| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved. |
| */ |
| |
| #include "xfs.h" |
| #include "xfs_fs.h" |
| #include "xfs_format.h" |
| #include "xfs_log_format.h" |
| #include "xfs_shared.h" |
| #include "xfs_trans_resv.h" |
| #include "xfs_mount.h" |
| #include "xfs_extent_busy.h" |
| #include "xfs_trans.h" |
| #include "xfs_trans_priv.h" |
| #include "xfs_log.h" |
| #include "xfs_log_priv.h" |
| #include "xfs_trace.h" |
| |
| struct workqueue_struct *xfs_discard_wq; |
| |
| /* |
| * Allocate a new ticket. Failing to get a new ticket makes it really hard to |
| * recover, so we don't allow failure here. Also, we allocate in a context that |
| * we don't want to be issuing transactions from, so we need to tell the |
| * allocation code this as well. |
| * |
| * We don't reserve any space for the ticket - we are going to steal whatever |
| * space we require from transactions as they commit. To ensure we reserve all |
| * the space required, we need to set the current reservation of the ticket to |
| * zero so that we know to steal the initial transaction overhead from the |
| * first transaction commit. |
| */ |
| static struct xlog_ticket * |
| xlog_cil_ticket_alloc( |
| struct xlog *log) |
| { |
| struct xlog_ticket *tic; |
| |
| tic = xlog_ticket_alloc(log, 0, 1, 0); |
| |
| /* |
| * set the current reservation to zero so we know to steal the basic |
| * transaction overhead reservation from the first transaction commit. |
| */ |
| tic->t_curr_res = 0; |
| return tic; |
| } |
| |
| /* |
| * Check if the current log item was first committed in this sequence. |
| * We can't rely on just the log item being in the CIL, we have to check |
| * the recorded commit sequence number. |
| * |
| * Note: for this to be used in a non-racy manner, it has to be called with |
| * CIL flushing locked out. As a result, it should only be used during the |
| * transaction commit process when deciding what to format into the item. |
| */ |
| static bool |
| xlog_item_in_current_chkpt( |
| struct xfs_cil *cil, |
| struct xfs_log_item *lip) |
| { |
| if (list_empty(&lip->li_cil)) |
| return false; |
| |
| /* |
| * li_seq is written on the first commit of a log item to record the |
| * first checkpoint it is written to. Hence if it is different to the |
| * current sequence, we're in a new checkpoint. |
| */ |
| return lip->li_seq == READ_ONCE(cil->xc_current_sequence); |
| } |
| |
| bool |
| xfs_log_item_in_current_chkpt( |
| struct xfs_log_item *lip) |
| { |
| return xlog_item_in_current_chkpt(lip->li_log->l_cilp, lip); |
| } |
| |
| /* |
| * Unavoidable forward declaration - xlog_cil_push_work() calls |
| * xlog_cil_ctx_alloc() itself. |
| */ |
| static void xlog_cil_push_work(struct work_struct *work); |
| |
| static struct xfs_cil_ctx * |
| xlog_cil_ctx_alloc(void) |
| { |
| struct xfs_cil_ctx *ctx; |
| |
| ctx = kmem_zalloc(sizeof(*ctx), KM_NOFS); |
| INIT_LIST_HEAD(&ctx->committing); |
| INIT_LIST_HEAD(&ctx->busy_extents); |
| INIT_WORK(&ctx->push_work, xlog_cil_push_work); |
| return ctx; |
| } |
| |
| static void |
| xlog_cil_ctx_switch( |
| struct xfs_cil *cil, |
| struct xfs_cil_ctx *ctx) |
| { |
| ctx->sequence = ++cil->xc_current_sequence; |
| ctx->cil = cil; |
| cil->xc_ctx = ctx; |
| } |
| |
| /* |
| * After the first stage of log recovery is done, we know where the head and |
| * tail of the log are. We need this log initialisation done before we can |
| * initialise the first CIL checkpoint context. |
| * |
| * Here we allocate a log ticket to track space usage during a CIL push. This |
| * ticket is passed to xlog_write() directly so that we don't slowly leak log |
| * space by failing to account for space used by log headers and additional |
| * region headers for split regions. |
| */ |
| void |
| xlog_cil_init_post_recovery( |
| struct xlog *log) |
| { |
| log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log); |
| log->l_cilp->xc_ctx->sequence = 1; |
| } |
| |
| static inline int |
| xlog_cil_iovec_space( |
| uint niovecs) |
| { |
| return round_up((sizeof(struct xfs_log_vec) + |
| niovecs * sizeof(struct xfs_log_iovec)), |
| sizeof(uint64_t)); |
| } |
| |
| /* |
| * Allocate or pin log vector buffers for CIL insertion. |
| * |
| * The CIL currently uses disposable buffers for copying a snapshot of the |
| * modified items into the log during a push. The biggest problem with this is |
| * the requirement to allocate the disposable buffer during the commit if: |
| * a) does not exist; or |
| * b) it is too small |
| * |
| * If we do this allocation within xlog_cil_insert_format_items(), it is done |
| * under the xc_ctx_lock, which means that a CIL push cannot occur during |
| * the memory allocation. This means that we have a potential deadlock situation |
| * under low memory conditions when we have lots of dirty metadata pinned in |
| * the CIL and we need a CIL commit to occur to free memory. |
| * |
| * To avoid this, we need to move the memory allocation outside the |
| * xc_ctx_lock, but because the log vector buffers are disposable, that opens |
| * up a TOCTOU race condition w.r.t. the CIL committing and removing the log |
| * vector buffers between the check and the formatting of the item into the |
| * log vector buffer within the xc_ctx_lock. |
| * |
| * Because the log vector buffer needs to be unchanged during the CIL push |
| * process, we cannot share the buffer between the transaction commit (which |
| * modifies the buffer) and the CIL push context that is writing the changes |
| * into the log. This means skipping preallocation of buffer space is |
| * unreliable, but we most definitely do not want to be allocating and freeing |
| * buffers unnecessarily during commits when overwrites can be done safely. |
| * |
| * The simplest solution to this problem is to allocate a shadow buffer when a |
| * log item is committed for the second time, and then to only use this buffer |
| * if necessary. The buffer can remain attached to the log item until such time |
| * it is needed, and this is the buffer that is reallocated to match the size of |
| * the incoming modification. Then during the formatting of the item we can swap |
| * the active buffer with the new one if we can't reuse the existing buffer. We |
| * don't free the old buffer as it may be reused on the next modification if |
| * it's size is right, otherwise we'll free and reallocate it at that point. |
| * |
| * This function builds a vector for the changes in each log item in the |
| * transaction. It then works out the length of the buffer needed for each log |
| * item, allocates them and attaches the vector to the log item in preparation |
| * for the formatting step which occurs under the xc_ctx_lock. |
| * |
| * While this means the memory footprint goes up, it avoids the repeated |
| * alloc/free pattern that repeated modifications of an item would otherwise |
| * cause, and hence minimises the CPU overhead of such behaviour. |
| */ |
| static void |
| xlog_cil_alloc_shadow_bufs( |
