+++ /dev/null
-/*
- * linux/fs/jbd/transaction.c
- *
- * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
- *
- * Copyright 1998 Red Hat corp --- 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.
- *
- * Generic filesystem transaction handling code; part of the ext2fs
- * journaling system.
- *
- * This file manages transactions (compound commits managed by the
- * journaling code) and handles (individual atomic operations by the
- * filesystem).
- */
-
-#include <linux/time.h>
-#include <linux/fs.h>
-#include <linux/jbd.h>
-#include <linux/errno.h>
-#include <linux/slab.h>
-#include <linux/timer.h>
-#include <linux/mm.h>
-#include <linux/highmem.h>
-#include <linux/hrtimer.h>
-
-static void __journal_temp_unlink_buffer(struct journal_head *jh);
-
-/*
- * get_transaction: obtain a new transaction_t object.
- *
- * Simply allocate and initialise a new transaction. Create it in
- * RUNNING state and add it to the current journal (which should not
- * have an existing running transaction: we only make a new transaction
- * once we have started to commit the old one).
- *
- * Preconditions:
- * The journal MUST be locked. We don't perform atomic mallocs on the
- * new transaction and we can't block without protecting against other
- * processes trying to touch the journal while it is in transition.
- *
- * Called under j_state_lock
- */
-
-static transaction_t *
-get_transaction(journal_t *journal, transaction_t *transaction)
-{
- transaction->t_journal = journal;
- transaction->t_state = T_RUNNING;
- transaction->t_start_time = ktime_get();
- transaction->t_tid = journal->j_transaction_sequence++;
- transaction->t_expires = jiffies + journal->j_commit_interval;
- spin_lock_init(&transaction->t_handle_lock);
-
- /* Set up the commit timer for the new transaction. */
- journal->j_commit_timer.expires =
- round_jiffies_up(transaction->t_expires);
- add_timer(&journal->j_commit_timer);
-
- J_ASSERT(journal->j_running_transaction == NULL);
- journal->j_running_transaction = transaction;
-
- return transaction;
-}
-
-/*
- * Handle management.
- *
- * A handle_t is an object which represents a single atomic update to a
- * filesystem, and which tracks all of the modifications which form part
- * of that one update.
- */
-
-/*
- * start_this_handle: Given a handle, deal with any locking or stalling
- * needed to make sure that there is enough journal space for the handle
- * to begin. Attach the handle to a transaction and set up the
- * transaction's buffer credits.
- */
-
-static int start_this_handle(journal_t *journal, handle_t *handle)
-{
- transaction_t *transaction;
- int needed;
- int nblocks = handle->h_buffer_credits;
- transaction_t *new_transaction = NULL;
- int ret = 0;
-
- if (nblocks > journal->j_max_transaction_buffers) {
- printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
- current->comm, nblocks,
- journal->j_max_transaction_buffers);
- ret = -ENOSPC;
- goto out;
- }
-
-alloc_transaction:
- if (!journal->j_running_transaction) {
- new_transaction = kzalloc(sizeof(*new_transaction),
- GFP_NOFS|__GFP_NOFAIL);
- if (!new_transaction) {
- ret = -ENOMEM;
- goto out;
- }
- }
-
- jbd_debug(3, "New handle %p going live.\n", handle);
-
-repeat:
-
- /*
- * We need to hold j_state_lock until t_updates has been incremented,
- * for proper journal barrier handling
- */
- spin_lock(&journal->j_state_lock);
-repeat_locked:
- if (is_journal_aborted(journal) ||
- (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
- spin_unlock(&journal->j_state_lock);
- ret = -EROFS;
- goto out;
- }
-
- /* Wait on the journal's transaction barrier if necessary */
- if (journal->j_barrier_count) {
- spin_unlock(&journal->j_state_lock);
- wait_event(journal->j_wait_transaction_locked,
- journal->j_barrier_count == 0);
- goto repeat;
- }
-
- if (!journal->j_running_transaction) {
- if (!new_transaction) {
- spin_unlock(&journal->j_state_lock);
- goto alloc_transaction;
- }
- get_transaction(journal, new_transaction);
- new_transaction = NULL;
- }
-
- transaction = journal->j_running_transaction;
-
- /*
- * If the current transaction is locked down for commit, wait for the
- * lock to be released.
- */
- if (transaction->t_state == T_LOCKED) {
- DEFINE_WAIT(wait);
-
- prepare_to_wait(&journal->j_wait_transaction_locked,
- &wait, TASK_UNINTERRUPTIBLE);
- spin_unlock(&journal->j_state_lock);
- schedule();
- finish_wait(&journal->j_wait_transaction_locked, &wait);
- goto repeat;
- }
-
- /*
- * If there is not enough space left in the log to write all potential
- * buffers requested by this operation, we need to stall pending a log
- * checkpoint to free some more log space.
- */
- spin_lock(&transaction->t_handle_lock);
- needed = transaction->t_outstanding_credits + nblocks;
-
- if (needed > journal->j_max_transaction_buffers) {
- /*
- * If the current transaction is already too large, then start
- * to commit it: we can then go back and attach this handle to
- * a new transaction.
- */
- DEFINE_WAIT(wait);
-
- jbd_debug(2, "Handle %p starting new commit...\n", handle);
- spin_unlock(&transaction->t_handle_lock);
- prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
- TASK_UNINTERRUPTIBLE);
- __log_start_commit(journal, transaction->t_tid);
- spin_unlock(&journal->j_state_lock);
- schedule();
- finish_wait(&journal->j_wait_transaction_locked, &wait);
- goto repeat;
- }
-
- /*
- * The commit code assumes that it can get enough log space
- * without forcing a checkpoint. This is *critical* for
- * correctness: a checkpoint of a buffer which is also
- * associated with a committing transaction creates a deadlock,
- * so commit simply cannot force through checkpoints.
- *
- * We must therefore ensure the necessary space in the journal
- * *before* starting to dirty potentially checkpointed buffers
- * in the new transaction.
- *
- * The worst part is, any transaction currently committing can
- * reduce the free space arbitrarily. Be careful to account for
- * those buffers when checkpointing.
- */
-
- /*
- * @@@ AKPM: This seems rather over-defensive. We're giving commit
- * a _lot_ of headroom: 1/4 of the journal plus the size of
- * the committing transaction. Really, we only need to give it
- * committing_transaction->t_outstanding_credits plus "enough" for
- * the log control blocks.
- * Also, this test is inconsistent with the matching one in
- * journal_extend().
- */
- if (__log_space_left(journal) < jbd_space_needed(journal)) {
- jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
- spin_unlock(&transaction->t_handle_lock);
- __log_wait_for_space(journal);
- goto repeat_locked;
- }
-
- /* OK, account for the buffers that this operation expects to
- * use and add the handle to the running transaction. */
-
- handle->h_transaction = transaction;
- transaction->t_outstanding_credits += nblocks;
- transaction->t_updates++;
- transaction->t_handle_count++;
- jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
- handle, nblocks, transaction->t_outstanding_credits,
- __log_space_left(journal));
- spin_unlock(&transaction->t_handle_lock);
- spin_unlock(&journal->j_state_lock);
-
- lock_map_acquire(&handle->h_lockdep_map);
-out:
- if (unlikely(new_transaction)) /* It's usually NULL */
- kfree(new_transaction);
- return ret;
-}
-
-static struct lock_class_key jbd_handle_key;
-
-/* Allocate a new handle. This should probably be in a slab... */
-static handle_t *new_handle(int nblocks)
-{
- handle_t *handle = jbd_alloc_handle(GFP_NOFS);
- if (!handle)
- return NULL;
- handle->h_buffer_credits = nblocks;
- handle->h_ref = 1;
-
- lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
-
- return handle;
-}
-
-/**
- * handle_t *journal_start() - Obtain a new handle.
- * @journal: Journal to start transaction on.
- * @nblocks: number of block buffer we might modify
- *
- * We make sure that the transaction can guarantee at least nblocks of
- * modified buffers in the log. We block until the log can guarantee
- * that much space.
- *
- * This function is visible to journal users (like ext3fs), so is not
- * called with the journal already locked.
- *
- * Return a pointer to a newly allocated handle, or an ERR_PTR() value
- * on failure.
