- 根目录:
- fs
- jbd2
- journal.c
/*
* linux/fs/jbd2/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/jbd2.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 <linux/seq_file.h>
#include <linux/math64.h>
#include <linux/hash.h>
#include <linux/log2.h>
#include <linux/vmalloc.h>
#include <linux/backing-dev.h>
#include <linux/bitops.h>
#include <linux/ratelimit.h>
#define CREATE_TRACE_POINTS
#include <trace/events/jbd2.h>
#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/system.h>
EXPORT_SYMBOL(jbd2_journal_extend);
EXPORT_SYMBOL(jbd2_journal_stop);
EXPORT_SYMBOL(jbd2_journal_lock_updates);
EXPORT_SYMBOL(jbd2_journal_unlock_updates);
EXPORT_SYMBOL(jbd2_journal_get_write_access);
EXPORT_SYMBOL(jbd2_journal_get_create_access);
EXPORT_SYMBOL(jbd2_journal_get_undo_access);
EXPORT_SYMBOL(jbd2_journal_set_triggers);
EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
EXPORT_SYMBOL(jbd2_journal_release_buffer);
EXPORT_SYMBOL(jbd2_journal_forget);
#if 0
EXPORT_SYMBOL(journal_sync_buffer);
#endif
EXPORT_SYMBOL(jbd2_journal_flush);
EXPORT_SYMBOL(jbd2_journal_revoke);
EXPORT_SYMBOL(jbd2_journal_init_dev);
EXPORT_SYMBOL(jbd2_journal_init_inode);
EXPORT_SYMBOL(jbd2_journal_update_format);
EXPORT_SYMBOL(jbd2_journal_check_used_features);
EXPORT_SYMBOL(jbd2_journal_check_available_features);
EXPORT_SYMBOL(jbd2_journal_set_features);
EXPORT_SYMBOL(jbd2_journal_load);
EXPORT_SYMBOL(jbd2_journal_destroy);
EXPORT_SYMBOL(jbd2_journal_abort);
EXPORT_SYMBOL(jbd2_journal_errno);
EXPORT_SYMBOL(jbd2_journal_ack_err);
EXPORT_SYMBOL(jbd2_journal_clear_err);
EXPORT_SYMBOL(jbd2_log_wait_commit);
EXPORT_SYMBOL(jbd2_log_start_commit);
EXPORT_SYMBOL(jbd2_journal_start_commit);
EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
EXPORT_SYMBOL(jbd2_journal_wipe);
EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
EXPORT_SYMBOL(jbd2_journal_invalidatepage);
EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
EXPORT_SYMBOL(jbd2_journal_force_commit);
EXPORT_SYMBOL(jbd2_journal_file_inode);
EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
EXPORT_SYMBOL(jbd2_inode_cache);
static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
static void __journal_abort_soft (journal_t *journal, int errno);
static int jbd2_journal_create_slab(size_t slab_size);
/*
* 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);
}
/*
* kjournald2: 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 kjournald2(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);
/*
* And now, wait forever for commit wakeup events.
*/
write_lock(&journal->j_state_lock);
loop:
if (journal->j_flags & JBD2_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");
write_unlock(&journal->j_state_lock);
del_timer_sync(&journal->j_commit_timer);
jbd2_journal_commit_transaction(journal);
write_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 kjournald2\n");
write_unlock(&journal->j_state_lock);
refrigerator();
write_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 & JBD2_UNMOUNT)
should_sleep = 0;
if (should_sleep) {
write_unlock(&journal->j_state_lock);
schedule();
write_lock(&journal->j_state_lock);
}
finish_wait(&journal->j_wait_commit, &wait);
}
jbd_debug(1, "kjournald2 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:
write_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 jbd2_journal_start_thread(journal_t *journal)
{
struct task_struct *t;
t = kthread_run(kjournald2, journal, "jbd2/%s",
journal->j_devname);
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)
{
write_lock(&journal->j_state_lock);
journal->j_flags |= JBD2_UNMOUNT;
while (journal->j_task) {
wake_up(&journal->j_wait_commit);
write_unlock(&journal->j_state_lock);
wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
write_lock(&journal->j_state_lock);
}
write_unlock(&journal->j_state_lock);
}
/*
* jbd2_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
* JBD2_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 jbd2_journal_write_metadata_buffer(transaction_t *transaction,
struct journal_head *jh_in,
struct journal_head **jh_out,
unsigned long 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);
journal_t *journal = transaction->t_journal;
/*
* 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));
retry_alloc:
new_bh = alloc_buffer_head(GFP_NOFS);
if (!new_bh) {
/*
* Failure is not an option, but __GFP_NOFAIL is going
* away; so we retry ourselves here.
