linux/fs/jbd/journal.c
Jan Kara 8fe4cd0dc5 jbd: fix return value of journal_start_commit()
journal_start_commit() returns 1 if either a transaction is committing or
the function has queued a transaction commit.  But it returns 0 if we
raced with somebody queueing the transaction commit as well.  This
resulted in ext3_sync_fs() not functioning correctly (description from
Arthur Jones): In the case of a data=ordered umount with pending long
symlinks which are delayed due to a long list of other I/O on the backing
block device, this causes the buffer associated with the long symlinks to
not be moved to the inode dirty list in the second phase of fsync_super.
Then, before they can be dirtied again, kjournald exits, seeing the UMOUNT
flag and the dirty pages are never written to the backing block device,
causing long symlink corruption and exposing new or previously freed block
data to userspace.

This can be reproduced with a script created by Eric Sandeen
<sandeen@redhat.com>:

        #!/bin/bash

        umount /mnt/test2
        mount /dev/sdb4 /mnt/test2
        rm -f /mnt/test2/*
        dd if=/dev/zero of=/mnt/test2/bigfile bs=1M count=512
        touch /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename
        ln -s /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename
        /mnt/test2/link
        umount /mnt/test2
        mount /dev/sdb4 /mnt/test2
        ls /mnt/test2/

This patch fixes journal_start_commit() to always return 1 when there's
a transaction committing or queued for commit.

Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Mike Snitzer <snitzer@gmail.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-11 14:25:35 -08:00

1986 lines
53 KiB
C

/*
* linux/fs/jbd/journal.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 journal-writing code; part of the ext2fs
* journaling system.
*
* This file manages journals: areas of disk reserved for logging
* transactional updates. This includes the kernel journaling thread
* which is responsible for scheduling updates to the log.
*
* We do not actually manage the physical storage of the journal in this
* file: that is left to a per-journal policy function, which allows us
* to store the journal within a filesystem-specified area for ext2
* journaling (ext2 can use a reserved inode for storing the log).
*/
#include <linux/module.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/jbd.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/freezer.h>
#include <linux/pagemap.h>
#include <linux/kthread.h>
#include <linux/poison.h>
#include <linux/proc_fs.h>
#include <linux/debugfs.h>
#include <asm/uaccess.h>
#include <asm/page.h>
EXPORT_SYMBOL(journal_start);
EXPORT_SYMBOL(journal_restart);
EXPORT_SYMBOL(journal_extend);
EXPORT_SYMBOL(journal_stop);
EXPORT_SYMBOL(journal_lock_updates);
EXPORT_SYMBOL(journal_unlock_updates);
EXPORT_SYMBOL(journal_get_write_access);
EXPORT_SYMBOL(journal_get_create_access);
EXPORT_SYMBOL(journal_get_undo_access);
EXPORT_SYMBOL(journal_dirty_data);
EXPORT_SYMBOL(journal_dirty_metadata);
EXPORT_SYMBOL(journal_release_buffer);
EXPORT_SYMBOL(journal_forget);
#if 0
EXPORT_SYMBOL(journal_sync_buffer);
#endif
EXPORT_SYMBOL(journal_flush);
EXPORT_SYMBOL(journal_revoke);
EXPORT_SYMBOL(journal_init_dev);
EXPORT_SYMBOL(journal_init_inode);
EXPORT_SYMBOL(journal_update_format);
EXPORT_SYMBOL(journal_check_used_features);
EXPORT_SYMBOL(journal_check_available_features);
EXPORT_SYMBOL(journal_set_features);
EXPORT_SYMBOL(journal_create);
EXPORT_SYMBOL(journal_load);
EXPORT_SYMBOL(journal_destroy);
EXPORT_SYMBOL(journal_abort);
EXPORT_SYMBOL(journal_errno);
EXPORT_SYMBOL(journal_ack_err);
EXPORT_SYMBOL(journal_clear_err);
EXPORT_SYMBOL(log_wait_commit);
EXPORT_SYMBOL(journal_start_commit);
EXPORT_SYMBOL(journal_force_commit_nested);
EXPORT_SYMBOL(journal_wipe);
EXPORT_SYMBOL(journal_blocks_per_page);
EXPORT_SYMBOL(journal_invalidatepage);
EXPORT_SYMBOL(journal_try_to_free_buffers);
EXPORT_SYMBOL(journal_force_commit);
static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
static void __journal_abort_soft (journal_t *journal, int errno);
/*
* Helper function used to manage commit timeouts
*/
static void commit_timeout(unsigned long __data)
{
struct task_struct * p = (struct task_struct *) __data;
wake_up_process(p);
}
/*
* kjournald: The main thread function used to manage a logging device
* journal.
*
* This kernel thread is responsible for two things:
*
* 1) COMMIT: Every so often we need to commit the current state of the
* filesystem to disk. The journal thread is responsible for writing
* all of the metadata buffers to disk.
*
* 2) CHECKPOINT: We cannot reuse a used section of the log file until all
* of the data in that part of the log has been rewritten elsewhere on
* the disk. Flushing these old buffers to reclaim space in the log is
* known as checkpointing, and this thread is responsible for that job.
*/
static int kjournald(void *arg)
{
journal_t *journal = arg;
transaction_t *transaction;
/*
* Set up an interval timer which can be used to trigger a commit wakeup
* after the commit interval expires
*/
setup_timer(&journal->j_commit_timer, commit_timeout,
(unsigned long)current);
/* Record that the journal thread is running */
journal->j_task = current;
wake_up(&journal->j_wait_done_commit);
printk(KERN_INFO "kjournald starting. Commit interval %ld seconds\n",
journal->j_commit_interval / HZ);
/*
* And now, wait forever for commit wakeup events.
*/
spin_lock(&journal->j_state_lock);
loop:
if (journal->j_flags & JFS_UNMOUNT)
goto end_loop;
jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
journal->j_commit_sequence, journal->j_commit_request);
if (journal->j_commit_sequence != journal->j_commit_request) {
jbd_debug(1, "OK, requests differ\n");
spin_unlock(&journal->j_state_lock);
del_timer_sync(&journal->j_commit_timer);
journal_commit_transaction(journal);
spin_lock(&journal->j_state_lock);
goto loop;
}
wake_up(&journal->j_wait_done_commit);
if (freezing(current)) {
/*
* The simpler the better. Flushing journal isn't a
* good idea, because that depends on threads that may
* be already stopped.
*/
jbd_debug(1, "Now suspending kjournald\n");
spin_unlock(&journal->j_state_lock);
refrigerator();
spin_lock(&journal->j_state_lock);
} else {
/*
* We assume on resume that commits are already there,
* so we don't sleep
*/
DEFINE_WAIT(wait);
int should_sleep = 1;
prepare_to_wait(&journal->j_wait_commit, &wait,
TASK_INTERRUPTIBLE);
if (journal->j_commit_sequence != journal->j_commit_request)
should_sleep = 0;
transaction = journal->j_running_transaction;
if (transaction && time_after_eq(jiffies,
transaction->t_expires))
should_sleep = 0;
if (journal->j_flags & JFS_UNMOUNT)
should_sleep = 0;
if (should_sleep) {
spin_unlock(&journal->j_state_lock);
schedule();
spin_lock(&journal->j_state_lock);
}
finish_wait(&journal->j_wait_commit, &wait);
}
jbd_debug(1, "kjournald wakes\n");
/*
* Were we woken up by a commit wakeup event?