- */
-handle_t *journal_start(journal_t *journal, int nblocks)
-{
- handle_t *handle = journal_current_handle();
- int err;
-
- if (!journal)
- return ERR_PTR(-EROFS);
-
- if (handle) {
- J_ASSERT(handle->h_transaction->t_journal == journal);
- handle->h_ref++;
- return handle;
- }
-
- handle = new_handle(nblocks);
- if (!handle)
- return ERR_PTR(-ENOMEM);
-
- current->journal_info = handle;
-
- err = start_this_handle(journal, handle);
- if (err < 0) {
- jbd_free_handle(handle);
- current->journal_info = NULL;
- handle = ERR_PTR(err);
- }
- return handle;
-}
-
-/**
- * int journal_extend() - extend buffer credits.
- * @handle: handle to 'extend'
- * @nblocks: nr blocks to try to extend by.
- *
- * Some transactions, such as large extends and truncates, can be done
- * atomically all at once or in several stages. The operation requests
- * a credit for a number of buffer modications in advance, but can
- * extend its credit if it needs more.
- *
- * journal_extend tries to give the running handle more buffer credits.
- * It does not guarantee that allocation - this is a best-effort only.
- * The calling process MUST be able to deal cleanly with a failure to
- * extend here.
- *
- * Return 0 on success, non-zero on failure.
- *
- * return code < 0 implies an error
- * return code > 0 implies normal transaction-full status.
- */
-int journal_extend(handle_t *handle, int nblocks)
-{
- transaction_t *transaction = handle->h_transaction;
- journal_t *journal = transaction->t_journal;
- int result;
- int wanted;
-
- result = -EIO;
- if (is_handle_aborted(handle))
- goto out;
-
- result = 1;
-
- spin_lock(&journal->j_state_lock);
-
- /* Don't extend a locked-down transaction! */
- if (handle->h_transaction->t_state != T_RUNNING) {
- jbd_debug(3, "denied handle %p %d blocks: "
- "transaction not running\n", handle, nblocks);
- goto error_out;
- }
-
- spin_lock(&transaction->t_handle_lock);
- wanted = transaction->t_outstanding_credits + nblocks;
-
- if (wanted > journal->j_max_transaction_buffers) {
- jbd_debug(3, "denied handle %p %d blocks: "
- "transaction too large\n", handle, nblocks);
- goto unlock;
- }
-
- if (wanted > __log_space_left(journal)) {
- jbd_debug(3, "denied handle %p %d blocks: "
- "insufficient log space\n", handle, nblocks);
- goto unlock;
- }
-
- handle->h_buffer_credits += nblocks;
- transaction->t_outstanding_credits += nblocks;
- result = 0;
-
- jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
-unlock:
- spin_unlock(&transaction->t_handle_lock);
-error_out:
- spin_unlock(&journal->j_state_lock);
-out:
- return result;
-}
-
-
-/**
- * int journal_restart() - restart a handle.
- * @handle: handle to restart
- * @nblocks: nr credits requested
- *
- * Restart a handle for a multi-transaction filesystem
- * operation.
- *
- * If the journal_extend() call above fails to grant new buffer credits
- * to a running handle, a call to journal_restart will commit the
- * handle's transaction so far and reattach the handle to a new
- * transaction capabable of guaranteeing the requested number of
- * credits.
- */
-
-int journal_restart(handle_t *handle, int nblocks)
-{
- transaction_t *transaction = handle->h_transaction;
- journal_t *journal = transaction->t_journal;
- int ret;
-
- /* If we've had an abort of any type, don't even think about
- * actually doing the restart! */
- if (is_handle_aborted(handle))
- return 0;
-
- /*
- * First unlink the handle from its current transaction, and start the
- * commit on that.
- */
- J_ASSERT(transaction->t_updates > 0);
- J_ASSERT(journal_current_handle() == handle);
-
- spin_lock(&journal->j_state_lock);
- spin_lock(&transaction->t_handle_lock);
- transaction->t_outstanding_credits -= handle->h_buffer_credits;
- transaction->t_updates--;
-
- if (!transaction->t_updates)
- wake_up(&journal->j_wait_updates);
- spin_unlock(&transaction->t_handle_lock);
-
- jbd_debug(2, "restarting handle %p\n", handle);
- __log_start_commit(journal, transaction->t_tid);
- spin_unlock(&journal->j_state_lock);
-
- lock_map_release(&handle->h_lockdep_map);
- handle->h_buffer_credits = nblocks;
- ret = start_this_handle(journal, handle);
- return ret;
-}
-
-
-/**
- * void journal_lock_updates () - establish a transaction barrier.
- * @journal: Journal to establish a barrier on.
- *
- * This locks out any further updates from being started, and blocks until all
- * existing updates have completed, returning only once the journal is in a
- * quiescent state with no updates running.
- *
- * We do not use simple mutex for synchronization as there are syscalls which
- * want to return with filesystem locked and that trips up lockdep. Also
- * hibernate needs to lock filesystem but locked mutex then blocks hibernation.
- * Since locking filesystem is rare operation, we use simple counter and
- * waitqueue for locking.
- */
-void journal_lock_updates(journal_t *journal)
-{
- DEFINE_WAIT(wait);
-
-wait:
- /* Wait for previous locked operation to finish */
- wait_event(journal->j_wait_transaction_locked,
- journal->j_barrier_count == 0);
-
- spin_lock(&journal->j_state_lock);
- /*
- * Check reliably under the lock whether we are the ones winning the race
- * and locking the journal
- */
- if (journal->j_barrier_count > 0) {
- spin_unlock(&journal->j_state_lock);
- goto wait;
- }
- ++journal->j_barrier_count;
-
- /* Wait until there are no running updates */
- while (1) {
- transaction_t *transaction = journal->j_running_transaction;
-
- if (!transaction)
- break;
-
- spin_lock(&transaction->t_handle_lock);
- if (!transaction->t_updates) {
- spin_unlock(&transaction->t_handle_lock);
- break;
- }
- prepare_to_wait(&journal->j_wait_updates, &wait,
- TASK_UNINTERRUPTIBLE);
- spin_unlock(&transaction->t_handle_lock);
- spin_unlock(&journal->j_state_lock);
- schedule();
- finish_wait(&journal->j_wait_updates, &wait);
- spin_lock(&journal->j_state_lock);
- }
- spin_unlock(&journal->j_state_lock);
-}
-
-/**
- * void journal_unlock_updates (journal_t* journal) - release barrier
- * @journal: Journal to release the barrier on.
- *
- * Release a transaction barrier obtained with journal_lock_updates().
- */
-void journal_unlock_updates (journal_t *journal)
-{
- J_ASSERT(journal->j_barrier_count != 0);
-
- spin_lock(&journal->j_state_lock);
- --journal->j_barrier_count;
- spin_unlock(&journal->j_state_lock);
- wake_up(&journal->j_wait_transaction_locked);
-}
-
-static void warn_dirty_buffer(struct buffer_head *bh)
-{
- char b[BDEVNAME_SIZE];
-
- printk(KERN_WARNING
- "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
- "There's a risk of filesystem corruption in case of system "
- "crash.\n",
- bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
-}
-
-/*
- * If the buffer is already part of the current transaction, then there
- * is nothing we need to do. If it is already part of a prior
- * transaction which we are still committing to disk, then we need to
- * make sure that we do not overwrite the old copy: we do copy-out to
- * preserve the copy going to disk. We also account the buffer against
- * the handle's metadata buffer credits (unless the buffer is already
- * part of the transaction, that is).
- *
- */
-static int
-do_get_write_access(handle_t *handle, struct journal_head *jh,
- int force_copy)
-{
- struct buffer_head *bh;
- transaction_t *transaction;
- journal_t *journal;
- int error;
- char *frozen_buffer = NULL;
- int need_copy = 0;
-
- if (is_handle_aborted(handle))
- return -EROFS;
-
- transaction = handle->h_transaction;
- journal = transaction->t_journal;
-
- jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
-
- JBUFFER_TRACE(jh, "entry");
-repeat:
- bh = jh2bh(jh);
-
- /* @@@ Need to check for errors here at some point. */
-
- lock_buffer(bh);
- jbd_lock_bh_state(bh);
-
- /* We now hold the buffer lock so it is safe to query the buffer
- * state. Is the buffer dirty?
- *
- * If so, there are two possibilities. The buffer may be
- * non-journaled, and undergoing a quite legitimate writeback.
- * Otherwise, it is journaled, and we don't expect dirty buffers
- * in that state (the buffers should be marked JBD_Dirty
- * instead.) So either the IO is being done under our own
- * control and this is a bug, or it's a third party IO such as
- * dump(8) (which may leave the buffer scheduled for read ---
- * ie. locked but not dirty) or tune2fs (which may actually have
- * the buffer dirtied, ugh.) */
-
- if (buffer_dirty(bh)) {
- /*
- * First question: is this buffer already part of the current
- * transaction or the existing committing transaction?
