--- /dev/null
+/*
+ * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#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_error.h"
+#include "xfs_alloc.h"
+#include "xfs_extent_busy.h"
+#include "xfs_discard.h"
+#include "xfs_trans.h"
+#include "xfs_trans_priv.h"
+#include "xfs_log.h"
+#include "xfs_log_priv.h"
+
+/*
+ * 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, XFS_TRANSACTION, 0,
+ KM_SLEEP|KM_NOFS);
+ tic->t_trans_type = XFS_TRANS_CHECKPOINT;
+
+ /*
+ * 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;
+}
+
+/*
+ * 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;
+}
+
+/*
+ * Prepare the log item for insertion into the CIL. Calculate the difference in
+ * log space and vectors 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,
+ int *diff_iovecs)
+{
+ /* Account for the new LV being passed in */
+ if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) {
+ *diff_len += lv->lv_bytes;
+ *diff_iovecs += lv->lv_niovecs;
+ }
+
+ /*
+ * 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 free it.
+ */
+ if (!old_lv)
+ lv->lv_item->li_ops->iop_pin(lv->lv_item);
+ else if (old_lv != lv) {
+ ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED);
+
+ *diff_len -= old_lv->lv_bytes;
+ *diff_iovecs -= old_lv->lv_niovecs;
+ kmem_free(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 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 formats the vector for the item into the buffer.
+ * The buffer is then attached to the log item are then inserted into the
+ * Committed Item List for tracking until the next checkpoint is written out.
+ *
+ * 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,
+ int *diff_iovecs)
+{
+ struct xfs_log_item_desc *lidp;
+
+
+ /* Bail out if we didn't find a log item. */
+ if (list_empty(&tp->t_items)) {
+ ASSERT(0);
+ return;
+ }
+
+ list_for_each_entry(lidp, &tp->t_items, lid_trans) {
+ struct xfs_log_item *lip = lidp->lid_item;
+ struct xfs_log_vec *lv;
+ struct xfs_log_vec *old_lv;
+ int niovecs = 0;
+ int nbytes = 0;
+ int buf_size;
+ bool ordered = false;
+
+ /* Skip items which aren't dirty in this transaction. */
+ if (!(lidp->lid_flags & XFS_LID_DIRTY))
+ continue;
+
+ /* get number of vecs and size of data to be stored */
+ lip->li_ops->iop_size(lip, &niovecs, &nbytes);
+
+ /* Skip items that do not have any vectors for writing */
+ if (!niovecs)
+ continue;
+
+ /*
+ * 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. 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);
+ nbytes = round_up(nbytes, sizeof(uint64_t));
+
+ /* grab the old item if it exists for reservation accounting */
+ old_lv = lip->li_lv;
+
+ /*
+ * 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 +
+ round_up((sizeof(struct xfs_log_vec) +
+ niovecs * sizeof(struct xfs_log_iovec)),
+ sizeof(uint64_t));
+
+ /* compare to existing item size */
+ if (lip->li_lv && buf_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_iovecs -= lv->lv_niovecs;
+ *diff_len -= lv->lv_bytes;
+ } else {
+ /* allocate new data chunk */
+ lv = kmem_zalloc(buf_size, KM_SLEEP|KM_NOFS);
+ lv->lv_item = lip;
+ lv->lv_size = buf_size;
+ if (ordered) {
+ /* track as an ordered logvec */
+ ASSERT(lip->li_lv == NULL);
+ lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
+ goto insert;
+ }
+ lv->lv_iovecp = (struct xfs_log_iovec *)&lv[1];
+ }
+
+ /* 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_len = 0;
+ lv->lv_bytes = 0;
+ lv->lv_buf = (char *)lv + buf_size - nbytes;
+ ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
+
+ lip->li_ops->iop_format(lip, lv);
+insert:
+ ASSERT(lv->lv_buf_len <= nbytes);
+ xfs_cil_prepare_item(log, lv, old_lv, diff_len, diff_iovecs);
+ }
+}
+
+/*
+ * 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)
+{
+ struct xfs_cil *cil = log->l_cilp;
+ struct xfs_cil_ctx *ctx = cil->xc_ctx;
+ struct xfs_log_item_desc *lidp;
+ int len = 0;
+ int diff_iovecs = 0;
+ int iclog_space;
+
+ 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, &diff_iovecs);
+
+ /*
+ * 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.