*/
congestion_wait(BLK_RW_ASYNC, HZ/50);
goto retry_alloc;
}
/* keep subsequent assertions sane */
new_bh->b_state = 0;
init_buffer(new_bh, NULL, NULL);
atomic_set(&new_bh->b_count, 1);
new_jh = jbd2_journal_add_journal_head(new_bh); /* This sleeps */
/*
* 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);
/*
* Fire data frozen trigger if data already wasn't frozen. Do this
* before checking for escaping, as the trigger may modify the magic
* offset. If a copy-out happens afterwards, it will have the correct
* data in the buffer.
*/
if (!done_copy_out)
jbd2_buffer_frozen_trigger(jh_in, mapped_data + new_offset,
jh_in->b_triggers);
/*
* Check for escaping
*/
if (*((__be32 *)(mapped_data + new_offset)) ==
cpu_to_be32(JBD2_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 = jbd2_alloc(bh_in->b_size, GFP_NOFS);
if (!tmp) {
jbd2_journal_put_journal_head(new_jh);
return -ENOMEM;
}
jbd_lock_bh_state(bh_in);
if (jh_in->b_frozen_data) {
jbd2_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;
/*
* This isn't strictly necessary, as we're using frozen
* data for the escaping, but it keeps consistency with
* b_frozen_data usage.
*/
jh_in->b_frozen_triggers = jh_in->b_triggers;
}
/*
* 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);
}
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");
spin_lock(&journal->j_list_lock);
__jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh_in);
JBUFFER_TRACE(new_jh, "file as BJ_IO");
jbd2_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.
*/
/*
* __jbd2_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 __jbd2_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 with j_state_lock locked for writing.
* Returns true if a transaction commit was started.
*/
int __jbd2_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 wakeup 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 jbd2_log_start_commit(journal_t *journal, tid_t tid)
{
int ret;
write_lock(&journal->j_state_lock);
ret = __jbd2_log_start_commit(journal, tid);
write_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 jbd2_journal_force_commit_nested(journal_t *journal)
{
transaction_t *transaction = NULL;
tid_t tid;
int need_to_start = 0;
read_lock(&journal->j_state_lock);
if (journal->j_running_transaction && !current->journal_info) {
transaction = journal->j_running_transaction;
if (!tid_geq(journal->j_commit_request, transaction->t_tid))
need_to_start = 1;
} else if (journal->j_committing_transaction)
transaction = journal->j_committing_transaction;
if (!transaction) {
read_unlock(&journal->j_state_lock);
return 0; /* Nothing to retry */
}
tid = transaction->t_tid;
read_unlock(&journal->j_state_lock);
if (need_to_start)
jbd2_log_start_commit(journal, tid);
jbd2_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 jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
{
int ret = 0;
write_lock(&journal->j_state_lock);
if (journal->j_running_transaction) {
tid_t tid = journal->j_running_transaction->t_tid;
__jbd2_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;
}
write_unlock(&journal->j_state_lock);
return ret;
}
/*
* Wait for a specified commit to complete.
* The caller may not hold the journal lock.
*/
int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
{
int err = 0;
read_lock(&journal->j_state_lock);
#ifdef CONFIG_JBD2_DEBUG
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);
}
#endif
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);
read_unlock(&journal->j_state_lock);
wait_event(journal->j_wait_done_commit,
!tid_gt(tid, journal->j_commit_sequence));
read_lock(&journal->j_state_lock);
}
read_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 jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
{
unsigned long blocknr;
write_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;
write_unlock(&journal->j_state_lock);
return jbd2_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 jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
unsigned long long *retp)
{
int err = 0;
unsigned long long ret;
if (journal->j_inode) {
ret = bmap(journal->j_inode, blocknr);
if (ret)
*retp = ret;
else {
printk(KERN_ALERT "%s: journal block not found "
"at offset %lu on %s\n",
__func__, blocknr, journal->j_devname);
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 jbd2_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 *jbd2_journal_get_descriptor_buffer(journal_t *journal)
{
struct buffer_head *bh;
unsigned long long blocknr;
int err;