| struct xlog *log, |
| struct xfs_trans *tp) |
| { |
| struct xfs_log_item *lip; |
| |
| list_for_each_entry(lip, &tp->t_items, li_trans) { |
| struct xfs_log_vec *lv; |
| int niovecs = 0; |
| int nbytes = 0; |
| int buf_size; |
| bool ordered = false; |
| |
| /* Skip items which aren't dirty in this transaction. */ |
| if (!test_bit(XFS_LI_DIRTY, &lip->li_flags)) |
| continue; |
| |
| /* get number of vecs and size of data to be stored */ |
| lip->li_ops->iop_size(lip, &niovecs, &nbytes); |
| |
| /* |
| * Ordered items need to be tracked but we do not wish to write |
| * them. We need a logvec to track the object, but we do not |
| * need an iovec or buffer to be allocated for copying data. |
| */ |
| if (niovecs == XFS_LOG_VEC_ORDERED) { |
| ordered = true; |
| niovecs = 0; |
| nbytes = 0; |
| } |
| |
| /* |
| * We 64-bit align the length of each iovec so that the start of |
| * the next one is naturally aligned. We'll need to account for |
| * that slack space here. |
| * |
| * We also add the xlog_op_header to each region when |
| * formatting, but that's not accounted to the size of the item |
| * at this point. Hence we'll need an addition number of bytes |
| * for each vector to hold an opheader. |
| * |
| * Then round nbytes up to 64-bit alignment so that the initial |
| * buffer alignment is easy to calculate and verify. |
| */ |
| nbytes += niovecs * |
| (sizeof(uint64_t) + sizeof(struct xlog_op_header)); |
| nbytes = round_up(nbytes, sizeof(uint64_t)); |
| |
| /* |
| * The data buffer needs to start 64-bit aligned, so round up |
| * that space to ensure we can align it appropriately and not |
| * overrun the buffer. |
| */ |
| buf_size = nbytes + xlog_cil_iovec_space(niovecs); |
| |
| /* |
| * if we have no shadow buffer, or it is too small, we need to |
| * reallocate it. |
| */ |
| if (!lip->li_lv_shadow || |
| buf_size > lip->li_lv_shadow->lv_size) { |
| /* |
| * We free and allocate here as a realloc would copy |
| * unnecessary data. We don't use kvzalloc() for the |
| * same reason - we don't need to zero the data area in |
| * the buffer, only the log vector header and the iovec |
| * storage. |
| */ |
| kmem_free(lip->li_lv_shadow); |
| lv = xlog_kvmalloc(buf_size); |
| |
| memset(lv, 0, xlog_cil_iovec_space(niovecs)); |
| |
| lv->lv_item = lip; |
| lv->lv_size = buf_size; |
| if (ordered) |
| lv->lv_buf_len = XFS_LOG_VEC_ORDERED; |
| else |
| lv->lv_iovecp = (struct xfs_log_iovec *)&lv[1]; |
| lip->li_lv_shadow = lv; |
| } else { |
| /* same or smaller, optimise common overwrite case */ |
| lv = lip->li_lv_shadow; |
| if (ordered) |
| lv->lv_buf_len = XFS_LOG_VEC_ORDERED; |
| else |
| lv->lv_buf_len = 0; |
| lv->lv_bytes = 0; |
| lv->lv_next = NULL; |
| } |
| |
| /* Ensure the lv is set up according to ->iop_size */ |
| lv->lv_niovecs = niovecs; |
| |
| /* The allocated data region lies beyond the iovec region */ |
| lv->lv_buf = (char *)lv + xlog_cil_iovec_space(niovecs); |
| } |
| |
| } |
| |
| /* |
| * Prepare the log item for insertion into the CIL. Calculate the difference in |
| * log space it will consume, and if it is a new item pin it as well. |
| */ |
| STATIC void |
| xfs_cil_prepare_item( |
| struct xlog *log, |
| struct xfs_log_vec *lv, |
| struct xfs_log_vec *old_lv, |
| int *diff_len) |
| { |
| /* Account for the new LV being passed in */ |
| if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) |
| *diff_len += lv->lv_bytes; |
| |
| /* |
| * If there is no old LV, this is the first time we've seen the item in |
| * this CIL context and so we need to pin it. If we are replacing the |
| * old_lv, then remove the space it accounts for and make it the shadow |
| * buffer for later freeing. In both cases we are now switching to the |
| * shadow buffer, so update the pointer to it appropriately. |
| */ |
| if (!old_lv) { |
| if (lv->lv_item->li_ops->iop_pin) |
| lv->lv_item->li_ops->iop_pin(lv->lv_item); |
| lv->lv_item->li_lv_shadow = NULL; |
| } else if (old_lv != lv) { |
| ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED); |
| |
| *diff_len -= old_lv->lv_bytes; |
| lv->lv_item->li_lv_shadow = old_lv; |
| } |
| |
| /* attach new log vector to log item */ |
| lv->lv_item->li_lv = lv; |
| |
| /* |
| * If this is the first time the item is being committed to the |
| * CIL, store the sequence number on the log item so we can |
| * tell in future commits whether this is the first checkpoint |
| * the item is being committed into. |
| */ |
| if (!lv->lv_item->li_seq) |
| lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence; |
| } |
| |
| /* |
| * Format log item into a flat buffers |
| * |
| * For delayed logging, we need to hold a formatted buffer containing all the |
| * changes on the log item. This enables us to relog the item in memory and |
| * write it out asynchronously without needing to relock the object that was |
| * modified at the time it gets written into the iclog. |
| * |
| * This function takes the prepared log vectors attached to each log item, and |
| * formats the changes into the log vector buffer. The buffer it uses is |
| * dependent on the current state of the vector in the CIL - the shadow lv is |
| * guaranteed to be large enough for the current modification, but we will only |
| * use that if we can't reuse the existing lv. If we can't reuse the existing |
| * lv, then simple swap it out for the shadow lv. We don't free it - that is |
| * done lazily either by th enext modification or the freeing of the log item. |
| * |
| * We don't set up region headers during this process; we simply copy the |
| * regions into the flat buffer. We can do this because we still have to do a |
| * formatting step to write the regions into the iclog buffer. Writing the |
| * ophdrs during the iclog write means that we can support splitting large |
| * regions across iclog boundares without needing a change in the format of the |
| * item/region encapsulation. |
| * |
| * Hence what we need to do now is change the rewrite the vector array to point |
| * to the copied region inside the buffer we just allocated. This allows us to |
| * format the regions into the iclog as though they are being formatted |
| * directly out of the objects themselves. |
| */ |
| static void |
| xlog_cil_insert_format_items( |
| struct xlog *log, |
| struct xfs_trans *tp, |
| int *diff_len) |
| { |
| struct xfs_log_item *lip; |
| |
| /* Bail out if we didn't find a log item. */ |
| if (list_empty(&tp->t_items)) { |
| ASSERT(0); |
| return; |
| } |
| |
| list_for_each_entry(lip, &tp->t_items, li_trans) { |
| struct xfs_log_vec *lv; |
| struct xfs_log_vec *old_lv = NULL; |
| struct xfs_log_vec *shadow; |
| bool ordered = false; |
| |
| /* Skip items which aren't dirty in this transaction. */ |
| if (!test_bit(XFS_LI_DIRTY, &lip->li_flags)) |
| continue; |
| |
| /* |
| * The formatting size information is already attached to |
| * the shadow lv on the log item. |
| */ |
| shadow = lip->li_lv_shadow; |
