xfs: factor xlog_write
xlog_write is a mess that takes a lot of effort to understand. It is a mass of nested loops with 4 space indents to get it to fit in 80 columns and lots of funky variables that aren't obvious what they mean or do. Break it down into understandable chunks. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Dave Chinner
Alex Elder
parent
9b9fc2b760
commit
b5203cd0a4
1 changed files with 225 additions and 112 deletions
337
fs/xfs/xfs_log.c
337
fs/xfs/xfs_log.c
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@ -1629,6 +1629,193 @@ xlog_print_tic_res(xfs_mount_t *mp, xlog_ticket_t *ticket)
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}
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}
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/*
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* Calculate the potential space needed by the log vector. Each region gets
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* its own xlog_op_header_t and may need to be double word aligned.
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*/
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static int
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xlog_write_calc_vec_length(
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struct xlog_ticket *ticket,
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struct xfs_log_iovec reg[],
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int nentries)
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{
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int headers = 0;
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int len = 0;
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int i;
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/* acct for start rec of xact */
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if (ticket->t_flags & XLOG_TIC_INITED)
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headers++;
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for (i = 0; i < nentries; i++) {
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/* each region gets >= 1 */
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headers++;
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len += reg[i].i_len;
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xlog_tic_add_region(ticket, reg[i].i_len, reg[i].i_type);
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}
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ticket->t_res_num_ophdrs += headers;
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len += headers * sizeof(struct xlog_op_header);
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return len;
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}
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/*
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* If first write for transaction, insert start record We can't be trying to
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* commit if we are inited. We can't have any "partial_copy" if we are inited.
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*/
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static int
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xlog_write_start_rec(
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__psint_t ptr,
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struct xlog_ticket *ticket)
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{
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struct xlog_op_header *ophdr = (struct xlog_op_header *)ptr;
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if (!(ticket->t_flags & XLOG_TIC_INITED))
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return 0;
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ophdr->oh_tid = cpu_to_be32(ticket->t_tid);
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ophdr->oh_clientid = ticket->t_clientid;
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ophdr->oh_len = 0;
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ophdr->oh_flags = XLOG_START_TRANS;
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ophdr->oh_res2 = 0;
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ticket->t_flags &= ~XLOG_TIC_INITED;
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return sizeof(struct xlog_op_header);
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}
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static xlog_op_header_t *
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xlog_write_setup_ophdr(
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struct log *log,
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__psint_t ptr,
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struct xlog_ticket *ticket,
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uint flags)
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{
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struct xlog_op_header *ophdr = (struct xlog_op_header *)ptr;
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ophdr->oh_tid = cpu_to_be32(ticket->t_tid);
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ophdr->oh_clientid = ticket->t_clientid;
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ophdr->oh_res2 = 0;
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/* are we copying a commit or unmount record? */
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ophdr->oh_flags = flags;
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/*
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* We've seen logs corrupted with bad transaction client ids. This
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* makes sure that XFS doesn't generate them on. Turn this into an EIO
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* and shut down the filesystem.
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*/
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switch (ophdr->oh_clientid) {
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case XFS_TRANSACTION:
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case XFS_VOLUME:
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case XFS_LOG:
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break;
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default:
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xfs_fs_cmn_err(CE_WARN, log->l_mp,
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"Bad XFS transaction clientid 0x%x in ticket 0x%p",
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ophdr->oh_clientid, ticket);
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return NULL;
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}
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return ophdr;
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}
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/*
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* Set up the parameters of the region copy into the log. This has
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* to handle region write split across multiple log buffers - this
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* state is kept external to this function so that this code can
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* can be written in an obvious, self documenting manner.