- */
- if (jh->b_transaction) {
- J_ASSERT_JH(jh,
- jh->b_transaction == transaction ||
- jh->b_transaction ==
- journal->j_committing_transaction);
- if (jh->b_next_transaction)
- J_ASSERT_JH(jh, jh->b_next_transaction ==
- transaction);
- warn_dirty_buffer(bh);
- }
- /*
- * In any case we need to clean the dirty flag and we must
- * do it under the buffer lock to be sure we don't race
- * with running write-out.
- */
- JBUFFER_TRACE(jh, "Journalling dirty buffer");
- clear_buffer_dirty(bh);
- set_buffer_jbddirty(bh);
- }
-
- unlock_buffer(bh);
-
- error = -EROFS;
- if (is_handle_aborted(handle)) {
- jbd_unlock_bh_state(bh);
- goto out;
- }
- error = 0;
-
- /*
- * The buffer is already part of this transaction if b_transaction or
- * b_next_transaction points to it
- */
- if (jh->b_transaction == transaction ||
- jh->b_next_transaction == transaction)
- goto done;
-
- /*
- * this is the first time this transaction is touching this buffer,
- * reset the modified flag
- */
- jh->b_modified = 0;
-
- /*
- * If there is already a copy-out version of this buffer, then we don't
- * need to make another one
- */
- if (jh->b_frozen_data) {
- JBUFFER_TRACE(jh, "has frozen data");
- J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
- jh->b_next_transaction = transaction;
- goto done;
- }
-
- /* Is there data here we need to preserve? */
-
- if (jh->b_transaction && jh->b_transaction != transaction) {
- JBUFFER_TRACE(jh, "owned by older transaction");
- J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
- J_ASSERT_JH(jh, jh->b_transaction ==
- journal->j_committing_transaction);
-
- /* There is one case we have to be very careful about.
- * If the committing transaction is currently writing
- * this buffer out to disk and has NOT made a copy-out,
- * then we cannot modify the buffer contents at all
- * right now. The essence of copy-out is that it is the
- * extra copy, not the primary copy, which gets
- * journaled. If the primary copy is already going to
- * disk then we cannot do copy-out here. */
-
- if (jh->b_jlist == BJ_Shadow) {
- DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
- wait_queue_head_t *wqh;
-
- wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
-
- JBUFFER_TRACE(jh, "on shadow: sleep");
- jbd_unlock_bh_state(bh);
- /* commit wakes up all shadow buffers after IO */
- for ( ; ; ) {
- prepare_to_wait(wqh, &wait.wait,
- TASK_UNINTERRUPTIBLE);
- if (jh->b_jlist != BJ_Shadow)
- break;
- schedule();
- }
- finish_wait(wqh, &wait.wait);
- goto repeat;
- }
-
- /* Only do the copy if the currently-owning transaction
- * still needs it. If it is on the Forget list, the
- * committing transaction is past that stage. The
- * buffer had better remain locked during the kmalloc,
- * but that should be true --- we hold the journal lock
- * still and the buffer is already on the BUF_JOURNAL
- * list so won't be flushed.
- *
- * Subtle point, though: if this is a get_undo_access,
- * then we will be relying on the frozen_data to contain
- * the new value of the committed_data record after the
- * transaction, so we HAVE to force the frozen_data copy
- * in that case. */
-
- if (jh->b_jlist != BJ_Forget || force_copy) {
- JBUFFER_TRACE(jh, "generate frozen data");
- if (!frozen_buffer) {
- JBUFFER_TRACE(jh, "allocate memory for buffer");
- jbd_unlock_bh_state(bh);
- frozen_buffer =
- jbd_alloc(jh2bh(jh)->b_size,
- GFP_NOFS);
- if (!frozen_buffer) {
- printk(KERN_ERR
- "%s: OOM for frozen_buffer\n",
- __func__);
- JBUFFER_TRACE(jh, "oom!");
- error = -ENOMEM;
- jbd_lock_bh_state(bh);
- goto done;
- }
- goto repeat;
- }
- jh->b_frozen_data = frozen_buffer;
- frozen_buffer = NULL;
- need_copy = 1;
- }
- jh->b_next_transaction = transaction;
- }
-
-
- /*
- * Finally, if the buffer is not journaled right now, we need to make
- * sure it doesn't get written to disk before the caller actually
- * commits the new data
- */
- if (!jh->b_transaction) {
- JBUFFER_TRACE(jh, "no transaction");
- J_ASSERT_JH(jh, !jh->b_next_transaction);
- JBUFFER_TRACE(jh, "file as BJ_Reserved");
- spin_lock(&journal->j_list_lock);
- __journal_file_buffer(jh, transaction, BJ_Reserved);
- spin_unlock(&journal->j_list_lock);
- }
-
-done:
- if (need_copy) {
- struct page *page;
- int offset;
- char *source;
-
- J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
- "Possible IO failure.\n");
- page = jh2bh(jh)->b_page;
- offset = offset_in_page(jh2bh(jh)->b_data);
- source = kmap_atomic(page);
- memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
- kunmap_atomic(source);
- }
- jbd_unlock_bh_state(bh);
-
- /*
- * If we are about to journal a buffer, then any revoke pending on it is
- * no longer valid
- */
- journal_cancel_revoke(handle, jh);
-
-out:
- if (unlikely(frozen_buffer)) /* It's usually NULL */
- jbd_free(frozen_buffer, bh->b_size);
-
- JBUFFER_TRACE(jh, "exit");
- return error;
-}
-
-/**
- * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
- * @handle: transaction to add buffer modifications to
- * @bh: bh to be used for metadata writes
- *
- * Returns an error code or 0 on success.
- *
- * In full data journalling mode the buffer may be of type BJ_AsyncData,
- * because we're write()ing a buffer which is also part of a shared mapping.
- */
-
-int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
-{
- struct journal_head *jh = journal_add_journal_head(bh);
- int rc;
-
- /* We do not want to get caught playing with fields which the
- * log thread also manipulates. Make sure that the buffer
- * completes any outstanding IO before proceeding. */
- rc = do_get_write_access(handle, jh, 0);
- journal_put_journal_head(jh);
- return rc;
-}
-
-
-/*
- * When the user wants to journal a newly created buffer_head
- * (ie. getblk() returned a new buffer and we are going to populate it
- * manually rather than reading off disk), then we need to keep the
- * buffer_head locked until it has been completely filled with new
- * data. In this case, we should be able to make the assertion that
- * the bh is not already part of an existing transaction.
- *
- * The buffer should already be locked by the caller by this point.
- * There is no lock ranking violation: it was a newly created,
- * unlocked buffer beforehand. */
-
-/**
- * int journal_get_create_access () - notify intent to use newly created bh
- * @handle: transaction to new buffer to
- * @bh: new buffer.
- *
- * Call this if you create a new bh.
- */
-int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
-{
- transaction_t *transaction = handle->h_transaction;
- journal_t *journal = transaction->t_journal;
- struct journal_head *jh = journal_add_journal_head(bh);
- int err;
-
- jbd_debug(5, "journal_head %p\n", jh);
- err = -EROFS;
- if (is_handle_aborted(handle))
- goto out;
- err = 0;
-
- JBUFFER_TRACE(jh, "entry");
- /*
- * The buffer may already belong to this transaction due to pre-zeroing
- * in the filesystem's new_block code. It may also be on the previous,
- * committing transaction's lists, but it HAS to be in Forget state in
- * that case: the transaction must have deleted the buffer for it to be
- * reused here.
- */
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
- J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
- jh->b_transaction == NULL ||
- (jh->b_transaction == journal->j_committing_transaction &&
- jh->b_jlist == BJ_Forget)));
-
- J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
- J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
-
- if (jh->b_transaction == NULL) {
- /*
- * Previous journal_forget() could have left the buffer
- * with jbddirty bit set because it was being committed. When
- * the commit finished, we've filed the buffer for
- * checkpointing and marked it dirty. Now we are reallocating
- * the buffer so the transaction freeing it must have
- * committed and so it's safe to clear the dirty bit.