| if (shadow->lv_buf_len == XFS_LOG_VEC_ORDERED) |
| ordered = true; |
| |
| /* Skip items that do not have any vectors for writing */ |
| if (!shadow->lv_niovecs && !ordered) |
| continue; |
| |
| /* compare to existing item size */ |
| old_lv = lip->li_lv; |
| if (lip->li_lv && shadow->lv_size <= lip->li_lv->lv_size) { |
| /* same or smaller, optimise common overwrite case */ |
| lv = lip->li_lv; |
| lv->lv_next = NULL; |
| |
| if (ordered) |
| goto insert; |
| |
| /* |
| * set the item up as though it is a new insertion so |
| * that the space reservation accounting is correct. |
| */ |
| *diff_len -= lv->lv_bytes; |
| |
| /* Ensure the lv is set up according to ->iop_size */ |
| lv->lv_niovecs = shadow->lv_niovecs; |
| |
| /* reset the lv buffer information for new formatting */ |
| lv->lv_buf_len = 0; |
| lv->lv_bytes = 0; |
| lv->lv_buf = (char *)lv + |
| xlog_cil_iovec_space(lv->lv_niovecs); |
| } else { |
| /* switch to shadow buffer! */ |
| lv = shadow; |
| lv->lv_item = lip; |
| if (ordered) { |
| /* track as an ordered logvec */ |
| ASSERT(lip->li_lv == NULL); |
| goto insert; |
| } |
| } |
| |
| ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t))); |
| lip->li_ops->iop_format(lip, lv); |
| insert: |
| xfs_cil_prepare_item(log, lv, old_lv, diff_len); |
| } |
| } |
| |
| /* |
| * Insert the log items into the CIL and calculate the difference in space |
| * consumed by the item. Add the space to the checkpoint ticket and calculate |
| * if the change requires additional log metadata. If it does, take that space |
| * as well. Remove the amount of space we added to the checkpoint ticket from |
| * the current transaction ticket so that the accounting works out correctly. |
| */ |
| static void |
| xlog_cil_insert_items( |
| struct xlog *log, |
| struct xfs_trans *tp, |
| uint32_t released_space) |
| { |
| struct xfs_cil *cil = log->l_cilp; |
| struct xfs_cil_ctx *ctx = cil->xc_ctx; |
| struct xfs_log_item *lip; |
| int len = 0; |
| int iclog_space; |
| int iovhdr_res = 0, split_res = 0, ctx_res = 0; |
| |
| ASSERT(tp); |
| |
| /* |
| * We can do this safely because the context can't checkpoint until we |
| * are done so it doesn't matter exactly how we update the CIL. |
| */ |
| xlog_cil_insert_format_items(log, tp, &len); |
| |
| spin_lock(&cil->xc_cil_lock); |
| |
| /* attach the transaction to the CIL if it has any busy extents */ |
| if (!list_empty(&tp->t_busy)) |
| list_splice_init(&tp->t_busy, &ctx->busy_extents); |
| |
| /* |
| * Now transfer enough transaction reservation to the context ticket |
| * for the checkpoint. The context ticket is special - the unit |
| * reservation has to grow as well as the current reservation as we |
| * steal from tickets so we can correctly determine the space used |
| * during the transaction commit. |
| */ |
| if (ctx->ticket->t_curr_res == 0) { |
| ctx_res = ctx->ticket->t_unit_res; |
| ctx->ticket->t_curr_res = ctx_res; |
| tp->t_ticket->t_curr_res -= ctx_res; |
| } |
| |
| /* do we need space for more log record headers? */ |
| iclog_space = log->l_iclog_size - log->l_iclog_hsize; |
| if (len > 0 && (ctx->space_used / iclog_space != |
| (ctx->space_used + len) / iclog_space)) { |
| split_res = (len + iclog_space - 1) / iclog_space; |
| /* need to take into account split region headers, too */ |
| split_res *= log->l_iclog_hsize + sizeof(struct xlog_op_header); |
| ctx->ticket->t_unit_res += split_res; |
| ctx->ticket->t_curr_res += split_res; |
| tp->t_ticket->t_curr_res -= split_res; |
| ASSERT(tp->t_ticket->t_curr_res >= len); |
| } |
| tp->t_ticket->t_curr_res -= len; |
| tp->t_ticket->t_curr_res += released_space; |
| ctx->space_used += len; |
| ctx->space_used -= released_space; |
| |
| /* |
| * If we've overrun the reservation, dump the tx details before we move |
| * the log items. Shutdown is imminent... |
| */ |
| if (WARN_ON(tp->t_ticket->t_curr_res < 0)) { |
| xfs_warn(log->l_mp, "Transaction log reservation overrun:"); |
| xfs_warn(log->l_mp, |
| " log items: %d bytes (iov hdrs: %d bytes)", |
| len, iovhdr_res); |
| xfs_warn(log->l_mp, " split region headers: %d bytes", |
| split_res); |
| xfs_warn(log->l_mp, " ctx ticket: %d bytes", ctx_res); |
| xlog_print_trans(tp); |
| } |
| |
| /* |
| * Now (re-)position everything modified at the tail of the CIL. |
| * We do this here so we only need to take the CIL lock once during |
| * the transaction commit. |
| */ |
| list_for_each_entry(lip, &tp->t_items, li_trans) { |
| |
| /* Skip items which aren't dirty in this transaction. */ |
| if (!test_bit(XFS_LI_DIRTY, &lip->li_flags)) |
| continue; |
| |
| /* |
| * Only move the item if it isn't already at the tail. This is |
| * to prevent a transient list_empty() state when reinserting |
| * an item that is already the only item in the CIL. |
| */ |
| if (!list_is_last(&lip->li_cil, &cil->xc_cil)) |
| list_move_tail(&lip->li_cil, &cil->xc_cil); |
| } |
| |
| spin_unlock(&cil->xc_cil_lock); |
| |
| if (tp->t_ticket->t_curr_res < 0) |
| xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR); |
| } |
| |
| static void |
| xlog_cil_free_logvec( |
| struct xfs_log_vec *log_vector) |
| { |
| struct xfs_log_vec *lv; |
| |
| for (lv = log_vector; lv; ) { |
| struct xfs_log_vec *next = lv->lv_next; |
| kmem_free(lv); |
| lv = next; |
| } |
| } |
| |
| static void |
| xlog_discard_endio_work( |
| struct work_struct *work) |
| { |
| struct xfs_cil_ctx *ctx = |
| container_of(work, struct xfs_cil_ctx, discard_endio_work); |
| struct xfs_mount *mp = ctx->cil->xc_log->l_mp; |
| |
| xfs_extent_busy_clear(mp, &ctx->busy_extents, false); |
| kmem_free(ctx); |
| } |
| |
| /* |
| * Queue up the actual completion to a thread to avoid IRQ-safe locking for |
| * pagb_lock. Note that we need a unbounded workqueue, otherwise we might |
| * get the execution delayed up to 30 seconds for weird reasons. |
| */ |
| static void |
| xlog_discard_endio( |
| struct bio *bio) |
| { |
| struct xfs_cil_ctx *ctx = bio->bi_private; |
| |
| INIT_WORK(&ctx->discard_endio_work, xlog_discard_endio_work); |
| queue_work(xfs_discard_wq, &ctx->discard_endio_work); |
| bio_put(bio); |
| } |
| |
| static void |
| xlog_discard_busy_extents( |
| struct xfs_mount *mp, |
| struct xfs_cil_ctx *ctx) |
| { |
| struct list_head *list = &ctx->busy_extents; |
| struct xfs_extent_busy *busyp; |
| struct bio *bio = NULL; |
| struct blk_plug plug; |
| int error = 0; |
| |
| ASSERT(xfs_has_discard(mp)); |
| |
| blk_start_plug(&plug); |
| list_for_each_entry(busyp, list, list) { |
| trace_xfs_discard_extent(mp, busyp->agno, busyp->bno, |
| busyp->length); |
| |
| error = __blkdev_issue_discard(mp->m_ddev_targp->bt_bdev, |
| XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno), |
| XFS_FSB_TO_BB(mp, busyp->length), |
| GFP_NOFS, &bio); |
| if (error && error != -EOPNOTSUPP) { |
| xfs_info(mp, |
| "discard failed for extent [0x%llx,%u], error %d", |
| (unsigned long long)busyp->bno, |
| busyp->length, |
| error); |
| break; |
| } |
| } |
| |
| if (bio) { |
| bio->bi_private = ctx; |
