ctx->sequence = 1;
ctx->cil = cil;
cil->xc_ctx = ctx;
+ cil->xc_current_sequence = ctx->sequence;
cil->xc_log = log;
log->l_cilp = cil;
}
}
-/*
- * 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.
- *
- * For more specific information about the order of operations in
- * xfs_log_commit_cil() please refer to the comments in
- * xfs_trans_commit_iclog().
- *
- * 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.
- */
-int
-xfs_log_commit_cil(
- struct xfs_mount *mp,
- struct xfs_trans *tp,
- struct xfs_log_vec *log_vector,
- xfs_lsn_t *commit_lsn,
- int flags)
-{
- struct log *log = mp->m_log;
- int log_flags = 0;
- int push = 0;
-
- if (flags & XFS_TRANS_RELEASE_LOG_RES)
- log_flags = XFS_LOG_REL_PERM_RESERV;
-
- if (XLOG_FORCED_SHUTDOWN(log)) {
- xlog_cil_free_logvec(log_vector);
- return XFS_ERROR(EIO);
- }
-
- /* lock out background commit */
- down_read(&log->l_cilp->xc_ctx_lock);
- xlog_cil_format_items(log, log_vector, tp->t_ticket, commit_lsn);
-
- /* check we didn't blow the reservation */
- if (tp->t_ticket->t_curr_res < 0)
- xlog_print_tic_res(log->l_mp, tp->t_ticket);
-
- /* attach the transaction to the CIL if it has any busy extents */
- if (!list_empty(&tp->t_busy)) {
- spin_lock(&log->l_cilp->xc_cil_lock);
- list_splice_init(&tp->t_busy,
- &log->l_cilp->xc_ctx->busy_extents);
- spin_unlock(&log->l_cilp->xc_cil_lock);
- }
-
- tp->t_commit_lsn = *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, *commit_lsn, 0);
-
- /* check for background commit before unlock */
- if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
- push = 1;
-
- up_read(&log->l_cilp->xc_ctx_lock);
-
- /*
- * 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 in most cases.
- */
- if (push)
- xlog_cil_push(log, 0);
- return 0;
-}
-
/*
* 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
}
/*
- * Push the Committed Item List to the log. If the push_now flag is not set,
- * then it is a background flush and so we can chose to ignore it.
+ * 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.
*/
-int
+STATIC int
xlog_cil_push(
struct log *log,
- int push_now)
+ xfs_lsn_t push_seq)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_log_vec *lv;
if (!cil)
return 0;
+ ASSERT(!push_seq || push_seq <= cil->xc_ctx->sequence);
+
new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
new_ctx->ticket = xlog_cil_ticket_alloc(log);
/* lock out transaction commit, but don't block on background push */
if (!down_write_trylock(&cil->xc_ctx_lock)) {
- if (!push_now)
+ if (!push_seq)
goto out_free_ticket;
down_write(&cil->xc_ctx_lock);
}
goto out_skip;
/* check for spurious background flush */
- if (!push_now && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
+ if (!push_seq && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
+ goto out_skip;
+
+ /* check for a previously pushed seqeunce */
+ if (push_seq < cil->xc_ctx->sequence)
goto out_skip;
/*
new_ctx->cil = cil;
cil->xc_ctx = new_ctx;
+ /*
+ * mirror the new sequence into the cil structure so that we can do
+ * unlocked checks against the current sequence in log forces without
+ * risking deferencing a freed context pointer.
+ */
+ cil->xc_current_sequence = new_ctx->sequence;
+
/*
* 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,
return XFS_ERROR(EIO);
}
+/*
+ * 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.
+ *
+ * For more specific information about the order of operations in
+ * xfs_log_commit_cil() please refer to the comments in
+ * xfs_trans_commit_iclog().
+ *
+ * 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.
+ */
+int
+xfs_log_commit_cil(
+ struct xfs_mount *mp,
+ struct xfs_trans *tp,
+ struct xfs_log_vec *log_vector,
+ xfs_lsn_t *commit_lsn,
+ int flags)
+{
+ struct log *log = mp->m_log;
+ int log_flags = 0;
+ int push = 0;
+
+ if (flags & XFS_TRANS_RELEASE_LOG_RES)
+ log_flags = XFS_LOG_REL_PERM_RESERV;
+
+ if (XLOG_FORCED_SHUTDOWN(log)) {
+ xlog_cil_free_logvec(log_vector);
+ return XFS_ERROR(EIO);
+ }
+
+ /* lock out background commit */
+ down_read(&log->l_cilp->xc_ctx_lock);
+ xlog_cil_format_items(log, log_vector, tp->t_ticket, commit_lsn);
+
+ /* check we didn't blow the reservation */
+ if (tp->t_ticket->t_curr_res < 0)
+ xlog_print_tic_res(log->l_mp, tp->t_ticket);
+
+ /* attach the transaction to the CIL if it has any busy extents */
+ if (!list_empty(&tp->t_busy)) {
+ spin_lock(&log->l_cilp->xc_cil_lock);
+ list_splice_init(&tp->t_busy,
+ &log->l_cilp->xc_ctx->busy_extents);
+ spin_unlock(&log->l_cilp->xc_cil_lock);
+ }
+
+ tp->t_commit_lsn = *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, *commit_lsn, 0);
+
+ /* check for background commit before unlock */
+ if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
+ push = 1;
+
+ up_read(&log->l_cilp->xc_ctx_lock);
+
+ /*
+ * 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 in most cases.
+ */
+ if (push)
+ xlog_cil_push(log, 0);
+ return 0;
+}
+
/*
* Conditionally push the CIL based on the sequence passed in.
*
* commit lsn is there. It'll be empty, so this is broken for now.
*/
xfs_lsn_t
-xlog_cil_push_lsn(
+xlog_cil_force_lsn(
struct log *log,
- xfs_lsn_t push_seq)
+ xfs_lsn_t sequence)
{
struct xfs_cil *cil = log->l_cilp;
struct xfs_cil_ctx *ctx;
xfs_lsn_t commit_lsn = NULLCOMMITLSN;
-restart:
- down_write(&cil->xc_ctx_lock);
- ASSERT(push_seq <= cil->xc_ctx->sequence);
-
- /* check to see if we need to force out the current context */
- if (push_seq == cil->xc_ctx->sequence) {
- up_write(&cil->xc_ctx_lock);
- xlog_cil_push(log, 1);
- goto restart;
- }
+ 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.
+ */
+ if (sequence == cil->xc_current_sequence)
+ xlog_cil_push(log, sequence);
/*
* See if we can find a previous sequence still committing.
- * We can drop the flush lock as soon as we have the cil lock
- * because we are now only comparing contexts protected by
- * the cil lock.
- *
* 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.
*/
+restart:
spin_lock(&cil->xc_cil_lock);
- up_write(&cil->xc_ctx_lock);
list_for_each_entry(ctx, &cil->xc_committing, committing) {
- if (ctx->sequence > push_seq)
+ if (ctx->sequence > sequence)
continue;
if (!ctx->commit_lsn) {
/*
sv_wait(&cil->xc_commit_wait, 0, &cil->xc_cil_lock, 0);
goto restart;
}
- if (ctx->sequence != push_seq)
+ if (ctx->sequence != sequence)
continue;
/* found it! */
commit_lsn = ctx->commit_lsn;
projects / users / dwmw2 / linux.git / commitdiff