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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /fs/xfs/xfs_log_cil.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/xfs/xfs_log_cil.c')
-rw-r--r--fs/xfs/xfs_log_cil.c1897
1 files changed, 1897 insertions, 0 deletions
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
new file mode 100644
index 000000000..eccbfb99e
--- /dev/null
+++ b/fs/xfs/xfs_log_cil.c
@@ -0,0 +1,1897 @@
+// 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;
+ tic->t_iclog_hdrs = 0;
+ return tic;
+}
+
+static inline void
+xlog_cil_set_iclog_hdr_count(struct xfs_cil *cil)
+{
+ struct xlog *log = cil->xc_log;
+
+ atomic_set(&cil->xc_iclog_hdrs,
+ (XLOG_CIL_BLOCKING_SPACE_LIMIT(log) /
+ (log->l_iclog_size - log->l_iclog_hsize)));
+}
+
+/*
+ * 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 (test_bit(XLOG_CIL_EMPTY, &cil->xc_flags))
+ 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_LIST_HEAD(&ctx->log_items);
+ INIT_LIST_HEAD(&ctx->lv_chain);
+ INIT_WORK(&ctx->push_work, xlog_cil_push_work);
+ return ctx;
+}
+
+/*
+ * Aggregate the CIL per cpu structures into global counts, lists, etc and
+ * clear the percpu state ready for the next context to use. This is called
+ * from the push code with the context lock held exclusively, hence nothing else
+ * will be accessing or modifying the per-cpu counters.
+ */
+static void
+xlog_cil_push_pcp_aggregate(
+ struct xfs_cil *cil,
+ struct xfs_cil_ctx *ctx)
+{
+ struct xlog_cil_pcp *cilpcp;
+ int cpu;
+
+ for_each_online_cpu(cpu) {
+ cilpcp = per_cpu_ptr(cil->xc_pcp, cpu);
+
+ ctx->ticket->t_curr_res += cilpcp->space_reserved;
+ cilpcp->space_reserved = 0;
+
+ if (!list_empty(&cilpcp->busy_extents)) {
+ list_splice_init(&cilpcp->busy_extents,
+ &ctx->busy_extents);
+ }
+ if (!list_empty(&cilpcp->log_items))
+ list_splice_init(&cilpcp->log_items, &ctx->log_items);
+
+ /*
+ * We're in the middle of switching cil contexts. Reset the
+ * counter we use to detect when the current context is nearing
+ * full.
+ */
+ cilpcp->space_used = 0;
+ }
+}
+
+/*
+ * Aggregate the CIL per-cpu space used counters into the global atomic value.
+ * This is called when the per-cpu counter aggregation will first pass the soft
+ * limit threshold so we can switch to atomic counter aggregation for accurate
+ * detection of hard limit traversal.
+ */
+static void
+xlog_cil_insert_pcp_aggregate(
+ struct xfs_cil *cil,
+ struct xfs_cil_ctx *ctx)
+{
+ struct xlog_cil_pcp *cilpcp;
+ int cpu;
+ int count = 0;
+
+ /* Trigger atomic updates then aggregate only for the first caller */
+ if (!test_and_clear_bit(XLOG_CIL_PCP_SPACE, &cil->xc_flags))
+ return;
+
+ for_each_online_cpu(cpu) {
+ int old, prev;
+
+ cilpcp = per_cpu_ptr(cil->xc_pcp, cpu);
+ do {
+ old = cilpcp->space_used;
+ prev = cmpxchg(&cilpcp->space_used, old, 0);
+ } while (old != prev);
+ count += old;
+ }
+ atomic_add(count, &ctx->space_used);
+}
+
+static void
+xlog_cil_ctx_switch(
+ struct xfs_cil *cil,
+ struct xfs_cil_ctx *ctx)
+{
+ xlog_cil_set_iclog_hdr_count(cil);
+ set_bit(XLOG_CIL_EMPTY, &cil->xc_flags);
+ set_bit(XLOG_CIL_PCP_SPACE, &cil->xc_flags);
+ 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;
+ xlog_cil_set_iclog_hdr_count(log->l_cilp);
+}
+
+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));
+
+ INIT_LIST_HEAD(&lv->lv_list);
+ 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;
+ }
+
+ /* 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;
+
+ 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);
+ }
+}
+
+/*
+ * The use of lockless waitqueue_active() requires that the caller has
+ * serialised itself against the wakeup call in xlog_cil_push_work(). That
+ * can be done by either holding the push lock or the context lock.