| bio->bi_end_io = xlog_discard_endio; |
| submit_bio(bio); |
| } else { |
| xlog_discard_endio_work(&ctx->discard_endio_work); |
| } |
| blk_finish_plug(&plug); |
| } |
| |
| /* |
| * Mark all items committed and clear busy extents. We free the log vector |
| * chains in a separate pass so that we unpin the log items as quickly as |
| * possible. |
| */ |
| static void |
| xlog_cil_committed( |
| struct xfs_cil_ctx *ctx) |
| { |
| struct xfs_mount *mp = ctx->cil->xc_log->l_mp; |
| bool abort = xlog_is_shutdown(ctx->cil->xc_log); |
| |
| /* |
| * If the I/O failed, we're aborting the commit and already shutdown. |
| * Wake any commit waiters before aborting the log items so we don't |
| * block async log pushers on callbacks. Async log pushers explicitly do |
| * not wait on log force completion because they may be holding locks |
| * required to unpin items. |
| */ |
| if (abort) { |
| spin_lock(&ctx->cil->xc_push_lock); |
| wake_up_all(&ctx->cil->xc_start_wait); |
| wake_up_all(&ctx->cil->xc_commit_wait); |
| spin_unlock(&ctx->cil->xc_push_lock); |
| } |
| |
| xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain, |
| ctx->start_lsn, abort); |
| |
| xfs_extent_busy_sort(&ctx->busy_extents); |
| xfs_extent_busy_clear(mp, &ctx->busy_extents, |
| xfs_has_discard(mp) && !abort); |
| |
| spin_lock(&ctx->cil->xc_push_lock); |
| list_del(&ctx->committing); |
| spin_unlock(&ctx->cil->xc_push_lock); |
| |
| xlog_cil_free_logvec(ctx->lv_chain); |
| |
| if (!list_empty(&ctx->busy_extents)) |
| xlog_discard_busy_extents(mp, ctx); |
| else |
| kmem_free(ctx); |
| } |
| |
| void |
| xlog_cil_process_committed( |
| struct list_head *list) |
| { |
| struct xfs_cil_ctx *ctx; |
| |
| while ((ctx = list_first_entry_or_null(list, |
| struct xfs_cil_ctx, iclog_entry))) { |
| list_del(&ctx->iclog_entry); |
| xlog_cil_committed(ctx); |
| } |
| } |
| |
| /* |
| * Record the LSN of the iclog we were just granted space to start writing into. |
| * If the context doesn't have a start_lsn recorded, then this iclog will |
| * contain the start record for the checkpoint. Otherwise this write contains |
| * the commit record for the checkpoint. |
| */ |
| void |
| xlog_cil_set_ctx_write_state( |
| struct xfs_cil_ctx *ctx, |
| struct xlog_in_core *iclog) |
| { |
| struct xfs_cil *cil = ctx->cil; |
| xfs_lsn_t lsn = be64_to_cpu(iclog->ic_header.h_lsn); |
| |
| ASSERT(!ctx->commit_lsn); |
| if (!ctx->start_lsn) { |
| spin_lock(&cil->xc_push_lock); |
| /* |
| * The LSN we need to pass to the log items on transaction |
| * commit is the LSN reported by the first log vector write, not |
| * the commit lsn. If we use the commit record lsn then we can |
| * move the grant write head beyond the tail LSN and overwrite |
| * it. |
| */ |
| ctx->start_lsn = lsn; |
| wake_up_all(&cil->xc_start_wait); |
| spin_unlock(&cil->xc_push_lock); |
| |
| /* |
| * Make sure the metadata we are about to overwrite in the log |
| * has been flushed to stable storage before this iclog is |
| * issued. |
| */ |
| spin_lock(&cil->xc_log->l_icloglock); |
| iclog->ic_flags |= XLOG_ICL_NEED_FLUSH; |
| spin_unlock(&cil->xc_log->l_icloglock); |
| return; |
| } |
| |
| /* |
| * Take a reference to the iclog for the context so that we still hold |
| * it when xlog_write is done and has released it. This means the |
| * context controls when the iclog is released for IO. |
| */ |
| atomic_inc(&iclog->ic_refcnt); |
| |
| /* |
| * xlog_state_get_iclog_space() guarantees there is enough space in the |
| * iclog for an entire commit record, so we can attach the context |
| * callbacks now. This needs to be done before we make the commit_lsn |
| * visible to waiters so that checkpoints with commit records in the |
| * same iclog order their IO completion callbacks in the same order that |
| * the commit records appear in the iclog. |
| */ |
| spin_lock(&cil->xc_log->l_icloglock); |
| list_add_tail(&ctx->iclog_entry, &iclog->ic_callbacks); |
| spin_unlock(&cil->xc_log->l_icloglock); |
| |
| /* |
| * Now we can record the commit LSN and wake anyone waiting for this |
| * sequence to have the ordered commit record assigned to a physical |
| * location in the log. |
| */ |
| spin_lock(&cil->xc_push_lock); |
| ctx->commit_iclog = iclog; |
| ctx->commit_lsn = lsn; |
| wake_up_all(&cil->xc_commit_wait); |
| spin_unlock(&cil->xc_push_lock); |
| } |
| |
| |
| /* |
| * Ensure that the order of log writes follows checkpoint sequence order. This |
| * relies on the context LSN being zero until the log write has guaranteed the |
| * LSN that the log write will start at via xlog_state_get_iclog_space(). |
| */ |
| enum _record_type { |
| _START_RECORD, |
| _COMMIT_RECORD, |
| }; |
| |
| static int |
| xlog_cil_order_write( |
| struct xfs_cil *cil, |
| xfs_csn_t sequence, |
| enum _record_type record) |
| { |
| struct xfs_cil_ctx *ctx; |
| |
| restart: |
| spin_lock(&cil->xc_push_lock); |
| list_for_each_entry(ctx, &cil->xc_committing, committing) { |
| /* |
| * Avoid getting stuck in this loop because we were woken by the |
| * shutdown, but then went back to sleep once already in the |
| * shutdown state. |
| */ |
| if (xlog_is_shutdown(cil->xc_log)) { |
| spin_unlock(&cil->xc_push_lock); |
| return -EIO; |
| } |
| |
| /* |
| * Higher sequences will wait for this one so skip them. |
| * Don't wait for our own sequence, either. |
| */ |
| if (ctx->sequence >= sequence) |
| continue; |
| |
| /* Wait until the LSN for the record has been recorded. */ |
| switch (record) { |
| case _START_RECORD: |
| if (!ctx->start_lsn) { |
| xlog_wait(&cil->xc_start_wait, &cil->xc_push_lock); |
| goto restart; |
| } |
| break; |
| case _COMMIT_RECORD: |
| if (!ctx->commit_lsn) { |
| xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock); |
| goto restart; |
| } |
| break; |
| } |
| } |
| spin_unlock(&cil->xc_push_lock); |
| return 0; |
| } |
| |
| /* |
| * Write out the log vector change now attached to the CIL context. This will |
| * write a start record that needs to be strictly ordered in ascending CIL |
| * sequence order so that log recovery will always use in-order start LSNs when |
| * replaying checkpoints. |
| */ |
| static int |
| xlog_cil_write_chain( |
| struct xfs_cil_ctx *ctx, |
| struct xfs_log_vec *chain, |
| uint32_t chain_len) |
| { |
| struct xlog *log = ctx->cil->xc_log; |
| int error; |
| |
| error = xlog_cil_order_write(ctx->cil, ctx->sequence, _START_RECORD); |
| if (error) |
| return error; |
| return xlog_write(log, ctx, chain, ctx->ticket, chain_len); |
| } |
| |
| /* |
| * Write out the commit record of a checkpoint transaction to close off a |
| * running log write. These commit records are strictly ordered in ascending CIL |
| * sequence order so that log recovery will always replay the checkpoints in the |
| * correct order. |
| */ |
| static int |
| xlog_cil_write_commit_record( |
| struct xfs_cil_ctx *ctx) |
| { |
| struct xlog *log = ctx->cil->xc_log; |
| struct xlog_op_header ophdr = { |
| .oh_clientid = XFS_TRANSACTION, |
