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jbd2: Make state lock a spinlock 

Bit-spinlocks are problematic on PREEMPT_RT if functions which might sleep
on RT, e.g. spin_lock(), alloc/free(), are invoked inside the lock held
region because bit spinlocks disable preemption even on RT.

A first attempt was to replace state lock with a spinlock placed in struct
buffer_head and make the locking conditional on PREEMPT_RT and
DEBUG_BIT_SPINLOCKS.

Jan pointed out that there is a 4 byte hole in struct journal_head where a
regular spinlock fits in and he would not object to convert the state lock
to a spinlock unconditionally.

Aside of solving the RT problem, this also gains lockdep coverage for the
journal head state lock (bit-spinlocks are not covered by lockdep as it's
hard to fit a lockdep map into a single bit).

The trivial change would have been to convert the jbd_*lock_bh_state()
inlines, but that comes with the downside that these functions take a
buffer head pointer which needs to be converted to a journal head pointer
which adds another level of indirection.

As almost all functions which use this lock have a journal head pointer
readily available, it makes more sense to remove the lock helper inlines
and write out spin_*lock() at all call sites.

Fixup all locking comments as well.

Suggested-by: Jan Kara <jack@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jan Kara <jack@suse.com>
Cc: linux-ext4@vger.kernel.org
Link: https://lore.kernel.org/r/20190809124233.13277-7-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Thomas Gleixner 2019-08-09 14:42:32 +02:00 коммит произвёл Theodore Ts'o
Родитель 2e710ff03f
Коммит 464170647b
6 изменённых файлов: 84 добавлений и 94 удалений
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8
fs/jbd2/commit.c
Просмотреть файл

@ -482,10 +482,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
if (jh->b_committed_data) {
struct buffer_head *bh = jh2bh(jh);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
jbd2_free(jh->b_committed_data, bh->b_size);
jh->b_committed_data = NULL;
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
}
jbd2_journal_refile_buffer(journal, jh);
}
@ -928,7 +928,7 @@ restart_loop:
* done with it.
*/
get_bh(bh);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
/*
@ -1024,7 +1024,7 @@ restart_loop:
}
JBUFFER_TRACE(jh, "refile or unfile buffer");
drop_ref = __jbd2_journal_refile_buffer(jh);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
if (drop_ref)
jbd2_journal_put_journal_head(jh);
if (try_to_free)

10
fs/jbd2/journal.c
Просмотреть файл

@ -363,7 +363,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
/* keep subsequent assertions sane */
atomic_set(&new_bh->b_count, 1);
jbd_lock_bh_state(bh_in);
spin_lock(&jh_in->b_state_lock);
repeat:
/*
* If a new transaction has already done a buffer copy-out, then
@ -405,13 +405,13 @@ repeat:
if (need_copy_out && !done_copy_out) {
char *tmp;
jbd_unlock_bh_state(bh_in);
spin_unlock(&jh_in->b_state_lock);
tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
if (!tmp) {
brelse(new_bh);
return -ENOMEM;
}
jbd_lock_bh_state(bh_in);
spin_lock(&jh_in->b_state_lock);
if (jh_in->b_frozen_data) {
jbd2_free(tmp, bh_in->b_size);
goto repeat;
@ -464,7 +464,7 @@ repeat:
__jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
spin_unlock(&journal->j_list_lock);
set_buffer_shadow(bh_in);
jbd_unlock_bh_state(bh_in);
spin_unlock(&jh_in->b_state_lock);
return do_escape | (done_copy_out << 1);
}
@ -2410,6 +2410,8 @@ static struct journal_head *journal_alloc_journal_head(void)
ret = kmem_cache_zalloc(jbd2_journal_head_cache,
GFP_NOFS | __GFP_NOFAIL);
}
if (ret)
spin_lock_init(&ret->b_state_lock);
return ret;
}

