ocfs2: Fix ocfs2_read_quota_block() error handling.

ocfs2_bread() has become ocfs2_read_virt_blocks(), with a prototype to
match ocfs2_read_blocks().  The quota code, converting from
ocfs2_bread(), wraps the call to ocfs2_read_virt_blocks() in
ocfs2_read_quota_block().  Unfortunately, the prototype of
ocfs2_read_quota_block() matches the old prototype of ocfs2_bread().

The problem is that ocfs2_bread() returned the buffer head, and callers
assumed that a NULL pointer was indicative of error.  It wasn't.  This
is why ocfs2_bread() took an int*err argument as well.

The new prototype of ocfs2_read_virt_blocks() avoids this error handling
confusion.  Let's change ocfs2_read_quota_block() to match.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/dlmglue.c

@@ -3519,7 +3519,7 @@ static int ocfs2_refresh_qinfo(struct ocfs2_mem_dqinfo *oinfo)
 					    oinfo->dqi_gi.dqi_type);
 	struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
 	struct ocfs2_qinfo_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
-	struct buffer_head *bh;
+	struct buffer_head *bh = NULL;
 	struct ocfs2_global_disk_dqinfo *gdinfo;
 	int status = 0;
 
@@ -3532,8 +3532,8 @@ static int ocfs2_refresh_qinfo(struct ocfs2_mem_dqinfo *oinfo)
 		oinfo->dqi_gi.dqi_free_entry =
 					be32_to_cpu(lvb->lvb_free_entry);
 	} else {
-		bh = ocfs2_read_quota_block(oinfo->dqi_gqinode, 0, &status);
-		if (!bh) {
+		status = ocfs2_read_quota_block(oinfo->dqi_gqinode, 0, &bh);
+		if (status) {
 			mlog_errno(status);
 			goto bail;
 		}

fs/ocfs2/quota.h

@@ -107,8 +107,8 @@ static inline int ocfs2_global_release_dquot(struct dquot *dquot)
 
 int ocfs2_lock_global_qf(struct ocfs2_mem_dqinfo *oinfo, int ex);
 void ocfs2_unlock_global_qf(struct ocfs2_mem_dqinfo *oinfo, int ex);
-struct buffer_head *ocfs2_read_quota_block(struct inode *inode,
-					   int block, int *err);
+int ocfs2_read_quota_block(struct inode *inode, u64 v_block,
+			   struct buffer_head **bh);
 
 extern struct dquot_operations ocfs2_quota_operations;
 extern struct quota_format_type ocfs2_quota_format;

fs/ocfs2/quota_global.c

@@ -87,16 +87,21 @@ struct qtree_fmt_operations ocfs2_global_ops = {
 	.is_id = ocfs2_global_is_id,
 };
 
-struct buffer_head *ocfs2_read_quota_block(struct inode *inode,
-					   int block, int *err)
+int ocfs2_read_quota_block(struct inode *inode, u64 v_block,
+			   struct buffer_head **bh)
 {
-	struct buffer_head *tmp = NULL;
+	int rc = 0;
+	struct buffer_head *tmp = *bh;
 
-	*err = ocfs2_read_virt_blocks(inode, block, 1, &tmp, 0, NULL);
-	if (*err)
-		mlog_errno(*err);
+	rc = ocfs2_read_virt_blocks(inode, v_block, 1, &tmp, 0, NULL);
+	if (rc)
+		mlog_errno(rc);
+
+	/* If ocfs2_read_virt_blocks() got us a new bh, pass it up. */
+	if (!rc && !*bh)
+		*bh = tmp;
 
-	return tmp;
+	return rc;
 }
 
 static struct buffer_head *ocfs2_get_quota_block(struct inode *inode,
@@ -143,8 +148,9 @@ ssize_t ocfs2_quota_read(struct super_block *sb, int type, char *data,
 	toread = len;
 	while (toread > 0) {
 		tocopy = min((size_t)(sb->s_blocksize - offset), toread);
-		bh = ocfs2_read_quota_block(gqinode, blk, &err);
-		if (!bh) {
+		bh = NULL;
+		err = ocfs2_read_quota_block(gqinode, blk, &bh);
+		if (err) {
 			mlog_errno(err);
 			return err;
 		}
@@ -169,7 +175,7 @@ ssize_t ocfs2_quota_write(struct super_block *sb, int type,
 	int offset = off & (sb->s_blocksize - 1);
 	sector_t blk = off >> sb->s_blocksize_bits;
 	int err = 0, new = 0;
-	struct buffer_head *bh;
+	struct buffer_head *bh = NULL;
 	handle_t *handle = journal_current_handle();
 
 	if (!handle) {
@@ -200,8 +206,8 @@ ssize_t ocfs2_quota_write(struct super_block *sb, int type,
 	/* Not rewriting whole block? */
 	if ((offset || len < sb->s_blocksize - OCFS2_QBLK_RESERVED_SPACE) &&
 	    !new) {
-		bh = ocfs2_read_quota_block(gqinode, blk, &err);
-		if (!bh) {
+		err = ocfs2_read_quota_block(gqinode, blk, &bh);
+		if (err) {
 			mlog_errno(err);
 			return err;
 		}

fs/ocfs2/quota_local.c

@@ -139,15 +139,15 @@ static int ocfs2_local_check_quota_file(struct super_block *sb, int type)
 	unsigned int gversions[MAXQUOTAS] = OCFS2_GLOBAL_QVERSIONS;
 	unsigned int ino[MAXQUOTAS] = { USER_QUOTA_SYSTEM_INODE,
 					GROUP_QUOTA_SYSTEM_INODE };
-	struct buffer_head *bh;
+	struct buffer_head *bh = NULL;
 	struct inode *linode = sb_dqopt(sb)->files[type];
 	struct inode *ginode = NULL;
 	struct ocfs2_disk_dqheader *dqhead;
 	int status, ret = 0;
 