+ */
+static inline bool
+xlog_cil_over_hard_limit(
+ struct xlog *log,
+ int32_t space_used)
+{
+ if (waitqueue_active(&log->l_cilp->xc_push_wait))
+ return true;
+ if (space_used >= XLOG_CIL_BLOCKING_SPACE_LIMIT(log))
+ return true;
+ return false;
+}
+
+/*
+ * 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 iovhdr_res = 0, split_res = 0, ctx_res = 0;
+ int space_used;
+ int order;
+ struct xlog_cil_pcp *cilpcp;
+
+ 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);
+
+ /*
+ * Subtract the space released by intent cancelation from the space we
+ * consumed so that we remove it from the CIL space and add it back to
+ * the current transaction reservation context.
+ */
+ len -= released_space;
+
+ /*
+ * Grab the per-cpu pointer for the CIL before we start any accounting.
+ * That ensures that we are running with pre-emption disabled and so we
+ * can't be scheduled away between split sample/update operations that
+ * are done without outside locking to serialise them.
+ */
+ cilpcp = get_cpu_ptr(cil->xc_pcp);
+
+ /*
+ * We need to take the CIL checkpoint unit reservation on the first
+ * commit into the CIL. Test the XLOG_CIL_EMPTY bit first so we don't
+ * unnecessarily do an atomic op in the fast path here. We can clear the
+ * XLOG_CIL_EMPTY bit as we are under the xc_ctx_lock here and that
+ * needs to be held exclusively to reset the XLOG_CIL_EMPTY bit.
+ */
+ if (test_bit(XLOG_CIL_EMPTY, &cil->xc_flags) &&
+ test_and_clear_bit(XLOG_CIL_EMPTY, &cil->xc_flags))
+ ctx_res = ctx->ticket->t_unit_res;
+
+ /*
+ * Check if we need to steal iclog headers. atomic_read() is not a
+ * locked atomic operation, so we can check the value before we do any
+ * real atomic ops in the fast path. If we've already taken the CIL unit
+ * reservation from this commit, we've already got one iclog header
+ * space reserved so we have to account for that otherwise we risk
+ * overrunning the reservation on this ticket.
+ *
+ * If the CIL is already at the hard limit, we might need more header
+ * space that originally reserved. So steal more header space from every
+ * commit that occurs once we are over the hard limit to ensure the CIL
+ * push won't run out of reservation space.
+ *
+ * This can steal more than we need, but that's OK.
+ *
+ * The cil->xc_ctx_lock provides the serialisation necessary for safely
+ * calling xlog_cil_over_hard_limit() in this context.
+ */
+ space_used = atomic_read(&ctx->space_used) + cilpcp->space_used + len;
+ if (atomic_read(&cil->xc_iclog_hdrs) > 0 ||
+ xlog_cil_over_hard_limit(log, space_used)) {
+ split_res = log->l_iclog_hsize +
+ sizeof(struct xlog_op_header);
+ if (ctx_res)
+ ctx_res += split_res * (tp->t_ticket->t_iclog_hdrs - 1);
+ else
+ ctx_res = split_res * tp->t_ticket->t_iclog_hdrs;
+ atomic_sub(tp->t_ticket->t_iclog_hdrs, &cil->xc_iclog_hdrs);
+ }
+ cilpcp->space_reserved += ctx_res;
+
+ /*
+ * Accurately account when over the soft limit, otherwise fold the
+ * percpu count into the global count if over the per-cpu threshold.