| .oh_tid = cpu_to_be32(ctx->ticket->t_tid), |
| .oh_flags = XLOG_COMMIT_TRANS, |
| }; |
| struct xfs_log_iovec reg = { |
| .i_addr = &ophdr, |
| .i_len = sizeof(struct xlog_op_header), |
| .i_type = XLOG_REG_TYPE_COMMIT, |
| }; |
| struct xfs_log_vec vec = { |
| .lv_niovecs = 1, |
| .lv_iovecp = ®, |
| }; |
| int error; |
| |
| if (xlog_is_shutdown(log)) |
| return -EIO; |
| |
| error = xlog_cil_order_write(ctx->cil, ctx->sequence, _COMMIT_RECORD); |
| if (error) |
| return error; |
| |
| /* account for space used by record data */ |
| ctx->ticket->t_curr_res -= reg.i_len; |
| error = xlog_write(log, ctx, &vec, ctx->ticket, reg.i_len); |
| if (error) |
| xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR); |
| return error; |
| } |
| |
| struct xlog_cil_trans_hdr { |
| struct xlog_op_header oph[2]; |
| struct xfs_trans_header thdr; |
| struct xfs_log_iovec lhdr[2]; |
| }; |
| |
| /* |
| * Build a checkpoint transaction header to begin the journal transaction. We |
| * need to account for the space used by the transaction header here as it is |
| * not accounted for in xlog_write(). |
| * |
| * This is the only place we write a transaction header, so we also build the |
| * log opheaders that indicate the start of a log transaction and wrap the |
| * transaction header. We keep the start record in it's own log vector rather |
| * than compacting them into a single region as this ends up making the logic |
| * in xlog_write() for handling empty opheaders for start, commit and unmount |
| * records much simpler. |
| */ |
| static void |
| xlog_cil_build_trans_hdr( |
| struct xfs_cil_ctx *ctx, |
| struct xlog_cil_trans_hdr *hdr, |
| struct xfs_log_vec *lvhdr, |
| int num_iovecs) |
| { |
| struct xlog_ticket *tic = ctx->ticket; |
| __be32 tid = cpu_to_be32(tic->t_tid); |
| |
| memset(hdr, 0, sizeof(*hdr)); |
| |
| /* Log start record */ |
| hdr->oph[0].oh_tid = tid; |
| hdr->oph[0].oh_clientid = XFS_TRANSACTION; |
| hdr->oph[0].oh_flags = XLOG_START_TRANS; |
| |
| /* log iovec region pointer */ |
| hdr->lhdr[0].i_addr = &hdr->oph[0]; |
| hdr->lhdr[0].i_len = sizeof(struct xlog_op_header); |
| hdr->lhdr[0].i_type = XLOG_REG_TYPE_LRHEADER; |
| |
| /* log opheader */ |
| hdr->oph[1].oh_tid = tid; |
| hdr->oph[1].oh_clientid = XFS_TRANSACTION; |
| hdr->oph[1].oh_len = cpu_to_be32(sizeof(struct xfs_trans_header)); |
| |
| /* transaction header in host byte order format */ |
| hdr->thdr.th_magic = XFS_TRANS_HEADER_MAGIC; |
| hdr->thdr.th_type = XFS_TRANS_CHECKPOINT; |
| hdr->thdr.th_tid = tic->t_tid; |
| hdr->thdr.th_num_items = num_iovecs; |
| |
| /* log iovec region pointer */ |
| hdr->lhdr[1].i_addr = &hdr->oph[1]; |
| hdr->lhdr[1].i_len = sizeof(struct xlog_op_header) + |
| sizeof(struct xfs_trans_header); |
| hdr->lhdr[1].i_type = XLOG_REG_TYPE_TRANSHDR; |
| |
| lvhdr->lv_niovecs = 2; |
| lvhdr->lv_iovecp = &hdr->lhdr[0]; |
| lvhdr->lv_bytes = hdr->lhdr[0].i_len + hdr->lhdr[1].i_len; |
| lvhdr->lv_next = ctx->lv_chain; |
| |
| tic->t_curr_res -= lvhdr->lv_bytes; |
| } |
| |
| /* |
| * Pull all the log vectors off the items in the CIL, and remove the items from |
| * the CIL. We don't need the CIL lock here because it's only needed on the |
| * transaction commit side which is currently locked out by the flush lock. |
| * |
| * If a log item is marked with a whiteout, we do not need to write it to the |
| * journal and so we just move them to the whiteout list for the caller to |
| * dispose of appropriately. |
| */ |
| static void |
| xlog_cil_build_lv_chain( |
| struct xfs_cil *cil, |
| struct xfs_cil_ctx *ctx, |
| struct list_head *whiteouts, |
| uint32_t *num_iovecs, |
| uint32_t *num_bytes) |
| { |
| struct xfs_log_vec *lv = NULL; |
| |
| while (!list_empty(&cil->xc_cil)) { |
| struct xfs_log_item *item; |
| |
| item = list_first_entry(&cil->xc_cil, |
| struct xfs_log_item, li_cil); |
| |
| if (test_bit(XFS_LI_WHITEOUT, &item->li_flags)) { |
| list_move(&item->li_cil, whiteouts); |
| trace_xfs_cil_whiteout_skip(item); |
| continue; |
| } |
| |
| list_del_init(&item->li_cil); |
| if (!ctx->lv_chain) |
| ctx->lv_chain = item->li_lv; |
| else |
| lv->lv_next = item->li_lv; |
| lv = item->li_lv; |
| item->li_lv = NULL; |
| *num_iovecs += lv->lv_niovecs; |
| |
| /* we don't write ordered log vectors */ |
| if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) |
| *num_bytes += lv->lv_bytes; |
| } |
| } |
| |
| static void |
| xlog_cil_cleanup_whiteouts( |
| struct list_head *whiteouts) |
| { |
| while (!list_empty(whiteouts)) { |
| struct xfs_log_item *item = list_first_entry(whiteouts, |
| struct xfs_log_item, li_cil); |
| list_del_init(&item->li_cil); |
| trace_xfs_cil_whiteout_unpin(item); |
| item->li_ops->iop_unpin(item, 1); |
| } |
| } |
| |
| /* |
| * Push the Committed Item List to the log. |
| * |
| * If the current sequence is the same as xc_push_seq we need to do a flush. If |
| * xc_push_seq is less than the current sequence, then it has already been |
| * flushed and we don't need to do anything - the caller will wait for it to |
| * complete if necessary. |
| * |
| * xc_push_seq is checked unlocked against the sequence number for a match. |
| * Hence we can allow log forces to run racily and not issue pushes for the |
| * same sequence twice. If we get a race between multiple pushes for the same |
| * sequence they will block on the first one and then abort, hence avoiding |
| * needless pushes. |
| */ |
| static void |
| xlog_cil_push_work( |
| struct work_struct *work) |
| { |
| struct xfs_cil_ctx *ctx = |
| container_of(work, struct xfs_cil_ctx, push_work); |
| struct xfs_cil *cil = ctx->cil; |
| struct xlog *log = cil->xc_log; |
| struct xfs_cil_ctx *new_ctx; |
| int num_iovecs = 0; |
| int num_bytes = 0; |
| int error = 0; |
| struct xlog_cil_trans_hdr thdr; |
| struct xfs_log_vec lvhdr = { NULL }; |
| xfs_csn_t push_seq; |
| bool push_commit_stable; |
| LIST_HEAD (whiteouts); |
| |
| new_ctx = xlog_cil_ctx_alloc(); |
| new_ctx->ticket = xlog_cil_ticket_alloc(log); |
| |
| down_write(&cil->xc_ctx_lock); |
| |
| spin_lock(&cil->xc_push_lock); |
| push_seq = cil->xc_push_seq; |
| ASSERT(push_seq <= ctx->sequence); |
| push_commit_stable = cil->xc_push_commit_stable; |
| cil->xc_push_commit_stable = false; |
| |
| /* |
| * As we are about to switch to a new, empty CIL context, we no longer |
| * need to throttle tasks on CIL space overruns. Wake any waiters that |
| * the hard push throttle may have caught so they can start committing |
| * to the new context. The ctx->xc_push_lock provides the serialisation |
| * necessary for safely using the lockless waitqueue_active() check in |
| * this context. |
| */ |
| if (waitqueue_active(&cil->xc_push_wait)) |
| wake_up_all(&cil->xc_push_wait); |
| |
| /* |
| * Check if we've anything to push. If there is nothing, then we don't |
| * move on to a new sequence number and so we have to be able to push |
| * this sequence again later. |
| */ |
| if (list_empty(&cil->xc_cil)) { |
| cil->xc_push_seq = 0; |