*/
transaction = journal->j_running_transaction;
if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
journal->j_commit_request = transaction->t_tid;
jbd_debug(1, "woke because of timeout\n");
}
goto loop;
end_loop:
spin_unlock(&journal->j_state_lock);
del_timer_sync(&journal->j_commit_timer);
journal->j_task = NULL;
wake_up(&journal->j_wait_done_commit);
jbd_debug(1, "Journal thread exiting.\n");
return 0;
}
static int journal_start_thread(journal_t *journal)
{
struct task_struct *t;
t = kthread_run(kjournald, journal, "kjournald");
if (IS_ERR(t))
return PTR_ERR(t);
wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
return 0;
}
static void journal_kill_thread(journal_t *journal)
{
spin_lock(&journal->j_state_lock);
journal->j_flags |= JFS_UNMOUNT;
while (journal->j_task) {
wake_up(&journal->j_wait_commit);
spin_unlock(&journal->j_state_lock);
wait_event(journal->j_wait_done_commit,
journal->j_task == NULL);
spin_lock(&journal->j_state_lock);
}
spin_unlock(&journal->j_state_lock);
}
/*
* journal_write_metadata_buffer: write a metadata buffer to the journal.
*
* Writes a metadata buffer to a given disk block. The actual IO is not
* performed but a new buffer_head is constructed which labels the data
* to be written with the correct destination disk block.
*
* Any magic-number escaping which needs to be done will cause a
* copy-out here. If the buffer happens to start with the
* JFS_MAGIC_NUMBER, then we can't write it to the log directly: the
* magic number is only written to the log for descripter blocks. In
* this case, we copy the data and replace the first word with 0, and we
* return a result code which indicates that this buffer needs to be
* marked as an escaped buffer in the corresponding log descriptor
* block. The missing word can then be restored when the block is read
* during recovery.
*
* If the source buffer has already been modified by a new transaction
* since we took the last commit snapshot, we use the frozen copy of
* that data for IO. If we end up using the existing buffer_head's data
* for the write, then we *have* to lock the buffer to prevent anyone
* else from using and possibly modifying it while the IO is in
* progress.
*
* The function returns a pointer to the buffer_heads to be used for IO.
*
* We assume that the journal has already been locked in this function.
*
* Return value:
* <0: Error
* >=0: Finished OK
*
* On success:
* Bit 0 set == escape performed on the data
* Bit 1 set == buffer copy-out performed (kfree the data after IO)
*/
int journal_write_metadata_buffer(transaction_t *transaction,
struct journal_head *jh_in,
struct journal_head **jh_out,
unsigned long blocknr)
{
int need_copy_out = 0;
int done_copy_out = 0;
int do_escape = 0;
char *mapped_data;
struct buffer_head *new_bh;
struct journal_head *new_jh;
struct page *new_page;
unsigned int new_offset;
struct buffer_head *bh_in = jh2bh(jh_in);
/*
* The buffer really shouldn't be locked: only the current committing
* transaction is allowed to write it, so nobody else is allowed
* to do any IO.
*
* akpm: except if we're journalling data, and write() output is
* also part of a shared mapping, and another thread has
* decided to launch a writepage() against this buffer.
*/
J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
/*
* If a new transaction has already done a buffer copy-out, then
* we use that version of the data for the commit.
*/
jbd_lock_bh_state(bh_in);
repeat:
if (jh_in->b_frozen_data) {
done_copy_out = 1;
new_page = virt_to_page(jh_in->b_frozen_data);
new_offset = offset_in_page(jh_in->b_frozen_data);
} else {
new_page = jh2bh(jh_in)->b_page;
new_offset = offset_in_page(jh2bh(jh_in)->b_data);
}
mapped_data = kmap_atomic(new_page, KM_USER0);
/*
* Check for escaping
*/
if (*((__be32 *)(mapped_data + new_offset)) ==
cpu_to_be32(JFS_MAGIC_NUMBER)) {
need_copy_out = 1;
do_escape = 1;
}
kunmap_atomic(mapped_data, KM_USER0);
/*
* Do we need to do a data copy?
*/
if (need_copy_out && !done_copy_out) {
char *tmp;
jbd_unlock_bh_state(bh_in);
tmp = jbd_alloc(bh_in->b_size, GFP_NOFS);
jbd_lock_bh_state(bh_in);
if (jh_in->b_frozen_data) {
jbd_free(tmp, bh_in->b_size);
goto repeat;
}
jh_in->b_frozen_data = tmp;
mapped_data = kmap_atomic(new_page, KM_USER0);
memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
kunmap_atomic(mapped_data, KM_USER0);
new_page = virt_to_page(tmp);
new_offset = offset_in_page(tmp);
done_copy_out = 1;
}
/*
* Did we need to do an escaping? Now we've done all the
* copying, we can finally do so.
*/
if (do_escape) {
mapped_data = kmap_atomic(new_page, KM_USER0);
*((unsigned int *)(mapped_data + new_offset)) = 0;
kunmap_atomic(mapped_data, KM_USER0);
}
/* keep subsequent assertions sane */
new_bh->b_state = 0;
init_buffer(new_bh, NULL, NULL);
atomic_set(&new_bh->b_count, 1);
jbd_unlock_bh_state(bh_in);
new_jh = journal_add_journal_head(new_bh); /* This sleeps */
set_bh_page(new_bh, new_page, new_offset);
new_jh->b_transaction = NULL;
new_bh->b_size = jh2bh(jh_in)->b_size;
new_bh->b_bdev = transaction->t_journal->j_dev;
new_bh->b_blocknr = blocknr;
set_buffer_mapped(new_bh);
set_buffer_dirty(new_bh);
*jh_out = new_jh;
/*
* The to-be-written buffer needs to get moved to the io queue,
* and the original buffer whose contents we are shadowing or
* copying is moved to the transaction's shadow queue.
*/
JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
journal_file_buffer(jh_in, transaction, BJ_Shadow);
JBUFFER_TRACE(new_jh, "file as BJ_IO");
journal_file_buffer(new_jh, transaction, BJ_IO);
return do_escape | (done_copy_out << 1);
}
/*
* Allocation code for the journal file. Manage the space left in the
* journal, so that we can begin checkpointing when appropriate.
*/
/*
* __log_space_left: Return the number of free blocks left in the journal.
*
* Called with the journal already locked.
*
* Called under j_state_lock
*/
int __log_space_left(journal_t *journal)
{
int left = journal->j_free;
assert_spin_locked(&journal->j_state_lock);
/*
* Be pessimistic here about the number of those free blocks which
* might be required for log descriptor control blocks.