+ */
+ if (!test_bit(XLOG_CIL_PCP_SPACE, &cil->xc_flags)) {
+ atomic_add(len, &ctx->space_used);
+ } else if (cilpcp->space_used + len >
+ (XLOG_CIL_SPACE_LIMIT(log) / num_online_cpus())) {
+ space_used = atomic_add_return(cilpcp->space_used + len,
+ &ctx->space_used);
+ cilpcp->space_used = 0;
+
+ /*
+ * If we just transitioned over the soft limit, we need to
+ * transition to the global atomic counter.
+ */
+ if (space_used >= XLOG_CIL_SPACE_LIMIT(log))
+ xlog_cil_insert_pcp_aggregate(cil, ctx);
+ } else {
+ cilpcp->space_used += len;
+ }
+ /* attach the transaction to the CIL if it has any busy extents */
+ if (!list_empty(&tp->t_busy))
+ list_splice_init(&tp->t_busy, &cilpcp->busy_extents);
+
+ /*
+ * Now update the order of everything modified in the transaction
+ * and insert items into the CIL if they aren't already there.
+ * We do this here so we only need to take the CIL lock once during
+ * the transaction commit.
+ */
+ order = atomic_inc_return(&ctx->order_id);
+ 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;
+
+ lip->li_order_id = order;
+ if (!list_empty(&lip->li_cil))
+ continue;
+ list_add_tail(&lip->li_cil, &cilpcp->log_items);
+ }
+ put_cpu_ptr(cilpcp);
+
+ /*
+ * If we've overrun the reservation, dump the tx details before we move
+ * the log items. Shutdown is imminent...
+ */
+ tp->t_ticket->t_curr_res -= ctx_res + len;
+ 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);
+ xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
+ }
+}
+
+static void
+xlog_cil_free_logvec(
+ struct list_head *lv_chain)
+{
+ struct xfs_log_vec *lv;
+
+ while (!list_empty(lv_chain)) {
+ lv = list_first_entry(lv_chain, struct xfs_log_vec, lv_list);
+ list_del_init(&lv->lv_list);
+ kmem_free(lv);
+ }
+}
+
+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,
+ 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, &ctx->lv_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 = &reg,
+ };
+ int error;
+ LIST_HEAD(lv_chain);
+ list_add(&vec.lv_list, &lv_chain);
+
+ 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, &lv_chain, 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;
+
+ tic->t_curr_res -= lvhdr->lv_bytes;
+}
+
+/*
+ * CIL item reordering compare function. We want to order in ascending ID order,
+ * but we want to leave items with the same ID in the order they were added to
+ * the list. This is important for operations like reflink where we log 4 order
+ * dependent intents in a single transaction when we overwrite an existing
+ * shared extent with a new shared extent. i.e. BUI(unmap), CUI(drop),
+ * CUI (inc), BUI(remap)...
+ */
+static int
+xlog_cil_order_cmp(
+ void *priv,
+ const struct list_head *a,
+ const struct list_head *b)
+{
+ struct xfs_log_vec *l1 = container_of(a, struct xfs_log_vec, lv_list);
+ struct xfs_log_vec *l2 = container_of(b, struct xfs_log_vec, lv_list);
+
+ return l1->lv_order_id > l2->lv_order_id;
+}
+
+/*
+ * 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_ctx *ctx,
+ struct list_head *whiteouts,
+ uint32_t *num_iovecs,
+ uint32_t *num_bytes)
+{
+ while (!list_empty(&ctx->log_items)) {
+ struct xfs_log_item *item;
+ struct xfs_log_vec *lv;
+
+ item = list_first_entry(&ctx->log_items,
+ 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;
+ }
+
+ lv = item->li_lv;
+ lv->lv_order_id = item->li_order_id;
+
+ /* we don't write ordered log vectors */
+ if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED)
+ *num_bytes += lv->lv_bytes;
+ *num_iovecs += lv->lv_niovecs;
+ list_add_tail(&lv->lv_list, &ctx->lv_chain);
+
+ list_del_init(&item->li_cil);
+ item->li_order_id = 0;
+ item->li_lv = NULL;
+ }
+}
+
+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 = {};
+ xfs_csn_t push_seq;
+ bool push_commit_stable;
+ LIST_HEAD (whiteouts);
+ struct xlog_ticket *ticket;
+
+ 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);
+
+ xlog_cil_push_pcp_aggregate(cil, ctx);
+
+ /*
+ * 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 (test_bit(XLOG_CIL_EMPTY, &cil->xc_flags)) {
+ 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(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);
+
+ /*
+ * Sort the log vector chain before we add the transaction headers.