| spin_unlock(&cil->xc_push_lock); |
| goto out_skip; |
| } |
| |
| |
| /* check for a previously pushed sequence */ |
| if (push_seq < ctx->sequence) { |
| spin_unlock(&cil->xc_push_lock); |
| goto out_skip; |
| } |
| |
| /* |
| * We are now going to push this context, so add it to the committing |
| * list before we do anything else. This ensures that anyone waiting on |
| * this push can easily detect the difference between a "push in |
| * progress" and "CIL is empty, nothing to do". |
| * |
| * IOWs, a wait loop can now check for: |
| * the current sequence not being found on the committing list; |
| * an empty CIL; and |
| * an unchanged sequence number |
| * to detect a push that had nothing to do and therefore does not need |
| * waiting on. If the CIL is not empty, we get put on the committing |
| * list before emptying the CIL and bumping the sequence number. Hence |
| * an empty CIL and an unchanged sequence number means we jumped out |
| * above after doing nothing. |
| * |
| * Hence the waiter will either find the commit sequence on the |
| * committing list or the sequence number will be unchanged and the CIL |
| * still dirty. In that latter case, the push has not yet started, and |
| * so the waiter will have to continue trying to check the CIL |
| * committing list until it is found. In extreme cases of delay, the |
| * sequence may fully commit between the attempts the wait makes to wait |
| * on the commit sequence. |
| */ |
| list_add(&ctx->committing, &cil->xc_committing); |
| spin_unlock(&cil->xc_push_lock); |
| |
| xlog_cil_build_lv_chain(cil, ctx, &whiteouts, &num_iovecs, &num_bytes); |
| |
| /* |
| * Switch the contexts so we can drop the context lock and move out |
| * of a shared context. We can't just go straight to the commit record, |
| * though - we need to synchronise with previous and future commits so |
| * that the commit records are correctly ordered in the log to ensure |
| * that we process items during log IO completion in the correct order. |
| * |
| * For example, if we get an EFI in one checkpoint and the EFD in the |
| * next (e.g. due to log forces), we do not want the checkpoint with |
| * the EFD to be committed before the checkpoint with the EFI. Hence |
| * we must strictly order the commit records of the checkpoints so |
| * that: a) the checkpoint callbacks are attached to the iclogs in the |
| * correct order; and b) the checkpoints are replayed in correct order |
| * in log recovery. |
| * |
| * Hence we need to add this context to the committing context list so |
| * that higher sequences will wait for us to write out a commit record |
| * before they do. |
| * |
| * xfs_log_force_seq requires us to mirror the new sequence into the cil |
| * structure atomically with the addition of this sequence to the |
| * committing list. This also ensures that we can do unlocked checks |
| * against the current sequence in log forces without risking |
| * deferencing a freed context pointer. |
| */ |
| spin_lock(&cil->xc_push_lock); |
| xlog_cil_ctx_switch(cil, new_ctx); |
| spin_unlock(&cil->xc_push_lock); |
| up_write(&cil->xc_ctx_lock); |
| |
| /* |
| * Build a checkpoint transaction header and write it to the log to |
| * begin the transaction. We need to account for the space used by the |
| * transaction header here as it is not accounted for in xlog_write(). |
| */ |
| xlog_cil_build_trans_hdr(ctx, &thdr, &lvhdr, num_iovecs); |
| num_bytes += lvhdr.lv_bytes; |
| |
| error = xlog_cil_write_chain(ctx, &lvhdr, num_bytes); |
| if (error) |
| goto out_abort_free_ticket; |
| |
| error = xlog_cil_write_commit_record(ctx); |
| if (error) |
| goto out_abort_free_ticket; |
| |
| xfs_log_ticket_ungrant(log, ctx->ticket); |
| |
| /* |
| * If the checkpoint spans multiple iclogs, wait for all previous iclogs |
| * to complete before we submit the commit_iclog. We can't use state |
| * checks for this - ACTIVE can be either a past completed iclog or a |
| * future iclog being filled, while WANT_SYNC through SYNC_DONE can be a |
| * past or future iclog awaiting IO or ordered IO completion to be run. |
| * In the latter case, if it's a future iclog and we wait on it, the we |
| * will hang because it won't get processed through to ic_force_wait |
| * wakeup until this commit_iclog is written to disk. Hence we use the |
| * iclog header lsn and compare it to the commit lsn to determine if we |
| * need to wait on iclogs or not. |
| */ |
| spin_lock(&log->l_icloglock); |
| if (ctx->start_lsn != ctx->commit_lsn) { |
| xfs_lsn_t plsn; |
| |
| plsn = be64_to_cpu(ctx->commit_iclog->ic_prev->ic_header.h_lsn); |
| if (plsn && XFS_LSN_CMP(plsn, ctx->commit_lsn) < 0) { |
| /* |
| * Waiting on ic_force_wait orders the completion of |
| * iclogs older than ic_prev. Hence we only need to wait |
| * on the most recent older iclog here. |
| */ |
| xlog_wait_on_iclog(ctx->commit_iclog->ic_prev); |
| spin_lock(&log->l_icloglock); |
| } |
| |
| /* |
| * We need to issue a pre-flush so that the ordering for this |
| * checkpoint is correctly preserved down to stable storage. |
| */ |
| ctx->commit_iclog->ic_flags |= XLOG_ICL_NEED_FLUSH; |
| } |
| |
| /* |
| * The commit iclog must be written to stable storage to guarantee |
| * journal IO vs metadata writeback IO is correctly ordered on stable |
| * storage. |
| * |
| * If the push caller needs the commit to be immediately stable and the |
| * commit_iclog is not yet marked as XLOG_STATE_WANT_SYNC to indicate it |
| * will be written when released, switch it's state to WANT_SYNC right |
| * now. |
| */ |
| ctx->commit_iclog->ic_flags |= XLOG_ICL_NEED_FUA; |
| if (push_commit_stable && |
| ctx->commit_iclog->ic_state == XLOG_STATE_ACTIVE) |
| xlog_state_switch_iclogs(log, ctx->commit_iclog, 0); |
| xlog_state_release_iclog(log, ctx->commit_iclog); |
| |
| /* Not safe to reference ctx now! */ |
| |
| spin_unlock(&log->l_icloglock); |
| xlog_cil_cleanup_whiteouts(&whiteouts); |
| return; |
| |
| out_skip: |
| up_write(&cil->xc_ctx_lock); |
| xfs_log_ticket_put(new_ctx->ticket); |
| kmem_free(new_ctx); |
| return; |
| |
| out_abort_free_ticket: |
| xfs_log_ticket_ungrant(log, ctx->ticket); |
| ASSERT(xlog_is_shutdown(log)); |
| xlog_cil_cleanup_whiteouts(&whiteouts); |
| if (!ctx->commit_iclog) { |
| xlog_cil_committed(ctx); |
| return; |
| } |
| spin_lock(&log->l_icloglock); |
| xlog_state_release_iclog(log, ctx->commit_iclog); |
| /* Not safe to reference ctx now! */ |
| spin_unlock(&log->l_icloglock); |
| } |
| |
| /* |
| * We need to push CIL every so often so we don't cache more than we can fit in |
| * the log. The limit really is that a checkpoint can't be more than half the |
| * log (the current checkpoint is not allowed to overwrite the previous |
| * checkpoint), but commit latency and memory usage limit this to a smaller |
| * size. |
| */ |
| static void |
| xlog_cil_push_background( |
| struct xlog *log) __releases(cil->xc_ctx_lock) |
| { |
| struct xfs_cil *cil = log->l_cilp; |
| |
| /* |
