Ocfs2 devel - Sep 2013 - [PATCH V3 RESENT] ocfs2: lighten up allocate transaction

Hi Andrew Morton,
   The patch "[patch 05/22] ocfs2: lighten up allocate transaction" in
mm tree
is not the newest one, please drop it from mm tree. This patch V3 is newest, 
please replace it. Thanks.

The issue scenario is as following:
When fallocating a very large disk space for a small file,
__ocfs2_extend_allocation attempts to get a very large transaction. 
For some journal sizes, there may be not enough room for this 
transaction, and the fallocate will fail.

The patch below extents & restarts the transaction as necessary while
allocating space, and should work with even the smallest journal.
This patch refers ext4 resize.

Test:
# mkfs.ocfs2 -b 4K -C 32K -T datafiles /dev/sdc
...(jounral size is 32M)
# mount.ocfs2 /dev/sdc /mnt/ocfs2/
# touch /mnt/ocfs2/1.log
# fallocate -o 0 -l 400G /mnt/ocfs2/1.log
fallocate: /mnt/ocfs2/1.log: fallocate failed: Cannot allocate memory
# tail -f /var/log/messages
[ 7372.278591] JBD: fallocate wants too many credits (2051 > 2048)
[ 7372.278597] (fallocate,6438,0):__ocfs2_extend_allocation:709 ERROR: status =
-12
[ 7372.278603] (fallocate,6438,0):ocfs2_allocate_unwritten_extents:1504 ERROR:
status = -12
[ 7372.278607] (fallocate,6438,0):__ocfs2_change_file_space:1955 ERROR: status =
-12
^C
With this patch, the test works well.

Compared with PATCH V2, this version is based on linux-3.11-rc2, 
and modified coding style.

Signed-off-by: Younger Liu <younger.liu at huawei.com>
Cc: Jie Liu <jeff.liu at oracle.com>
---
 fs/ocfs2/file.c        |    6 +-----
 fs/ocfs2/journal.c     |   35 +++++++++++++++++++++++++++++++++++
 fs/ocfs2/journal.h     |   11 +++++++++++
 fs/ocfs2/ocfs2_trace.h |    2 ++
 4 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 41000f2..833a09b 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -671,11 +671,7 @@ restarted_transaction:
 		} else {
 			BUG_ON(why != RESTART_TRANS);
 
-			/* TODO: This can be more intelligent. */
-			credits = ocfs2_calc_extend_credits(osb->sb,
-							    &fe->id2.i_list,
-							    clusters_to_add);
-			status = ocfs2_extend_trans(handle, credits);
+			status = ocfs2_allocate_extend_trans(handle, 1);
 			if (status < 0) {
 				/* handle still has to be committed at
 				 * this point. */
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 242170d..883eba3 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -455,6 +455,41 @@ bail:
 	return status;
 }
 
+/*
+ * If we have fewer than thresh credits, extend by OCFS2_MAX_TRANS_DATA.
+ * If that fails, restart the transaction & regain write access for the
+ * buffer head which is used for metadata modifications.
+ * Taken from Ext4: extend_or_restart_transaction()
+ */
+int ocfs2_allocate_extend_trans(handle_t *handle, int thresh)
+{
+	int status, old_nblks;
+
+	BUG_ON(!handle);
+
+	old_nblks = handle->h_buffer_credits;
+	trace_ocfs2_allocate_extend_trans(old_nblks, thresh);
+
+	if (old_nblks < thresh)
+		return 0;
+
+	status = jbd2_journal_extend(handle, OCFS2_MAX_TRANS_DATA);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	if (status > 0) {
+		status = jbd2_journal_restart(handle, OCFS2_MAX_TRANS_DATA);
+		if (status < 0)
+			mlog_errno(status);
+	}
+
+bail:
+	return status;
+}
+
+
 struct ocfs2_triggers {
 	struct jbd2_buffer_trigger_type	ot_triggers;
 	int				ot_offset;
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 96f9ac2..4ee41bb 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -258,6 +258,17 @@ handle_t		    *ocfs2_start_trans(struct ocfs2_super *osb,
 int			     ocfs2_commit_trans(struct ocfs2_super *osb,
 						handle_t *handle);
 int			     ocfs2_extend_trans(handle_t *handle, int nblocks);
+int			     ocfs2_allocate_extend_trans(handle_t *handle,
+						int thresh);
+
+/*
+ * Define an arbitrary limit for the amount of data we will anticipate
+ * writing to any given transaction.  For unbounded transactions such as
+ * fallocate(2) we can write more than this, but we always
+ * start off at the maximum transaction size and grow the transaction
+ * optimistically as we go.
+ */
+#define OCFS2_MAX_TRANS_DATA	64U
 
 /*
  * Create access is for when we get a newly created buffer and we're
diff --git a/fs/ocfs2/ocfs2_trace.h b/fs/ocfs2/ocfs2_trace.h
index 3b481f4..1b60c62 100644
--- a/fs/ocfs2/ocfs2_trace.h
+++ b/fs/ocfs2/ocfs2_trace.h
@@ -2579,6 +2579,8 @@ DEFINE_OCFS2_INT_INT_EVENT(ocfs2_extend_trans);
 
 DEFINE_OCFS2_INT_EVENT(ocfs2_extend_trans_restart);
 
+DEFINE_OCFS2_INT_INT_EVENT(ocfs2_allocate_extend_trans);
+
 DEFINE_OCFS2_ULL_ULL_UINT_UINT_EVENT(ocfs2_journal_access);
 
 DEFINE_OCFS2_ULL_EVENT(ocfs2_journal_dirty);
-- 1.7.9.7

On Tue, 3 Sep 2013 11:09:56 +0800 Younger Liu <younger.liu at huawei.com>
wrote:
>    The patch "[patch 05/22] ocfs2: lighten up allocate
transaction" in mm tree
> is not the newest one, please drop it from mm tree. This patch V3 is
newest,
> please replace it. Thanks.
Too late :(  Please send an update against current mainline?