+ */
+ spin_lock(&cil->xc_cil_lock);
+ list_for_each_entry(lidp, &tp->t_items, lid_trans) {
+ struct xfs_log_item *lip = lidp->lid_item;
+
+ /* Skip items which aren't dirty in this transaction. */
+ if (!(lidp->lid_flags & XFS_LID_DIRTY))
+ continue;
+
+ list_move_tail(&lip->li_cil, &cil->xc_cil);
+ }
+
+ /* account for space used by new iovec headers */
+ len += diff_iovecs * sizeof(xlog_op_header_t);
+ ctx->nvecs += diff_iovecs;
+
+ /* 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->ticket->t_curr_res = ctx->ticket->t_unit_res;
+ tp->t_ticket->t_curr_res -= ctx->ticket->t_unit_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)) {
+ int hdrs;
+
+ hdrs = (len + iclog_space - 1) / iclog_space;
+ /* need to take into account split region headers, too */
+ hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
+ ctx->ticket->t_unit_res += hdrs;
+ ctx->ticket->t_curr_res += hdrs;
+ tp->t_ticket->t_curr_res -= hdrs;
+ ASSERT(tp->t_ticket->t_curr_res >= len);
+ }
+ tp->t_ticket->t_curr_res -= len;
+ ctx->space_used += len;
+
+ spin_unlock(&cil->xc_cil_lock);
+}
+
+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;
+ }
+}
+
+/*
+ * 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(
+ void *args,
+ int abort)
+{
+ struct xfs_cil_ctx *ctx = args;
+ struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
+
+ 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,
+ (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
+
+ /*
+ * If we are aborting the commit, wake up anyone waiting on the
+ * committing list. If we don't, then a shutdown we can leave processes
+ * waiting in xlog_cil_force_lsn() waiting on a sequence commit that
+ * will never happen because we aborted it.
+ */
+ spin_lock(&ctx->cil->xc_push_lock);
+ if (abort)
+ wake_up_all(&ctx->cil->xc_commit_wait);
+ list_del(&ctx->committing);
+ spin_unlock(&ctx->cil->xc_push_lock);
+
+ xlog_cil_free_logvec(ctx->lv_chain);
+
+ if (!list_empty(&ctx->busy_extents)) {
+ ASSERT(mp->m_flags & XFS_MOUNT_DISCARD);
+
+ xfs_discard_extents(mp, &ctx->busy_extents);
+ xfs_extent_busy_clear(mp, &ctx->busy_extents, false);
+ }
+
+ kmem_free(ctx);
+}
+
+/*
+ * Push the Committed Item List to the log. If @push_seq flag is zero, then it
+ * is a background flush and so we can chose to ignore it. Otherwise, if the
+ * current sequence is the same as @push_seq we need to do a flush. If
+ * @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.
+ *
+ * @push_seq is a value rather than a flag because that allows us to do an
+ * unlocked check of the sequence number for a match. Hence we can allows 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 int
+xlog_cil_push(
+ struct xlog *log)
+{
+ struct xfs_cil *cil = log->l_cilp;
+ struct xfs_log_vec *lv;
+ struct xfs_cil_ctx *ctx;
+ struct xfs_cil_ctx *new_ctx;
+ struct xlog_in_core *commit_iclog;
+ struct xlog_ticket *tic;
+ int num_iovecs;
+ int error = 0;
+ struct xfs_trans_header thdr;
+ struct xfs_log_iovec lhdr;
+ struct xfs_log_vec lvhdr = { NULL };
+ xfs_lsn_t commit_lsn;
+ xfs_lsn_t push_seq;
+
+ if (!cil)
+ return 0;
+
+ new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
+ new_ctx->ticket = xlog_cil_ticket_alloc(log);
+
+ down_write(&cil->xc_ctx_lock);
+ ctx = cil->xc_ctx;
+
+ spin_lock(&cil->xc_push_lock);
+ push_seq = cil->xc_push_seq;
+ ASSERT(push_seq <= ctx->sequence);
+
+ /*
+ * 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 seqeunce */
+ if (push_seq < cil->xc_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);
+
+ /*
+ * 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.
