Consistency between mem_info and dq_dqb is weak because we just copy
data from dqi_{bi}grace to dqb_{bi}time. So we protect dqb_{bi}time from
races with quota_ctl call.
Nothing actually happens if we relax this consistency requirement.
Since dqi_{bi}grace is (int) it is possible read it atomically without lock.
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
---
fs/quota/dquot.c | 16 ----------------
include/linux/quota.h | 2 ++
2 files changed, 2 insertions(+), 16 deletions(-)
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 794c486..33dc32e 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1668,7 +1668,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
warntype[cnt] = QUOTA_NL_NOWARN;
- spin_lock(&dqopts(inode->i_sb)->dq_data_lock);
lock_inode_dquots(inode->i_dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!inode->i_dquot[cnt])
@@ -1677,7 +1676,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
warntype + cnt);
if (ret && !nofail) {
unlock_inode_dquots(inode->i_dquot);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
goto out_flush_warn;
}
}
@@ -1691,7 +1689,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
}
inode_incr_space(inode, number, reserve);
unlock_inode_dquots(inode->i_dquot);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
if (reserve)
goto out_flush_warn;
@@ -1726,7 +1723,6 @@ int dquot_alloc_inode(const struct inode *inode)
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
warntype[cnt] = QUOTA_NL_NOWARN;
down_read(&dqopts(inode->i_sb)->dqptr_sem);
- spin_lock(&dqopts(inode->i_sb)->dq_data_lock);
lock_inode_dquots(inode->i_dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!inode->i_dquot[cnt])
@@ -1744,7 +1740,6 @@ int dquot_alloc_inode(const struct inode *inode)
warn_put_all:
unlock_inode_dquots(inode->i_dquot);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
if (ret == 0)
mark_all_dquot_dirty(inode->i_dquot);
flush_warnings(inode->i_dquot, warntype);
@@ -1770,7 +1765,6 @@ int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
idx = srcu_read_lock(&dqopts(inode->i_sb)->dq_srcu);
rcu_read_unlock();
down_read(&dqopts(inode->i_sb)->dqptr_sem);
- spin_lock(&dqopts(inode->i_sb)->dq_data_lock);
lock_inode_dquots(inode->i_dquot);
/* Claim reserved quotas to allocated quotas */
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
@@ -1781,7 +1775,6 @@ int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
/* Update inode bytes */
inode_claim_rsv_space(inode, number);
unlock_inode_dquots(inode->i_dquot);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
mark_all_dquot_dirty(inode->i_dquot);
up_read(&dqopts(inode->i_sb)->dqptr_sem);
srcu_read_unlock(&dqopts(inode->i_sb)->dq_srcu, idx);
@@ -1810,7 +1803,6 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
idx = srcu_read_lock(&dqopts(inode->i_sb)->dq_srcu);
rcu_read_unlock();
down_read(&dqopts(inode->i_sb)->dqptr_sem);
- spin_lock(&dqopts(inode->i_sb)->dq_data_lock);
lock_inode_dquots(inode->i_dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!inode->i_dquot[cnt])
@@ -1823,7 +1815,6 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
}
inode_decr_space(inode, number, reserve);
unlock_inode_dquots(inode->i_dquot);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
if (reserve)
goto out_unlock;
@@ -1853,7 +1844,6 @@ void dquot_free_inode(const struct inode *inode)
idx = srcu_read_lock(&dqopts(inode->i_sb)->dq_srcu);
rcu_read_unlock();
down_read(&dqopts(inode->i_sb)->dqptr_sem);
- spin_lock(&dqopts(inode->i_sb)->dq_data_lock);
lock_inode_dquots(inode->i_dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!inode->i_dquot[cnt])
@@ -1862,7 +1852,6 @@ void dquot_free_inode(const struct inode *inode)
dquot_decr_inodes(inode->i_dquot[cnt], 1);
}
unlock_inode_dquots(inode->i_dquot);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
mark_all_dquot_dirty(inode->i_dquot);
flush_warnings(inode->i_dquot, warntype);
up_read(&dqopts(inode->i_sb)->dqptr_sem);
@@ -1909,7 +1898,6 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
srcu_read_unlock(&dqopts(inode->i_sb)->dq_srcu, idx);
return 0;
}
- spin_lock(&dqopts(inode->i_sb)->dq_data_lock);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
/*
* Skip changes for same uid or gid or for turned off quota-type.
@@ -1968,7 +1956,6 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
}
unlock_inode_dquots(transfer_to);
unlock_inode_dquots(transfer_from);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
up_write(&dqopts(inode->i_sb)->dqptr_sem);
srcu_read_unlock(&dqopts(inode->i_sb)->dq_srcu, idx);
mark_all_dquot_dirty(transfer_from);
@@ -1984,7 +1971,6 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
over_quota:
unlock_inode_dquots(transfer_to);
unlock_inode_dquots(transfer_from);
- spin_unlock(&dqopts(inode->i_sb)->dq_data_lock);
up_write(&dqopts(inode->i_sb)->dqptr_sem);
srcu_read_unlock(&dqopts(inode->i_sb)->dq_srcu, idx);
flush_warnings(transfer_to, warntype_to);
@@ -2596,7 +2582,6 @@ static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
(di->d_ino_hardlimit > dqi->dqi_maxilimit)))
return -ERANGE;
- spin_lock(&sb_dqopts(dquot)->dq_data_lock);
spin_lock(&dquot->dq_lock);
if (di->d_fieldmask & FS_DQ_BCOUNT) {
dm->dqb_curspace = di->d_bcount - dm->dqb_rsvspace;
@@ -2664,7 +2649,6 @@ static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
else
set_bit(DQ_FAKE_B, &dquot->dq_flags);
spin_unlock(&dquot->dq_lock);
- spin_unlock(&sb_dqopts(dquot)->dq_data_lock);
mark_dquot_dirty(dquot);
return 0;
diff --git a/include/linux/quota.h b/include/linux/quota.h
index c88a352..949347a 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -221,6 +221,8 @@ struct mem_dqinfo {
* quotas on after remount RW */
struct list_head dqi_dirty_list; /* List of dirty dquots */
unsigned long dqi_flags;
+ /* Readers are allowed to read following two variables without
+ ->dq_data_lock held */
unsigned int dqi_bgrace;
unsigned int dqi_igrace;
qsize_t dqi_maxblimit;
--
1.6.5.2
--
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