100
fs/jbd2/transaction.c
Просмотреть файл

@ -879,7 +879,7 @@ repeat:
start_lock = jiffies;
lock_buffer(bh);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
/* If it takes too long to lock the buffer, trace it */
time_lock = jbd2_time_diff(start_lock, jiffies);
@ -929,7 +929,7 @@ repeat:
error = -EROFS;
if (is_handle_aborted(handle)) {
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
goto out;
}
error = 0;
@ -993,7 +993,7 @@ repeat:
*/
if (buffer_shadow(bh)) {
JBUFFER_TRACE(jh, "on shadow: sleep");
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
wait_on_bit_io(&bh->b_state, BH_Shadow, TASK_UNINTERRUPTIBLE);
goto repeat;
}
@ -1014,7 +1014,7 @@ repeat:
JBUFFER_TRACE(jh, "generate frozen data");
if (!frozen_buffer) {
JBUFFER_TRACE(jh, "allocate memory for buffer");
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
GFP_NOFS | __GFP_NOFAIL);
goto repeat;
@ -1033,7 +1033,7 @@ attach_next:
jh->b_next_transaction = transaction;
done:
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
/*
* If we are about to journal a buffer, then any revoke pending on it is
@ -1172,7 +1172,7 @@ int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
* that case: the transaction must have deleted the buffer for it to be
* reused here.
*/
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
jh->b_transaction == NULL ||
(jh->b_transaction == journal->j_committing_transaction &&
@ -1207,7 +1207,7 @@ int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
jh->b_next_transaction = transaction;
spin_unlock(&journal->j_list_lock);
}
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
/*
* akpm: I added this. ext3_alloc_branch can pick up new indirect
@ -1275,13 +1275,13 @@ repeat:
committed_data = jbd2_alloc(jh2bh(jh)->b_size,
GFP_NOFS|__GFP_NOFAIL);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
if (!jh->b_committed_data) {
/* Copy out the current buffer contents into the
* preserved, committed copy. */
JBUFFER_TRACE(jh, "generate b_committed data");
if (!committed_data) {
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
goto repeat;
}
@ -1289,7 +1289,7 @@ repeat:
committed_data = NULL;
memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
}
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
out:
jbd2_journal_put_journal_head(jh);
if (unlikely(committed_data))
@ -1390,16 +1390,16 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
*/
if (jh->b_transaction != transaction &&
jh->b_next_transaction != transaction) {
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
J_ASSERT_JH(jh, jh->b_transaction == transaction ||
jh->b_next_transaction == transaction);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
}
if (jh->b_modified == 1) {
/* If it's in our transaction it must be in BJ_Metadata list. */
if (jh->b_transaction == transaction &&
jh->b_jlist != BJ_Metadata) {
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
if (jh->b_transaction == transaction &&
jh->b_jlist != BJ_Metadata)
pr_err("JBD2: assertion failure: h_type=%u "
@ -1409,13 +1409,13 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
jh->b_jlist);
J_ASSERT_JH(jh, jh->b_transaction != transaction ||
jh->b_jlist == BJ_Metadata);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
}
goto out;
}
journal = transaction->t_journal;
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
if (jh->b_modified == 0) {
/*
@ -1501,7 +1501,7 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
__jbd2_journal_file_buffer(jh, transaction, BJ_Metadata);
spin_unlock(&journal->j_list_lock);
out_unlock_bh:
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
out:
JBUFFER_TRACE(jh, "exit");
return ret;
@ -1539,11 +1539,13 @@ int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
BUFFER_TRACE(bh, "entry");
jbd_lock_bh_state(bh);
jh = jbd2_journal_grab_journal_head(bh);
if (!jh) {
__bforget(bh);
return 0;
}
if (!buffer_jbd(bh))
goto not_jbd;
jh = bh2jh(bh);
spin_lock(&jh->b_state_lock);
/* Critical error: attempting to delete a bitmap buffer, maybe?
* Don't do any jbd operations, and return an error. */
@ -1664,18 +1666,14 @@ int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
spin_unlock(&journal->j_list_lock);
}
drop:
jbd_unlock_bh_state(bh);
__brelse(bh);
spin_unlock(&jh->b_state_lock);
jbd2_journal_put_journal_head(jh);
if (drop_reserve) {
/* no need to reserve log space for this block -bzzz */
handle->h_buffer_credits++;
}
return err;
not_jbd:
jbd_unlock_bh_state(bh);
__bforget(bh);
goto drop;
}
/**
@ -1874,7 +1872,7 @@ free_and_exit:
*
* j_list_lock is held.
*
* jbd_lock_bh_state(jh2bh(jh)) is held.
* jh->b_state_lock is held.
*/
static inline void
@ -1898,7 +1896,7 @@ __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
*
* Called with j_list_lock held, and the journal may not be locked.
*
* jbd_lock_bh_state(jh2bh(jh)) is held.
* jh->b_state_lock is held.
*/
