[PATCH 5/5] quota: handle IO errors in dquot_transfer()

[Dmitry Monakhov <dmonakhov@openvz.org>]

transfer_to[cnt] = dqget() may returns NULL due to IO error.
But NULL value in transfer_to[cnt] means a dquot transfer
optimization. So after operation succeed inode will have new
i_uid or i_gid but accounted to old dquot. This behaviour
is differ from dquot_initialize(). Let's handle IO error from
dqget() equally in all functions.

In appliance to dquot_transfer() this means that we have to finish
operation regardless to IO errors from dqget().

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 fs/quota/dquot.c |   46 +++++++++++++++++++++++++++-------------------
 1 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index d6d535c..fbbaa4e 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1733,27 +1733,29 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
 	struct dquot *transfer_from[MAXQUOTAS];
 	struct dquot *transfer_to[MAXQUOTAS];
 	int cnt, ret = QUOTA_OK;
-	int chuid = iattr->ia_valid & ATTR_UID && inode->i_uid != iattr->ia_uid,
-	    chgid = iattr->ia_valid & ATTR_GID && inode->i_gid != iattr->ia_gid;
 	char warntype_to[MAXQUOTAS];
 	char warntype_from_inodes[MAXQUOTAS], warntype_from_space[MAXQUOTAS];
+	char valid[MAXQUOTAS];
 
 	/* First test before acquiring mutex - solves deadlocks when we
          * re-enter the quota code and are already holding the mutex */
 	if (IS_NOQUOTA(inode))
 		return QUOTA_OK;
 	/* Initialize the arrays */
+	memset(transfer_to, 0, sizeof(transfer_to));
+	memset(transfer_from, 0, sizeof(transfer_from));
+	memset(valid, 0, sizeof(valid));
+	valid[USRQUOTA] = iattr->ia_valid & ATTR_UID &&
+		inode->i_uid != iattr->ia_uid,
+	valid[GRPQUOTA] = iattr->ia_valid & ATTR_GID &&
+		inode->i_gid != iattr->ia_gid;
+
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
-		transfer_from[cnt] = NULL;
-		transfer_to[cnt] = NULL;
 		warntype_to[cnt] = QUOTA_NL_NOWARN;
+		if (!valid[cnt])
+			continue;
+		transfer_to[cnt] = dqget(inode->i_sb, iattr->ia_uid, cnt);
 	}
-	if (chuid)
-		transfer_to[USRQUOTA] = dqget(inode->i_sb, iattr->ia_uid,
-					      USRQUOTA);
-	if (chgid)
-		transfer_to[GRPQUOTA] = dqget(inode->i_sb, iattr->ia_gid,
-					      GRPQUOTA);
 
 	down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
 	/* Now recheck reliably when holding dqptr_sem */
@@ -1767,9 +1769,11 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
 	space = cur_space + rsv_space;
 	/* Build the transfer_from list and check the limits */
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
-		if (!transfer_to[cnt])
+		if (!valid[cnt])
 			continue;
 		transfer_from[cnt] = inode->i_dquot[cnt];
+		if (!transfer_to[cnt])
+			continue;
 		if (check_idq(transfer_to[cnt], 1, warntype_to + cnt) ==
 		    NO_QUOTA || check_bdq(transfer_to[cnt], space, 0,
 		    warntype_to + cnt) == NO_QUOTA)
@@ -1783,10 +1787,15 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
 		/*
 		 * Skip changes for same uid or gid or for turned off quota-type.
 		 */
-		if (!transfer_to[cnt])
+		if (!valid[cnt])
 			continue;
+		/*
+		 * Due to IO error we might not have transfer_to[] or
+		 * transfer_from[] structure. Nor than less the operation must
+		 * being done regardless quota io errors.
+		 */
+		inode->i_dquot[cnt] = transfer_to[cnt];
 
-		/* Due to IO error we might not have transfer_from[] structure */
 		if (transfer_from[cnt]) {
 			warntype_from_inodes[cnt] =
 				info_idq_free(transfer_from[cnt], 1);
@@ -1797,12 +1806,11 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
 			dquot_free_reserved_space(transfer_from[cnt],
 						  rsv_space);
 		}
-
-		dquot_incr_inodes(transfer_to[cnt], 1);
-		dquot_incr_space(transfer_to[cnt], cur_space);
-		dquot_resv_space(transfer_to[cnt], rsv_space);
-
-		inode->i_dquot[cnt] = transfer_to[cnt];
+		if (transfer_to[cnt]) {
+			dquot_incr_inodes(transfer_to[cnt], 1);
+			dquot_incr_space(transfer_to[cnt], cur_space);
+			dquot_resv_space(transfer_to[cnt], rsv_space);
+		}
 	}
 	spin_unlock(&dq_data_lock);
 	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
-- 
1.6.0.4