*/
#define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
left -= MIN_LOG_RESERVED_BLOCKS;
if (left <= 0)
return 0;
left -= (left >> 3);
return left;
}
/*
* Called under j_state_lock. Returns true if a transaction commit was started.
*/
int __log_start_commit(journal_t *journal, tid_t target)
{
/*
* Are we already doing a recent enough commit?
*/
if (!tid_geq(journal->j_commit_request, target)) {
/*
* We want a new commit: OK, mark the request and wakup the
* commit thread. We do _not_ do the commit ourselves.
*/
journal->j_commit_request = target;
jbd_debug(1, "JBD: requesting commit %d/%d\n",
journal->j_commit_request,
journal->j_commit_sequence);
wake_up(&journal->j_wait_commit);
return 1;
}
return 0;
}
int log_start_commit(journal_t *journal, tid_t tid)
{
int ret;
spin_lock(&journal->j_state_lock);
ret = __log_start_commit(journal, tid);
spin_unlock(&journal->j_state_lock);
return ret;
}
/*
* Force and wait upon a commit if the calling process is not within
* transaction. This is used for forcing out undo-protected data which contains
* bitmaps, when the fs is running out of space.
*
* We can only force the running transaction if we don't have an active handle;
* otherwise, we will deadlock.
*
* Returns true if a transaction was started.
*/
int journal_force_commit_nested(journal_t *journal)
{
transaction_t *transaction = NULL;
tid_t tid;
spin_lock(&journal->j_state_lock);
if (journal->j_running_transaction && !current->journal_info) {
transaction = journal->j_running_transaction;
__log_start_commit(journal, transaction->t_tid);
} else if (journal->j_committing_transaction)
transaction = journal->j_committing_transaction;
if (!transaction) {
spin_unlock(&journal->j_state_lock);
return 0; /* Nothing to retry */
}
tid = transaction->t_tid;
spin_unlock(&journal->j_state_lock);
log_wait_commit(journal, tid);
return 1;
}
/*
* Start a commit of the current running transaction (if any). Returns true
* if a transaction is going to be committed (or is currently already
* committing), and fills its tid in at *ptid
*/
int journal_start_commit(journal_t *journal, tid_t *ptid)
{
int ret = 0;
spin_lock(&journal->j_state_lock);
if (journal->j_running_transaction) {
tid_t tid = journal->j_running_transaction->t_tid;
__log_start_commit(journal, tid);
/* There's a running transaction and we've just made sure
* it's commit has been scheduled. */
if (ptid)
*ptid = tid;
ret = 1;
} else if (journal->j_committing_transaction) {
/*
* If ext3_write_super() recently started a commit, then we
* have to wait for completion of that transaction
*/
if (ptid)
*ptid = journal->j_committing_transaction->t_tid;
ret = 1;
}
spin_unlock(&journal->j_state_lock);
return ret;
}
/*
* Wait for a specified commit to complete.
* The caller may not hold the journal lock.
*/
int log_wait_commit(journal_t *journal, tid_t tid)
{
int err = 0;
#ifdef CONFIG_JBD_DEBUG
spin_lock(&journal->j_state_lock);
if (!tid_geq(journal->j_commit_request, tid)) {
printk(KERN_EMERG
"%s: error: j_commit_request=%d, tid=%d\n",
__func__, journal->j_commit_request, tid);
}
spin_unlock(&journal->j_state_lock);
#endif
spin_lock(&journal->j_state_lock);
while (tid_gt(tid, journal->j_commit_sequence)) {
jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
tid, journal->j_commit_sequence);
wake_up(&journal->j_wait_commit);
spin_unlock(&journal->j_state_lock);
wait_event(journal->j_wait_done_commit,
!tid_gt(tid, journal->j_commit_sequence));
spin_lock(&journal->j_state_lock);
}
spin_unlock(&journal->j_state_lock);
if (unlikely(is_journal_aborted(journal))) {
printk(KERN_EMERG "journal commit I/O error\n");
err = -EIO;
}
return err;
}
/*
* Log buffer allocation routines:
*/
int journal_next_log_block(journal_t *journal, unsigned long *retp)
{
unsigned long blocknr;
spin_lock(&journal->j_state_lock);
J_ASSERT(journal->j_free > 1);
blocknr = journal->j_head;
journal->j_head++;
journal->j_free--;
if (journal->j_head == journal->j_last)
journal->j_head = journal->j_first;
spin_unlock(&journal->j_state_lock);
return journal_bmap(journal, blocknr, retp);
}
/*
* Conversion of logical to physical block numbers for the journal
*
* On external journals the journal blocks are identity-mapped, so
* this is a no-op. If needed, we can use j_blk_offset - everything is
* ready.
*/
int journal_bmap(journal_t *journal, unsigned long blocknr,
unsigned long *retp)
{
int err = 0;
unsigned long ret;
if (journal->j_inode) {
ret = bmap(journal->j_inode, blocknr);
if (ret)
*retp = ret;
else {
char b[BDEVNAME_SIZE];
printk(KERN_ALERT "%s: journal block not found "
"at offset %lu on %s\n",
__func__,
blocknr,
bdevname(journal->j_dev, b));
err = -EIO;
__journal_abort_soft(journal, err);
}
} else {
*retp = blocknr; /* +journal->j_blk_offset */
}
return err;
}
/*
* We play buffer_head aliasing tricks to write data/metadata blocks to
* the journal without copying their contents, but for journal
* descriptor blocks we do need to generate bona fide buffers.
*
* After the caller of journal_get_descriptor_buffer() has finished modifying
* the buffer's contents they really should run flush_dcache_page(bh->b_page).
* But we don't bother doing that, so there will be coherency problems with
* mmaps of blockdevs which hold live JBD-controlled filesystems.
*/
struct journal_head *journal_get_descriptor_buffer(journal_t *journal)
{
struct buffer_head *bh;
unsigned long blocknr;
int err;
err = journal_next_log_block(journal, &blocknr);
if (err)
return NULL;
bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
lock_buffer(bh);
memset(bh->b_data, 0, journal->j_blocksize);
set_buffer_uptodate(bh);
unlock_buffer(bh);
BUFFER_TRACE(bh, "return this buffer");
return journal_add_journal_head(bh);
}
/*
* Management for journal control blocks: functions to create and
* destroy journal_t structures, and to initialise and read existing
* journal blocks from disk. */
/* First: create and setup a journal_t object in memory. We initialise
* very few fields yet: that has to wait until we have created the
* journal structures from from scratch, or loaded them from disk. */
static journal_t * journal_init_common (void)
{
journal_t *journal;
int err;
journal = kzalloc(sizeof(*journal), GFP_KERNEL);
if (!journal)
goto fail;
init_waitqueue_head(&journal->j_wait_transaction_locked);
init_waitqueue_head(&journal->j_wait_logspace);
init_waitqueue_head(&journal->j_wait_done_commit);
init_waitqueue_head(&journal->j_wait_checkpoint);
init_waitqueue_head(&journal->j_wait_commit);
init_waitqueue_head(&journal->j_wait_updates);
mutex_init(&journal->j_barrier);
mutex_init(&journal->j_checkpoint_mutex);
spin_lock_init(&journal->j_revoke_lock);
spin_lock_init(&journal->j_list_lock);
spin_lock_init(&journal->j_state_lock);
journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE);
/* The journal is marked for error until we succeed with recovery! */
journal->j_flags = JFS_ABORT;
/* Set up a default-sized revoke table for the new mount. */
err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
if (err) {
kfree(journal);
goto fail;
}
return journal;
fail:
return NULL;
}
/* journal_init_dev and journal_init_inode:
*
* Create a journal structure assigned some fixed set of disk blocks to
* the journal. We don't actually touch those disk blocks yet, but we
* need to set up all of the mapping information to tell the journaling
* system where the journal blocks are.