- */
- clear_buffer_dirty(jh2bh(jh));
-
- /* first access by this transaction */
- jh->b_modified = 0;
-
- JBUFFER_TRACE(jh, "file as BJ_Reserved");
- __journal_file_buffer(jh, transaction, BJ_Reserved);
- } else if (jh->b_transaction == journal->j_committing_transaction) {
- /* first access by this transaction */
- jh->b_modified = 0;
-
- JBUFFER_TRACE(jh, "set next transaction");
- jh->b_next_transaction = transaction;
- }
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
-
- /*
- * akpm: I added this. ext3_alloc_branch can pick up new indirect
- * blocks which contain freed but then revoked metadata. We need
- * to cancel the revoke in case we end up freeing it yet again
- * and the reallocating as data - this would cause a second revoke,
- * which hits an assertion error.
- */
- JBUFFER_TRACE(jh, "cancelling revoke");
- journal_cancel_revoke(handle, jh);
-out:
- journal_put_journal_head(jh);
- return err;
-}
-
-/**
- * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
- * @handle: transaction
- * @bh: buffer to undo
- *
- * Sometimes there is a need to distinguish between metadata which has
- * been committed to disk and that which has not. The ext3fs code uses
- * this for freeing and allocating space, we have to make sure that we
- * do not reuse freed space until the deallocation has been committed,
- * since if we overwrote that space we would make the delete
- * un-rewindable in case of a crash.
- *
- * To deal with that, journal_get_undo_access requests write access to a
- * buffer for parts of non-rewindable operations such as delete
- * operations on the bitmaps. The journaling code must keep a copy of
- * the buffer's contents prior to the undo_access call until such time
- * as we know that the buffer has definitely been committed to disk.
- *
- * We never need to know which transaction the committed data is part
- * of, buffers touched here are guaranteed to be dirtied later and so
- * will be committed to a new transaction in due course, at which point
- * we can discard the old committed data pointer.
- *
- * Returns error number or 0 on success.
- */
-int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
-{
- int err;
- struct journal_head *jh = journal_add_journal_head(bh);
- char *committed_data = NULL;
-
- JBUFFER_TRACE(jh, "entry");
-
- /*
- * Do this first --- it can drop the journal lock, so we want to
- * make sure that obtaining the committed_data is done
- * atomically wrt. completion of any outstanding commits.
- */
- err = do_get_write_access(handle, jh, 1);
- if (err)
- goto out;
-
-repeat:
- if (!jh->b_committed_data) {
- committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
- if (!committed_data) {
- printk(KERN_ERR "%s: No memory for committed data\n",
- __func__);
- err = -ENOMEM;
- goto out;
- }
- }
-
- jbd_lock_bh_state(bh);
- if (!jh->b_committed_data) {
- /* Copy out the current buffer contents into the
- * preserved, committed copy. */
- JBUFFER_TRACE(jh, "generate b_committed data");
- if (!committed_data) {
- jbd_unlock_bh_state(bh);
- goto repeat;
- }
-
- jh->b_committed_data = committed_data;
- committed_data = NULL;
- memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
- }
- jbd_unlock_bh_state(bh);
-out:
- journal_put_journal_head(jh);
- if (unlikely(committed_data))
- jbd_free(committed_data, bh->b_size);
- return err;
-}
-
-/**
- * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
- * @handle: transaction
- * @bh: bufferhead to mark
- *
- * Description:
- * Mark a buffer as containing dirty data which needs to be flushed before
- * we can commit the current transaction.
- *
- * The buffer is placed on the transaction's data list and is marked as
- * belonging to the transaction.
- *
- * Returns error number or 0 on success.
- *
- * journal_dirty_data() can be called via page_launder->ext3_writepage
- * by kswapd.
- */
-int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
-{
- journal_t *journal = handle->h_transaction->t_journal;
- int need_brelse = 0;
- struct journal_head *jh;
- int ret = 0;
-
- if (is_handle_aborted(handle))
- return ret;
-
- jh = journal_add_journal_head(bh);
- JBUFFER_TRACE(jh, "entry");
-
- /*
- * The buffer could *already* be dirty. Writeout can start
- * at any time.
- */
- jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
-
- /*
- * What if the buffer is already part of a running transaction?
- *
- * There are two cases:
- * 1) It is part of the current running transaction. Refile it,
- * just in case we have allocated it as metadata, deallocated
- * it, then reallocated it as data.
- * 2) It is part of the previous, still-committing transaction.
- * If all we want to do is to guarantee that the buffer will be
- * written to disk before this new transaction commits, then
- * being sure that the *previous* transaction has this same
- * property is sufficient for us! Just leave it on its old
- * transaction.
- *
- * In case (2), the buffer must not already exist as metadata
- * --- that would violate write ordering (a transaction is free
- * to write its data at any point, even before the previous
- * committing transaction has committed). The caller must
- * never, ever allow this to happen: there's nothing we can do
- * about it in this layer.
- */
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
-
- /* Now that we have bh_state locked, are we really still mapped? */
- if (!buffer_mapped(bh)) {
- JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
- goto no_journal;
- }
-
- if (jh->b_transaction) {
- JBUFFER_TRACE(jh, "has transaction");
- if (jh->b_transaction != handle->h_transaction) {
- JBUFFER_TRACE(jh, "belongs to older transaction");
- J_ASSERT_JH(jh, jh->b_transaction ==
- journal->j_committing_transaction);
-
- /* @@@ IS THIS TRUE ? */
- /*
- * Not any more. Scenario: someone does a write()
- * in data=journal mode. The buffer's transaction has
- * moved into commit. Then someone does another
- * write() to the file. We do the frozen data copyout
- * and set b_next_transaction to point to j_running_t.
- * And while we're in that state, someone does a
- * writepage() in an attempt to pageout the same area
- * of the file via a shared mapping. At present that
- * calls journal_dirty_data(), and we get right here.
- * It may be too late to journal the data. Simply
- * falling through to the next test will suffice: the
- * data will be dirty and wil be checkpointed. The
- * ordering comments in the next comment block still
- * apply.
- */
- //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
-
- /*
- * If we're journalling data, and this buffer was
- * subject to a write(), it could be metadata, forget
- * or shadow against the committing transaction. Now,
- * someone has dirtied the same darn page via a mapping
- * and it is being writepage()'d.
- * We *could* just steal the page from commit, with some
- * fancy locking there. Instead, we just skip it -
- * don't tie the page's buffers to the new transaction
- * at all.
- * Implication: if we crash before the writepage() data
- * is written into the filesystem, recovery will replay
- * the write() data.
- */
- if (jh->b_jlist != BJ_None &&
- jh->b_jlist != BJ_SyncData &&
- jh->b_jlist != BJ_Locked) {
- JBUFFER_TRACE(jh, "Not stealing");
- goto no_journal;
- }
-
- /*
- * This buffer may be undergoing writeout in commit. We
- * can't return from here and let the caller dirty it
- * again because that can cause the write-out loop in
- * commit to never terminate.
- */
- if (buffer_dirty(bh)) {
- get_bh(bh);
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- need_brelse = 1;
- sync_dirty_buffer(bh);
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
- /* Since we dropped the lock... */
- if (!buffer_mapped(bh)) {
- JBUFFER_TRACE(jh, "buffer got unmapped");
- goto no_journal;
- }
- /* The buffer may become locked again at any
- time if it is redirtied */
- }
-
- /*
- * We cannot remove the buffer with io error from the
- * committing transaction, because otherwise it would
- * miss the error and the commit would not abort.
- */
- if (unlikely(!buffer_uptodate(bh))) {
- ret = -EIO;
- goto no_journal;
- }
- /* We might have slept so buffer could be refiled now */
- if (jh->b_transaction != NULL &&
- jh->b_transaction != handle->h_transaction) {
- JBUFFER_TRACE(jh, "unfile from commit");
- __journal_temp_unlink_buffer(jh);
- /* It still points to the committing
- * transaction; move it to this one so
- * that the refile assert checks are
- * happy. */
- jh->b_transaction = handle->h_transaction;
- }
- /* The buffer will be refiled below */
-
- }
- /*
- * Special case --- the buffer might actually have been
- * allocated and then immediately deallocated in the previous,
- * committing transaction, so might still be left on that
- * transaction's metadata lists.
- */
- if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
- JBUFFER_TRACE(jh, "not on correct data list: unfile");
- J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
- JBUFFER_TRACE(jh, "file as data");
- __journal_file_buffer(jh, handle->h_transaction,
- BJ_SyncData);
- }
- } else {
- JBUFFER_TRACE(jh, "not on a transaction");
- __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
- }
-no_journal:
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- if (need_brelse) {
- BUFFER_TRACE(bh, "brelse");
- __brelse(bh);
- }
- JBUFFER_TRACE(jh, "exit");
- journal_put_journal_head(jh);
- return ret;
-}
-
-/**
- * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
- * @handle: transaction to add buffer to.