| * The cil won't be empty because we are called while holding the |
| * context lock so whatever we added to the CIL will still be there |
| */ |
| ASSERT(!list_empty(&cil->xc_cil)); |
| |
| /* |
| * Don't do a background push if we haven't used up all the |
| * space available yet. |
| */ |
| if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log)) { |
| up_read(&cil->xc_ctx_lock); |
| return; |
| } |
| |
| spin_lock(&cil->xc_push_lock); |
| if (cil->xc_push_seq < cil->xc_current_sequence) { |
| cil->xc_push_seq = cil->xc_current_sequence; |
| queue_work(cil->xc_push_wq, &cil->xc_ctx->push_work); |
| } |
| |
| /* |
| * Drop the context lock now, we can't hold that if we need to sleep |
| * because we are over the blocking threshold. The push_lock is still |
| * held, so blocking threshold sleep/wakeup is still correctly |
| * serialised here. |
| */ |
| up_read(&cil->xc_ctx_lock); |
| |
| /* |
| * If we are well over the space limit, throttle the work that is being |
| * done until the push work on this context has begun. Enforce the hard |
| * throttle on all transaction commits once it has been activated, even |
| * if the committing transactions have resulted in the space usage |
| * dipping back down under the hard limit. |
| * |
| * The ctx->xc_push_lock provides the serialisation necessary for safely |
| * using the lockless waitqueue_active() check in this context. |
| */ |
| if (cil->xc_ctx->space_used >= XLOG_CIL_BLOCKING_SPACE_LIMIT(log) || |
| waitqueue_active(&cil->xc_push_wait)) { |
| trace_xfs_log_cil_wait(log, cil->xc_ctx->ticket); |
| ASSERT(cil->xc_ctx->space_used < log->l_logsize); |
| xlog_wait(&cil->xc_push_wait, &cil->xc_push_lock); |
| return; |
| } |
| |
| spin_unlock(&cil->xc_push_lock); |
| |
| } |
| |
| /* |
| * xlog_cil_push_now() is used to trigger an immediate CIL push to the sequence |
| * number that is passed. When it returns, the work will be queued for |
| * @push_seq, but it won't be completed. |
| * |
| * If the caller is performing a synchronous force, we will flush the workqueue |
| * to get previously queued work moving to minimise the wait time they will |
| * undergo waiting for all outstanding pushes to complete. The caller is |
| * expected to do the required waiting for push_seq to complete. |
| * |
| * If the caller is performing an async push, we need to ensure that the |
| * checkpoint is fully flushed out of the iclogs when we finish the push. If we |
| * don't do this, then the commit record may remain sitting in memory in an |
| * ACTIVE iclog. This then requires another full log force to push to disk, |
| * which defeats the purpose of having an async, non-blocking CIL force |
| * mechanism. Hence in this case we need to pass a flag to the push work to |
| * indicate it needs to flush the commit record itself. |
| */ |
| static void |
| xlog_cil_push_now( |
| struct xlog *log, |
| xfs_lsn_t push_seq, |
| bool async) |
| { |
| struct xfs_cil *cil = log->l_cilp; |
| |
| if (!cil) |
| return; |
| |
| ASSERT(push_seq && push_seq <= cil->xc_current_sequence); |
| |
| /* start on any pending background push to minimise wait time on it */ |
| if (!async) |
| flush_workqueue(cil->xc_push_wq); |
| |
| spin_lock(&cil->xc_push_lock); |
| |
| /* |
| * If this is an async flush request, we always need to set the |
| * xc_push_commit_stable flag even if something else has already queued |
| * a push. The flush caller is asking for the CIL to be on stable |
| * storage when the next push completes, so regardless of who has queued |
| * the push, the flush requires stable semantics from it. |
| */ |
| cil->xc_push_commit_stable = async; |
| |
| /* |
| * If the CIL is empty or we've already pushed the sequence then |
| * there's no more work that we need to do. |
| */ |
| if (list_empty(&cil->xc_cil) || push_seq <= cil->xc_push_seq) { |
| spin_unlock(&cil->xc_push_lock); |
| return; |
| } |
| |
| cil->xc_push_seq = push_seq; |
| queue_work(cil->xc_push_wq, &cil->xc_ctx->push_work); |
| spin_unlock(&cil->xc_push_lock); |
| } |
| |
| bool |
| xlog_cil_empty( |
| struct xlog *log) |
| { |
| struct xfs_cil *cil = log->l_cilp; |
| bool empty = false; |
| |
| spin_lock(&cil->xc_push_lock); |
| if (list_empty(&cil->xc_cil)) |
| empty = true; |
| spin_unlock(&cil->xc_push_lock); |
| return empty; |
| } |
| |
| /* |
| * If there are intent done items in this transaction and the related intent was |
| * committed in the current (same) CIL checkpoint, we don't need to write either |
| * the intent or intent done item to the journal as the change will be |
| * journalled atomically within this checkpoint. As we cannot remove items from |
| * the CIL here, mark the related intent with a whiteout so that the CIL push |
| * can remove it rather than writing it to the journal. Then remove the intent |
| * done item from the current transaction and release it so it doesn't get put |
| * into the CIL at all. |
| */ |
| static uint32_t |
| xlog_cil_process_intents( |
| struct xfs_cil *cil, |
| struct xfs_trans *tp) |
| { |
| struct xfs_log_item *lip, *ilip, *next; |
| uint32_t len = 0; |
| |
| list_for_each_entry_safe(lip, next, &tp->t_items, li_trans) { |
| if (!(lip->li_ops->flags & XFS_ITEM_INTENT_DONE)) |
| continue; |
| |
| ilip = lip->li_ops->iop_intent(lip); |
| if (!ilip || !xlog_item_in_current_chkpt(cil, ilip)) |
| continue; |
| set_bit(XFS_LI_WHITEOUT, &ilip->li_flags); |
| trace_xfs_cil_whiteout_mark(ilip); |
| len += ilip->li_lv->lv_bytes; |
| kmem_free(ilip->li_lv); |
| ilip->li_lv = NULL; |
| |
| xfs_trans_del_item(lip); |
| lip->li_ops->iop_release(lip); |
| } |
| return len; |
| } |
| |
| /* |
| * Commit a transaction with the given vector to the Committed Item List. |
| * |
| * To do this, we need to format the item, pin it in memory if required and |
| * account for the space used by the transaction. Once we have done that we |
| * need to release the unused reservation for the transaction, attach the |
| * transaction to the checkpoint context so we carry the busy extents through |
| * to checkpoint completion, and then unlock all the items in the transaction. |
| * |
| * Called with the context lock already held in read mode to lock out |
| * background commit, returns without it held once background commits are |
| * allowed again. |
| */ |
| void |
| xlog_cil_commit( |
| struct xlog *log, |
| struct xfs_trans *tp, |
| xfs_csn_t *commit_seq, |
| bool regrant) |
| { |
| struct xfs_cil *cil = log->l_cilp; |
| struct xfs_log_item *lip, *next; |
| uint32_t released_space = 0; |
| |
| /* |
| * Do all necessary memory allocation before we lock the CIL. |
| * This ensures the allocation does not deadlock with a CIL |
| * push in memory reclaim (e.g. from kswapd). |
| */ |
| xlog_cil_alloc_shadow_bufs(log, tp); |
| |
| /* lock out background commit */ |
| down_read(&cil->xc_ctx_lock); |
| |
| if (tp->t_flags & XFS_TRANS_HAS_INTENT_DONE) |
| released_space = xlog_cil_process_intents(cil, tp); |
| |
| xlog_cil_insert_items(log, tp, released_space); |
