }


dave kleikampdave kleikamp72100.00%1100.00%

/* * 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; } }


dave kleikampdave kleikamp57100.00%1100.00%

/* * 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; }


dave kleikampdave kleikamp87100.00%1100.00%

/* * 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)) { JBUFFER_TRACE(jh, "remove from checkpoint list"); ret = __jbd2_journal_remove_checkpoint(jh) + 1; } return ret; }


dave kleikampdave kleikamp6487.67%125.00%
hidehiro kawaihidehiro kawai68.22%125.00%
jan karajan kara22.74%125.00%
mingming caomingming cao11.37%125.00%

/* * __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) { 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); if (journal->j_flags & JBD2_ABORT) { mutex_unlock(&journal->j_checkpoint_mutex); return; } 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_journal_commit_transaction() may want * to take the checkpoint_mutex if JBD2_FLUSHED * is set. So we need to temporarily drop it. */ mutex_unlock(&journal->j_checkpoint_mutex); jbd2_log_wait_commit(journal, tid); write_lock(&journal->j_state_lock); continue; } 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); } }


dave kleikampdave kleikamp8932.25%112.50%
theodore tsotheodore tso8530.80%225.00%
duane griffinduane griffin5921.38%112.50%
dmitriy monakhovdmitriy monakhov196.88%112.50%
paul gortmakerpaul gortmaker186.52%112.50%
jan karajan kara41.45%112.50%
mingming caomingming cao20.72%112.50%

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], REQ_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; }


dave kleikampdave kleikamp6360.58%120.00%
christoph hellwigchristoph hellwig1918.27%240.00%
tao matao ma1615.38%120.00%
theodore tsotheodore tso65.77%120.00%

/* * 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) { struct journal_head *jh; struct buffer_head *bh; transaction_t *transaction; tid_t this_tid; int result, batch_count = 0; 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) goto out; /* checkpoint all of the transaction's buffers */ while (transaction->t_checkpoint_list) { jh = transaction->t_checkpoint_list; bh = jh2bh(jh); if (buffer_locked(bh)) { spin_unlock(&journal->j_list_lock); get_bh(bh); wait_on_buffer(bh); /* the journal_head may have gone by now */ BUFFER_TRACE(bh, "brelse"); __brelse(bh); goto retry; } 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); goto retry; } if (!buffer_dirty(bh)) { if (unlikely(buffer_write_io_error(bh)) && !result) result = -EIO; BUFFER_TRACE(bh, "remove from checkpoint"); if (__jbd2_journal_remove_checkpoint(jh)) /* The transaction was released; we're done */ goto out; continue; } /* * 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++; if ((batch_count == JBD2_NR_BATCH) || need_resched() || spin_needbreak(&journal->j_list_lock)) goto unlock_and_flush; } if (batch_count) { unlock_and_flush: spin_unlock(&journal->j_list_lock); retry: if (batch_count) __flush_batch(journal, &batch_count); spin_lock(&journal->j_list_lock); goto restart; } /* * Now we issued all of the transaction's buffers, let's deal * with the buffers that are out for I/O. */ restart2: /* Did somebody clean up the transaction in the meanwhile? */ if (journal->j_checkpoint_transactions != transaction || transaction->t_tid != this_tid) goto out; while (transaction->t_checkpoint_io_list) { jh = transaction->t_checkpoint_io_list; bh = jh2bh(jh); if (buffer_locked(bh)) { spin_unlock(&journal->j_list_lock); get_bh(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 restart2; } if (unlikely(buffer_write_io_error(bh)) && !result) result = -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 */ if (__jbd2_journal_remove_checkpoint(jh)) break; } 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; }


theodore tsotheodore tso31951.70%550.00%
dave kleikampdave kleikamp23237.60%110.00%
hidehiro kawaihidehiro kawai426.81%110.00%
johann lombardijohann lombardi142.27%110.00%
jan karajan kara60.97%110.00%
mingming caomingming cao40.65%110.00%

