gfs2: Clean up on-stack transactions

Replace the TR_ALLOCED flag by its inverse, TR_ONSTACK: that way, the flag only
needs to be set in the exceptional case of on-stack transactions.  Split off
__gfs2_trans_begin from gfs2_trans_begin and use it to replace the open-coded
version in gfs2_ail_empty_gl.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/glops.c

@@ -86,16 +86,12 @@ static int gfs2_ail_empty_gl(struct gfs2_glock *gl)
 {
 	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 	struct gfs2_trans tr;
+	unsigned int revokes;
 	int ret;
 
-	memset(&tr, 0, sizeof(tr));
-	INIT_LIST_HEAD(&tr.tr_buf);
-	INIT_LIST_HEAD(&tr.tr_databuf);
-	INIT_LIST_HEAD(&tr.tr_ail1_list);
-	INIT_LIST_HEAD(&tr.tr_ail2_list);
-	tr.tr_revokes = atomic_read(&gl->gl_ail_count);
+	revokes = atomic_read(&gl->gl_ail_count);
 
-	if (!tr.tr_revokes) {
+	if (!revokes) {
 		bool have_revokes;
 		bool log_in_flight;
 
@@ -122,23 +118,14 @@ static int gfs2_ail_empty_gl(struct gfs2_glock *gl)
 		return 0;
 	}
 
-	/* A shortened, inline version of gfs2_trans_begin()
-         * tr->alloced is not set since the transaction structure is
-         * on the stack */
-	tr.tr_reserved = 1 + gfs2_struct2blk(sdp, tr.tr_revokes);
-	tr.tr_ip = _RET_IP_;
-	sb_start_intwrite(sdp->sd_vfs);
-	ret = gfs2_log_reserve(sdp, tr.tr_reserved);
-	if (ret < 0) {
-		sb_end_intwrite(sdp->sd_vfs);
-		return ret;
-	}
-	WARN_ON_ONCE(current->journal_info);
-	current->journal_info = &tr;
-
-	__gfs2_ail_flush(gl, 0, tr.tr_revokes);
-
+	memset(&tr, 0, sizeof(tr));
+	set_bit(TR_ONSTACK, &tr.tr_flags);
+	ret = __gfs2_trans_begin(&tr, sdp, 0, revokes, _RET_IP_);
+	if (ret)
+		goto flush;
+	__gfs2_ail_flush(gl, 0, revokes);
 	gfs2_trans_end(sdp);
+
 flush:
 	gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
 		       GFS2_LFC_AIL_EMPTY_GL);

fs/gfs2/incore.h

@@ -490,7 +490,7 @@ struct gfs2_quota_data {
 enum {
 	TR_TOUCHED = 1,
 	TR_ATTACHED = 2,
-	TR_ALLOCED = 3,
+	TR_ONSTACK = 3,
 };
 
 struct gfs2_trans {

fs/gfs2/log.c

@@ -1114,7 +1114,7 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 	if (sdp->sd_log_tr) {
 		gfs2_merge_trans(sdp, tr);
 	} else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) {
-		gfs2_assert_withdraw(sdp, test_bit(TR_ALLOCED, &tr->tr_flags));
+		gfs2_assert_withdraw(sdp, !test_bit(TR_ONSTACK, &tr->tr_flags));
 		sdp->sd_log_tr = tr;
 		set_bit(TR_ATTACHED, &tr->tr_flags);
 	}

fs/gfs2/trans.c

@@ -37,10 +37,10 @@ static void gfs2_print_trans(struct gfs2_sbd *sdp, const struct gfs2_trans *tr)
 		tr->tr_num_revoke, tr->tr_num_revoke_rm);
 }
 
-int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
-		     unsigned int revokes)
+int __gfs2_trans_begin(struct gfs2_trans *tr, struct gfs2_sbd *sdp,
+		       unsigned int blocks, unsigned int revokes,
+		       unsigned long ip)
 {
-	struct gfs2_trans *tr;
 	int error;
 
 	if (current->journal_info) {
@@ -52,15 +52,10 @@ int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
 	if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
 		return -EROFS;
 
-	tr = kmem_cache_zalloc(gfs2_trans_cachep, GFP_NOFS);
-	if (!tr)
-		return -ENOMEM;
-
-	tr->tr_ip = _RET_IP_;
+	tr->tr_ip = ip;
 	tr->tr_blocks = blocks;
 	tr->tr_revokes = revokes;
 	tr->tr_reserved = 1;
-	set_bit(TR_ALLOCED, &tr->tr_flags);
 	if (blocks)
 		tr->tr_reserved += 6 + blocks;
 	if (revokes)
@@ -74,17 +69,28 @@ int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
 	sb_start_intwrite(sdp->sd_vfs);
 
 	error = gfs2_log_reserve(sdp, tr->tr_reserved);
-	if (error)
-		goto fail;
+	if (error) {
+		sb_end_intwrite(sdp->sd_vfs);
+		return error;
+	}
 
 	current->journal_info = tr;
 
 	return 0;
+}
 
-fail:
-	sb_end_intwrite(sdp->sd_vfs);
-	kmem_cache_free(gfs2_trans_cachep, tr);
+int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
+		     unsigned int revokes)
+{
+	struct gfs2_trans *tr;
+	int error;
 
+	tr = kmem_cache_zalloc(gfs2_trans_cachep, GFP_NOFS);
+	if (!tr)
+		return -ENOMEM;
+	error = __gfs2_trans_begin(tr, sdp, blocks, revokes, _RET_IP_);
+	if (error)
+		kmem_cache_free(gfs2_trans_cachep, tr);
 	return error;
 }
 
@@ -92,13 +98,12 @@ void gfs2_trans_end(struct gfs2_sbd *sdp)
 {
 	struct gfs2_trans *tr = current->journal_info;
 	s64 nbuf;
-	int alloced = test_bit(TR_ALLOCED, &tr->tr_flags);
 
 	current->journal_info = NULL;
 
 	if (!test_bit(TR_TOUCHED, &tr->tr_flags)) {
 		gfs2_log_release(sdp, tr->tr_reserved);
-		if (alloced)
+		if (!test_bit(TR_ONSTACK, &tr->tr_flags))
 			gfs2_trans_free(sdp, tr);
 		sb_end_intwrite(sdp->sd_vfs);
 		return;
@@ -113,7 +118,8 @@ void gfs2_trans_end(struct gfs2_sbd *sdp)
 		gfs2_print_trans(sdp, tr);
 
 	gfs2_log_commit(sdp, tr);
-	if (alloced && !test_bit(TR_ATTACHED, &tr->tr_flags))
+	if (!test_bit(TR_ONSTACK, &tr->tr_flags) &&
+	    !test_bit(TR_ATTACHED, &tr->tr_flags))
 		gfs2_trans_free(sdp, tr);
 	up_read(&sdp->sd_log_flush_lock);
 

fs/gfs2/trans.h

@@ -34,6 +34,9 @@ static inline unsigned int gfs2_rg_blocks(const struct gfs2_inode *ip, unsigned
 	return rgd->rd_length;
 }
 
+extern int __gfs2_trans_begin(struct gfs2_trans *tr, struct gfs2_sbd *sdp,
+			      unsigned int blocks, unsigned int revokes,
+			      unsigned long ip);
 extern int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
 			    unsigned int revokes);