[PATCH 1/6] quota: Propagate error from ->acquire_dquot()

[Jan Kara <jack@suse.com>]

From: Jan Kara <jack@suse.cz>

Currently when some error happened in ->acquire_dquot(), dqget() just
returned NULL. That was indistinguishable from a case when e.g. someone
run quotaoff and so was generally silently ignored. However
->acquire_dquot() can fail because of ENOSPC or EIO in which case user
should better know. So propagate error up from ->acquire_dquot properly.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/file.c          |  8 ++---
 fs/ocfs2/quota_local.c   |  4 +--
 fs/quota/dquot.c         | 88 ++++++++++++++++++++++++++++++++++--------------
 include/linux/quotaops.h |  2 +-
 4 files changed, 70 insertions(+), 32 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 719f7f4c7a37..4d9e8275ed99 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1209,8 +1209,8 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
 		    && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
 		    OCFS2_FEATURE_RO_COMPAT_USRQUOTA)) {
 			transfer_to[USRQUOTA] = dqget(sb, make_kqid_uid(attr->ia_uid));
-			if (!transfer_to[USRQUOTA]) {
-				status = -ESRCH;
+			if (IS_ERR(transfer_to[USRQUOTA])) {
+				status = PTR_ERR(transfer_to[USRQUOTA]);
 				goto bail_unlock;
 			}
 		}
@@ -1218,8 +1218,8 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
 		    && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
 		    OCFS2_FEATURE_RO_COMPAT_GRPQUOTA)) {
 			transfer_to[GRPQUOTA] = dqget(sb, make_kqid_gid(attr->ia_gid));
-			if (!transfer_to[GRPQUOTA]) {
-				status = -ESRCH;
+			if (IS_ERR(transfer_to[GRPQUOTA])) {
+				status = PTR_ERR(transfer_to[GRPQUOTA]);
 				goto bail_unlock;
 			}
 		}
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index 3d0b63d34225..bb07004df72a 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -499,8 +499,8 @@ static int ocfs2_recover_local_quota_file(struct inode *lqinode,
 			dquot = dqget(sb,
 				      make_kqid(&init_user_ns, type,
 						le64_to_cpu(dqblk->dqb_id)));
-			if (!dquot) {
-				status = -EIO;
+			if (IS_ERR(dquot)) {
+				status = PTR_ERR(dquot);
 				mlog(ML_ERROR, "Failed to get quota structure "
 				     "for id %u, type %d. Cannot finish quota "
 				     "file recovery.\n",
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 20d1f74561cf..e9354c2ae0b0 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -247,7 +247,7 @@ struct dqstats dqstats;
 EXPORT_SYMBOL(dqstats);
 
 static qsize_t inode_get_rsv_space(struct inode *inode);
-static void __dquot_initialize(struct inode *inode, int type);
+static int __dquot_initialize(struct inode *inode, int type);
 
 static inline unsigned int
 hashfn(const struct super_block *sb, struct kqid qid)
@@ -832,16 +832,17 @@ static struct dquot *get_empty_dquot(struct super_block *sb, int type)
 struct dquot *dqget(struct super_block *sb, struct kqid qid)
 {
 	unsigned int hashent = hashfn(sb, qid);
-	struct dquot *dquot = NULL, *empty = NULL;
+	struct dquot *dquot, *empty = NULL;
 
         if (!sb_has_quota_active(sb, qid.type))
-		return NULL;
+		return ERR_PTR(-ESRCH);
 we_slept:
 	spin_lock(&dq_list_lock);
 	spin_lock(&dq_state_lock);
 	if (!sb_has_quota_active(sb, qid.type)) {
 		spin_unlock(&dq_state_lock);
 		spin_unlock(&dq_list_lock);
+		dquot = ERR_PTR(-ESRCH);
 		goto out;
 	}
 	spin_unlock(&dq_state_lock);
@@ -876,11 +877,15 @@ we_slept:
 	 * already finished or it will be canceled due to dq_count > 1 test */
 	wait_on_dquot(dquot);
 	/* Read the dquot / allocate space in quota file */
-	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) &&
-	    sb->dq_op->acquire_dquot(dquot) < 0) {
-		dqput(dquot);
-		dquot = NULL;
-		goto out;
+	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
+		int err;
+
+		err = sb->dq_op->acquire_dquot(dquot);
+		if (err < 0) {
+			dqput(dquot);
+			dquot = ERR_PTR(err);
+			goto out;
+		}
 	}
 #ifdef CONFIG_QUOTA_DEBUG
 	BUG_ON(!dquot->dq_sb);	/* Has somebody invalidated entry under us? */
@@ -1390,15 +1395,16 @@ static int dquot_active(const struct inode *inode)
  * It is better to call this function outside of any transaction as it
  * might need a lot of space in journal for dquot structure allocation.
  */
-static void __dquot_initialize(struct inode *inode, int type)
+static int __dquot_initialize(struct inode *inode, int type)
 {
 	int cnt, init_needed = 0;
 	struct dquot **dquots, *got[MAXQUOTAS];
 	struct super_block *sb = inode->i_sb;
 	qsize_t rsv;
+	int ret = 0;
 
 	if (!dquot_active(inode))
-		return;
+		return 0;
 
 	dquots = i_dquot(inode);
 