err = jbd2_journal_next_log_block(journal, &blocknr);
if (err)
return NULL;
bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
if (!bh)
return NULL;
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 jbd2_journal_add_journal_head(bh);
}
struct jbd2_stats_proc_session {
journal_t *journal;
struct transaction_stats_s *stats;
int start;
int max;
};
static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
{
return *pos ? NULL : SEQ_START_TOKEN;
}
static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
{
return NULL;
}
static int jbd2_seq_info_show(struct seq_file *seq, void *v)
{
struct jbd2_stats_proc_session *s = seq->private;
if (v != SEQ_START_TOKEN)
return 0;
seq_printf(seq, "%lu transaction, each up to %u blocks\n",
s->stats->ts_tid,
s->journal->j_max_transaction_buffers);
if (s->stats->ts_tid == 0)
return 0;
seq_printf(seq, "average: \n %ums waiting for transaction\n",
jiffies_to_msecs(s->stats->run.rs_wait / s->stats->ts_tid));
seq_printf(seq, " %ums running transaction\n",
jiffies_to_msecs(s->stats->run.rs_running / s->stats->ts_tid));
seq_printf(seq, " %ums transaction was being locked\n",
jiffies_to_msecs(s->stats->run.rs_locked / s->stats->ts_tid));
seq_printf(seq, " %ums flushing data (in ordered mode)\n",
jiffies_to_msecs(s->stats->run.rs_flushing / s->stats->ts_tid));
seq_printf(seq, " %ums logging transaction\n",
jiffies_to_msecs(s->stats->run.rs_logging / s->stats->ts_tid));
seq_printf(seq, " %lluus average transaction commit time\n",
div_u64(s->journal->j_average_commit_time, 1000));
seq_printf(seq, " %lu handles per transaction\n",
s->stats->run.rs_handle_count / s->stats->ts_tid);
seq_printf(seq, " %lu blocks per transaction\n",
s->stats->run.rs_blocks / s->stats->ts_tid);
seq_printf(seq, " %lu logged blocks per transaction\n",
s->stats->run.rs_blocks_logged / s->stats->ts_tid);
return 0;
}
static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
{
}
static const struct seq_operations jbd2_seq_info_ops = {
.start = jbd2_seq_info_start,
.next = jbd2_seq_info_next,
.stop = jbd2_seq_info_stop,
.show = jbd2_seq_info_show,
};
static int jbd2_seq_info_open(struct inode *inode, struct file *file)
{
journal_t *journal = PDE(inode)->data;
struct jbd2_stats_proc_session *s;
int rc, size;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL)
return -ENOMEM;
size = sizeof(struct transaction_stats_s);
s->stats = kmalloc(size, GFP_KERNEL);
if (s->stats == NULL) {
kfree(s);
return -ENOMEM;
}
spin_lock(&journal->j_history_lock);
memcpy(s->stats, &journal->j_stats, size);
s->journal = journal;
spin_unlock(&journal->j_history_lock);
rc = seq_open(file, &jbd2_seq_info_ops);
if (rc == 0) {
struct seq_file *m = file->private_data;
m->private = s;
} else {
kfree(s->stats);
kfree(s);
}
return rc;
}
static int jbd2_seq_info_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
struct jbd2_stats_proc_session *s = seq->private;
kfree(s->stats);
kfree(s);
return seq_release(inode, file);
}
static const struct file_operations jbd2_seq_info_fops = {
.owner = THIS_MODULE,
.open = jbd2_seq_info_open,
.read = seq_read,
.llseek = seq_lseek,
.release = jbd2_seq_info_release,
};
static struct proc_dir_entry *proc_jbd2_stats;
static void jbd2_stats_proc_init(journal_t *journal)
{
journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
if (journal->j_proc_entry) {
proc_create_data("info", S_IRUGO, journal->j_proc_entry,
&jbd2_seq_info_fops, journal);
}
}
static void jbd2_stats_proc_exit(journal_t *journal)
{
remove_proc_entry("info", journal->j_proc_entry);
remove_proc_entry(journal->j_devname, proc_jbd2_stats);
}
/*
* 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)
return NULL;
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);
rwlock_init(&journal->j_state_lock);
journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
journal->j_min_batch_time = 0;
journal->j_max_batch_time = 15000; /* 15ms */
/* The journal is marked for error until we succeed with recovery! */
journal->j_flags = JBD2_ABORT;
/* Set up a default-sized revoke table for the new mount. */
err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
if (err) {
kfree(journal);
return NULL;
}
spin_lock_init(&journal->j_history_lock);
return journal;
}
/* jbd2_journal_init_dev and jbd2_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 * jbd2_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 *
*
* jbd2_journal_init_dev creates a journal which maps a fixed contiguous
* range of blocks on an arbitrary block device.
