e2555fde41
Commit ae4647fb (jbd2: reduce journal_head size) introduced a
regression where we occasionally hit panic in
jbd2_journal_put_journal_head() because of wrong b_jcount. The bug is
caused by gcc making 64-bit access to 32-bit bitfield and thus
clobbering b_jcount.
At least for now, those 8 bytes saved in struct journal_head are not
worth the trouble with gcc bitfield handling so revert that part of
the patch.
Reported-by: EUNBONG SONG <eunb.song@samsung.com>
Reported-by: Tony Luck <tony.luck@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
106 lines
2.8 KiB
C
106 lines
2.8 KiB
C
/*
|
|
* include/linux/journal-head.h
|
|
*
|
|
* buffer_head fields for JBD
|
|
*
|
|
* 27 May 2001 Andrew Morton
|
|
* Created - pulled out of fs.h
|
|
*/
|
|
|
|
#ifndef JOURNAL_HEAD_H_INCLUDED
|
|
#define JOURNAL_HEAD_H_INCLUDED
|
|
|
|
typedef unsigned int tid_t; /* Unique transaction ID */
|
|
typedef struct transaction_s transaction_t; /* Compound transaction type */
|
|
|
|
|
|
struct buffer_head;
|
|
|
|
struct journal_head {
|
|
/*
|
|
* Points back to our buffer_head. [jbd_lock_bh_journal_head()]
|
|
*/
|
|
struct buffer_head *b_bh;
|
|
|
|
/*
|
|
* Reference count - see description in journal.c
|
|
* [jbd_lock_bh_journal_head()]
|
|
*/
|
|
int b_jcount;
|
|
|
|
/*
|
|
* Journalling list for this buffer [jbd_lock_bh_state()]
|
|
* 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
|
|
* b_jcount if its update races with bitfield modification.
|
|
*/
|
|
unsigned b_jlist;
|
|
|
|
/*
|
|
* This flag signals the buffer has been modified by
|
|
* the currently running transaction
|
|
* [jbd_lock_bh_state()]
|
|
*/
|
|
unsigned b_modified;
|
|
|
|
/*
|
|
* Copy of the buffer data frozen for writing to the log.
|
|
* [jbd_lock_bh_state()]
|
|
*/
|
|
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()]
|
|
*/
|
|
char *b_committed_data;
|
|
|
|
/*
|
|
* Pointer to the compound transaction which owns this buffer's
|
|
* 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()]
|
|
* Either of these locks is enough for reading, both are needed for
|
|
* changes.
|
|
*/
|
|
transaction_t *b_transaction;
|
|
|
|
/*
|
|
* 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()]
|
|
*/
|
|
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()]
|
|
*/
|
|
struct journal_head *b_tnext, *b_tprev;
|
|
|
|
/*
|
|
* Pointer to the compound transaction against which this buffer
|
|
* is checkpointed. Only dirty buffers can be checkpointed.
|
|
* [j_list_lock]
|
|
*/
|
|
transaction_t *b_cp_transaction;
|
|
|
|
/*
|
|
* Doubly-linked list of buffers still remaining to be flushed
|
|
* before an old transaction can be checkpointed.
|
|
* [j_list_lock]
|
|
*/
|
|
struct journal_head *b_cpnext, *b_cpprev;
|
|
|
|
/* Trigger type */
|
|
struct jbd2_buffer_trigger_type *b_triggers;
|
|
|
|
/* Trigger type for the committing transaction's frozen data */
|
|
struct jbd2_buffer_trigger_type *b_frozen_triggers;
|
|
};
|
|
|
|
#endif /* JOURNAL_HEAD_H_INCLUDED */
|