- * @bh: buffer to mark
- *
- * Mark dirty metadata which needs to be journaled as part of the current
- * transaction.
- *
- * The buffer is placed on the transaction's metadata list and is marked
- * as belonging to the transaction.
- *
- * Returns error number or 0 on success.
- *
- * Special care needs to be taken if the buffer already belongs to the
- * current committing transaction (in which case we should have frozen
- * data present for that commit). In that case, we don't relink the
- * buffer: that only gets done when the old transaction finally
- * completes its commit.
- */
-int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
-{
- transaction_t *transaction = handle->h_transaction;
- journal_t *journal = transaction->t_journal;
- struct journal_head *jh = bh2jh(bh);
-
- jbd_debug(5, "journal_head %p\n", jh);
- JBUFFER_TRACE(jh, "entry");
- if (is_handle_aborted(handle))
- goto out;
-
- jbd_lock_bh_state(bh);
-
- if (jh->b_modified == 0) {
- /*
- * This buffer's got modified and becoming part
- * of the transaction. This needs to be done
- * once a transaction -bzzz
- */
- jh->b_modified = 1;
- J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
- handle->h_buffer_credits--;
- }
-
- /*
- * fastpath, to avoid expensive locking. If this buffer is already
- * on the running transaction's metadata list there is nothing to do.
- * Nobody can take it off again because there is a handle open.
- * I _think_ we're OK here with SMP barriers - a mistaken decision will
- * result in this test being false, so we go in and take the locks.
- */
- if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
- JBUFFER_TRACE(jh, "fastpath");
- J_ASSERT_JH(jh, jh->b_transaction ==
- journal->j_running_transaction);
- goto out_unlock_bh;
- }
-
- set_buffer_jbddirty(bh);
-
- /*
- * Metadata already on the current transaction list doesn't
- * need to be filed. Metadata on another transaction's list must
- * be committing, and will be refiled once the commit completes:
- * leave it alone for now.
- */
- if (jh->b_transaction != transaction) {
- JBUFFER_TRACE(jh, "already on other transaction");
- J_ASSERT_JH(jh, jh->b_transaction ==
- journal->j_committing_transaction);
- J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
- /* And this case is illegal: we can't reuse another
- * transaction's data buffer, ever. */
- goto out_unlock_bh;
- }
-
- /* That test should have eliminated the following case: */
- J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
-
- JBUFFER_TRACE(jh, "file as BJ_Metadata");
- spin_lock(&journal->j_list_lock);
- __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
- spin_unlock(&journal->j_list_lock);
-out_unlock_bh:
- jbd_unlock_bh_state(bh);
-out:
- JBUFFER_TRACE(jh, "exit");
- return 0;
-}
-
-/*
- * journal_release_buffer: undo a get_write_access without any buffer
- * updates, if the update decided in the end that it didn't need access.
- *
- */
-void
-journal_release_buffer(handle_t *handle, struct buffer_head *bh)
-{
- BUFFER_TRACE(bh, "entry");
-}
-
-/**
- * void journal_forget() - bforget() for potentially-journaled buffers.
- * @handle: transaction handle
- * @bh: bh to 'forget'
- *
- * We can only do the bforget if there are no commits pending against the
- * buffer. If the buffer is dirty in the current running transaction we
- * can safely unlink it.
- *
- * bh may not be a journalled buffer at all - it may be a non-JBD
- * buffer which came off the hashtable. Check for this.
- *
- * Decrements bh->b_count by one.
- *
- * Allow this call even if the handle has aborted --- it may be part of
- * the caller's cleanup after an abort.
- */
-int journal_forget (handle_t *handle, struct buffer_head *bh)
-{
- transaction_t *transaction = handle->h_transaction;
- journal_t *journal = transaction->t_journal;
- struct journal_head *jh;
- int drop_reserve = 0;
- int err = 0;
- int was_modified = 0;
-
- BUFFER_TRACE(bh, "entry");
-
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
-
- if (!buffer_jbd(bh))
- goto not_jbd;
- jh = bh2jh(bh);
-
- /* Critical error: attempting to delete a bitmap buffer, maybe?
- * Don't do any jbd operations, and return an error. */
- if (!J_EXPECT_JH(jh, !jh->b_committed_data,
- "inconsistent data on disk")) {
- err = -EIO;
- goto not_jbd;
- }
-
- /* keep track of whether or not this transaction modified us */
- was_modified = jh->b_modified;
-
- /*
- * The buffer's going from the transaction, we must drop
- * all references -bzzz
- */
- jh->b_modified = 0;
-
- if (jh->b_transaction == handle->h_transaction) {
- J_ASSERT_JH(jh, !jh->b_frozen_data);
-
- /* If we are forgetting a buffer which is already part
- * of this transaction, then we can just drop it from
- * the transaction immediately. */
- clear_buffer_dirty(bh);
- clear_buffer_jbddirty(bh);
-
- JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
-
- /*
- * we only want to drop a reference if this transaction
- * modified the buffer
- */
- if (was_modified)
- drop_reserve = 1;
-
- /*
- * We are no longer going to journal this buffer.
- * However, the commit of this transaction is still
- * important to the buffer: the delete that we are now
- * processing might obsolete an old log entry, so by
- * committing, we can satisfy the buffer's checkpoint.
- *
- * So, if we have a checkpoint on the buffer, we should
- * now refile the buffer on our BJ_Forget list so that
- * we know to remove the checkpoint after we commit.
- */
-
- if (jh->b_cp_transaction) {
- __journal_temp_unlink_buffer(jh);
- __journal_file_buffer(jh, transaction, BJ_Forget);
- } else {
- __journal_unfile_buffer(jh);
- if (!buffer_jbd(bh)) {
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- __bforget(bh);
- goto drop;
- }
- }
- } else if (jh->b_transaction) {
- J_ASSERT_JH(jh, (jh->b_transaction ==
- journal->j_committing_transaction));
- /* However, if the buffer is still owned by a prior
- * (committing) transaction, we can't drop it yet... */
- JBUFFER_TRACE(jh, "belongs to older transaction");
- /* ... but we CAN drop it from the new transaction if we
- * have also modified it since the original commit. */
-
- if (jh->b_next_transaction) {
- J_ASSERT(jh->b_next_transaction == transaction);
- jh->b_next_transaction = NULL;
-
- /*
- * only drop a reference if this transaction modified
- * the buffer
- */
- if (was_modified)
- drop_reserve = 1;
- }
- }
-
-not_jbd:
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- __brelse(bh);
-drop:
- if (drop_reserve) {
- /* no need to reserve log space for this block -bzzz */
- handle->h_buffer_credits++;
- }
- return err;
-}
-
-/**
- * int journal_stop() - complete a transaction
- * @handle: tranaction to complete.
- *
- * All done for a particular handle.
- *
- * There is not much action needed here. We just return any remaining
- * buffer credits to the transaction and remove the handle. The only
- * complication is that we need to start a commit operation if the
- * filesystem is marked for synchronous update.
- *
- * journal_stop itself will not usually return an error, but it may
- * do so in unusual circumstances. In particular, expect it to
- * return -EIO if a journal_abort has been executed since the
- * transaction began.
- */
-int journal_stop(handle_t *handle)
-{
- transaction_t *transaction = handle->h_transaction;
- journal_t *journal = transaction->t_journal;
- int err;
- pid_t pid;
-
- J_ASSERT(journal_current_handle() == handle);
-
- if (is_handle_aborted(handle))
- err = -EIO;
- else {
- J_ASSERT(transaction->t_updates > 0);
- err = 0;
- }
-
- if (--handle->h_ref > 0) {
- jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
- handle->h_ref);
- return err;
- }
-
- jbd_debug(4, "Handle %p going down\n", handle);
-
- /*
- * Implement synchronous transaction batching. If the handle
- * was synchronous, don't force a commit immediately. Let's
- * yield and let another thread piggyback onto this transaction.
- * Keep doing that while new threads continue to arrive.
- * It doesn't cost much - we're about to run a commit and sleep
- * on IO anyway. Speeds up many-threaded, many-dir operations
- * by 30x or more...
- *
- * We try and optimize the sleep time against what the underlying disk
- * can do, instead of having a static sleep time. This is useful for
- * the case where our storage is so fast that it is more optimal to go
- * ahead and force a flush and wait for the transaction to be committed
- * than it is to wait for an arbitrary amount of time for new writers to
- * join the transaction. We achieve this by measuring how long it takes
- * to commit a transaction, and compare it with how long this
- * transaction has been running, and if run time < commit time then we
- * sleep for the delta and commit. This greatly helps super fast disks
- * that would see slowdowns as more threads started doing fsyncs.