+ * This ensures we always have the transaction headers at the start
+ * of the chain.
+ */
+ list_sort(NULL, &ctx->lv_chain, xlog_cil_order_cmp);
+
+ /*
+ * 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().
+ * Add the lvhdr to the head of the lv chain we pass to xlog_write() so
+ * it gets written into the iclog first.
+ */
+ xlog_cil_build_trans_hdr(ctx, &thdr, &lvhdr, num_iovecs);
+ num_bytes += lvhdr.lv_bytes;
+ list_add(&lvhdr.lv_list, &ctx->lv_chain);
+
+ /*
+ * Take the lvhdr back off the lv_chain immediately after calling
+ * xlog_cil_write_chain() as it should not be passed to log IO
+ * completion.
+ */
+ error = xlog_cil_write_chain(ctx, num_bytes);
+ list_del(&lvhdr.lv_list);
+ if (error)
+ goto out_abort_free_ticket;
+
+ error = xlog_cil_write_commit_record(ctx);
+ if (error)
+ goto out_abort_free_ticket;
+
+ /*
+ * Grab the ticket from the ctx so we can ungrant it after releasing the
+ * commit_iclog. The ctx may be freed by the time we return from
+ * releasing the commit_iclog (i.e. checkpoint has been completed and
+ * callback run) so we can't reference the ctx after the call to
+ * xlog_state_release_iclog().
+ */
+ ticket = 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);
+ ticket = ctx->ticket;
+ xlog_state_release_iclog(log, ctx->commit_iclog, ticket);
+
+ /* Not safe to reference ctx now! */
+
+ spin_unlock(&log->l_icloglock);
+ xlog_cil_cleanup_whiteouts(&whiteouts);
+ xfs_log_ticket_ungrant(log, ticket);
+ 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:
+ ASSERT(xlog_is_shutdown(log));
+ xlog_cil_cleanup_whiteouts(&whiteouts);
+ if (!ctx->commit_iclog) {
+ xfs_log_ticket_ungrant(log, ctx->ticket);
+ xlog_cil_committed(ctx);
+ return;
+ }
+ spin_lock(&log->l_icloglock);
+ ticket = ctx->ticket;
+ xlog_state_release_iclog(log, ctx->commit_iclog, ticket);
+ /* Not safe to reference ctx now! */
+ spin_unlock(&log->l_icloglock);
+ xfs_log_ticket_ungrant(log, ticket);
+}
+
+/*
+ * 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;
+ int space_used = atomic_read(&cil->xc_ctx->space_used);
+
+ /*
+ * 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(!test_bit(XLOG_CIL_EMPTY, &cil->xc_flags));
+
+ /*
+ * We are done if:
+ * - we haven't used up all the space available yet; or
+ * - we've already queued up a push; and
+ * - we're not over the hard limit; and
+ * - nothing has been over the hard limit.
+ *
+ * If so, we don't need to take the push lock as there's nothing to do.
+ */
+ if (space_used < XLOG_CIL_SPACE_LIMIT(log) ||
+ (cil->xc_push_seq == cil->xc_current_sequence &&
+ space_used < XLOG_CIL_BLOCKING_SPACE_LIMIT(log) &&
+ !waitqueue_active(&cil->xc_push_wait))) {
+ 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
+ * calling xlog_cil_over_hard_limit() in this context.
