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authorDave Chinner <david@fromorbit.com>2014-03-13 19:12:13 +1100
committerDave Chinner <david@fromorbit.com>2014-03-13 19:12:13 +1100
commit730357a5cb72d9754a396a350653ff98a9e44783 (patch)
tree8d97cc0f756e803c8c2f991cab8f1ba00d6dbbe4 /fs/xfs/xfs_log_cil.c
parentb6db0551fddfc8826bc07fc99d64d830530b2d77 (diff)
parent93a8614e3a4dccd526aca34e892ac0b27f64b506 (diff)
downloadlinux-730357a5cb72d9754a396a350653ff98a9e44783.tar.bz2
Merge branch 'xfs-stack-fixes' into for-next
Diffstat (limited to 'fs/xfs/xfs_log_cil.c')
-rw-r--r--fs/xfs/xfs_log_cil.c52
1 files changed, 39 insertions, 13 deletions
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index b57a8e08b3d1..7e5455391176 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -499,13 +499,6 @@ xlog_cil_push(
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,
* though - we need to synchronise with previous and future commits so
@@ -523,8 +516,15 @@ xlog_cil_push(
* 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;
list_add(&ctx->committing, &cil->xc_committing);
spin_unlock(&cil->xc_push_lock);
up_write(&cil->xc_ctx_lock);
@@ -662,8 +662,14 @@ xlog_cil_push_background(
}
+/*
+ * 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_foreground(
+xlog_cil_push_now(
struct xlog *log,
xfs_lsn_t push_seq)
{
@@ -688,10 +694,8 @@ xlog_cil_push_foreground(
}
cil->xc_push_seq = push_seq;
+ queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
spin_unlock(&cil->xc_push_lock);
-
- /* do the push now */
- xlog_cil_push(log);
}
bool
@@ -795,7 +799,8 @@ xlog_cil_force_lsn(
* xlog_cil_push() handles racing pushes for the same sequence,
* so no need to deal with it here.
*/
- xlog_cil_push_foreground(log, sequence);
+restart:
+ xlog_cil_push_now(log, sequence);
/*
* See if we can find a previous sequence still committing.
@@ -803,7 +808,6 @@ xlog_cil_force_lsn(
* before allowing the force of push_seq to go ahead. Hence block
* on commits for those as well.
*/
-restart:
spin_lock(&cil->xc_push_lock);
list_for_each_entry(ctx, &cil->xc_committing, committing) {
if (ctx->sequence > sequence)
@@ -821,6 +825,28 @@ restart:
/* 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.
+ *
+ * When the push occurs, it will empty the CIL and
+ * atomically increment the currect sequence past the push sequence and
+ * move it into the committing list. Of course, if the CIL is clean at
+ * the time of the push, it won't have pushed the CIL at all, so in that
+ * case we should try the push for this sequence again from the start
+ * just in case.
+ */
+
+ 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;
}