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*/
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static int
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xlog_write_setup_copy(
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struct xlog_ticket *ticket,
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struct xlog_op_header *ophdr,
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int space_available,
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int space_required,
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int *copy_off,
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int *copy_len,
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int *last_was_partial_copy,
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int *bytes_consumed)
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{
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int still_to_copy;
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still_to_copy = space_required - *bytes_consumed;
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*copy_off = *bytes_consumed;
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if (still_to_copy <= space_available) {
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/* write of region completes here */
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*copy_len = still_to_copy;
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ophdr->oh_len = cpu_to_be32(*copy_len);
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if (*last_was_partial_copy)
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ophdr->oh_flags |= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS);
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*last_was_partial_copy = 0;
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*bytes_consumed = 0;
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return 0;
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}
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/* partial write of region, needs extra log op header reservation */
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*copy_len = space_available;
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ophdr->oh_len = cpu_to_be32(*copy_len);
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ophdr->oh_flags |= XLOG_CONTINUE_TRANS;
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if (*last_was_partial_copy)
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ophdr->oh_flags |= XLOG_WAS_CONT_TRANS;
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*bytes_consumed += *copy_len;
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(*last_was_partial_copy)++;
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/* account for new log op header */
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ticket->t_curr_res -= sizeof(struct xlog_op_header);
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ticket->t_res_num_ophdrs++;
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return sizeof(struct xlog_op_header);
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}
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static int
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xlog_write_copy_finish(
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struct log *log,
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struct xlog_in_core *iclog,
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uint flags,
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int *record_cnt,
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int *data_cnt,
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int *partial_copy,
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int *partial_copy_len,
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int log_offset,
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struct xlog_in_core **commit_iclog)
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{
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if (*partial_copy) {
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/*
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* This iclog has already been marked WANT_SYNC by
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* xlog_state_get_iclog_space.
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*/
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xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
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*record_cnt = 0;
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*data_cnt = 0;
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return xlog_state_release_iclog(log, iclog);
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}
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*partial_copy = 0;
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*partial_copy_len = 0;
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if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
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/* no more space in this iclog - push it. */
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xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
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*record_cnt = 0;
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*data_cnt = 0;
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spin_lock(&log->l_icloglock);
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xlog_state_want_sync(log, iclog);
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spin_unlock(&log->l_icloglock);
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if (!commit_iclog)
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return xlog_state_release_iclog(log, iclog);
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ASSERT(flags & XLOG_COMMIT_TRANS);
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*commit_iclog = iclog;
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}
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return 0;
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}
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/*
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* Write some region out to in-core log
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*
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@ -1689,7 +1876,6 @@ xlog_write(
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int start_rec_copy; /* # bytes to copy for start record */
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int partial_copy; /* did we split a region? */
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int partial_copy_len;/* # bytes copied if split region */
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int need_copy; /* # bytes need to memcpy this region */
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int copy_len; /* # bytes actually memcpy'ing */
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int copy_off; /* # bytes from entry start */
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int contwr; /* continued write of in-core log? */
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@ -1697,24 +1883,9 @@ xlog_write(
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int record_cnt = 0, data_cnt = 0;
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partial_copy_len = partial_copy = 0;
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/* Calculate potential maximum space. Each region gets its own
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* xlog_op_header_t and may need to be double word aligned.
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*/
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len = 0;
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if (ticket->t_flags & XLOG_TIC_INITED) { /* acct for start rec of xact */
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len += sizeof(xlog_op_header_t);
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ticket->t_res_num_ophdrs++;
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}
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for (index = 0; index < nentries; index++) {
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len += sizeof(xlog_op_header_t); /* each region gets >= 1 */
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ticket->t_res_num_ophdrs++;
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len += reg[index].i_len;
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xlog_tic_add_region(ticket, reg[index].i_len, reg[index].i_type);
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}
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contwr = *start_lsn = 0;
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len = xlog_write_calc_vec_length(ticket, reg, nentries);
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if (ticket->t_curr_res < len) {
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xlog_print_tic_res(mp, ticket);
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#ifdef DEBUG
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@ -1748,81 +1919,23 @@ xlog_write(
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while (index < nentries) {
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ASSERT(reg[index].i_len % sizeof(__int32_t) == 0);
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ASSERT((__psint_t)ptr % sizeof(__int32_t) == 0);
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start_rec_copy = 0;
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/* If first write for transaction, insert start record.
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* We can't be trying to commit if we are inited. We can't
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* have any "partial_copy" if we are inited.
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*/
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if (ticket->t_flags & XLOG_TIC_INITED) {
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logop_head = (xlog_op_header_t *)ptr;
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logop_head->oh_tid = cpu_to_be32(ticket->t_tid);
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logop_head->oh_clientid = ticket->t_clientid;
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logop_head->oh_len = 0;
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logop_head->oh_flags = XLOG_START_TRANS;
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logop_head->oh_res2 = 0;
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ticket->t_flags &= ~XLOG_TIC_INITED; /* clear bit */
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start_rec_copy = xlog_write_start_rec(ptr, ticket);
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if (start_rec_copy) {
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record_cnt++;
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start_rec_copy = sizeof(xlog_op_header_t);
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xlog_write_adv_cnt(ptr, len, log_offset, start_rec_copy);
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}
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/* Copy log operation header directly into data section */
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logop_head = (xlog_op_header_t *)ptr;
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logop_head->oh_tid = cpu_to_be32(ticket->t_tid);
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logop_head->oh_clientid = ticket->t_clientid;
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logop_head->oh_res2 = 0;
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/* header copied directly */
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logop_head = xlog_write_setup_ophdr(log, ptr, ticket, flags);
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if (!logop_head)
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return XFS_ERROR(EIO);
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xlog_write_adv_cnt(ptr, len, log_offset, sizeof(xlog_op_header_t));
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/* are we copying a commit or unmount record? */
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logop_head->oh_flags = flags;
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/*
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* We've seen logs corrupted with bad transaction client
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* ids. This makes sure that XFS doesn't generate them on.