+ */
+ if (xlog_cil_over_hard_limit(log, space_used)) {
+ trace_xfs_log_cil_wait(log, cil->xc_ctx->ticket);
+ ASSERT(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 (test_bit(XLOG_CIL_EMPTY, &cil->xc_flags) ||
+ 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 (test_bit(XLOG_CIL_EMPTY, &cil->xc_flags))
+ 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 (test_bit(XLOG_CIL_EMPTY, &log->l_cilp->xc_flags))
+ 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 &&
+ !test_bit(XLOG_CIL_EMPTY, &cil->xc_flags)) {
+ 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;
+}
+
+/*
+ * Move dead percpu state to the relevant CIL context structures.
+ *
+ * We have to lock the CIL context here to ensure that nothing is modifying
+ * the percpu state, either addition or removal. Both of these are done under
+ * the CIL context lock, so grabbing that exclusively here will ensure we can
+ * safely drain the cilpcp for the CPU that is dying.
+ */
+void
+xlog_cil_pcp_dead(
+ struct xlog *log,
+ unsigned int cpu)
+{
+ struct xfs_cil *cil = log->l_cilp;
+ struct xlog_cil_pcp *cilpcp = per_cpu_ptr(cil->xc_pcp, cpu);
+ struct xfs_cil_ctx *ctx;
+
+ down_write(&cil->xc_ctx_lock);
+ ctx = cil->xc_ctx;
+ if (ctx->ticket)
+ ctx->ticket->t_curr_res += cilpcp->space_reserved;
+ cilpcp->space_reserved = 0;
+
+ if (!list_empty(&cilpcp->log_items))
+ list_splice_init(&cilpcp->log_items, &ctx->log_items);
+ if (!list_empty(&cilpcp->busy_extents))
+ list_splice_init(&cilpcp->busy_extents, &ctx->busy_extents);
+ atomic_add(cilpcp->space_used, &ctx->space_used);
+ cilpcp->space_used = 0;
+ up_write(&cil->xc_ctx_lock);
+}
+
+/*
+ * Perform initial CIL structure initialisation.
+ */
+int
+xlog_cil_init(
+ struct xlog *log)
+{
+ struct xfs_cil *cil;
+ struct xfs_cil_ctx *ctx;
+ struct xlog_cil_pcp *cilpcp;
+ int cpu;
+
+ 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;
+
+ cil->xc_log = log;
+ cil->xc_pcp = alloc_percpu(struct xlog_cil_pcp);
+ if (!cil->xc_pcp)
+ goto out_destroy_wq;
+
+ for_each_possible_cpu(cpu) {
+ cilpcp = per_cpu_ptr(cil->xc_pcp, cpu);
+ INIT_LIST_HEAD(&cilpcp->busy_extents);
+ INIT_LIST_HEAD(&cilpcp->log_items);
+ }
+
+ INIT_LIST_HEAD(&cil->xc_committing);
+ 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);
+ log->l_cilp = cil;
+
+ ctx = xlog_cil_ctx_alloc();
+ xlog_cil_ctx_switch(cil, ctx);
+ return 0;
+
+out_destroy_wq:
+ destroy_workqueue(cil->xc_push_wq);
+out_destroy_cil:
+ kmem_free(cil);
+ return -ENOMEM;
+}
+
+void
+xlog_cil_destroy(
+ struct xlog *log)
+{
+ struct xfs_cil *cil = log->l_cilp;
+
+ if (cil->xc_ctx) {
+ if (cil->xc_ctx->ticket)
+ xfs_log_ticket_put(cil->xc_ctx->ticket);
+ kmem_free(cil->xc_ctx);
+ }
+
+ ASSERT(test_bit(XLOG_CIL_EMPTY, &cil->xc_flags));
+ free_percpu(cil->xc_pcp);
+ destroy_workqueue(cil->xc_push_wq);
+ kmem_free(cil);
+}
+