+ */
+ lv = NULL;
+ num_iovecs = 0;
+ while (!list_empty(&cil->xc_cil)) {
+ struct xfs_log_item *item;
+
+ item = list_first_entry(&cil->xc_cil,
+ struct xfs_log_item, li_cil);
+ 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;
+ }
+
+ /*
+ * initialise the new context and attach it to the CIL. Then attach
+ * the current context to the CIL committing lsit so it can be found
+ * during log forces to extract the commit lsn of the sequence that
+ * needs to be forced.
+ */
+ INIT_LIST_HEAD(&new_ctx->committing);
+ INIT_LIST_HEAD(&new_ctx->busy_extents);
+ new_ctx->sequence = ctx->sequence + 1;
+ new_ctx->cil = cil;
+ cil->xc_ctx = new_ctx;
+
+ /*
+ * The switch is now done, 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_lsn 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);
+ cil->xc_current_sequence = new_ctx->sequence;
+ 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().
+ *
+ * The LSN we need to pass to the log items on transaction commit is
+ * the LSN reported by the first log vector write. If we use the commit
+ * record lsn then we can move the tail beyond the grant write head.
+ */
+ tic = ctx->ticket;
+ thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
+ thdr.th_type = XFS_TRANS_CHECKPOINT;
+ thdr.th_tid = tic->t_tid;
+ thdr.th_num_items = num_iovecs;
+ lhdr.i_addr = &thdr;
+ lhdr.i_len = sizeof(xfs_trans_header_t);
+ lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
+ tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
+
+ lvhdr.lv_niovecs = 1;
+ lvhdr.lv_iovecp = &lhdr;
+ lvhdr.lv_next = ctx->lv_chain;
+
+ error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);
+ if (error)
+ goto out_abort_free_ticket;
+
+ /*
+ * now that we've written the checkpoint into the log, strictly
+ * order the commit records so replay will get them in the right order.
+ */
+restart:
+ spin_lock(&cil->xc_push_lock);
+ list_for_each_entry(new_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_FORCED_SHUTDOWN(log)) {
+ spin_unlock(&cil->xc_push_lock);
+ goto out_abort_free_ticket;
+ }
+
+ /*
+ * Higher sequences will wait for this one so skip them.
+ * Don't wait for our own sequence, either.
+ */
+ if (new_ctx->sequence >= ctx->sequence)
+ continue;
+ if (!new_ctx->commit_lsn) {
+ /*
+ * It is still being pushed! Wait for the push to
+ * complete, then start again from the beginning.
+ */
+ xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
+ goto restart;
+ }
+ }
+ spin_unlock(&cil->xc_push_lock);
+
+ /* xfs_log_done always frees the ticket on error. */
+ commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
+ if (commit_lsn == -1)
+ goto out_abort;
+
+ /* attach all the transactions w/ busy extents to iclog */
+ ctx->log_cb.cb_func = xlog_cil_committed;
+ ctx->log_cb.cb_arg = ctx;
+ error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb);
+ if (error)
+ goto out_abort;
+
+ /*
+ * now the checkpoint commit is complete and we've attached the
+ * callbacks to the iclog we can assign the commit LSN to the context
+ * and wake up anyone who is waiting for the commit to complete.