*
*/
journal_t * jbd2_journal_init_dev(struct block_device *bdev,
struct block_device *fs_dev,
unsigned long long start, int len, int blocksize)
{
journal_t *journal = journal_init_common();
struct buffer_head *bh;
char *p;
int n;
if (!journal)
return NULL;
/* journal descriptor can store up to n blocks -bzzz */
journal->j_blocksize = blocksize;
journal->j_dev = bdev;
journal->j_fs_dev = fs_dev;
journal->j_blk_offset = start;
journal->j_maxlen = len;
bdevname(journal->j_dev, journal->j_devname);
p = journal->j_devname;
while ((p = strchr(p, '/')))
*p = '!';
jbd2_stats_proc_init(journal);
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: Can't allocate bhs for commit thread\n",
__func__);
goto out_err;
}
bh = __getblk(journal->j_dev, start, journal->j_blocksize);
if (!bh) {
printk(KERN_ERR
"%s: Cannot get buffer for journal superblock\n",
__func__);
goto out_err;
}
journal->j_sb_buffer = bh;
journal->j_superblock = (journal_superblock_t *)bh->b_data;
return journal;
out_err:
kfree(journal->j_wbuf);
jbd2_stats_proc_exit(journal);
kfree(journal);
return NULL;
}
/**
* journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
* @inode: An inode to create the journal in
*
* jbd2_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 * jbd2_journal_init_inode (struct inode *inode)
{
struct buffer_head *bh;
journal_t *journal = journal_init_common();
char *p;
int err;
int n;
unsigned long long blocknr;
if (!journal)
return NULL;
journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
journal->j_inode = inode;
bdevname(journal->j_dev, journal->j_devname);
p = journal->j_devname;
while ((p = strchr(p, '/')))
*p = '!';
p = journal->j_devname + strlen(journal->j_devname);
sprintf(p, "-%lu", journal->j_inode->i_ino);
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;
jbd2_stats_proc_init(journal);
/* 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: Can't allocate bhs for commit thread\n",
__func__);
goto out_err;
}
err = jbd2_journal_bmap(journal, 0, &blocknr);
/* If that failed, give up */
if (err) {
printk(KERN_ERR "%s: Cannot locate journal superblock\n",
__func__);
goto out_err;
}
bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
if (!bh) {
printk(KERN_ERR
"%s: Cannot get buffer for journal superblock\n",
__func__);
goto out_err;
}
journal->j_sb_buffer = bh;
journal->j_superblock = (journal_superblock_t *)bh->b_data;
return journal;
out_err:
kfree(journal->j_wbuf);
jbd2_stats_proc_exit(journal);
kfree(journal);
return NULL;
}
/*
* 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 long first, last;
first = be32_to_cpu(sb->s_first);
last = be32_to_cpu(sb->s_maxlen);
if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
printk(KERN_ERR "JBD: Journal too short (blocks %llu-%llu).\n",
first, last);
journal_fail_superblock(journal);
return -EINVAL;
}
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. */
jbd2_journal_update_superblock(journal, 1);
return jbd2_journal_start_thread(journal);
}
/**
* void jbd2_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 jbd2_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 JBD2_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;
}
if (buffer_write_io_error(bh)) {
/*
* Oh, dear. A previous attempt to write the journal
* superblock failed. This could happen because the
* USB device was yanked out. Or it could happen to
* be a transient write error and maybe the block will
* be remapped. Nothing we can do but to retry the
* write and hope for the best.
*/
printk(KERN_ERR "JBD2: previous I/O error detected "
"for journal superblock update for %s.\n",
journal->j_devname);
clear_buffer_write_io_error(bh);
set_buffer_uptodate(bh);
}
read_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);
read_unlock(&journal->j_state_lock);
BUFFER_TRACE(bh, "marking dirty");
mark_buffer_dirty(bh);
if (wait) {
sync_dirty_buffer(bh);
if (buffer_write_io_error(bh)) {
printk(KERN_ERR "JBD2: I/O error detected "
"when updating journal superblock for %s.\n",
journal->j_devname);
clear_buffer_write_io_error(bh);
set_buffer_uptodate(bh);
}
} else
write_dirty_buffer(bh, WRITE);
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. */
write_lock(&journal->j_state_lock);
if (sb->s_start)
journal->j_flags &= ~JBD2_FLUSHED;
else
journal->j_flags |= JBD2_FLUSHED;
write_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(JBD2_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 JBD2_SUPERBLOCK_V1:
journal->j_format_version = 1;
break;
case JBD2_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 jbd2_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 jbd2_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(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
(sb->s_feature_incompat &
~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
printk (KERN_WARNING
"JBD: Unrecognised features on journal\n");
return -EINVAL;
}
}
/*
* Create a slab for this blocksize
*/
err = jbd2_journal_create_slab(be32_to_cpu(sb->s_blocksize));
if (err)
return err;
/* Let the recovery code check whether it needs to recover any
* data from the journal. */
if (jbd2_journal_recover(journal))
goto recovery_error;
if (journal->j_failed_commit) {
printk(KERN_ERR "JBD2: journal transaction %u on %s "
"is corrupt.\n", journal->j_failed_commit,
journal->j_devname);
return -EIO;
}