static inline void
@ -1930,7 +1928,7 @@ static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
transaction_t *transaction;
struct buffer_head *bh = jh2bh(jh);
J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
lockdep_assert_held(&jh->b_state_lock);
transaction = jh->b_transaction;
if (transaction)
assert_spin_locked(&transaction->t_journal->j_list_lock);
@ -1984,11 +1982,11 @@ void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
/* Get reference so that buffer cannot be freed before we unlock it */
get_bh(bh);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
spin_lock(&journal->j_list_lock);
__jbd2_journal_unfile_buffer(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
jbd2_journal_put_journal_head(jh);
__brelse(bh);
}
@ -1996,7 +1994,7 @@ void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
/*
* Called from jbd2_journal_try_to_free_buffers().
*
* Called under jbd_lock_bh_state(bh)
* Called under jh->b_state_lock
*/
static void
__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
@ -2083,10 +2081,10 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal,
if (!jh)
continue;
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
__journal_try_to_free_buffer(journal, bh);
spin_unlock(&jh->b_state_lock);
jbd2_journal_put_journal_head(jh);
jbd_unlock_bh_state(bh);
if (buffer_jbd(bh))
goto busy;
} while ((bh = bh->b_this_page) != head);
@ -2107,7 +2105,7 @@ busy:
*
* Called under j_list_lock.
*
* Called under jbd_lock_bh_state(bh).
* Called under jh->b_state_lock.
*/
static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
{
@ -2201,7 +2199,7 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
/* OK, we have data buffer in journaled mode */
write_lock(&journal->j_state_lock);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
spin_lock(&journal->j_list_lock);
/*
@ -2282,10 +2280,10 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
* for commit and try again.
*/
if (partial_page) {
jbd2_journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
write_unlock(&journal->j_state_lock);
jbd2_journal_put_journal_head(jh);
return -EBUSY;
}
/*
@ -2297,10 +2295,10 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
set_buffer_freed(bh);
if (journal->j_running_transaction && buffer_jbddirty(bh))
jh->b_next_transaction = journal->j_running_transaction;
jbd2_journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
write_unlock(&journal->j_state_lock);
jbd2_journal_put_journal_head(jh);
return 0;
} else {
/* Good, the buffer belongs to the running transaction.
@ -2324,10 +2322,10 @@ zap_buffer:
* here.
*/
jh->b_modified = 0;
jbd2_journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
write_unlock(&journal->j_state_lock);
jbd2_journal_put_journal_head(jh);
zap_buffer_unlocked:
clear_buffer_dirty(bh);
J_ASSERT_BH(bh, !buffer_jbddirty(bh));
@ -2414,7 +2412,7 @@ void __jbd2_journal_file_buffer(struct journal_head *jh,
int was_dirty = 0;
struct buffer_head *bh = jh2bh(jh);
J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
lockdep_assert_held(&jh->b_state_lock);
assert_spin_locked(&transaction->t_journal->j_list_lock);
J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
@ -2476,11 +2474,11 @@ void __jbd2_journal_file_buffer(struct journal_head *jh,
void jbd2_journal_file_buffer(struct journal_head *jh,
transaction_t *transaction, int jlist)
{
jbd_lock_bh_state(jh2bh(jh));
spin_lock(&jh->b_state_lock);
spin_lock(&transaction->t_journal->j_list_lock);
__jbd2_journal_file_buffer(jh, transaction, jlist);
spin_unlock(&transaction->t_journal->j_list_lock);
jbd_unlock_bh_state(jh2bh(jh));
spin_unlock(&jh->b_state_lock);
}
/*
@ -2490,7 +2488,7 @@ void jbd2_journal_file_buffer(struct journal_head *jh,
* buffer on that transaction's metadata list.
*
* Called under j_list_lock
* Called under jbd_lock_bh_state(jh2bh(jh))
* Called under jh->b_state_lock
*
* When this function returns true, there's no next transaction to refile to
* and the caller has to drop jh reference through
@ -2501,7 +2499,7 @@ bool __jbd2_journal_refile_buffer(struct journal_head *jh)
int was_dirty, jlist;
struct buffer_head *bh = jh2bh(jh);
J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
lockdep_assert_held(&jh->b_state_lock);
if (jh->b_transaction)
assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
@ -2547,17 +2545,13 @@ bool __jbd2_journal_refile_buffer(struct journal_head *jh)
*/
void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
{
struct buffer_head *bh = jh2bh(jh);
bool drop;
/* Get reference so that buffer cannot be freed before we unlock it */
get_bh(bh);
jbd_lock_bh_state(bh);
spin_lock(&jh->b_state_lock);
spin_lock(&journal->j_list_lock);
drop = __jbd2_journal_refile_buffer(jh);
jbd_unlock_bh_state(bh);
spin_unlock(&jh->b_state_lock);
spin_unlock(&journal->j_list_lock);
__brelse(bh);
if (drop)
jbd2_journal_put_journal_head(jh);
}

