From b5203cd0a43c17dfb9d498bc9e3146624e8c9622 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 23 Mar 2010 11:29:44 +1100 Subject: [PATCH] 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 Signed-off-by: Dave Chinner Reviewed-by: Dave Chinner --- fs/xfs/xfs_log.c | 339 +++++++++++++++++++++++++++++++---------------- 1 file changed, 226 insertions(+), 113 deletions(-) diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 81323d73a4ee..4a0ec592564c 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1629,6 +1629,193 @@ xlog_print_tic_res(xfs_mount_t *mp, xlog_ticket_t *ticket) } } +/* + * Calculate the potential space needed by the log vector. Each region gets + * its own xlog_op_header_t and may need to be double word aligned. + */ +static int +xlog_write_calc_vec_length( + struct xlog_ticket *ticket, + struct xfs_log_iovec reg[], + int nentries) +{ + int headers = 0; + int len = 0; + int i; + + /* acct for start rec of xact */ + if (ticket->t_flags & XLOG_TIC_INITED) + headers++; + + for (i = 0; i < nentries; i++) { + /* each region gets >= 1 */ + headers++; + + len += reg[i].i_len; + xlog_tic_add_region(ticket, reg[i].i_len, reg[i].i_type); + } + + ticket->t_res_num_ophdrs += headers; + len += headers * sizeof(struct xlog_op_header); + + return len; +} + +/* + * If first write for transaction, insert start record We can't be trying to + * commit if we are inited. We can't have any "partial_copy" if we are inited. + */ +static int +xlog_write_start_rec( + __psint_t ptr, + struct xlog_ticket *ticket) +{ + struct xlog_op_header *ophdr = (struct xlog_op_header *)ptr; + + if (!(ticket->t_flags & XLOG_TIC_INITED)) + return 0; + + ophdr->oh_tid = cpu_to_be32(ticket->t_tid); + ophdr->oh_clientid = ticket->t_clientid; + ophdr->oh_len = 0; + ophdr->oh_flags = XLOG_START_TRANS; + ophdr->oh_res2 = 0; + + ticket->t_flags &= ~XLOG_TIC_INITED; + + return sizeof(struct xlog_op_header); +} + +static xlog_op_header_t * +xlog_write_setup_ophdr( + struct log *log, + __psint_t ptr, + struct xlog_ticket *ticket, + uint flags) +{ + struct xlog_op_header *ophdr = (struct xlog_op_header *)ptr; + + ophdr->oh_tid = cpu_to_be32(ticket->t_tid); + ophdr->oh_clientid = ticket->t_clientid; + ophdr->oh_res2 = 0; + + /* are we copying a commit or unmount record? */ + ophdr->oh_flags = flags; + + /* + * We've seen logs corrupted with bad transaction client ids. This + * makes sure that XFS doesn't generate them on. Turn this into an EIO + * and shut down the filesystem. + */ + switch (ophdr->oh_clientid) { + case XFS_TRANSACTION: + case XFS_VOLUME: + case XFS_LOG: + break; + default: + xfs_fs_cmn_err(CE_WARN, log->l_mp, + "Bad XFS transaction clientid 0x%x in ticket 0x%p", + ophdr->oh_clientid, ticket); + return NULL; + } + + return ophdr; +} + +/* + * Set up the parameters of the region copy into the log. This has + * to handle region write split across multiple log buffers - this + * state is kept external to this function so that this code can + * can be written in an obvious, self documenting manner. + */ +static int +xlog_write_setup_copy( + struct xlog_ticket *ticket, + struct xlog_op_header *ophdr, + int space_available, + int space_required, + int *copy_off, + int *copy_len, + int *last_was_partial_copy, + int *bytes_consumed) +{ + int still_to_copy; + + still_to_copy = space_required - *bytes_consumed; + *copy_off = *bytes_consumed; + + if (still_to_copy <= space_available) { + /* write of region completes here */ + *copy_len = still_to_copy; + ophdr->oh_len = cpu_to_be32(*copy_len); + if (*last_was_partial_copy) + ophdr->oh_flags |= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS); + *last_was_partial_copy = 0; + *bytes_consumed = 0; + return 0; + } + + /* partial write of region, needs extra log op header reservation */ + *copy_len = space_available; + ophdr->oh_len = cpu_to_be32(*copy_len); + ophdr->oh_flags |= XLOG_CONTINUE_TRANS; + if (*last_was_partial_copy) + ophdr->oh_flags |= XLOG_WAS_CONT_TRANS; + *bytes_consumed += *copy_len; + (*last_was_partial_copy)++; + + /* account for new log op header */ + ticket->t_curr_res -= sizeof(struct xlog_op_header); + ticket->t_res_num_ophdrs++; + + return sizeof(struct xlog_op_header); +} + +static int +xlog_write_copy_finish( + struct log *log, + struct xlog_in_core *iclog, + uint flags, + int *record_cnt, + int *data_cnt, + int *partial_copy, + int *partial_copy_len, + int log_offset, + struct xlog_in_core **commit_iclog) +{ + if (*partial_copy) { + /* + * This iclog has already been marked WANT_SYNC by + * xlog_state_get_iclog_space. + */ + xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt); + *record_cnt = 0; + *data_cnt = 0; + return xlog_state_release_iclog(log, iclog); + } + + *partial_copy = 0; + *partial_copy_len = 0; + + if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) { + /* no more space in this iclog - push it. */ + xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt); + *record_cnt = 0; + *data_cnt = 0; + + spin_lock(&log->l_icloglock); + xlog_state_want_sync(log, iclog); + spin_unlock(&log->l_icloglock); + + if (!commit_iclog) + return xlog_state_release_iclog(log, iclog); + ASSERT(flags & XLOG_COMMIT_TRANS); + *commit_iclog = iclog; + } + + return 0; +} + /* * Write some region out to in-core log * @@ -1689,7 +1876,6 @@ xlog_write( int start_rec_copy; /* # bytes to copy for start record */ int partial_copy; /* did we split a region? */ int partial_copy_len;/* # bytes copied if split region */ - int need_copy; /* # bytes need to memcpy this region */ int copy_len; /* # bytes actually memcpy'ing */ int copy_off; /* # bytes from entry start */ int contwr; /* continued write of in-core log? */ @@ -1697,24 +1883,9 @@ xlog_write( int record_cnt = 0, data_cnt = 0; partial_copy_len = partial_copy = 0; - - /* Calculate potential maximum space. Each region gets its own - * xlog_op_header_t and may need to be double word aligned. - */ - len = 0; - if (ticket->t_flags & XLOG_TIC_INITED) { /* acct for start rec of xact */ - len += sizeof(xlog_op_header_t); - ticket->t_res_num_ophdrs++; - } - - for (index = 0; index < nentries; index++) { - len += sizeof(xlog_op_header_t); /* each region gets >= 1 */ - ticket->t_res_num_ophdrs++; - len += reg[index].i_len; - xlog_tic_add_region(ticket, reg[index].i_len, reg[index].i_type); - } contwr = *start_lsn = 0; + len = xlog_write_calc_vec_length(ticket, reg, nentries); if (ticket->t_curr_res < len) { xlog_print_tic_res(mp, ticket); #ifdef DEBUG @@ -1748,81 +1919,23 @@ xlog_write( while (index < nentries) { ASSERT(reg[index].i_len % sizeof(__int32_t) == 0); ASSERT((__psint_t)ptr % sizeof(__int32_t) == 0); - start_rec_copy = 0; - /* If first write for transaction, insert start record. - * We can't be trying to commit if we are inited. We can't - * have any "partial_copy" if we are inited. - */ - if (ticket->t_flags & XLOG_TIC_INITED) { - logop_head = (xlog_op_header_t *)ptr; - logop_head->oh_tid = cpu_to_be32(ticket->t_tid); - logop_head->oh_clientid = ticket->t_clientid; - logop_head->oh_len = 0; - logop_head->oh_flags = XLOG_START_TRANS; - logop_head->oh_res2 = 0; - ticket->t_flags &= ~XLOG_TIC_INITED; /* clear bit */ + start_rec_copy = xlog_write_start_rec(ptr, ticket); + if (start_rec_copy) { record_cnt++; - - start_rec_copy = sizeof(xlog_op_header_t); xlog_write_adv_cnt(ptr, len, log_offset, start_rec_copy); } - /* Copy log operation header directly into data section */ - logop_head = (xlog_op_header_t *)ptr; - logop_head->oh_tid = cpu_to_be32(ticket->t_tid); - logop_head->oh_clientid = ticket->t_clientid; - logop_head->oh_res2 = 0; - - /* header copied