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* Turn this into an EIO and shut down the filesystem.
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*/
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switch (logop_head->oh_clientid) {
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case XFS_TRANSACTION:
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case XFS_VOLUME:
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case XFS_LOG:
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break;
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default:
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xfs_fs_cmn_err(CE_WARN, mp,
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"Bad XFS transaction clientid 0x%x in ticket 0x%p",
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logop_head->oh_clientid, ticket);
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return XFS_ERROR(EIO);
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}
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/* Partial write last time? => (partial_copy != 0)
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* need_copy is the amount we'd like to copy if everything could
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* fit in the current memcpy.
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*/
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need_copy = reg[index].i_len - partial_copy_len;
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copy_off = partial_copy_len;
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if (need_copy <= iclog->ic_size - log_offset) { /*complete write */
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copy_len = need_copy;
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logop_head->oh_len = cpu_to_be32(copy_len);
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if (partial_copy)
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logop_head->oh_flags|= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS);
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partial_copy_len = partial_copy = 0;
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} else { /* partial write */
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copy_len = iclog->ic_size - log_offset;
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logop_head->oh_len = cpu_to_be32(copy_len);
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logop_head->oh_flags |= XLOG_CONTINUE_TRANS;
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if (partial_copy)
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logop_head->oh_flags |= XLOG_WAS_CONT_TRANS;
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partial_copy_len += copy_len;
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partial_copy++;
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len += sizeof(xlog_op_header_t); /* from splitting of region */
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/* account for new log op header */
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ticket->t_curr_res -= sizeof(xlog_op_header_t);
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ticket->t_res_num_ophdrs++;
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}
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len += xlog_write_setup_copy(ticket, logop_head,
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iclog->ic_size - log_offset,
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reg[index].i_len, ©_off,
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©_len, &partial_copy,
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&partial_copy_len);
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xlog_verify_dest_ptr(log, ptr);
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/* copy region */
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@ -1834,34 +1947,34 @@ xlog_write(
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copy_len += start_rec_copy + sizeof(xlog_op_header_t);
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record_cnt++;
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data_cnt += contwr ? copy_len : 0;
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if (partial_copy) { /* copied partial region */
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/* already marked WANT_SYNC by xlog_state_get_iclog_space */
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xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
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record_cnt = data_cnt = 0;
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if ((error = xlog_state_release_iclog(log, iclog)))
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return error;
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break; /* don't increment index */
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} else { /* copied entire region */
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index++;
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partial_copy_len = partial_copy = 0;
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if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
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xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
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record_cnt = data_cnt = 0;
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spin_lock(&log->l_icloglock);
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xlog_state_want_sync(log, iclog);
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spin_unlock(&log->l_icloglock);
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if (commit_iclog) {
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ASSERT(flags & XLOG_COMMIT_TRANS);
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*commit_iclog = iclog;
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} else if ((error = xlog_state_release_iclog(log, iclog)))
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return error;
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if (index == nentries)
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return 0; /* we are done */
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else
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break;
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}
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} /* if (partial_copy) */
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error = xlog_write_copy_finish(log, iclog, flags,
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&record_cnt, &data_cnt,
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&partial_copy, &partial_copy_len,
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log_offset, commit_iclog);
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if (error)
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return error;
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/*
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* if we had a partial copy, we need to get more iclog
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* space but we don't want to increment the region
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* index because there is still more is this region to write.
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*
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* If we completed writing this region, and we flushed
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* the iclog (indicated by resetting of the record
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* count), then we also need to get more log space. If
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* this was the last record, though, we are done and
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* can just return.
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*/
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if (partial_copy)
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break;
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index++;
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if (record_cnt == 0) {
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if (index == nentries)
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return 0;
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break;
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}
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} /* while (index < nentries) */
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} /* for (index = 0; index < nentries; ) */
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ASSERT(len == 0);
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