diff options
Diffstat (limited to 'fs/jbd/transaction.c')
| -rw-r--r-- | fs/jbd/transaction.c | 2237 |
1 files changed, 0 insertions, 2237 deletions
diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c deleted file mode 100644 index 1695ba8334a2..000000000000 --- a/fs/jbd/transaction.c +++ /dev/null @@ -1,2237 +0,0 @@ -/* - * 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); -} |