*
*/
/**
* journal_t * journal_init_dev() - creates and initialises a journal structure
* @bdev: Block device on which to create the journal
* @fs_dev: Device which hold journalled filesystem for this journal.
* @start: Block nr Start of journal.
* @len: Length of the journal in blocks.
* @blocksize: blocksize of journalling device
*
* Returns: a newly created journal_t *
*
* journal_init_dev creates a journal which maps a fixed contiguous
* range of blocks on an arbitrary block device.
*
*/
journal_t * journal_init_dev(struct block_device *bdev,
struct block_device *fs_dev,
int start, int len, int blocksize)
{
journal_t *journal = journal_init_common();
struct buffer_head *bh;
int n;
if (!journal)
return NULL;
/* journal descriptor can store up to n blocks -bzzz */
journal->j_blocksize = blocksize;
n = journal->j_blocksize / sizeof(journal_block_tag_t);
journal->j_wbufsize = n;
journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
if (!journal->j_wbuf) {
printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
__func__);
kfree(journal);
journal = NULL;
goto out;
}
journal->j_dev = bdev;
journal->j_fs_dev = fs_dev;
journal->j_blk_offset = start;
journal->j_maxlen = len;
bh = __getblk(journal->j_dev, start, journal->j_blocksize);
J_ASSERT(bh != NULL);
journal->j_sb_buffer = bh;
journal->j_superblock = (journal_superblock_t *)bh->b_data;
out:
return journal;
}
/**
* journal_t * journal_init_inode () - creates a journal which maps to a inode.
* @inode: An inode to create the journal in
*
* journal_init_inode creates a journal which maps an on-disk inode as
* the journal. The inode must exist already, must support bmap() and
* must have all data blocks preallocated.
*/
journal_t * journal_init_inode (struct inode *inode)
{
struct buffer_head *bh;
journal_t *journal = journal_init_common();
int err;
int n;
unsigned long blocknr;
if (!journal)
return NULL;
journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
journal->j_inode = inode;
jbd_debug(1,
"journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
journal, inode->i_sb->s_id, inode->i_ino,
(long long) inode->i_size,
inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
journal->j_blocksize = inode->i_sb->s_blocksize;
/* journal descriptor can store up to n blocks -bzzz */
n = journal->j_blocksize / sizeof(journal_block_tag_t);
journal->j_wbufsize = n;
journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
if (!journal->j_wbuf) {
printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
__func__);
kfree(journal);
return NULL;
}
err = journal_bmap(journal, 0, &blocknr);
/* If that failed, give up */
if (err) {
printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
__func__);
kfree(journal);
return NULL;
}
bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
J_ASSERT(bh != NULL);
journal->j_sb_buffer = bh;
journal->j_superblock = (journal_superblock_t *)bh->b_data;
return journal;
}
/*
* If the journal init or create aborts, we need to mark the journal
* superblock as being NULL to prevent the journal destroy from writing
* back a bogus superblock.
*/
static void journal_fail_superblock (journal_t *journal)
{
struct buffer_head *bh = journal->j_sb_buffer;
brelse(bh);
journal->j_sb_buffer = NULL;
}
/*
* Given a journal_t structure, initialise the various fields for
* startup of a new journaling session. We use this both when creating
* a journal, and after recovering an old journal to reset it for
* subsequent use.
*/
static int journal_reset(journal_t *journal)
{
journal_superblock_t *sb = journal->j_superblock;
unsigned long first, last;
first = be32_to_cpu(sb->s_first);
last = be32_to_cpu(sb->s_maxlen);
journal->j_first = first;
journal->j_last = last;
journal->j_head = first;
journal->j_tail = first;
journal->j_free = last - first;
journal->j_tail_sequence = journal->j_transaction_sequence;
journal->j_commit_sequence = journal->j_transaction_sequence - 1;
journal->j_commit_request = journal->j_commit_sequence;
journal->j_max_transaction_buffers = journal->j_maxlen / 4;
/* Add the dynamic fields and write it to disk. */
journal_update_superblock(journal, 1);
return journal_start_thread(journal);
}
/**
* int journal_create() - Initialise the new journal file
* @journal: Journal to create. This structure must have been initialised
*
* Given a journal_t structure which tells us which disk blocks we can
* use, create a new journal superblock and initialise all of the
* journal fields from scratch.
**/
int journal_create(journal_t *journal)
{
unsigned long blocknr;
struct buffer_head *bh;
journal_superblock_t *sb;
int i, err;
if (journal->j_maxlen < JFS_MIN_JOURNAL_BLOCKS) {
printk (KERN_ERR "Journal length (%d blocks) too short.\n",
journal->j_maxlen);
journal_fail_superblock(journal);
return -EINVAL;
}
if (journal->j_inode == NULL) {
/*
* We don't know what block to start at!
*/
printk(KERN_EMERG
"%s: creation of journal on external device!\n",
__func__);
BUG();
}
/* Zero out the entire journal on disk. We cannot afford to
have any blocks on disk beginning with JFS_MAGIC_NUMBER. */
jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
for (i = 0; i < journal->j_maxlen; i++) {
err = journal_bmap(journal, i, &blocknr);
if (err)
return err;
bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
lock_buffer(bh);
memset (bh->b_data, 0, journal->j_blocksize);
BUFFER_TRACE(bh, "marking dirty");
mark_buffer_dirty(bh);
BUFFER_TRACE(bh, "marking uptodate");
set_buffer_uptodate(bh);
unlock_buffer(bh);
__brelse(bh);
}
sync_blockdev(journal->j_dev);
jbd_debug(1, "JBD: journal cleared.\n");
/* OK, fill in the initial static fields in the new superblock */
sb = journal->j_superblock;
sb->s_header.h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
sb->s_maxlen = cpu_to_be32(journal->j_maxlen);
sb->s_first = cpu_to_be32(1);
journal->j_transaction_sequence = 1;
journal->j_flags &= ~JFS_ABORT;
journal->j_format_version = 2;
return journal_reset(journal);
}
/**
* void journal_update_superblock() - Update journal sb on disk.
