In fact 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@xxxxxxxxx>
---
fs/quota/dquot.c | 28 ++++++++--------------------
1 files changed, 8 insertions(+), 20 deletions(-)
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index fc3b63a..0c9cf67 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1254,7 +1254,7 @@ static int ignore_hardlimit(struct dquot *dquot)
!(info->dqi_flags & V1_DQF_RSQUASH));
}
-/* needs dq_data_lock, ->dq_lock */
+/* needs ->dq_lock */
static int check_idq(struct dquot *dquot, qsize_t inodes, char *warntype)
{
qsize_t newinodes = dquot->dq_dqb.dqb_curinodes + inodes;
@@ -1284,6 +1284,7 @@ static int check_idq(struct dquot *dquot, qsize_t inodes, char *warntype)
newinodes > dquot->dq_dqb.dqb_isoftlimit &&
dquot->dq_dqb.dqb_itime == 0) {
*warntype = QUOTA_NL_ISOFTWARN;
+ /* It is ok to read dqi_bgrace without lock here */
dquot->dq_dqb.dqb_itime = get_seconds() +
dq_opt(dquot)->info[dquot->dq_type].dqi_igrace;
}
@@ -1291,7 +1292,7 @@ static int check_idq(struct dquot *dquot, qsize_t inodes, char *warntype)
return 0;
}
-/* needs dq_data_lock, ->dq_lock */
+/* needs ->dq_lock */
static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *warntype)
{
qsize_t tspace;
@@ -1328,6 +1329,7 @@ static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *war
dquot->dq_dqb.dqb_btime == 0) {
if (!prealloc) {
*warntype = QUOTA_NL_BSOFTWARN;
+ /* It is ok to read dqi_bgrace without lock here */
dquot->dq_dqb.dqb_btime = get_seconds() +
sb_dqopt(sb)->info[dquot->dq_type].dqi_bgrace;
}
@@ -1596,7 +1598,6 @@ 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(&sb_dqopt(inode->i_sb)->dq_data_lock);
inode_dquot_lock(inode, dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!dquot[cnt])
@@ -1604,7 +1605,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
ret = check_bdq(dquot[cnt], number, !warn, warntype+cnt);
if (ret && !nofail) {
dquot_unlock_all(dquot);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
goto out_flush_warn;
}
}
@@ -1618,7 +1618,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
}
inode_incr_space(inode, number, reserve);
dquot_unlock_all(dquot);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
if (reserve)
goto out_flush_warn;
@@ -1647,7 +1646,6 @@ int dquot_alloc_inode(const struct inode *inode)
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
warntype[cnt] = QUOTA_NL_NOWARN;
down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
- spin_lock(&sb_dqopt(inode->i_sb)->dq_data_lock);
inode_dquot_lock(inode, dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!dquot[cnt])
@@ -1665,7 +1663,6 @@ int dquot_alloc_inode(const struct inode *inode)
warn_put_all:
dquot_unlock_all(dquot);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
if (ret == 0)
mark_all_dquot_dirty(dquot);
flush_warnings(dquot, warntype);
@@ -1688,7 +1685,6 @@ int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
}
down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
- spin_lock(&sb_dqopt(inode->i_sb)->dq_data_lock);
inode_dquot_lock(inode, dquot);
/* Claim reserved quotas to allocated quotas */
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
@@ -1698,7 +1694,6 @@ int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
/* Update inode bytes */
inode_claim_rsv_space(inode, number);
dquot_unlock_all(dquot);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
mark_all_dquot_dirty(dquot);
up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
return 0;
@@ -1723,7 +1718,6 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
}
down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
- spin_lock(&sb_dqopt(inode->i_sb)->dq_data_lock);
inode_dquot_lock(inode, dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!dquot[cnt])
@@ -1736,7 +1730,6 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
}
inode_decr_space(inode, number, reserve);
dquot_unlock_all(dquot);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
if (reserve)
goto out_unlock;
@@ -1762,7 +1755,6 @@ void dquot_free_inode(const struct inode *inode)
return;
down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
- spin_lock(&sb_dqopt(inode->i_sb)->dq_data_lock);
inode_dquot_lock(inode, dquot);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (!dquot[cnt])
@@ -1771,7 +1763,6 @@ void dquot_free_inode(const struct inode *inode)
dquot_decr_inodes(dquot[cnt], 1);
}
dquot_unlock_all(dquot);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
mark_all_dquot_dirty(dquot);
flush_warnings(dquot, warntype);
up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
@@ -1809,7 +1800,6 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
return 0;
}
- spin_lock(&sb_dqopt(inode->i_sb)->dq_data_lock);
inode_dquot_lock(inode, transfer_from);
cur_space = inode_get_bytes(inode);
rsv_space = inode_get_rsv_space(inode);
@@ -1858,7 +1848,6 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
}
dquot_unlock_all(transfer_to);
dquot_unlock_all(transfer_from);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
mark_all_dquot_dirty(transfer_from);
@@ -1874,7 +1863,6 @@ warn:
over_quota:
dquot_unlock_all(transfer_to);
dquot_unlock_all(transfer_from);
- spin_unlock(&sb_dqopt(inode->i_sb)->dq_data_lock);
up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
goto warn;
}
@@ -2468,7 +2456,6 @@ static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
(di->d_ino_hardlimit > dqi->dqi_maxilimit)))
return -ERANGE;
- spin_lock(&dq_opt(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;
@@ -2518,7 +2505,8 @@ static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
dm->dqb_btime = 0;
clear_bit(DQ_BLKS_B, &dquot->dq_flags);
} else if (!(di->d_fieldmask & FS_DQ_BTIMER))
- /* Set grace only if user hasn't provided his own... */
+ /* Set grace only if user hasn't provided his own...
+ Read dqi_bgrace without lock */
dm->dqb_btime = get_seconds() + dqi->dqi_bgrace;
}
if (check_ilim) {
@@ -2527,7 +2515,8 @@ static int do_set_dqblk(struct dquot *dquot, struct fs_disk_quota *di)
dm->dqb_itime = 0;
clear_bit(DQ_INODES_B, &dquot->dq_flags);
} else if (!(di->d_fieldmask & FS_DQ_ITIMER))
- /* Set grace only if user hasn't provided his own... */
+ /* Set grace only if user hasn't provided his own...
+ Read dqi_bgrace without lock */
dm->dqb_itime = get_seconds() + dqi->dqi_igrace;
}
if (dm->dqb_bhardlimit || dm->dqb_bsoftlimit || dm->dqb_ihardlimit ||
@@ -2536,7 +2525,6 @@ 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(&dq_opt(dquot)->dq_data_lock);
mark_dquot_dirty(dquot);
return 0;
--
1.6.6.1
--
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