journal_wipe(9) [centos man page]
JOURNAL_WIPE(9) The Linux Journalling API JOURNAL_WIPE(9) NAME
journal_wipe - Wipe journal contents SYNOPSIS
int journal_wipe(journal_t * journal, int write); ARGUMENTS
journal Journal to act on. write flag (see below) DESCRIPTION
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. AUTHORS
Roger Gammans <rgammans@computer-surgery.co.uk> Author. Stephen Tweedie <sct@redhat.com> Author. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 JOURNAL_WIPE(9)
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STRUCT
JOURNAL_S(9) The Linux Journalling API STRUCT JOURNAL_S(9) NAME
struct_journal_s - this is the concrete type associated with journal_t. SYNOPSIS
struct journal_s { unsigned long j_flags; int j_errno; struct buffer_head * j_sb_buffer; journal_superblock_t * j_superblock; int j_format_version; spinlock_t j_state_lock; int j_barrier_count; transaction_t * j_running_transaction; transaction_t * j_committing_transaction; transaction_t * j_checkpoint_transactions; wait_queue_head_t j_wait_transaction_locked; wait_queue_head_t j_wait_logspace; wait_queue_head_t j_wait_done_commit; wait_queue_head_t j_wait_checkpoint; wait_queue_head_t j_wait_commit; wait_queue_head_t j_wait_updates; struct mutex j_checkpoint_mutex; unsigned int j_head; unsigned int j_tail; unsigned int j_free; unsigned int j_first; unsigned int j_last; struct block_device * j_dev; int j_blocksize; unsigned int j_blk_offset; struct block_device * j_fs_dev; unsigned int j_maxlen; spinlock_t j_list_lock; struct inode * j_inode; tid_t j_tail_sequence; tid_t j_transaction_sequence; tid_t j_commit_sequence; tid_t j_commit_request; tid_t j_commit_waited; __u8 j_uuid[16]; struct task_struct * j_task; int j_max_transaction_buffers; unsigned long j_commit_interval; struct timer_list j_commit_timer; spinlock_t j_revoke_lock; struct jbd_revoke_table_s * j_revoke; struct jbd_revoke_table_s * j_revoke_table[2]; struct buffer_head ** j_wbuf; int j_wbufsize; pid_t j_last_sync_writer; u64 j_average_commit_time; void * j_private; }; MEMBERS
j_flags General journaling state flags j_errno Is there an outstanding uncleared error on the journal (from a prior abort)? j_sb_buffer First part of superblock buffer j_superblock Second part of superblock buffer j_format_version Version of the superblock format j_state_lock Protect the various scalars in the journal j_barrier_count Number of processes waiting to create a barrier lock j_running_transaction The current running transaction.. j_committing_transaction the transaction we are pushing to disk j_checkpoint_transactions a linked circular list of all transactions waiting for checkpointing j_wait_transaction_locked Wait queue for waiting for a locked transaction to start committing, or for a barrier lock to be released j_wait_logspace Wait queue for waiting for checkpointing to complete j_wait_done_commit Wait queue for waiting for commit to complete j_wait_checkpoint Wait queue to trigger checkpointing j_wait_commit Wait queue to trigger commit j_wait_updates Wait queue to wait for updates to complete j_checkpoint_mutex Mutex for locking against concurrent checkpoints j_head Journal head - identifies the first unused block in the journal j_tail Journal tail - identifies the oldest still-used block in the journal. j_free Journal free - how many free blocks are there in the journal? j_first The block number of the first usable block j_last The block number one beyond the last usable block j_dev Device where we store the journal j_blocksize blocksize for the location where we store the journal. j_blk_offset starting block offset for into the device where we store the journal j_fs_dev Device which holds the client fs. For internal journal this will be equal to j_dev j_maxlen Total maximum capacity of the journal region on disk. j_list_lock Protects the buffer lists and internal buffer state. j_inode Optional inode where we store the journal. If present, all journal block numbers are mapped into this inode via bmap. j_tail_sequence Sequence number of the oldest transaction in the log j_transaction_sequence Sequence number of the next transaction to grant j_commit_sequence Sequence number of the most recently committed transaction j_commit_request Sequence number of the most recent transaction wanting commit j_commit_waited Sequence number of the most recent transaction someone is waiting for to commit. j_uuid[16] Uuid of client object. j_task Pointer to the current commit thread for this journal j_max_transaction_buffers Maximum number of metadata buffers to allow in a single compound commit transaction j_commit_interval What is the maximum transaction lifetime before we begin a commit? j_commit_timer The timer used to wakeup the commit thread j_revoke_lock Protect the revoke table j_revoke The revoke table - maintains the list of revoked blocks in the current transaction. j_revoke_table[2] alternate revoke tables for j_revoke j_wbuf array of buffer_heads for journal_commit_transaction j_wbufsize maximum number of buffer_heads allowed in j_wbuf, the number that will fit in j_blocksize j_last_sync_writer most recent pid which did a synchronous write j_average_commit_time the average amount of time in nanoseconds it takes to commit a transaction to the disk. j_private An opaque pointer to fs-private information. AUTHORS
Roger Gammans <rgammans@computer-surgery.co.uk> Author. Stephen Tweedie <sct@redhat.com> Author. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 STRUCT JOURNAL_S(9)