* @journal: The journal to update.
* @wait: Set to '0' if you don't want to wait for IO completion.
*
* Update a journal's dynamic superblock fields and write it to disk,
* optionally waiting for the IO to complete.
*/
void journal_update_superblock(journal_t *journal, int wait)
{
journal_superblock_t *sb = journal->j_superblock;
struct buffer_head *bh = journal->j_sb_buffer;
/*
* As a special case, if the on-disk copy is already marked as needing
* no recovery (s_start == 0) and there are no outstanding transactions
* in the filesystem, then we can safely defer the superblock update
* until the next commit by setting JFS_FLUSHED. This avoids
* attempting a write to a potential-readonly device.
*/
if (sb->s_start == 0 && journal->j_tail_sequence ==
journal->j_transaction_sequence) {
jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
"(start %ld, seq %d, errno %d)\n",
journal->j_tail, journal->j_tail_sequence,
journal->j_errno);
goto out;
}
spin_lock(&journal->j_state_lock);
jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
journal->j_tail, journal->j_tail_sequence, journal->j_errno);
sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
sb->s_start = cpu_to_be32(journal->j_tail);
sb->s_errno = cpu_to_be32(journal->j_errno);
spin_unlock(&journal->j_state_lock);
BUFFER_TRACE(bh, "marking dirty");
mark_buffer_dirty(bh);
if (wait)
sync_dirty_buffer(bh);
else
ll_rw_block(SWRITE, 1, &bh);
out:
/* If we have just flushed the log (by marking s_start==0), then
* any future commit will have to be careful to update the
* superblock again to re-record the true start of the log. */
spin_lock(&journal->j_state_lock);
if (sb->s_start)
journal->j_flags &= ~JFS_FLUSHED;
else
journal->j_flags |= JFS_FLUSHED;
spin_unlock(&journal->j_state_lock);
}
/*
* Read the superblock for a given journal, performing initial
* validation of the format.
*/
static int journal_get_superblock(journal_t *journal)
{
struct buffer_head *bh;
journal_superblock_t *sb;
int err = -EIO;
bh = journal->j_sb_buffer;
J_ASSERT(bh != NULL);
if (!buffer_uptodate(bh)) {
ll_rw_block(READ, 1, &bh);
wait_on_buffer(bh);
if (!buffer_uptodate(bh)) {
printk (KERN_ERR
"JBD: IO error reading journal superblock\n");
goto out;
}
}
sb = journal->j_superblock;
err = -EINVAL;
if (sb->s_header.h_magic != cpu_to_be32(JFS_MAGIC_NUMBER) ||
sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
printk(KERN_WARNING "JBD: no valid journal superblock found\n");
goto out;
}
switch(be32_to_cpu(sb->s_header.h_blocktype)) {
case JFS_SUPERBLOCK_V1:
journal->j_format_version = 1;
break;
case JFS_SUPERBLOCK_V2:
journal->j_format_version = 2;
break;
default:
printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
goto out;
}
if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
printk (KERN_WARNING "JBD: journal file too short\n");
goto out;
}
return 0;
out:
journal_fail_superblock(journal);
return err;
}
/*
* Load the on-disk journal superblock and read the key fields into the
* journal_t.
*/
static int load_superblock(journal_t *journal)
{
int err;
journal_superblock_t *sb;
err = journal_get_superblock(journal);
if (err)
return err;
sb = journal->j_superblock;
journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
journal->j_tail = be32_to_cpu(sb->s_start);
journal->j_first = be32_to_cpu(sb->s_first);
journal->j_last = be32_to_cpu(sb->s_maxlen);
journal->j_errno = be32_to_cpu(sb->s_errno);
return 0;
}
/**
* int journal_load() - Read journal from disk.
* @journal: Journal to act on.
*
* Given a journal_t structure which tells us which disk blocks contain
* a journal, read the journal from disk to initialise the in-memory
* structures.
*/
int journal_load(journal_t *journal)
{
int err;
journal_superblock_t *sb;
err = load_superblock(journal);
if (err)
return err;
sb = journal->j_superblock;
/* If this is a V2 superblock, then we have to check the
* features flags on it. */
if (journal->j_format_version >= 2) {
if ((sb->s_feature_ro_compat &
~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) ||
(sb->s_feature_incompat &
~cpu_to_be32(JFS_KNOWN_INCOMPAT_FEATURES))) {
printk (KERN_WARNING
"JBD: Unrecognised features on journal\n");
return -EINVAL;
}
}
/* Let the recovery code check whether it needs to recover any
* data from the journal. */
if (journal_recover(journal))
goto recovery_error;
/* OK, we've finished with the dynamic journal bits:
* reinitialise the dynamic contents of the superblock in memory
* and reset them on disk. */
if (journal_reset(journal))
goto recovery_error;
journal->j_flags &= ~JFS_ABORT;
journal->j_flags |= JFS_LOADED;
return 0;
recovery_error:
printk (KERN_WARNING "JBD: recovery failed\n");
return -EIO;
}
/**
* void journal_destroy() - Release a journal_t structure.
* @journal: Journal to act on.
*
* Release a journal_t structure once it is no longer in use by the
* journaled object.
* Return <0 if we couldn't clean up the journal.
*/
int journal_destroy(journal_t *journal)
{
int err = 0;
/* Wait for the commit thread to wake up and die. */
journal_kill_thread(journal);
/* Force a final log commit */
if (journal->j_running_transaction)
journal_commit_transaction(journal);
/* Force any old transactions to disk */
/* Totally anal locking here... */
spin_lock(&journal->j_list_lock);
while (journal->j_checkpoint_transactions != NULL) {
spin_unlock(&journal->j_list_lock);
log_do_checkpoint(journal);
spin_lock(&journal->j_list_lock);
}
J_ASSERT(journal->j_running_transaction == NULL);
J_ASSERT(journal->j_committing_transaction == NULL);
J_ASSERT(journal->j_checkpoint_transactions == NULL);
spin_unlock(&journal->j_list_lock);
if (journal->j_sb_buffer) {
if (!is_journal_aborted(journal)) {
/* We can now mark the journal as empty. */
journal->j_tail = 0;
journal->j_tail_sequence =
++journal->j_transaction_sequence;
journal_update_superblock(journal, 1);
} else {
err = -EIO;
}
brelse(journal->j_sb_buffer);
}
if (journal->j_inode)
iput(journal->j_inode);
if (journal->j_revoke)
journal_destroy_revoke(journal);
kfree(journal->j_wbuf);
kfree(journal);
return err;
}
/**
*int journal_check_used_features () - Check if features specified are used.
* @journal: Journal to check.
* @compat: bitmask of compatible features
* @ro: bitmask of features that force read-only mount
* @incompat: bitmask of incompatible features
*
* Check whether the journal uses all of a given set of
* features. Return true (non-zero) if it does.