/* 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 &= ~JBD2_ABORT;
journal->j_flags |= JBD2_LOADED;
return 0;
recovery_error:
printk (KERN_WARNING "JBD: recovery failed\n");
return -EIO;
}
/**
* void jbd2_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 jbd2_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)
jbd2_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);
mutex_lock(&journal->j_checkpoint_mutex);
jbd2_log_do_checkpoint(journal);
mutex_unlock(&journal->j_checkpoint_mutex);
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;
jbd2_journal_update_superblock(journal, 1);
} else {
err = -EIO;
}
brelse(journal->j_sb_buffer);
}
if (journal->j_proc_entry)
jbd2_stats_proc_exit(journal);
if (journal->j_inode)
iput(journal->j_inode);
if (journal->j_revoke)
jbd2_journal_destroy_revoke(journal);
kfree(journal->j_wbuf);
kfree(journal);
return err;
}
/**
*int jbd2_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 jbd2_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;
/* Load journal superblock if it is not loaded yet. */
if (journal->j_format_version == 0 &&
journal_get_superblock(journal) != 0)
return 0;
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 jbd2_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 jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
unsigned long ro, unsigned long incompat)
{
if (!compat && !ro && !incompat)
return 1;
/* 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 & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
(ro & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
(incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
return 1;
return 0;
}
/**
* int jbd2_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 jbd2_journal_set_features (journal_t *journal, unsigned long compat,
unsigned long ro, unsigned long incompat)
{
journal_superblock_t *sb;
if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
return 1;
if (!jbd2_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;
}
/*
* jbd2_journal_clear_features () - Clear 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
*
* Clear a given journal feature as present on the
* superblock.
*/
void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
unsigned long ro, unsigned long incompat)
{
journal_superblock_t *sb;
jbd_debug(1, "Clear 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);
}
EXPORT_SYMBOL(jbd2_journal_clear_features);
/**
* int jbd2_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 jbd2_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 JBD2_SUPERBLOCK_V2:
return 0;
case JBD2_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(JBD2_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 jbd2_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 jbd2_journal_flush(journal_t *journal)
{
int err = 0;
transaction_t *transaction = NULL;
unsigned long old_tail;
write_lock(&journal->j_state_lock);
/* Force everything buffered to the log... */
if (journal->j_running_transaction) {
transaction = journal->j_running_transaction;
__jbd2_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;
write_unlock(&journal->j_state_lock);
jbd2_log_wait_commit(journal, tid);
} else {
write_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 = jbd2_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;
jbd2_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. */
write_lock(&journal->j_state_lock);
old_tail = journal->j_tail;
journal->j_tail = 0;
write_unlock(&journal->j_state_lock);
jbd2_journal_update_superblock(journal, 1);
write_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);
write_unlock(&journal->j_state_lock);
return 0;
}
/**
* int jbd2_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 jbd2_journal_load().
*
* If 'write' is non-zero, then we wipe out the journal on disk; otherwise
* we merely suppress recovery.
*/
int jbd2_journal_wipe(journal_t *journal, int write)
{
int err = 0;
J_ASSERT (!(journal->j_flags & JBD2_LOADED));
err = load_superblock(journal);
if (err)
return err;
if (!journal->j_tail)
goto no_recovery;
printk (KERN_WARNING "JBD: %s recovery information on journal\n",
write ? "Clearing" : "Ignoring");
err = jbd2_journal_skip_recovery(journal);
if (write)
jbd2_journal_update_superblock(journal, 1);
no_recovery:
return err;
}
/*
* Journal abort has very specific semantics, which we describe
* for journal abort.
*
* Two internal functions, which provide abort to the 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.
*/
void __jbd2_journal_abort_hard(journal_t *journal)
{
transaction_t *transaction;
if (journal->j_flags & JBD2_ABORT)
return;
printk(KERN_ERR "Aborting journal on device %s.\n",
journal->j_devname);
write_lock(&journal->j_state_lock);
journal->j_flags |= JBD2_ABORT;
transaction = journal->j_running_transaction;
if (transaction)
__jbd2_log_start_commit(journal, transaction->t_tid);
write_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 & JBD2_ABORT)
return;
if (!journal->j_errno)
journal->j_errno = errno;
__jbd2_journal_abort_hard(journal);
if (errno)
jbd2_journal_update_superblock(journal, 1);
}
/**
* void jbd2_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 jbd2_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
* jbd2_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 jbd2_journal_stop, which will receive the -EIO error.