directly */ + logop_head = xlog_write_setup_ophdr(log, ptr, ticket, flags); + if (!logop_head) + return XFS_ERROR(EIO); xlog_write_adv_cnt(ptr, len, log_offset, sizeof(xlog_op_header_t)); - /* are we copying a commit or unmount record? */ - logop_head->oh_flags = flags; - - /* - * We've seen logs corrupted with bad transaction client - * ids. This makes sure that XFS doesn't generate them on. - * Turn this into an EIO and shut down the filesystem. - */ - switch (logop_head->oh_clientid) { - case XFS_TRANSACTION: - case XFS_VOLUME: - case XFS_LOG: - break; - default: - xfs_fs_cmn_err(CE_WARN, mp, - "Bad XFS transaction clientid 0x%x in ticket 0x%p", - logop_head->oh_clientid, ticket); - return XFS_ERROR(EIO); - } - - /* Partial write last time? => (partial_copy != 0) - * need_copy is the amount we'd like to copy if everything could - * fit in the current memcpy. - */ - need_copy = reg[index].i_len - partial_copy_len; - - copy_off = partial_copy_len; - if (need_copy <= iclog->ic_size - log_offset) { /*complete write */ - copy_len = need_copy; - logop_head->oh_len = cpu_to_be32(copy_len); - if (partial_copy) - logop_head->oh_flags|= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS); - partial_copy_len = partial_copy = 0; - } else { /* partial write */ - copy_len = iclog->ic_size - log_offset; - logop_head->oh_len = cpu_to_be32(copy_len); - logop_head->oh_flags |= XLOG_CONTINUE_TRANS; - if (partial_copy) - logop_head->oh_flags |= XLOG_WAS_CONT_TRANS; - partial_copy_len += copy_len; - partial_copy++; - len += sizeof(xlog_op_header_t); /* from splitting of region */ - /* account for new log op header */ - ticket->t_curr_res -= sizeof(xlog_op_header_t); - ticket->t_res_num_ophdrs++; - } + len += xlog_write_setup_copy(ticket, logop_head, + iclog->ic_size - log_offset, + reg[index].i_len, ©_off, + ©_len, &partial_copy, + &partial_copy_len); xlog_verify_dest_ptr(log, ptr); /* copy region */ @@ -1834,34 +1947,34 @@ xlog_write( copy_len += start_rec_copy + sizeof(xlog_op_header_t); record_cnt++; data_cnt += contwr ? copy_len : 0; - if (partial_copy) { /* copied partial region */ - /* already marked WANT_SYNC by xlog_state_get_iclog_space */ - xlog_state_finish_copy(log, iclog, record_cnt, data_cnt); - record_cnt = data_cnt = 0; - if ((error = xlog_state_release_iclog(log, iclog))) - return error; - break; /* don't increment index */ - } else { /* copied entire region */ - index++; - partial_copy_len = partial_copy = 0; - - if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) { - xlog_state_finish_copy(log, iclog, record_cnt, data_cnt); - record_cnt = data_cnt = 0; - spin_lock(&log->l_icloglock); - xlog_state_want_sync(log, iclog); - spin_unlock(&log->l_icloglock); - if (commit_iclog) { - ASSERT(flags & XLOG_COMMIT_TRANS); - *commit_iclog = iclog; - } else if ((error = xlog_state_release_iclog(log, iclog))) - return error; - if (index == nentries) - return 0; /* we are done */ - else - break; - } - } /* if (partial_copy) */ + + error = xlog_write_copy_finish(log, iclog, flags, + &record_cnt, &data_cnt, + &partial_copy, &partial_copy_len, + log_offset, commit_iclog); + if (error) + return error; + + /* + * if we had a partial copy, we need to get more iclog + * space but we don't want to increment the region + * index because there is still more is this region to write. + * + * If we completed writing this region, and we flushed + * the iclog (indicated by resetting of the record + * count), then we also need to get more log space. If + * this was the last record, though, we are done and + * can just return. + */ + if (partial_copy) + break; + + index++; + if (record_cnt == 0) { + if (index == nentries) + return 0; + break; + } } /* while (index < nentries) */ } /* for (index = 0; index < nentries; ) */ ASSERT(len == 0); -- GitLab