- *
- * But don't do this if this process was the most recent one to
- * perform a synchronous write. We do this to detect the case where a
- * single process is doing a stream of sync writes. No point in waiting
- * for joiners in that case.
- */
- pid = current->pid;
- if (handle->h_sync && journal->j_last_sync_writer != pid) {
- u64 commit_time, trans_time;
-
- journal->j_last_sync_writer = pid;
-
- spin_lock(&journal->j_state_lock);
- commit_time = journal->j_average_commit_time;
- spin_unlock(&journal->j_state_lock);
-
- trans_time = ktime_to_ns(ktime_sub(ktime_get(),
- transaction->t_start_time));
-
- commit_time = min_t(u64, commit_time,
- 1000*jiffies_to_usecs(1));
-
- if (trans_time < commit_time) {
- ktime_t expires = ktime_add_ns(ktime_get(),
- commit_time);
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
- }
- }
-
- current->journal_info = NULL;
- spin_lock(&journal->j_state_lock);
- spin_lock(&transaction->t_handle_lock);
- transaction->t_outstanding_credits -= handle->h_buffer_credits;
- transaction->t_updates--;
- if (!transaction->t_updates) {
- wake_up(&journal->j_wait_updates);
- if (journal->j_barrier_count)
- wake_up(&journal->j_wait_transaction_locked);
- }
-
- /*
- * If the handle is marked SYNC, we need to set another commit
- * going! We also want to force a commit if the current
- * transaction is occupying too much of the log, or if the
- * transaction is too old now.
- */
- if (handle->h_sync ||
- transaction->t_outstanding_credits >
- journal->j_max_transaction_buffers ||
- time_after_eq(jiffies, transaction->t_expires)) {
- /* Do this even for aborted journals: an abort still
- * completes the commit thread, it just doesn't write
- * anything to disk. */
- tid_t tid = transaction->t_tid;
-
- spin_unlock(&transaction->t_handle_lock);
- jbd_debug(2, "transaction too old, requesting commit for "
- "handle %p\n", handle);
- /* This is non-blocking */
- __log_start_commit(journal, transaction->t_tid);
- spin_unlock(&journal->j_state_lock);
-
- /*
- * Special case: JFS_SYNC synchronous updates require us
- * to wait for the commit to complete.
- */
- if (handle->h_sync && !(current->flags & PF_MEMALLOC))
- err = log_wait_commit(journal, tid);
- } else {
- spin_unlock(&transaction->t_handle_lock);
- spin_unlock(&journal->j_state_lock);
- }
-
- lock_map_release(&handle->h_lockdep_map);
-
- jbd_free_handle(handle);
- return err;
-}
-
-/**
- * int journal_force_commit() - force any uncommitted transactions
- * @journal: journal to force
- *
- * For synchronous operations: force any uncommitted transactions
- * to disk. May seem kludgy, but it reuses all the handle batching
- * code in a very simple manner.
- */
-int journal_force_commit(journal_t *journal)
-{
- handle_t *handle;
- int ret;
-
- handle = journal_start(journal, 1);
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- } else {
- handle->h_sync = 1;
- ret = journal_stop(handle);
- }
- return ret;
-}
-
-/*
- *
- * List management code snippets: various functions for manipulating the
- * transaction buffer lists.
- *
- */
-
-/*
- * Append a buffer to a transaction list, given the transaction's list head
- * pointer.
- *
- * j_list_lock is held.
- *
- * jbd_lock_bh_state(jh2bh(jh)) is held.
- */
-
-static inline void
-__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
-{
- if (!*list) {
- jh->b_tnext = jh->b_tprev = jh;
- *list = jh;
- } else {
- /* Insert at the tail of the list to preserve order */
- struct journal_head *first = *list, *last = first->b_tprev;
- jh->b_tprev = last;
- jh->b_tnext = first;
- last->b_tnext = first->b_tprev = jh;
- }
-}
-
-/*
- * Remove a buffer from a transaction list, given the transaction's list
- * head pointer.
- *
- * Called with j_list_lock held, and the journal may not be locked.
- *
- * jbd_lock_bh_state(jh2bh(jh)) is held.
- */
-
-static inline void
-__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
-{
- if (*list == jh) {
- *list = jh->b_tnext;
- if (*list == jh)
- *list = NULL;
- }
- jh->b_tprev->b_tnext = jh->b_tnext;
- jh->b_tnext->b_tprev = jh->b_tprev;
-}
-
-/*
- * Remove a buffer from the appropriate transaction list.
- *
- * Note that this function can *change* the value of
- * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
- * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
- * is holding onto a copy of one of thee pointers, it could go bad.
- * Generally the caller needs to re-read the pointer from the transaction_t.
- *
- * Called under j_list_lock. The journal may not be locked.
- */
-static void __journal_temp_unlink_buffer(struct journal_head *jh)
-{
- struct journal_head **list = NULL;
- transaction_t *transaction;
- struct buffer_head *bh = jh2bh(jh);
-
- J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
- transaction = jh->b_transaction;
- if (transaction)
- assert_spin_locked(&transaction->t_journal->j_list_lock);
-
- J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
- if (jh->b_jlist != BJ_None)
- J_ASSERT_JH(jh, transaction != NULL);
-
- switch (jh->b_jlist) {
- case BJ_None:
- return;
- case BJ_SyncData:
- list = &transaction->t_sync_datalist;
- break;
- case BJ_Metadata:
- transaction->t_nr_buffers--;
- J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
- list = &transaction->t_buffers;
- break;
- case BJ_Forget:
- list = &transaction->t_forget;
- break;
- case BJ_IO:
- list = &transaction->t_iobuf_list;
- break;
- case BJ_Shadow:
- list = &transaction->t_shadow_list;
- break;
- case BJ_LogCtl:
- list = &transaction->t_log_list;
- break;
- case BJ_Reserved:
- list = &transaction->t_reserved_list;
- break;
- case BJ_Locked:
- list = &transaction->t_locked_list;
- break;
- }
-
- __blist_del_buffer(list, jh);
- jh->b_jlist = BJ_None;
- if (test_clear_buffer_jbddirty(bh))
- mark_buffer_dirty(bh); /* Expose it to the VM */
-}
-
-/*
- * Remove buffer from all transactions.
- *
- * Called with bh_state lock and j_list_lock
- *
- * jh and bh may be already freed when this function returns.
- */
-void __journal_unfile_buffer(struct journal_head *jh)
-{
- __journal_temp_unlink_buffer(jh);
- jh->b_transaction = NULL;
- journal_put_journal_head(jh);
-}
-
-void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
-{
- struct buffer_head *bh = jh2bh(jh);
-
- /* Get reference so that buffer cannot be freed before we unlock it */
- get_bh(bh);
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
- __journal_unfile_buffer(jh);
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- __brelse(bh);
-}
-
-/*
- * Called from journal_try_to_free_buffers().
- *
- * Called under jbd_lock_bh_state(bh)
- */
-static void
-__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
-{
- struct journal_head *jh;
-
- jh = bh2jh(bh);
-
- if (buffer_locked(bh) || buffer_dirty(bh))
- goto out;
-
- if (jh->b_next_transaction != NULL)
- goto out;
-
- spin_lock(&journal->j_list_lock);
- if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
- if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
- /* A written-back ordered data buffer */
- JBUFFER_TRACE(jh, "release data");
- __journal_unfile_buffer(jh);
- }
- } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
- /* written-back checkpointed metadata buffer */
- if (jh->b_jlist == BJ_None) {
- JBUFFER_TRACE(jh, "remove from checkpoint list");
- __journal_remove_checkpoint(jh);
- }
- }
- spin_unlock(&journal->j_list_lock);
-out:
- return;
-}
-
-/**
- * int journal_try_to_free_buffers() - try to free page buffers.
- * @journal: journal for operation
- * @page: to try and free
- * @gfp_mask: we use the mask to detect how hard should we try to release
- * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
- * release the buffers.
- *
- *
- * For all the buffers on this page,
- * if they are fully written out ordered data, move them onto BUF_CLEAN
- * so try_to_free_buffers() can reap them.
- *
- * This function returns non-zero if we wish try_to_free_buffers()
- * to be called. We do this if the page is releasable by try_to_free_buffers().