*
* Finally, the jbd2_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 jbd2_journal_abort(journal_t *journal, int errno)
{
__journal_abort_soft(journal, errno);
}
/**
* int jbd2_journal_errno () - returns the journal's error state.
* @journal: journal to examine.
*
* This is the errno number set with jbd2_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 jbd2_journal_errno(journal_t *journal)
{
int err;
read_lock(&journal->j_state_lock);
if (journal->j_flags & JBD2_ABORT)
err = -EROFS;
else
err = journal->j_errno;
read_unlock(&journal->j_state_lock);
return err;
}
/**
* int jbd2_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 jbd2_journal_clear_err(journal_t *journal)
{
int err = 0;
write_lock(&journal->j_state_lock);
if (journal->j_flags & JBD2_ABORT)
err = -EROFS;
else
journal->j_errno = 0;
write_unlock(&journal->j_state_lock);
return err;
}
/**
* void jbd2_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 jbd2_journal_ack_err(journal_t *journal)
{
write_lock(&journal->j_state_lock);
if (journal->j_errno)
journal->j_flags |= JBD2_ACK_ERR;
write_unlock(&journal->j_state_lock);
}
int jbd2_journal_blocks_per_page(struct inode *inode)
{
return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
}
/*
* helper functions to deal with 32 or 64bit block numbers.
*/
size_t journal_tag_bytes(journal_t *journal)
{
if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
return JBD2_TAG_SIZE64;
else
return JBD2_TAG_SIZE32;
}
/*
* JBD memory management
*
* These functions are used to allocate block-sized chunks of memory
* used for making copies of buffer_head data. Very often it will be
* page-sized chunks of data, but sometimes it will be in
* sub-page-size chunks. (For example, 16k pages on Power systems
* with a 4k block file system.) For blocks smaller than a page, we
* use a SLAB allocator. There are slab caches for each block size,
* which are allocated at mount time, if necessary, and we only free
* (all of) the slab caches when/if the jbd2 module is unloaded. For
* this reason we don't need to a mutex to protect access to
* jbd2_slab[] allocating or releasing memory; only in
* jbd2_journal_create_slab().
*/
#define JBD2_MAX_SLABS 8
static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
"jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
"jbd2_16k", "jbd2_32k", "jbd2_64k", "jbd2_128k"
};
static void jbd2_journal_destroy_slabs(void)
{
int i;
for (i = 0; i < JBD2_MAX_SLABS; i++) {
if (jbd2_slab[i])
kmem_cache_destroy(jbd2_slab[i]);
jbd2_slab[i] = NULL;
}
}
static int jbd2_journal_create_slab(size_t size)
{
static DEFINE_MUTEX(jbd2_slab_create_mutex);
int i = order_base_2(size) - 10;
size_t slab_size;
if (size == PAGE_SIZE)
return 0;
if (i >= JBD2_MAX_SLABS)
return -EINVAL;
if (unlikely(i < 0))
i = 0;
mutex_lock(&jbd2_slab_create_mutex);
if (jbd2_slab[i]) {
mutex_unlock(&jbd2_slab_create_mutex);
return 0; /* Already created */
}
slab_size = 1 << (i+10);
jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
slab_size, 0, NULL);
mutex_unlock(&jbd2_slab_create_mutex);
if (!jbd2_slab[i]) {
printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
return -ENOMEM;
}
return 0;
}
static struct kmem_cache *get_slab(size_t size)
{
int i = order_base_2(size) - 10;
BUG_ON(i >= JBD2_MAX_SLABS);
if (unlikely(i < 0))
i = 0;
BUG_ON(jbd2_slab[i] == NULL);
return jbd2_slab[i];
}
void *jbd2_alloc(size_t size, gfp_t flags)
{
void *ptr;
BUG_ON(size & (size-1)); /* Must be a power of 2 */
flags |= __GFP_REPEAT;
if (size == PAGE_SIZE)
ptr = (void *)__get_free_pages(flags, 0);
else if (size > PAGE_SIZE) {
int order = get_order(size);
if (order < 3)
ptr = (void *)__get_free_pages(flags, order);
else
ptr = vmalloc(size);
} else
ptr = kmem_cache_alloc(get_slab(size), flags);
/* Check alignment; SLUB has gotten this wrong in the past,
* and this can lead to user data corruption! */
BUG_ON(((unsigned long) ptr) & (size-1));
return ptr;
}
void jbd2_free(void *ptr, size_t size)
{
if (size == PAGE_SIZE) {
free_pages((unsigned long)ptr, 0);
return;
}
if (size > PAGE_SIZE) {