**/
int journal_check_used_features (journal_t *journal, unsigned long compat,
unsigned long ro, unsigned long incompat)
{
journal_superblock_t *sb;
if (!compat && !ro && !incompat)
return 1;
if (journal->j_format_version == 1)
return 0;
sb = journal->j_superblock;
if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
return 1;
return 0;
}
/**
* int journal_check_available_features() - Check feature set in journalling layer
* @journal: Journal to check.
* @compat: bitmask of compatible features
* @ro: bitmask of features that force read-only mount
* @incompat: bitmask of incompatible features
*
* Check whether the journaling code supports the use of
* all of a given set of features on this journal. Return true
* (non-zero) if it can. */
int journal_check_available_features (journal_t *journal, unsigned long compat,
unsigned long ro, unsigned long incompat)
{
journal_superblock_t *sb;
if (!compat && !ro && !incompat)
return 1;
sb = journal->j_superblock;
/* We can support any known requested features iff the
* superblock is in version 2. Otherwise we fail to support any
* extended sb features. */
if (journal->j_format_version != 2)
return 0;
if ((compat & JFS_KNOWN_COMPAT_FEATURES) == compat &&
(ro & JFS_KNOWN_ROCOMPAT_FEATURES) == ro &&
(incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat)
return 1;
return 0;
}
/**
* int journal_set_features () - Mark a given journal feature in the superblock
* @journal: Journal to act on.
* @compat: bitmask of compatible features
* @ro: bitmask of features that force read-only mount
* @incompat: bitmask of incompatible features
*
* Mark a given journal feature as present on the
* superblock. Returns true if the requested features could be set.
*
*/
int journal_set_features (journal_t *journal, unsigned long compat,
unsigned long ro, unsigned long incompat)
{
journal_superblock_t *sb;
if (journal_check_used_features(journal, compat, ro, incompat))
return 1;
if (!journal_check_available_features(journal, compat, ro, incompat))
return 0;
jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
compat, ro, incompat);
sb = journal->j_superblock;
sb->s_feature_compat |= cpu_to_be32(compat);
sb->s_feature_ro_compat |= cpu_to_be32(ro);
sb->s_feature_incompat |= cpu_to_be32(incompat);
return 1;
}
/**
* int journal_update_format () - Update on-disk journal structure.
* @journal: Journal to act on.
*
* Given an initialised but unloaded journal struct, poke about in the
* on-disk structure to update it to the most recent supported version.
*/
int journal_update_format (journal_t *journal)
{
journal_superblock_t *sb;
int err;
err = journal_get_superblock(journal);
if (err)
return err;
sb = journal->j_superblock;
switch (be32_to_cpu(sb->s_header.h_blocktype)) {
case JFS_SUPERBLOCK_V2:
return 0;
case JFS_SUPERBLOCK_V1:
return journal_convert_superblock_v1(journal, sb);
default:
break;
}
return -EINVAL;
}
static int journal_convert_superblock_v1(journal_t *journal,
journal_superblock_t *sb)
{
int offset, blocksize;
struct buffer_head *bh;
printk(KERN_WARNING
"JBD: Converting superblock from version 1 to 2.\n");
/* Pre-initialise new fields to zero */
offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
blocksize = be32_to_cpu(sb->s_blocksize);
memset(&sb->s_feature_compat, 0, blocksize-offset);
sb->s_nr_users = cpu_to_be32(1);
sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
journal->j_format_version = 2;
bh = journal->j_sb_buffer;
BUFFER_TRACE(bh, "marking dirty");
mark_buffer_dirty(bh);
sync_dirty_buffer(bh);
return 0;
}
/**
* int journal_flush () - Flush journal
* @journal: Journal to act on.
*
* Flush all data for a given journal to disk and empty the journal.
* Filesystems can use this when remounting readonly to ensure that
* recovery does not need to happen on remount.
*/
int journal_flush(journal_t *journal)
{
int err = 0;
transaction_t *transaction = NULL;
unsigned long old_tail;
spin_lock(&journal->j_state_lock);
/* Force everything buffered to the log... */
if (journal->j_running_transaction) {
transaction = journal->j_running_transaction;
__log_start_commit(journal, transaction->t_tid);
} else if (journal->j_committing_transaction)
transaction = journal->j_committing_transaction;
/* Wait for the log commit to complete... */
if (transaction) {
tid_t tid = transaction->t_tid;
spin_unlock(&journal->j_state_lock);
log_wait_commit(journal, tid);
} else {
spin_unlock(&journal->j_state_lock);
}
/* ...and flush everything in the log out to disk. */
spin_lock(&journal->j_list_lock);
while (!err && journal->j_checkpoint_transactions != NULL) {
spin_unlock(&journal->j_list_lock);
mutex_lock(&journal->j_checkpoint_mutex);
err = log_do_checkpoint(journal);
mutex_unlock(&journal->j_checkpoint_mutex);
spin_lock(&journal->j_list_lock);
}
spin_unlock(&journal->j_list_lock);
if (is_journal_aborted(journal))
return -EIO;
cleanup_journal_tail(journal);
/* Finally, mark the journal as really needing no recovery.
* This sets s_start==0 in the underlying superblock, which is
* the magic code for a fully-recovered superblock. Any future
* commits of data to the journal will restore the current
* s_start value. */
spin_lock(&journal->j_state_lock);
old_tail = journal->j_tail;
journal->j_tail = 0;
spin_unlock(&journal->j_state_lock);
journal_update_superblock(journal, 1);
spin_lock(&journal->j_state_lock);
journal->j_tail = old_tail;
J_ASSERT(!journal->j_running_transaction);
J_ASSERT(!journal->j_committing_transaction);
J_ASSERT(!journal->j_checkpoint_transactions);
J_ASSERT(journal->j_head == journal->j_tail);
J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
spin_unlock(&journal->j_state_lock);
return 0;
}
/**
* int journal_wipe() - Wipe journal contents
* @journal: Journal to act on.
* @write: flag (see below)
*
* Wipe out all of the contents of a journal, safely. This will produce
* a warning if the journal contains any valid recovery information.
* Must be called between journal_init_*() and journal_load().
*
* If 'write' is non-zero, then we wipe out the journal on disk; otherwise
* we merely suppress recovery.
*/
int journal_wipe(journal_t *journal, int write)
{
journal_superblock_t *sb;
int err = 0;
J_ASSERT (!(journal->j_flags & JFS_LOADED));
err = load_superblock(journal);
if (err)
return err;
sb = journal->j_superblock;
if (!journal->j_tail)
goto no_recovery;
printk (KERN_WARNING "JBD: %s recovery information on journal\n",
write ? "Clearing" : "Ignoring");
err = journal_skip_recovery(journal);
if (write)
journal_update_superblock(journal, 1);
no_recovery:
return err;
}
/*
* journal_dev_name: format a character string to describe on what
* device this journal is present.
*/
static const char *journal_dev_name(journal_t *journal, char *buffer)
{
struct block_device *bdev;
if (journal->j_inode)
bdev = journal->j_inode->i_sb->s_bdev;
else
bdev = journal->j_dev;
return bdevname(bdev, buffer);
}
/*
* Journal abort has very specific semantics, which we describe
* for journal abort.