/* * 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 -EIO; 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_NOFS, NULL); return __jbd2_update_log_tail(journal, first_tid, blocknr); }


dave kleikampdave kleikamp3239.51%111.11%
theodore tsotheodore tso1923.46%222.22%
jan karajan kara1518.52%111.11%
hidehiro kawaihidehiro kawai911.11%111.11%
joseph qijoseph qi33.70%111.11%
dmitriy monakhovdmitriy monakhov22.47%222.22%
mingming caomingming cao11.23%111.11%

/* Checkpoint list management */ /* * journal_clean_one_cp_list * * Find all the written-back checkpoint buffers in the given list and * release them. If 'destroy' is set, clean all buffers unconditionally. * * Called with j_list_lock held. * Returns 1 if we freed the transaction, 0 otherwise. */
static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy) { struct journal_head *last_jh; struct journal_head *next_jh = jh; int ret; if (!jh) return 0; last_jh = jh->b_cpprev; do { jh = next_jh; next_jh = jh->b_cpnext; if (!destroy) ret = __try_to_free_cp_buf(jh); else ret = __jbd2_journal_remove_checkpoint(jh) + 1; if (!ret) return 0; if (ret == 2) return 1; /* * 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 0; } while (jh != last_jh); return 0; }


dave kleikampdave kleikamp8675.44%120.00%
jan karajan kara2824.56%480.00%

/* * journal_clean_checkpoint_list * * Find all the written-back checkpoint buffers in the journal and release them. * If 'destroy' is set, release all buffers unconditionally. * * Called with j_list_lock held. */
void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy) { transaction_t *transaction, *last_transaction, *next_transaction; int ret; transaction = journal->j_checkpoint_transactions; if (!transaction) return; 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, destroy); /* * 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; if (ret) 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, destroy); if (need_resched()) return; /* * Stop scanning if we couldn't free the transaction. This * avoids pointless scanning of transactions which still * weren't checkpointed. */ if (!ret) return; } while (transaction != last_transaction); }


dave kleikampdave kleikamp9179.13%120.00%
jan karajan kara2320.00%360.00%
mingming caomingming cao10.87%120.00%

/* * Remove buffers from all checkpoint lists as journal is aborted and we just * need to free memory */
void jbd2_journal_destroy_checkpoint(journal_t *journal) { /* * We loop because __jbd2_journal_clean_checkpoint_list() may abort * early due to a need of rescheduling. */ while (1) { spin_lock(&journal->j_list_lock); if (!journal->j_checkpoint_transactions) { spin_unlock(&journal->j_list_lock); break; } __jbd2_journal_clean_checkpoint_list(journal, true); spin_unlock(&journal->j_list_lock); cond_resched(); } }


jan karajan kara60100.00%1100.00%

/* * 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; }


dave kleikampdave kleikamp11161.67%114.29%
theodore tsotheodore tso4625.56%114.29%
jan karajan kara168.89%228.57%
aneesh kumaraneesh kumar42.22%114.29%
mingming caomingming cao21.11%114.29%
yongqiang yangyongqiang yang10.56%114.29%

/* * 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; }


dave kleikampdave kleikamp12092.31%133.33%
jan karajan kara96.92%133.33%
mingming caomingming cao10.77%133.33%

/* * 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); }


dave kleikampdave kleikamp17093.41%125.00%
seiji aguchiseiji aguchi73.85%125.00%
theodore tsotheodore tso42.20%125.00%
mingming caomingming cao10.55%125.00%

Overall Contributors

dave kleikampdave kleikamp129259.16%12.50%
theodore tsotheodore tso48822.34%1332.50%
jan karajan kara1687.69%1025.00%
duane griffinduane griffin592.70%12.50%
hidehiro kawaihidehiro kawai582.66%12.50%
dmitriy monakhovdmitriy monakhov210.96%37.50%
christoph hellwigchristoph hellwig190.87%25.00%
paul gortmakerpaul gortmaker180.82%12.50%
tao matao ma160.73%12.50%
mingming caomingming cao150.69%12.50%
johann lombardijohann lombardi140.64%12.50%
seiji aguchiseiji aguchi70.32%12.50%
aneesh kumaraneesh kumar40.18%12.50%
joseph qijoseph qi30.14%12.50%
uwe kleine-koeniguwe kleine-koenig10.05%12.50%
yongqiang yangyongqiang yang10.05%12.50%
Directory: fs/jbd2
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