int order = get_order(size);
if (order < 3)
free_pages((unsigned long)ptr, order);
else
vfree(ptr);
return;
}
kmem_cache_free(get_slab(size), ptr);
};
/*
* Journal_head storage management
*/
static struct kmem_cache *jbd2_journal_head_cache;
#ifdef CONFIG_JBD2_DEBUG
static atomic_t nr_journal_heads = ATOMIC_INIT(0);
#endif
static int journal_init_jbd2_journal_head_cache(void)
{
int retval;
J_ASSERT(jbd2_journal_head_cache == NULL);
jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
sizeof(struct journal_head),
0, /* offset */
SLAB_TEMPORARY, /* flags */
NULL); /* ctor */
retval = 0;
if (!jbd2_journal_head_cache) {
retval = -ENOMEM;
printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
}
return retval;
}
static void jbd2_journal_destroy_jbd2_journal_head_cache(void)
{
if (jbd2_journal_head_cache) {
kmem_cache_destroy(jbd2_journal_head_cache);
jbd2_journal_head_cache = NULL;
}
}
/*
* journal_head splicing and dicing
*/
static struct journal_head *journal_alloc_journal_head(void)
{
struct journal_head *ret;
#ifdef CONFIG_JBD2_DEBUG
atomic_inc(&nr_journal_heads);
#endif
ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
if (!ret) {
jbd_debug(1, "out of memory for journal_head\n");
pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
while (!ret) {
yield();
ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
}
}
return ret;
}
static void journal_free_journal_head(struct journal_head *jh)
{
#ifdef CONFIG_JBD2_DEBUG
atomic_dec(&nr_journal_heads);
memset(jh, JBD2_POISON_FREE, sizeof(*jh));
#endif
kmem_cache_free(jbd2_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 jbd2_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, jbd2_journal_add_journal_head elevates the
* journal_head's b_jcount refcount by one. The caller must call
* jbd2_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 = jbd2_journal_add_journal_head(bh);
* ...
* jh->b_transaction = xxx;
* jbd2_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 *jbd2_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 *jbd2_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__);
jbd2_free(jh->b_frozen_data, bh->b_size);
}
if (jh->b_committed_data) {
printk(KERN_WARNING "%s: freeing "
"b_committed_data\n",
__func__);
jbd2_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");
}
}
}
/*
* jbd2_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 jbd2_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 jbd2_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 jbd2_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);
}
/*
* Initialize jbd inode head
*/
void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
{
jinode->i_transaction = NULL;
jinode->i_next_transaction = NULL;
jinode->i_vfs_inode = inode;
jinode->i_flags = 0;
INIT_LIST_HEAD(&jinode->i_list);
}
/*
* Function to be called before we start removing inode from memory (i.e.,
* clear_inode() is a fine place to be called from). It removes inode from
* transaction's lists.
*/
void jbd2_journal_release_jbd_inode(journal_t *journal,
struct jbd2_inode *jinode)
{
if (!journal)
return;
restart:
spin_lock(&journal->j_list_lock);
/* Is commit writing out inode - we have to wait */
if (test_bit(__JI_COMMIT_RUNNING, &jinode->i_flags)) {
wait_queue_head_t *wq;
DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&journal->j_list_lock);
schedule();
finish_wait(wq, &wait.wait);
goto restart;
}
if (jinode->i_transaction) {
list_del(&jinode->i_list);
jinode->i_transaction = NULL;
}
spin_unlock(&journal->j_list_lock);
}
/*
* debugfs tunables
*/
#ifdef CONFIG_JBD2_DEBUG
u8 jbd2_journal_enable_debug __read_mostly;
EXPORT_SYMBOL(jbd2_journal_enable_debug);
#define JBD2_DEBUG_NAME "jbd2-debug"
static struct dentry *jbd2_debugfs_dir;
static struct dentry *jbd2_debug;
static void __init jbd2_create_debugfs_entry(void)
{
jbd2_debugfs_dir = debugfs_create_dir("jbd2", NULL);
if (jbd2_debugfs_dir)
jbd2_debug = debugfs_create_u8(JBD2_DEBUG_NAME,
S_IRUGO | S_IWUSR,
jbd2_debugfs_dir,
&jbd2_journal_enable_debug);
}
static void __exit jbd2_remove_debugfs_entry(void)
{