19
fs/ocfs2/suballoc.c
Просмотреть файл

@ -1252,6 +1252,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
int nr)
{
struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
struct journal_head *jh;
int ret;
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
@ -1260,13 +1261,14 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
if (!buffer_jbd(bg_bh))
return 1;
jbd_lock_bh_state(bg_bh);
bg = (struct ocfs2_group_desc *) bh2jh(bg_bh)->b_committed_data;
jh = bh2jh(bg_bh);
spin_lock(&jh->b_state_lock);
bg = (struct ocfs2_group_desc *) jh->b_committed_data;
if (bg)
ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
else
ret = 1;
jbd_unlock_bh_state(bg_bh);
spin_unlock(&jh->b_state_lock);
return ret;
}
@ -2387,6 +2389,7 @@ static int ocfs2_block_group_clear_bits(handle_t *handle,
int status;
unsigned int tmp;
struct ocfs2_group_desc *undo_bg = NULL;
struct journal_head *jh;
/* The caller got this descriptor from
* ocfs2_read_group_descriptor(). Any corruption is a code bug. */
@ -2405,10 +2408,10 @@ static int ocfs2_block_group_clear_bits(handle_t *handle,
goto bail;
}
jh = bh2jh(group_bh);
if (undo_fn) {
jbd_lock_bh_state(group_bh);
undo_bg = (struct ocfs2_group_desc *)
bh2jh(group_bh)->b_committed_data;
spin_lock(&jh->b_state_lock);
undo_bg = (struct ocfs2_group_desc *) jh->b_committed_data;
BUG_ON(!undo_bg);
}
@ -2423,7 +2426,7 @@ static int ocfs2_block_group_clear_bits(handle_t *handle,
le16_add_cpu(&bg->bg_free_bits_count, num_bits);
if (le16_to_cpu(bg->bg_free_bits_count) > le16_to_cpu(bg->bg_bits)) {
if (undo_fn)
jbd_unlock_bh_state(group_bh);
spin_unlock(&jh->b_state_lock);
return ocfs2_error(alloc_inode->i_sb, "Group descriptor # %llu has bit count %u but claims %u are freed. num_bits %d\n",
(unsigned long long)le64_to_cpu(bg->bg_blkno),
le16_to_cpu(bg->bg_bits),
@ -2432,7 +2435,7 @@ static int ocfs2_block_group_clear_bits(handle_t *handle,
}
if (undo_fn)
jbd_unlock_bh_state(group_bh);
spin_unlock(&jh->b_state_lock);
ocfs2_journal_dirty(handle, group_bh);
bail:

20
include/linux/jbd2.h
Просмотреть файл

@ -313,7 +313,6 @@ enum jbd_state_bits {
BH_Revoked, /* Has been revoked from the log */
BH_RevokeValid, /* Revoked flag is valid */
BH_JBDDirty, /* Is dirty but journaled */
BH_State, /* Pins most journal_head state */
BH_JournalHead, /* Pins bh->b_private and jh->b_bh */
BH_Shadow, /* IO on shadow buffer is running */
BH_Verified, /* Metadata block has been verified ok */
@ -342,21 +341,6 @@ static inline struct journal_head *bh2jh(struct buffer_head *bh)
return bh->b_private;
}
static inline void jbd_lock_bh_state(struct buffer_head *bh)
{
bit_spin_lock(BH_State, &bh->b_state);
}
static inline int jbd_is_locked_bh_state(struct buffer_head *bh)
{
return bit_spin_is_locked(BH_State, &bh->b_state);
}
static inline void jbd_unlock_bh_state(struct buffer_head *bh)
{
bit_spin_unlock(BH_State, &bh->b_state);
}
static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)
{
bit_spin_lock(BH_JournalHead, &bh->b_state);
@ -551,9 +535,9 @@ struct transaction_chp_stats_s {
* ->jbd_lock_bh_journal_head() (This is "innermost")
*
* j_state_lock
* ->jbd_lock_bh_state()
* ->b_state_lock
*
* jbd_lock_bh_state()
* b_state_lock
* ->j_list_lock
*
* j_state_lock

21
include/linux/journal-head.h
Просмотреть файл

@ -11,6 +11,8 @@
#ifndef JOURNAL_HEAD_H_INCLUDED
#define JOURNAL_HEAD_H_INCLUDED
#include <linux/spinlock.h>
typedef unsigned int tid_t; /* Unique transaction ID */
typedef struct transaction_s transaction_t; /* Compound transaction type */
@ -23,6 +25,11 @@ struct journal_head {
*/
struct buffer_head *b_bh;
/*
* Protect the buffer head state
*/
spinlock_t b_state_lock;
/*
* Reference count - see description in journal.c
* [jbd_lock_bh_journal_head()]
@ -30,7 +37,7 @@ struct journal_head {
int b_jcount;
/*
* Journalling list for this buffer [jbd_lock_bh_state()]
* Journalling list for this buffer [b_state_lock]
* NOTE: We *cannot* combine this with b_modified into a bitfield
* as gcc would then (which the C standard allows but which is
* very unuseful) make 64-bit accesses to the bitfield and clobber
@ -41,20 +48,20 @@ struct journal_head {
/*
* This flag signals the buffer has been modified by
* the currently running transaction
* [jbd_lock_bh_state()]
* [b_state_lock]
*/
unsigned b_modified;
/*
* Copy of the buffer data frozen for writing to the log.
* [jbd_lock_bh_state()]
* [b_state_lock]
*/
char *b_frozen_data;
/*
* Pointer to a saved copy of the buffer containing no uncommitted
* deallocation references, so that allocations can avoid overwriting
* uncommitted deletes. [jbd_lock_bh_state()]
* uncommitted deletes. [b_state_lock]
*/
char *b_committed_data;
@ -63,7 +70,7 @@ struct journal_head {
* metadata: either the running transaction or the committing
* transaction (if there is one). Only applies to buffers on a
* transaction's data or metadata journaling list.
* [j_list_lock] [jbd_lock_bh_state()]
* [j_list_lock] [b_state_lock]
* Either of these locks is enough for reading, both are needed for
* changes.
*/
@ -73,13 +80,13 @@ struct journal_head {
* Pointer to the running compound transaction which is currently
* modifying the buffer's metadata, if there was already a transaction
* committing it when the new transaction touched it.
* [t_list_lock] [jbd_lock_bh_state()]
* [t_list_lock] [b_state_lock]
*/
transaction_t *b_next_transaction;
/*
* Doubly-linked list of buffers on a transaction's data, metadata or
* forget queue. [t_list_lock] [jbd_lock_bh_state()]
* forget queue. [t_list_lock] [b_state_lock]
*/
struct journal_head *b_tnext, *b_tprev;