+ */
+ spin_lock(&cil->xc_push_lock);
+ ctx->commit_lsn = commit_lsn;
+ wake_up_all(&cil->xc_commit_wait);
+ spin_unlock(&cil->xc_push_lock);
+
+ /* release the hounds! */
+ return xfs_log_release_iclog(log->l_mp, commit_iclog);
+
+out_skip:
+ up_write(&cil->xc_ctx_lock);
+ xfs_log_ticket_put(new_ctx->ticket);
+ kmem_free(new_ctx);
+ return 0;
+
+out_abort_free_ticket:
+ xfs_log_ticket_put(tic);
+out_abort:
+ xlog_cil_committed(ctx, XFS_LI_ABORTED);
+ return -EIO;
+}
+
+static void
+xlog_cil_push_work(
+ struct work_struct *work)
+{
+ struct xfs_cil *cil = container_of(work, struct xfs_cil,
+ xc_push_work);
+ xlog_cil_push(cil->xc_log);
+}
+
+/*
+ * 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)
+{
+ 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))
+ 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(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
+ }
+ 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. The caller is expected to do any
+ * waiting for push_seq to complete if it is required.
+ */
+static void
+xlog_cil_push_now(
+ struct xlog *log,
+ xfs_lsn_t push_seq)
+{
+ 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 */
+ flush_work(&cil->xc_push_work);
+
+ /*
+ * If the CIL is empty or we've already pushed the sequence then
+ * there's no work we need to do.
+ */
+ spin_lock(&cil->xc_push_lock);
+ 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(log->l_mp->m_cil_workqueue, &cil->xc_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;
+}
+
+/*
+ * 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
+xfs_log_commit_cil(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ xfs_lsn_t *commit_lsn,
+ int flags)
+{
+ struct xlog *log = mp->m_log;
+ struct xfs_cil *cil = log->l_cilp;
+ int log_flags = 0;
+
+ if (flags & XFS_TRANS_RELEASE_LOG_RES)
+ log_flags = XFS_LOG_REL_PERM_RESERV;
+
+ /* lock out background commit */
+ down_read(&cil->xc_ctx_lock);
+
+ xlog_cil_insert_items(log, tp);
+
+ /* check we didn't blow the reservation */
+ if (tp->t_ticket->t_curr_res < 0)
+ xlog_print_tic_res(mp, tp->t_ticket);
+
+ tp->t_commit_lsn = cil->xc_ctx->sequence;
+ if (commit_lsn)
+ *commit_lsn = tp->t_commit_lsn;
+
+ xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
+ 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 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.
+ */
+ xfs_trans_free_items(tp, tp->t_commit_lsn, 0);
+
+ xlog_cil_push_background(log);
+
+ up_read(&cil->xc_ctx_lock);
+}
+
+/*
+ * 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_lsn(
+ struct xlog *log,
+ xfs_lsn_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);
+
+ /*
+ * 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);
+
+ /*
+ * 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_FORCED_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.
+ */
+ 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;
+}
+
+/*
+ * 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.
+ */
+bool
+xfs_log_item_in_current_chkpt(
+ struct xfs_log_item *lip)
+{
+ struct xfs_cil_ctx *ctx;
+
+ if (list_empty(&lip->li_cil))
+ return false;
+
+ ctx = lip->li_mountp->m_log->l_cilp->xc_ctx;
+
+ /*
+ * 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.
+ */
+ if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0)
+ return false;
+ return true;
+}
+
+/*
+ * 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_SLEEP|KM_MAYFAIL);
+ if (!cil)
+ return -ENOMEM;
+
+ ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
+ if (!ctx) {
+ kmem_free(cil);
+ return -ENOMEM;
+ }
+
+ INIT_WORK(&cil->xc_push_work, xlog_cil_push_work);
+ 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_rwsem(&cil->xc_ctx_lock);
+ init_waitqueue_head(&cil->xc_commit_wait);
+
+ INIT_LIST_HEAD(&ctx->committing);
+ INIT_LIST_HEAD(&ctx->busy_extents);
+ ctx->sequence = 1;
+ ctx->cil = cil;
+ cil->xc_ctx = ctx;
+ cil->xc_current_sequence = ctx->sequence;
+
+ cil->xc_log = log;
+ log->l_cilp = cil;
+ return 0;
+}
+
+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));
+ kmem_free(log->l_cilp);
+}
+
Code Review / kvmfornfv.git / blobdiff