- * We also do it if the page has locked or dirty buffers and the caller wants
- * us to perform sync or async writeout.
- *
- * This complicates JBD locking somewhat. We aren't protected by the
- * BKL here. We wish to remove the buffer from its committing or
- * running transaction's ->t_datalist via __journal_unfile_buffer.
- *
- * This may *change* the value of transaction_t->t_datalist, so anyone
- * who looks at t_datalist needs to lock against this function.
- *
- * Even worse, someone may be doing a journal_dirty_data on this
- * buffer. So we need to lock against that. journal_dirty_data()
- * will come out of the lock with the buffer dirty, which makes it
- * ineligible for release here.
- *
- * Who else is affected by this? hmm... Really the only contender
- * is do_get_write_access() - it could be looking at the buffer while
- * journal_try_to_free_buffer() is changing its state. But that
- * cannot happen because we never reallocate freed data as metadata
- * while the data is part of a transaction. Yes?
- *
- * Return 0 on failure, 1 on success
- */
-int journal_try_to_free_buffers(journal_t *journal,
- struct page *page, gfp_t gfp_mask)
-{
- struct buffer_head *head;
- struct buffer_head *bh;
- int ret = 0;
-
- J_ASSERT(PageLocked(page));
-
- head = page_buffers(page);
- bh = head;
- do {
- struct journal_head *jh;
-
- /*
- * We take our own ref against the journal_head here to avoid
- * having to add tons of locking around each instance of
- * journal_put_journal_head().
- */
- jh = journal_grab_journal_head(bh);
- if (!jh)
- continue;
-
- jbd_lock_bh_state(bh);
- __journal_try_to_free_buffer(journal, bh);
- journal_put_journal_head(jh);
- jbd_unlock_bh_state(bh);
- if (buffer_jbd(bh))
- goto busy;
- } while ((bh = bh->b_this_page) != head);
-
- ret = try_to_free_buffers(page);
-
-busy:
- return ret;
-}
-
-/*
- * This buffer is no longer needed. If it is on an older transaction's
- * checkpoint list we need to record it on this transaction's forget list
- * to pin this buffer (and hence its checkpointing transaction) down until
- * this transaction commits. If the buffer isn't on a checkpoint list, we
- * release it.
- * Returns non-zero if JBD no longer has an interest in the buffer.
- *
- * Called under j_list_lock.
- *
- * Called under jbd_lock_bh_state(bh).
- */
-static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
-{
- int may_free = 1;
- struct buffer_head *bh = jh2bh(jh);
-
- if (jh->b_cp_transaction) {
- JBUFFER_TRACE(jh, "on running+cp transaction");
- __journal_temp_unlink_buffer(jh);
- /*
- * We don't want to write the buffer anymore, clear the
- * bit so that we don't confuse checks in
- * __journal_file_buffer
- */
- clear_buffer_dirty(bh);
- __journal_file_buffer(jh, transaction, BJ_Forget);
- may_free = 0;
- } else {
- JBUFFER_TRACE(jh, "on running transaction");
- __journal_unfile_buffer(jh);
- }
- return may_free;
-}
-
-/*
- * journal_invalidatepage
- *
- * This code is tricky. It has a number of cases to deal with.
- *
- * There are two invariants which this code relies on:
- *
- * i_size must be updated on disk before we start calling invalidatepage on the
- * data.
- *
- * This is done in ext3 by defining an ext3_setattr method which
- * updates i_size before truncate gets going. By maintaining this
- * invariant, we can be sure that it is safe to throw away any buffers
- * attached to the current transaction: once the transaction commits,
- * we know that the data will not be needed.
- *
- * Note however that we can *not* throw away data belonging to the
- * previous, committing transaction!
- *
- * Any disk blocks which *are* part of the previous, committing
- * transaction (and which therefore cannot be discarded immediately) are
- * not going to be reused in the new running transaction
- *
- * The bitmap committed_data images guarantee this: any block which is
- * allocated in one transaction and removed in the next will be marked
- * as in-use in the committed_data bitmap, so cannot be reused until
- * the next transaction to delete the block commits. This means that
- * leaving committing buffers dirty is quite safe: the disk blocks
- * cannot be reallocated to a different file and so buffer aliasing is
- * not possible.
- *
- *
- * The above applies mainly to ordered data mode. In writeback mode we
- * don't make guarantees about the order in which data hits disk --- in
- * particular we don't guarantee that new dirty data is flushed before
- * transaction commit --- so it is always safe just to discard data
- * immediately in that mode. --sct
- */
-
-/*
- * The journal_unmap_buffer helper function returns zero if the buffer
- * concerned remains pinned as an anonymous buffer belonging to an older
- * transaction.
- *
- * We're outside-transaction here. Either or both of j_running_transaction
- * and j_committing_transaction may be NULL.
- */
-static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
- int partial_page)
-{
- transaction_t *transaction;
- struct journal_head *jh;
- int may_free = 1;
-
- BUFFER_TRACE(bh, "entry");
-
-retry:
- /*
- * It is safe to proceed here without the j_list_lock because the
- * buffers cannot be stolen by try_to_free_buffers as long as we are
- * holding the page lock. --sct
- */
-
- if (!buffer_jbd(bh))
- goto zap_buffer_unlocked;
-
- spin_lock(&journal->j_state_lock);
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
-
- jh = journal_grab_journal_head(bh);
- if (!jh)
- goto zap_buffer_no_jh;
-
- /*
- * We cannot remove the buffer from checkpoint lists until the
- * transaction adding inode to orphan list (let's call it T)
- * is committed. Otherwise if the transaction changing the
- * buffer would be cleaned from the journal before T is
- * committed, a crash will cause that the correct contents of
- * the buffer will be lost. On the other hand we have to
- * clear the buffer dirty bit at latest at the moment when the
- * transaction marking the buffer as freed in the filesystem
- * structures is committed because from that moment on the
- * block can be reallocated and used by a different page.
- * Since the block hasn't been freed yet but the inode has
- * already been added to orphan list, it is safe for us to add
- * the buffer to BJ_Forget list of the newest transaction.
- *
- * Also we have to clear buffer_mapped flag of a truncated buffer
- * because the buffer_head may be attached to the page straddling
- * i_size (can happen only when blocksize < pagesize) and thus the
- * buffer_head can be reused when the file is extended again. So we end
- * up keeping around invalidated buffers attached to transactions'
- * BJ_Forget list just to stop checkpointing code from cleaning up
- * the transaction this buffer was modified in.
- */
- transaction = jh->b_transaction;
- if (transaction == NULL) {
- /* First case: not on any transaction. If it
- * has no checkpoint link, then we can zap it:
- * it's a writeback-mode buffer so we don't care
- * if it hits disk safely. */
- if (!jh->b_cp_transaction) {
- JBUFFER_TRACE(jh, "not on any transaction: zap");
- goto zap_buffer;
- }
-
- if (!buffer_dirty(bh)) {
- /* bdflush has written it. We can drop it now */
- goto zap_buffer;
- }
-
- /* OK, it must be in the journal but still not
- * written fully to disk: it's metadata or
- * journaled data... */
-
- if (journal->j_running_transaction) {
- /* ... and once the current transaction has
- * committed, the buffer won't be needed any
- * longer. */
- JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
- may_free = __dispose_buffer(jh,
- journal->j_running_transaction);
- goto zap_buffer;
- } else {
- /* There is no currently-running transaction. So the
- * orphan record which we wrote for this file must have
- * passed into commit. We must attach this buffer to
- * the committing transaction, if it exists. */
- if (journal->j_committing_transaction) {
- JBUFFER_TRACE(jh, "give to committing trans");
- may_free = __dispose_buffer(jh,
- journal->j_committing_transaction);
- goto zap_buffer;
- } else {
- /* The orphan record's transaction has
- * committed. We can cleanse this buffer */
- clear_buffer_jbddirty(bh);
- goto zap_buffer;
- }
- }
- } else if (transaction == journal->j_committing_transaction) {
- JBUFFER_TRACE(jh, "on committing transaction");
- if (jh->b_jlist == BJ_Locked) {
- /*
- * The buffer is on the committing transaction's locked
- * list. We have the buffer locked, so I/O has
- * completed. So we can nail the buffer now.
- */
- may_free = __dispose_buffer(jh, transaction);
- goto zap_buffer;
- }
- /*
- * The buffer is committing, we simply cannot touch
- * it. If the page is straddling i_size we have to wait
- * for commit and try again.