*
* Two internal function, which provide abort to te jbd layer
* itself are here.
*/
/*
* Quick version for internal journal use (doesn't lock the journal).
* Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
* and don't attempt to make any other journal updates.
*/
static void __journal_abort_hard(journal_t *journal)
{
transaction_t *transaction;
char b[BDEVNAME_SIZE];
if (journal->j_flags & JFS_ABORT)
return;
printk(KERN_ERR "Aborting journal on device %s.\n",
journal_dev_name(journal, b));
spin_lock(&journal->j_state_lock);
journal->j_flags |= JFS_ABORT;
transaction = journal->j_running_transaction;
if (transaction)
__log_start_commit(journal, transaction->t_tid);
spin_unlock(&journal->j_state_lock);
}
/* Soft abort: record the abort error status in the journal superblock,
* but don't do any other IO. */
static void __journal_abort_soft (journal_t *journal, int errno)
{
if (journal->j_flags & JFS_ABORT)
return;
if (!journal->j_errno)
journal->j_errno = errno;
__journal_abort_hard(journal);
if (errno)
journal_update_superblock(journal, 1);
}
/**
* void journal_abort () - Shutdown the journal immediately.
* @journal: the journal to shutdown.
* @errno: an error number to record in the journal indicating
* the reason for the shutdown.
*
* Perform a complete, immediate shutdown of the ENTIRE
* journal (not of a single transaction). This operation cannot be
* undone without closing and reopening the journal.
*
* The journal_abort function is intended to support higher level error
* recovery mechanisms such as the ext2/ext3 remount-readonly error
* mode.
*
* Journal abort has very specific semantics. Any existing dirty,
* unjournaled buffers in the main filesystem will still be written to
* disk by bdflush, but the journaling mechanism will be suspended
* immediately and no further transaction commits will be honoured.
*
* Any dirty, journaled buffers will be written back to disk without
* hitting the journal. Atomicity cannot be guaranteed on an aborted
* filesystem, but we _do_ attempt to leave as much data as possible
* behind for fsck to use for cleanup.
*
* Any attempt to get a new transaction handle on a journal which is in
* ABORT state will just result in an -EROFS error return. A
* journal_stop on an existing handle will return -EIO if we have
* entered abort state during the update.
*
* Recursive transactions are not disturbed by journal abort until the
* final journal_stop, which will receive the -EIO error.
*
* Finally, the journal_abort call allows the caller to supply an errno
* which will be recorded (if possible) in the journal superblock. This
* allows a client to record failure conditions in the middle of a
* transaction without having to complete the transaction to record the
* failure to disk. ext3_error, for example, now uses this
* functionality.
*
* Errors which originate from within the journaling layer will NOT
* supply an errno; a null errno implies that absolutely no further
* writes are done to the journal (unless there are any already in
* progress).
*
*/
void journal_abort(journal_t *journal, int errno)
{
__journal_abort_soft(journal, errno);
}
/**
* int journal_errno () - returns the journal's error state.
* @journal: journal to examine.
*
* This is the errno numbet set with journal_abort(), the last
* time the journal was mounted - if the journal was stopped
* without calling abort this will be 0.
*
* If the journal has been aborted on this mount time -EROFS will
* be returned.
*/
int journal_errno(journal_t *journal)
{
int err;
spin_lock(&journal->j_state_lock);
if (journal->j_flags & JFS_ABORT)
err = -EROFS;
else
err = journal->j_errno;
spin_unlock(&journal->j_state_lock);
return err;
}
/**
* int journal_clear_err () - clears the journal's error state
* @journal: journal to act on.
*
* An error must be cleared or Acked to take a FS out of readonly
* mode.
*/
int journal_clear_err(journal_t *journal)
{
int err = 0;
spin_lock(&journal->j_state_lock);
if (journal->j_flags & JFS_ABORT)
err = -EROFS;
else
journal->j_errno = 0;
spin_unlock(&journal->j_state_lock);
return err;
}
/**
* void journal_ack_err() - Ack journal err.
* @journal: journal to act on.
*
* An error must be cleared or Acked to take a FS out of readonly
* mode.
*/
void journal_ack_err(journal_t *journal)
{
spin_lock(&journal->j_state_lock);
if (journal->j_errno)
journal->j_flags |= JFS_ACK_ERR;
spin_unlock(&journal->j_state_lock);
}
int journal_blocks_per_page(struct inode *inode)
{
return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
}
/*
* Journal_head storage management
*/
static struct kmem_cache *journal_head_cache;
#ifdef CONFIG_JBD_DEBUG
static atomic_t nr_journal_heads = ATOMIC_INIT(0);
#endif
static int journal_init_journal_head_cache(void)
{
int retval;
J_ASSERT(journal_head_cache == NULL);
journal_head_cache = kmem_cache_create("journal_head",
sizeof(struct journal_head),
0, /* offset */
SLAB_TEMPORARY, /* flags */
NULL); /* ctor */
retval = 0;
if (!journal_head_cache) {
retval = -ENOMEM;
printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
}
return retval;
}
static void journal_destroy_journal_head_cache(void)
{
if (journal_head_cache) {
kmem_cache_destroy(journal_head_cache);
journal_head_cache = NULL;
}
}
/*
* journal_head splicing and dicing
*/
static struct journal_head *journal_alloc_journal_head(void)
{
struct journal_head *ret;
static unsigned long last_warning;
#ifdef CONFIG_JBD_DEBUG
atomic_inc(&nr_journal_heads);
#endif
ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
if (ret == NULL) {
jbd_debug(1, "out of memory for journal_head\n");
if (time_after(jiffies, last_warning + 5*HZ)) {
printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
__func__);
last_warning = jiffies;
}
while (ret == NULL) {
yield();
ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
}
}
return ret;
}
static void journal_free_journal_head(struct journal_head *jh)
{
#ifdef CONFIG_JBD_DEBUG
atomic_dec(&nr_journal_heads);
memset(jh, JBD_POISON_FREE, sizeof(*jh));
#endif
kmem_cache_free(journal_head_cache, jh);
}
/*
* A journal_head is attached to a buffer_head whenever JBD has an
* interest in the buffer.
*
* Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
* is set. This bit is tested in core kernel code where we need to take
* JBD-specific actions. Testing the zeroness of ->b_private is not reliable
* there.
*
* When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
*
* When a buffer has its BH_JBD bit set it is immune from being released by
* core kernel code, mainly via ->b_count.
*
* A journal_head may be detached from its buffer_head when the journal_head's
* b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
* Various places in JBD call journal_remove_journal_head() to indicate that the
* journal_head can be dropped if needed.
*
* Various places in the kernel want to attach a journal_head to a buffer_head
* _before_ attaching the journal_head to a transaction. To protect the
* journal_head in this situation, journal_add_journal_head elevates the
* journal_head's b_jcount refcount by one. The caller must call
* journal_put_journal_head() to undo this.