| |
| if (regrant && !xlog_is_shutdown(log)) |
| xfs_log_ticket_regrant(log, tp->t_ticket); |
| else |
| xfs_log_ticket_ungrant(log, tp->t_ticket); |
| tp->t_ticket = NULL; |
| xfs_trans_unreserve_and_mod_sb(tp); |
| |
| /* |
| * Once all the items of the transaction have been copied to the CIL, |
| * the items can be unlocked and possibly freed. |
| * |
| * This needs to be done before we drop the CIL context lock because we |
| * have to update state in the log items and unlock them before they go |
| * to disk. If we don't, then the CIL checkpoint can race with us and |
| * we can run checkpoint completion before we've updated and unlocked |
| * the log items. This affects (at least) processing of stale buffers, |
| * inodes and EFIs. |
| */ |
| trace_xfs_trans_commit_items(tp, _RET_IP_); |
| list_for_each_entry_safe(lip, next, &tp->t_items, li_trans) { |
| xfs_trans_del_item(lip); |
| if (lip->li_ops->iop_committing) |
| lip->li_ops->iop_committing(lip, cil->xc_ctx->sequence); |
| } |
| if (commit_seq) |
| *commit_seq = cil->xc_ctx->sequence; |
| |
| /* xlog_cil_push_background() releases cil->xc_ctx_lock */ |
| xlog_cil_push_background(log); |
| } |
| |
| /* |
| * Flush the CIL to stable storage but don't wait for it to complete. This |
| * requires the CIL push to ensure the commit record for the push hits the disk, |
| * but otherwise is no different to a push done from a log force. |
| */ |
| void |
| xlog_cil_flush( |
| struct xlog *log) |
| { |
| xfs_csn_t seq = log->l_cilp->xc_current_sequence; |
| |
| trace_xfs_log_force(log->l_mp, seq, _RET_IP_); |
| xlog_cil_push_now(log, seq, true); |
| |
| /* |
| * If the CIL is empty, make sure that any previous checkpoint that may |
| * still be in an active iclog is pushed to stable storage. |
| */ |
| if (list_empty(&log->l_cilp->xc_cil)) |
| xfs_log_force(log->l_mp, 0); |
| } |
| |
| /* |
| * Conditionally push the CIL based on the sequence passed in. |
| * |
| * We only need to push if we haven't already pushed the sequence number given. |
| * Hence the only time we will trigger a push here is if the push sequence is |
| * the same as the current context. |
| * |
| * We return the current commit lsn to allow the callers to determine if a |
| * iclog flush is necessary following this call. |
| */ |
| xfs_lsn_t |
| xlog_cil_force_seq( |
| struct xlog *log, |
| xfs_csn_t sequence) |
| { |
| struct xfs_cil *cil = log->l_cilp; |
| struct xfs_cil_ctx *ctx; |
| xfs_lsn_t commit_lsn = NULLCOMMITLSN; |
| |
| ASSERT(sequence <= cil->xc_current_sequence); |
| |
| if (!sequence) |
| sequence = cil->xc_current_sequence; |
| trace_xfs_log_force(log->l_mp, sequence, _RET_IP_); |
| |
| /* |
| * check to see if we need to force out the current context. |
| * xlog_cil_push() handles racing pushes for the same sequence, |
| * so no need to deal with it here. |
| */ |
| restart: |
| xlog_cil_push_now(log, sequence, false); |
| |
| /* |
| * See if we can find a previous sequence still committing. |
| * We need to wait for all previous sequence commits to complete |
| * before allowing the force of push_seq to go ahead. Hence block |
| * on commits for those as well. |
| */ |
| spin_lock(&cil->xc_push_lock); |
| list_for_each_entry(ctx, &cil->xc_committing, committing) { |
| /* |
| * Avoid getting stuck in this loop because we were woken by the |
| * shutdown, but then went back to sleep once already in the |
| * shutdown state. |
| */ |
| if (xlog_is_shutdown(log)) |
| goto out_shutdown; |
| if (ctx->sequence > sequence) |
| continue; |
| if (!ctx->commit_lsn) { |
| /* |
| * It is still being pushed! Wait for the push to |
| * complete, then start again from the beginning. |
| */ |
| XFS_STATS_INC(log->l_mp, xs_log_force_sleep); |
| xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock); |
| goto restart; |
| } |
| if (ctx->sequence != sequence) |
| continue; |
| /* found it! */ |
| commit_lsn = ctx->commit_lsn; |
| } |
| |
| /* |
| * The call to xlog_cil_push_now() executes the push in the background. |
| * Hence by the time we have got here it our sequence may not have been |
| * pushed yet. This is true if the current sequence still matches the |
| * push sequence after the above wait loop and the CIL still contains |
| * dirty objects. This is guaranteed by the push code first adding the |
| * context to the committing list before emptying the CIL. |
| * |
| * Hence if we don't find the context in the committing list and the |
| * current sequence number is unchanged then the CIL contents are |
| * significant. If the CIL is empty, if means there was nothing to push |
| * and that means there is nothing to wait for. If the CIL is not empty, |
| * it means we haven't yet started the push, because if it had started |
| * we would have found the context on the committing list. |
| */ |
| if (sequence == cil->xc_current_sequence && |
| !list_empty(&cil->xc_cil)) { |
| spin_unlock(&cil->xc_push_lock); |
| goto restart; |
| } |
| |
| spin_unlock(&cil->xc_push_lock); |
| return commit_lsn; |
| |
| /* |
| * We detected a shutdown in progress. We need to trigger the log force |
| * to pass through it's iclog state machine error handling, even though |
| * we are already in a shutdown state. Hence we can't return |
| * NULLCOMMITLSN here as that has special meaning to log forces (i.e. |
| * LSN is already stable), so we return a zero LSN instead. |
| */ |
| out_shutdown: |
| spin_unlock(&cil->xc_push_lock); |
| return 0; |
| } |
| |
| /* |
| * Perform initial CIL structure initialisation. |
| */ |
| int |
| xlog_cil_init( |
| struct xlog *log) |
| { |
| struct xfs_cil *cil; |
| struct xfs_cil_ctx *ctx; |
| |
| cil = kmem_zalloc(sizeof(*cil), KM_MAYFAIL); |
| if (!cil) |
| return -ENOMEM; |
| /* |
| * Limit the CIL pipeline depth to 4 concurrent works to bound the |
| * concurrency the log spinlocks will be exposed to. |
| */ |
| cil->xc_push_wq = alloc_workqueue("xfs-cil/%s", |
| XFS_WQFLAGS(WQ_FREEZABLE | WQ_MEM_RECLAIM | WQ_UNBOUND), |
| 4, log->l_mp->m_super->s_id); |
| if (!cil->xc_push_wq) |
| goto out_destroy_cil; |
| |
| INIT_LIST_HEAD(&cil->xc_cil); |
| INIT_LIST_HEAD(&cil->xc_committing); |
| spin_lock_init(&cil->xc_cil_lock); |
| spin_lock_init(&cil->xc_push_lock); |
| init_waitqueue_head(&cil->xc_push_wait); |
| init_rwsem(&cil->xc_ctx_lock); |
| init_waitqueue_head(&cil->xc_start_wait); |
| init_waitqueue_head(&cil->xc_commit_wait); |
| cil->xc_log = log; |
| log->l_cilp = cil; |
| |
| ctx = xlog_cil_ctx_alloc(); |
| xlog_cil_ctx_switch(cil, ctx); |
| |
| return 0; |
| |
| out_destroy_cil: |
| kmem_free(cil); |
| return -ENOMEM; |
| } |
| |
| void |
| xlog_cil_destroy( |
| struct xlog *log) |
| { |
| if (log->l_cilp->xc_ctx) { |
| if (log->l_cilp->xc_ctx->ticket) |
| xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket); |
| kmem_free(log->l_cilp->xc_ctx); |
| } |
| |
| ASSERT(list_empty(&log->l_cilp->xc_cil)); |
| destroy_workqueue(log->l_cilp->xc_push_wq); |
| kmem_free(log->l_cilp); |
| } |
| |