 	/* First check whether we understand local quota file */
-	bh = ocfs2_read_quota_block(linode, 0, &status);
-	if (!bh) {
+	status = ocfs2_read_quota_block(linode, 0, &bh);
+	if (status) {
 		mlog_errno(status);
 		mlog(ML_ERROR, "failed to read quota file header (type=%d)\n",
 			type);
@@ -178,8 +178,8 @@ static int ocfs2_local_check_quota_file(struct super_block *sb, int type)
 		goto out_err;
 	}
 	/* Since the header is read only, we don't care about locking */
-	bh = ocfs2_read_quota_block(ginode, 0, &status);
-	if (!bh) {
+	status = ocfs2_read_quota_block(ginode, 0, &bh);
+	if (status) {
 		mlog_errno(status);
 		mlog(ML_ERROR, "failed to read global quota file header "
 				"(type=%d)\n", type);
@@ -235,10 +235,11 @@ static int ocfs2_load_local_quota_bitmaps(struct inode *inode,
 			return -ENOMEM;
 		}
 		newchunk->qc_num = i;
-		newchunk->qc_headerbh = ocfs2_read_quota_block(inode,
+		newchunk->qc_headerbh = NULL;
+		status = ocfs2_read_quota_block(inode,
 				ol_quota_chunk_block(inode->i_sb, i),
-				&status);
-		if (!newchunk->qc_headerbh) {
+				&newchunk->qc_headerbh);
+		if (status) {
 			mlog_errno(status);
 			kmem_cache_free(ocfs2_qf_chunk_cachep, newchunk);
 			ocfs2_release_local_quota_bitmaps(head);
@@ -320,10 +321,11 @@ static int ocfs2_recovery_load_quota(struct inode *lqinode,
 	int status = 0;
 
 	for (i = 0; i < chunks; i++) {
-		hbh = ocfs2_read_quota_block(lqinode,
+		hbh = NULL;
+		status = ocfs2_read_quota_block(lqinode,
 						ol_quota_chunk_block(sb, i),
-					     &status);
-		if (!hbh) {
+						&hbh);
+		if (status) {
 			mlog_errno(status);
 			break;
 		}
@@ -392,8 +394,9 @@ struct ocfs2_quota_recovery *ocfs2_begin_quota_recovery(
 			goto out_put;
 		}
 		/* Now read local header */
-		bh = ocfs2_read_quota_block(lqinode, 0, &status);
-		if (!bh) {
+		bh = NULL;
+		status = ocfs2_read_quota_block(lqinode, 0, &bh);
+		if (status) {
 			mlog_errno(status);
 			mlog(ML_ERROR, "failed to read quota file info header "
 				"(slot=%d type=%d)\n", slot_num, type);
@@ -447,19 +450,21 @@ static int ocfs2_recover_local_quota_file(struct inode *lqinode,
 
 	list_for_each_entry_safe(rchunk, next, &(rec->r_list[type]), rc_list) {
 		chunk = rchunk->rc_chunk;
-		hbh = ocfs2_read_quota_block(lqinode,
+		hbh = NULL;
+		status = ocfs2_read_quota_block(lqinode,
 						ol_quota_chunk_block(sb, chunk),
-					     &status);
-		if (!hbh) {
+						&hbh);
+		if (status) {
 			mlog_errno(status);
 			break;
 		}
 		dchunk = (struct ocfs2_local_disk_chunk *)hbh->b_data;
 		for_each_bit(bit, rchunk->rc_bitmap, ol_chunk_entries(sb)) {
-			qbh = ocfs2_read_quota_block(lqinode,
+			qbh = NULL;
+			status = ocfs2_read_quota_block(lqinode,
 						ol_dqblk_block(sb, chunk, bit),
-						&status);
-			if (!qbh) {
+						&qbh);
+			if (status) {
 				mlog_errno(status);
 				break;
 			}
@@ -581,8 +586,9 @@ int ocfs2_finish_quota_recovery(struct ocfs2_super *osb,
 			goto out_put;
 		}
 		/* Now read local header */
-		bh = ocfs2_read_quota_block(lqinode, 0, &status);
-		if (!bh) {
+		bh = NULL;
+		status = ocfs2_read_quota_block(lqinode, 0, &bh);
+		if (status) {
 			mlog_errno(status);
 			mlog(ML_ERROR, "failed to read quota file info header "
 				"(slot=%d type=%d)\n", slot_num, type);
@@ -676,8 +682,8 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
 	locked = 1;
 
 	/* Now read local header */
-	bh = ocfs2_read_quota_block(lqinode, 0, &status);
-	if (!bh) {
+	status = ocfs2_read_quota_block(lqinode, 0, &bh);
+	if (status) {
 		mlog_errno(status);
 		mlog(ML_ERROR, "failed to read quota file info header "
 			"(type=%d)\n", type);
@@ -850,13 +856,13 @@ static int ocfs2_local_write_dquot(struct dquot *dquot)
 {
 	struct super_block *sb = dquot->dq_sb;
 	struct ocfs2_dquot *od = OCFS2_DQUOT(dquot);
-	struct buffer_head *bh;
+	struct buffer_head *bh = NULL;
 	int status;
 
-	bh = ocfs2_read_quota_block(sb_dqopt(sb)->files[dquot->dq_type],
+	status = ocfs2_read_quota_block(sb_dqopt(sb)->files[dquot->dq_type],
 				    ol_dqblk_file_block(sb, od->dq_local_off),
-				    &status);
-	if (!bh) {
+				    &bh);
+	if (status) {
 		mlog_errno(status);
 		goto out;
 	}