debugfs_remove(jbd2_debug);
debugfs_remove(jbd2_debugfs_dir);
}
#else
static void __init jbd2_create_debugfs_entry(void)
{
}
static void __exit jbd2_remove_debugfs_entry(void)
{
}
#endif
#ifdef CONFIG_PROC_FS
#define JBD2_STATS_PROC_NAME "fs/jbd2"
static void __init jbd2_create_jbd_stats_proc_entry(void)
{
proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
}
static void __exit jbd2_remove_jbd_stats_proc_entry(void)
{
if (proc_jbd2_stats)
remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
}
#else
#define jbd2_create_jbd_stats_proc_entry() do {} while (0)
#define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
#endif
struct kmem_cache *jbd2_handle_cache, *jbd2_inode_cache;
static int __init journal_init_handle_cache(void)
{
jbd2_handle_cache = KMEM_CACHE(jbd2_journal_handle, SLAB_TEMPORARY);
if (jbd2_handle_cache == NULL) {
printk(KERN_EMERG "JBD2: failed to create handle cache\n");
return -ENOMEM;
}
jbd2_inode_cache = KMEM_CACHE(jbd2_inode, 0);
if (jbd2_inode_cache == NULL) {
printk(KERN_EMERG "JBD2: failed to create inode cache\n");
kmem_cache_destroy(jbd2_handle_cache);
return -ENOMEM;
}
return 0;
}
static void jbd2_journal_destroy_handle_cache(void)
{
if (jbd2_handle_cache)
kmem_cache_destroy(jbd2_handle_cache);
if (jbd2_inode_cache)
kmem_cache_destroy(jbd2_inode_cache);
}
/*
* Module startup and shutdown
*/
static int __init journal_init_caches(void)
{
int ret;
ret = jbd2_journal_init_revoke_caches();
if (ret == 0)
ret = journal_init_jbd2_journal_head_cache();
if (ret == 0)
ret = journal_init_handle_cache();
return ret;
}
static void jbd2_journal_destroy_caches(void)
{
jbd2_journal_destroy_revoke_caches();
jbd2_journal_destroy_jbd2_journal_head_cache();
jbd2_journal_destroy_handle_cache();
jbd2_journal_destroy_slabs();
}
static int __init journal_init(void)
{
int ret;
BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
ret = journal_init_caches();
if (ret == 0) {
jbd2_create_debugfs_entry();
jbd2_create_jbd_stats_proc_entry();
} else {
jbd2_journal_destroy_caches();
}
return ret;
}
static void __exit journal_exit(void)
{
#ifdef CONFIG_JBD2_DEBUG
int n = atomic_read(&nr_journal_heads);
if (n)
printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
#endif
jbd2_remove_debugfs_entry();
jbd2_remove_jbd_stats_proc_entry();
jbd2_journal_destroy_caches();
}
/*
* jbd2_dev_to_name is a utility function used by the jbd2 and ext4
* tracing infrastructure to map a dev_t to a device name.
*
* The caller should use rcu_read_lock() in order to make sure the
* device name stays valid until its done with it. We use
* rcu_read_lock() as well to make sure we're safe in case the caller
* gets sloppy, and because rcu_read_lock() is cheap and can be safely
* nested.
*/
struct devname_cache {
struct rcu_head rcu;
dev_t device;
char devname[BDEVNAME_SIZE];
};
#define CACHE_SIZE_BITS 6
static struct devname_cache *devcache[1 << CACHE_SIZE_BITS];
static DEFINE_SPINLOCK(devname_cache_lock);
static void free_devcache(struct rcu_head *rcu)
{
kfree(rcu);
}
const char *jbd2_dev_to_name(dev_t device)
{
int i = hash_32(device, CACHE_SIZE_BITS);
char *ret;
struct block_device *bd;
static struct devname_cache *new_dev;
rcu_read_lock();
if (devcache[i] && devcache[i]->device == device) {
ret = devcache[i]->devname;
rcu_read_unlock();
return ret;
}
rcu_read_unlock();
new_dev = kmalloc(sizeof(struct devname_cache), GFP_KERNEL);
if (!new_dev)
return "NODEV-ALLOCFAILURE"; /* Something non-NULL */
bd = bdget(device);
spin_lock(&devname_cache_lock);
if (devcache[i]) {
if (devcache[i]->device == device) {
kfree(new_dev);
bdput(bd);
ret = devcache[i]->devname;
spin_unlock(&devname_cache_lock);
return ret;
}
call_rcu(&devcache[i]->rcu, free_devcache);
}
devcache[i] = new_dev;
devcache[i]->device = device;
if (bd) {
bdevname(bd, devcache[i]->devname);
bdput(bd);
} else
__bdevname(device, devcache[i]->devname);
ret = devcache[i]->devname;
spin_unlock(&devname_cache_lock);
return ret;
}
EXPORT_SYMBOL(jbd2_dev_to_name);
MODULE_LICENSE("GPL");
module_init(journal_init);
module_exit(journal_exit);