- */
- if (partial_page) {
- tid_t tid = journal->j_committing_transaction->t_tid;
-
- journal_put_journal_head(jh);
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- spin_unlock(&journal->j_state_lock);
- unlock_buffer(bh);
- log_wait_commit(journal, tid);
- lock_buffer(bh);
- goto retry;
- }
- /*
- * OK, buffer won't be reachable after truncate. We just set
- * j_next_transaction to the running transaction (if there is
- * one) and mark buffer as freed so that commit code knows it
- * should clear dirty bits when it is done with the buffer.
- */
- set_buffer_freed(bh);
- if (journal->j_running_transaction && buffer_jbddirty(bh))
- jh->b_next_transaction = journal->j_running_transaction;
- journal_put_journal_head(jh);
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- spin_unlock(&journal->j_state_lock);
- return 0;
- } else {
- /* Good, the buffer belongs to the running transaction.
- * We are writing our own transaction's data, not any
- * previous one's, so it is safe to throw it away
- * (remember that we expect the filesystem to have set
- * i_size already for this truncate so recovery will not
- * expose the disk blocks we are discarding here.) */
- J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
- JBUFFER_TRACE(jh, "on running transaction");
- may_free = __dispose_buffer(jh, transaction);
- }
-
-zap_buffer:
- /*
- * This is tricky. Although the buffer is truncated, it may be reused
- * if blocksize < pagesize and it is attached to the page straddling
- * EOF. Since the buffer might have been added to BJ_Forget list of the
- * running transaction, journal_get_write_access() won't clear
- * b_modified and credit accounting gets confused. So clear b_modified
- * here. */
- jh->b_modified = 0;
- journal_put_journal_head(jh);
-zap_buffer_no_jh:
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- spin_unlock(&journal->j_state_lock);
-zap_buffer_unlocked:
- clear_buffer_dirty(bh);
- J_ASSERT_BH(bh, !buffer_jbddirty(bh));
- clear_buffer_mapped(bh);
- clear_buffer_req(bh);
- clear_buffer_new(bh);
- bh->b_bdev = NULL;
- return may_free;
-}
-
-/**
- * void journal_invalidatepage() - invalidate a journal page
- * @journal: journal to use for flush
- * @page: page to flush
- * @offset: offset of the range to invalidate
- * @length: length of the range to invalidate
- *
- * Reap page buffers containing data in specified range in page.
- */
-void journal_invalidatepage(journal_t *journal,
- struct page *page,
- unsigned int offset,
- unsigned int length)
-{
- struct buffer_head *head, *bh, *next;
- unsigned int stop = offset + length;
- unsigned int curr_off = 0;
- int partial_page = (offset || length < PAGE_CACHE_SIZE);
- int may_free = 1;
-
- if (!PageLocked(page))
- BUG();
- if (!page_has_buffers(page))
- return;
-
- BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
-
- /* We will potentially be playing with lists other than just the
- * data lists (especially for journaled data mode), so be
- * cautious in our locking. */
-
- head = bh = page_buffers(page);
- do {
- unsigned int next_off = curr_off + bh->b_size;
- next = bh->b_this_page;
-
- if (next_off > stop)
- return;
-
- if (offset <= curr_off) {
- /* This block is wholly outside the truncation point */
- lock_buffer(bh);
- may_free &= journal_unmap_buffer(journal, bh,
- partial_page);
- unlock_buffer(bh);
- }
- curr_off = next_off;
- bh = next;
-
- } while (bh != head);
-
- if (!partial_page) {
- if (may_free && try_to_free_buffers(page))
- J_ASSERT(!page_has_buffers(page));
- }
-}
-
-/*
- * File a buffer on the given transaction list.
- */
-void __journal_file_buffer(struct journal_head *jh,
- transaction_t *transaction, int jlist)
-{
- struct journal_head **list = NULL;
- int was_dirty = 0;
- struct buffer_head *bh = jh2bh(jh);
-
- J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
- assert_spin_locked(&transaction->t_journal->j_list_lock);
-
- J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
- J_ASSERT_JH(jh, jh->b_transaction == transaction ||
- jh->b_transaction == NULL);
-
- if (jh->b_transaction && jh->b_jlist == jlist)
- return;
-
- if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
- jlist == BJ_Shadow || jlist == BJ_Forget) {
- /*
- * For metadata buffers, we track dirty bit in buffer_jbddirty
- * instead of buffer_dirty. We should not see a dirty bit set
- * here because we clear it in do_get_write_access but e.g.
- * tune2fs can modify the sb and set the dirty bit at any time
- * so we try to gracefully handle that.
- */
- if (buffer_dirty(bh))
- warn_dirty_buffer(bh);
- if (test_clear_buffer_dirty(bh) ||
- test_clear_buffer_jbddirty(bh))
- was_dirty = 1;
- }
-
- if (jh->b_transaction)
- __journal_temp_unlink_buffer(jh);
- else
- journal_grab_journal_head(bh);
- jh->b_transaction = transaction;
-
- switch (jlist) {
- case BJ_None:
- J_ASSERT_JH(jh, !jh->b_committed_data);
- J_ASSERT_JH(jh, !jh->b_frozen_data);
- return;
- case BJ_SyncData:
- list = &transaction->t_sync_datalist;
- break;
- case BJ_Metadata:
- transaction->t_nr_buffers++;
- list = &transaction->t_buffers;
- break;
- case BJ_Forget:
- list = &transaction->t_forget;
- break;
- case BJ_IO:
- list = &transaction->t_iobuf_list;
- break;
- case BJ_Shadow:
- list = &transaction->t_shadow_list;
- break;
- case BJ_LogCtl:
- list = &transaction->t_log_list;
- break;
- case BJ_Reserved:
- list = &transaction->t_reserved_list;
- break;
- case BJ_Locked:
- list = &transaction->t_locked_list;
- break;
- }
-
- __blist_add_buffer(list, jh);
- jh->b_jlist = jlist;
-
- if (was_dirty)
- set_buffer_jbddirty(bh);
-}
-
-void journal_file_buffer(struct journal_head *jh,
- transaction_t *transaction, int jlist)
-{
- jbd_lock_bh_state(jh2bh(jh));
- spin_lock(&transaction->t_journal->j_list_lock);
- __journal_file_buffer(jh, transaction, jlist);
- spin_unlock(&transaction->t_journal->j_list_lock);
- jbd_unlock_bh_state(jh2bh(jh));
-}
-
-/*
- * Remove a buffer from its current buffer list in preparation for
- * dropping it from its current transaction entirely. If the buffer has
- * already started to be used by a subsequent transaction, refile the
- * buffer on that transaction's metadata list.
- *
- * Called under j_list_lock
- * Called under jbd_lock_bh_state(jh2bh(jh))
- *
- * jh and bh may be already free when this function returns
- */
-void __journal_refile_buffer(struct journal_head *jh)
-{
- int was_dirty, jlist;
- struct buffer_head *bh = jh2bh(jh);
-
- J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
- if (jh->b_transaction)
- assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
-
- /* If the buffer is now unused, just drop it. */
- if (jh->b_next_transaction == NULL) {
- __journal_unfile_buffer(jh);
- return;
- }
-
- /*
- * It has been modified by a later transaction: add it to the new
- * transaction's metadata list.
- */
-
- was_dirty = test_clear_buffer_jbddirty(bh);
- __journal_temp_unlink_buffer(jh);
- /*
- * We set b_transaction here because b_next_transaction will inherit
- * our jh reference and thus __journal_file_buffer() must not take a
- * new one.
- */
- jh->b_transaction = jh->b_next_transaction;
- jh->b_next_transaction = NULL;
- if (buffer_freed(bh))
- jlist = BJ_Forget;
- else if (jh->b_modified)
- jlist = BJ_Metadata;
- else
- jlist = BJ_Reserved;
- __journal_file_buffer(jh, jh->b_transaction, jlist);
- J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
-
- if (was_dirty)
- set_buffer_jbddirty(bh);
-}
-
-/*
- * __journal_refile_buffer() with necessary locking added. We take our bh
- * reference so that we can safely unlock bh.
- *
- * The jh and bh may be freed by this call.
- */
-void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
-{
- struct buffer_head *bh = jh2bh(jh);
-
- /* Get reference so that buffer cannot be freed before we unlock it */
- get_bh(bh);
- jbd_lock_bh_state(bh);
- spin_lock(&journal->j_list_lock);
- __journal_refile_buffer(jh);
- jbd_unlock_bh_state(bh);
- spin_unlock(&journal->j_list_lock);
- __brelse(bh);
-}
Code Review / kvmfornfv.git / blobdiff