@@ -1407,6 +1413,7 @@ static void __dquot_initialize(struct inode *inode, int type)
 		struct kqid qid;
 		kprojid_t projid;
 		int rc;
+		struct dquot *dquot;
 
 		got[cnt] = NULL;
 		if (type != -1 && cnt != type)
@@ -1438,16 +1445,25 @@ static void __dquot_initialize(struct inode *inode, int type)
 			qid = make_kqid_projid(projid);
 			break;
 		}
-		got[cnt] = dqget(sb, qid);
+		dquot = dqget(sb, qid);
+		if (IS_ERR(dquot)) {
+			/* We raced with somebody turning quotas off... */
+			if (PTR_ERR(dquot) != -ESRCH) {
+				ret = PTR_ERR(dquot);
+				goto out_put;
+			}
+			dquot = NULL;
+		}
+		got[cnt] = dquot;
 	}
 
 	/* All required i_dquot has been initialized */
 	if (!init_needed)
-		return;
+		return 0;
 
 	spin_lock(&dq_data_lock);
 	if (IS_NOQUOTA(inode))
-		goto out_err;
+		goto out_lock;
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		if (type != -1 && cnt != type)
 			continue;
@@ -1469,15 +1485,18 @@ static void __dquot_initialize(struct inode *inode, int type)
 				dquot_resv_space(dquots[cnt], rsv);
 		}
 	}
-out_err:
+out_lock:
 	spin_unlock(&dq_data_lock);
+out_put:
 	/* Drop unused references */
 	dqput_all(got);
+
+	return ret;
 }
 
-void dquot_initialize(struct inode *inode)
+int dquot_initialize(struct inode *inode)
 {
-	__dquot_initialize(inode, -1);
+	return __dquot_initialize(inode, -1);
 }
 EXPORT_SYMBOL(dquot_initialize);
 
@@ -1961,18 +1980,37 @@ EXPORT_SYMBOL(__dquot_transfer);
 int dquot_transfer(struct inode *inode, struct iattr *iattr)
 {
 	struct dquot *transfer_to[MAXQUOTAS] = {};
+	struct dquot *dquot;
 	struct super_block *sb = inode->i_sb;
 	int ret;
 
 	if (!dquot_active(inode))
 		return 0;
 
-	if (iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid))
-		transfer_to[USRQUOTA] = dqget(sb, make_kqid_uid(iattr->ia_uid));
-	if (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))
-		transfer_to[GRPQUOTA] = dqget(sb, make_kqid_gid(iattr->ia_gid));
-
+	if (iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)){
+		dquot = dqget(sb, make_kqid_uid(iattr->ia_uid));
+		if (IS_ERR(dquot)) {
+			if (PTR_ERR(dquot) != -ESRCH) {
+				ret = PTR_ERR(dquot);
+				goto out_put;
+			}
+			dquot = NULL;
+		}
+		transfer_to[USRQUOTA] = dquot;;
+	}
+	if (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid)){
+		dquot = dqget(sb, make_kqid_gid(iattr->ia_gid));
+		if (IS_ERR(dquot)) {
+			if (PTR_ERR(dquot) != -ESRCH) {
+				ret = PTR_ERR(dquot);
+				goto out_put;
+			}
+			dquot = NULL;
+		}
+		transfer_to[GRPQUOTA] = dquot;
+	}
 	ret = __dquot_transfer(inode, transfer_to);
+out_put:
 	dqput_all(transfer_to);
 	return ret;
 }
@@ -2518,8 +2556,8 @@ int dquot_get_dqblk(struct super_block *sb, struct kqid qid,
 	struct dquot *dquot;
 
 	dquot = dqget(sb, qid);
-	if (!dquot)
-		return -ESRCH;
+	if (IS_ERR(dquot))
+		return PTR_ERR(dquot);
 	do_get_dqblk(dquot, di);
 	dqput(dquot);
 
@@ -2631,8 +2669,8 @@ int dquot_set_dqblk(struct super_block *sb, struct kqid qid,
 	int rc;
 
 	dquot = dqget(sb, qid);
-	if (!dquot) {
-		rc = -ESRCH;
+	if (IS_ERR(dquot)) {
+		rc = PTR_ERR(dquot);
 		goto out;
 	}
 	rc = do_set_dqblk(dquot, di);
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 77ca6601ff25..06c9ea8971fb 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -43,7 +43,7 @@ void inode_claim_rsv_space(struct inode *inode, qsize_t number);
 void inode_sub_rsv_space(struct inode *inode, qsize_t number);
 void inode_reclaim_rsv_space(struct inode *inode, qsize_t number);
 
-void dquot_initialize(struct inode *inode);
+int dquot_initialize(struct inode *inode);
 void dquot_drop(struct inode *inode);
 struct dquot *dqget(struct super_block *sb, struct kqid qid);
 static inline struct dquot *dqgrab(struct dquot *dquot)
-- 
2.1.4