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Subject[PATCH 14/56] quota: Allow negative usage of space and inodes
Date
From: Jan Kara <jack@suse.cz>

For clustered filesystems, it can happen that space / inode usage goes
negative temporarily (because some node is allocating another node
is freeing and they are not completely in sync). So let quota code
allow this and change qsize_t so a signed type so that we don't
underflow the variables.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
---
fs/dquot.c | 6 ++++--
include/linux/quota.h | 3 ++-
2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/dquot.c b/fs/dquot.c
index f4d6f7e..cf0dac7 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -847,7 +847,8 @@ static inline void dquot_incr_space(struct dquot *dquot, qsize_t number)

static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number)
{
- if (dquot->dq_dqb.dqb_curinodes > number)
+ if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
+ dquot->dq_dqb.dqb_curinodes >= number)
dquot->dq_dqb.dqb_curinodes -= number;
else
dquot->dq_dqb.dqb_curinodes = 0;
@@ -858,7 +859,8 @@ static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number)

static inline void dquot_decr_space(struct dquot *dquot, qsize_t number)
{
- if (dquot->dq_dqb.dqb_curspace > number)
+ if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
+ dquot->dq_dqb.dqb_curspace >= number)
dquot->dq_dqb.dqb_curspace -= number;
else
dquot->dq_dqb.dqb_curspace = 0;
diff --git a/include/linux/quota.h b/include/linux/quota.h
index e51dfdc..75bf761 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -168,7 +168,7 @@ enum {
#include <asm/atomic.h>

typedef __kernel_uid32_t qid_t; /* Type in which we store ids in memory */
-typedef __u64 qsize_t; /* Type in which we store sizes */
+typedef long long qsize_t; /* Type in which we store sizes */

extern spinlock_t dq_data_lock;

@@ -336,6 +336,7 @@ enum {
* responsible for setting
* S_NOQUOTA, S_NOATIME flags
*/
+#define DQUOT_NEGATIVE_USAGE (1 << 7) /* Allow negative quota usage */

static inline unsigned int dquot_state_flag(unsigned int flags, int type)
{
--
1.5.6


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