*
* So the typical usage would be:
*
* (Attach a journal_head if needed. Increments b_jcount)
* struct journal_head *jh = journal_add_journal_head(bh);
* ...
* jh->b_transaction = xxx;
* journal_put_journal_head(jh);
*
* Now, the journal_head's b_jcount is zero, but it is safe from being released
* because it has a non-zero b_transaction.
*/
/*
* Give a buffer_head a journal_head.
*
* Doesn't need the journal lock.
* May sleep.
*/
struct journal_head *journal_add_journal_head(struct buffer_head *bh)
{
struct journal_head *jh;
struct journal_head *new_jh = NULL;
repeat:
if (!buffer_jbd(bh)) {
new_jh = journal_alloc_journal_head();
memset(new_jh, 0, sizeof(*new_jh));
}
jbd_lock_bh_journal_head(bh);
if (buffer_jbd(bh)) {
jh = bh2jh(bh);
} else {
J_ASSERT_BH(bh,
(atomic_read(&bh->b_count) > 0) ||
(bh->b_page && bh->b_page->mapping));
if (!new_jh) {
jbd_unlock_bh_journal_head(bh);
goto repeat;
}
jh = new_jh;
new_jh = NULL; /* We consumed it */
set_buffer_jbd(bh);
bh->b_private = jh;
jh->b_bh = bh;
get_bh(bh);
BUFFER_TRACE(bh, "added journal_head");
}
jh->b_jcount++;
jbd_unlock_bh_journal_head(bh);
if (new_jh)
journal_free_journal_head(new_jh);
return bh->b_private;
}
/*
* Grab a ref against this buffer_head's journal_head. If it ended up not
* having a journal_head, return NULL
*/
struct journal_head *journal_grab_journal_head(struct buffer_head *bh)
{
struct journal_head *jh = NULL;
jbd_lock_bh_journal_head(bh);
if (buffer_jbd(bh)) {
jh = bh2jh(bh);
jh->b_jcount++;
}
jbd_unlock_bh_journal_head(bh);
return jh;
}
static void __journal_remove_journal_head(struct buffer_head *bh)
{
struct journal_head *jh = bh2jh(bh);
J_ASSERT_JH(jh, jh->b_jcount >= 0);
get_bh(bh);
if (jh->b_jcount == 0) {
if (jh->b_transaction == NULL &&
jh->b_next_transaction == NULL &&
jh->b_cp_transaction == NULL) {
J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
J_ASSERT_BH(bh, buffer_jbd(bh));
J_ASSERT_BH(bh, jh2bh(jh) == bh);
BUFFER_TRACE(bh, "remove journal_head");
if (jh->b_frozen_data) {
printk(KERN_WARNING "%s: freeing "
"b_frozen_data\n",
__func__);
jbd_free(jh->b_frozen_data, bh->b_size);
}
if (jh->b_committed_data) {
printk(KERN_WARNING "%s: freeing "
"b_committed_data\n",
__func__);
jbd_free(jh->b_committed_data, bh->b_size);
}
bh->b_private = NULL;
jh->b_bh = NULL; /* debug, really */
clear_buffer_jbd(bh);
__brelse(bh);
journal_free_journal_head(jh);
} else {
BUFFER_TRACE(bh, "journal_head was locked");
}
}
}
/*
* journal_remove_journal_head(): if the buffer isn't attached to a transaction
* and has a zero b_jcount then remove and release its journal_head. If we did
* see that the buffer is not used by any transaction we also "logically"
* decrement ->b_count.
*
* We in fact take an additional increment on ->b_count as a convenience,
* because the caller usually wants to do additional things with the bh
* after calling here.
* The caller of journal_remove_journal_head() *must* run __brelse(bh) at some
* time. Once the caller has run __brelse(), the buffer is eligible for
* reaping by try_to_free_buffers().
*/
void journal_remove_journal_head(struct buffer_head *bh)
{
jbd_lock_bh_journal_head(bh);
__journal_remove_journal_head(bh);
jbd_unlock_bh_journal_head(bh);
}
/*
* Drop a reference on the passed journal_head. If it fell to zero then try to
* release the journal_head from the buffer_head.
*/
void journal_put_journal_head(struct journal_head *jh)
{
struct buffer_head *bh = jh2bh(jh);
jbd_lock_bh_journal_head(bh);
J_ASSERT_JH(jh, jh->b_jcount > 0);
--jh->b_jcount;
if (!jh->b_jcount && !jh->b_transaction) {
__journal_remove_journal_head(bh);
__brelse(bh);
}
jbd_unlock_bh_journal_head(bh);
}
/*
* debugfs tunables
*/
#ifdef CONFIG_JBD_DEBUG
u8 journal_enable_debug __read_mostly;
EXPORT_SYMBOL(journal_enable_debug);
static struct dentry *jbd_debugfs_dir;
static struct dentry *jbd_debug;
static void __init jbd_create_debugfs_entry(void)
{
jbd_debugfs_dir = debugfs_create_dir("jbd", NULL);
if (jbd_debugfs_dir)
jbd_debug = debugfs_create_u8("jbd-debug", S_IRUGO,
jbd_debugfs_dir,
&journal_enable_debug);
}
static void __exit jbd_remove_debugfs_entry(void)
{
debugfs_remove(jbd_debug);
debugfs_remove(jbd_debugfs_dir);
}
#else
static inline void jbd_create_debugfs_entry(void)
{
}
static inline void jbd_remove_debugfs_entry(void)
{
}
#endif
struct kmem_cache *jbd_handle_cache;
static int __init journal_init_handle_cache(void)
{
jbd_handle_cache = kmem_cache_create("journal_handle",
sizeof(handle_t),
0, /* offset */
SLAB_TEMPORARY, /* flags */
NULL); /* ctor */
if (jbd_handle_cache == NULL) {
printk(KERN_EMERG "JBD: failed to create handle cache\n");
return -ENOMEM;
}
return 0;
}
static void journal_destroy_handle_cache(void)
{
if (jbd_handle_cache)
kmem_cache_destroy(jbd_handle_cache);
}
/*
* Module startup and shutdown
*/
static int __init journal_init_caches(void)
{
int ret;
ret = journal_init_revoke_caches();
if (ret == 0)
ret = journal_init_journal_head_cache();
if (ret == 0)
ret = journal_init_handle_cache();
return ret;
}
static void journal_destroy_caches(void)
{
journal_destroy_revoke_caches();
journal_destroy_journal_head_cache();
journal_destroy_handle_cache();
}
static int __init journal_init(void)
{
int ret;
BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
ret = journal_init_caches();
if (ret != 0)
journal_destroy_caches();
jbd_create_debugfs_entry();
return ret;
}
static void __exit journal_exit(void)
{
#ifdef CONFIG_JBD_DEBUG
int n = atomic_read(&nr_journal_heads);
if (n)
printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
#endif
jbd_remove_debugfs_entry();
journal_destroy_caches();
}
MODULE_LICENSE("GPL");
module_init(journal_init);
module_exit(journal_exit);