[PATCH 6.6 392/638] quota: Fix rcu annotations of inode dquot pointers

Sasha Levin
2024-03-24T23:07:42Z

From: Jan Kara <jack@suse.cz>

[ Upstream commit 179b8c97ebf63429589f5afeba59a181fe70603e ]

Dquot pointers in i_dquot array in the inode are protected by
dquot_srcu. Annotate the array pointers with __rcu, perform the locked
dereferences with srcu_dereference_check() instead of plain reads, and
set the array elements with rcu_assign_pointer().

Fixes: b9ba6f94b238 ("quota: remove dqptr_sem")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402061900.rTuYDlo6-lkp@intel.com/
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/quota/dquot.c | 66 ++++++++++++++++++++++++++++--------------------
1 file changed, 39 insertions(+), 27 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 9707aa34f52e7..c6bd7ee20f009 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -399,7 +399,7 @@ int dquot_mark_dquot_dirty(struct dquot *dquot)
EXPORT_SYMBOL(dquot_mark_dquot_dirty);

/* Dirtify all the dquots - this can block when journalling */
-static inline int mark_all_dquot_dirty(struct dquot * const *dquots)
+static inline int mark_all_dquot_dirty(struct dquot __rcu * const *dquots)
{
int ret, err, cnt;
struct dquot *dquot;
@@ -1006,14 +1006,15 @@ struct dquot *dqget(struct super_block *sb, struct kqid qid)
}
EXPORT_SYMBOL(dqget);

-static inline struct dquot **i_dquot(struct inode *inode)
+static inline struct dquot __rcu **i_dquot(struct inode *inode)
{
- return inode->i_sb->s_op->get_dquots(inode);
+ /* Force __rcu for now until filesystems are fixed */
+ return (struct dquot __rcu **)inode->i_sb->s_op->get_dquots(inode);
}

static int dqinit_needed(struct inode *inode, int type)
{
- struct dquot * const *dquots;
+ struct dquot __rcu * const *dquots;
int cnt;

if (IS_NOQUOTA(inode))
@@ -1103,14 +1104,16 @@ static void remove_dquot_ref(struct super_block *sb, int type)
*/
spin_lock(&dq_data_lock);
if (!IS_NOQUOTA(inode)) {
- struct dquot **dquots = i_dquot(inode);
- struct dquot *dquot = dquots[type];
+ struct dquot __rcu **dquots = i_dquot(inode);
+ struct dquot *dquot = srcu_dereference_check(
+ dquots[type], &dquot_srcu,
+ lockdep_is_held(&dq_data_lock));

#ifdef CONFIG_QUOTA_DEBUG
if (unlikely(inode_get_rsv_space(inode) > 0))
reserved = 1;
#endif
- dquots[type] = NULL;
+ rcu_assign_pointer(dquots[type], NULL);
if (dquot)
dqput(dquot);
}
@@ -1463,7 +1466,8 @@ static int inode_quota_active(const struct inode *inode)
static int __dquot_initialize(struct inode *inode, int type)
{
int cnt, init_needed = 0;
- struct dquot **dquots, *got[MAXQUOTAS] = {};
+ struct dquot __rcu **dquots;
+ struct dquot *got[MAXQUOTAS] = {};
struct super_block *sb = inode->i_sb;
qsize_t rsv;
int ret = 0;
@@ -1538,7 +1542,7 @@ static int __dquot_initialize(struct inode *inode, int type)
if (!got[cnt])
continue;
if (!dquots[cnt]) {
- dquots[cnt] = got[cnt];
+ rcu_assign_pointer(dquots[cnt], got[cnt]);
got[cnt] = NULL;
/*
* Make quota reservation system happy if someone
@@ -1546,12 +1550,16 @@ static int __dquot_initialize(struct inode *inode, int type)
*/
rsv = inode_get_rsv_space(inode);
if (unlikely(rsv)) {
+ struct dquot *dquot = srcu_dereference_check(
+ dquots[cnt], &dquot_srcu,
+ lockdep_is_held(&dq_data_lock));
+
spin_lock(&inode->i_lock);
/* Get reservation again under proper lock */
rsv = __inode_get_rsv_space(inode);
- spin_lock(&dquots[cnt]->dq_dqb_lock);
- dquots[cnt]->dq_dqb.dqb_rsvspace += rsv;
- spin_unlock(&dquots[cnt]->dq_dqb_lock);
+ spin_lock(&dquot->dq_dqb_lock);
+ dquot->dq_dqb.dqb_rsvspace += rsv;
+ spin_unlock(&dquot->dq_dqb_lock);
spin_unlock(&inode->i_lock);
}
}
@@ -1573,7 +1581,7 @@ EXPORT_SYMBOL(dquot_initialize);

bool dquot_initialize_needed(struct inode *inode)
{
- struct dquot **dquots;
+ struct dquot __rcu **dquots;
int i;

if (!inode_quota_active(inode))
@@ -1598,13 +1606,14 @@ EXPORT_SYMBOL(dquot_initialize_needed);
static void __dquot_drop(struct inode *inode)
{
int cnt;
- struct dquot **dquots = i_dquot(inode);
+ struct dquot __rcu **dquots = i_dquot(inode);
struct dquot *put[MAXQUOTAS];

spin_lock(&dq_data_lock);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
- put[cnt] = dquots[cnt];
- dquots[cnt] = NULL;
+ put[cnt] = srcu_dereference_check(dquots[cnt], &dquot_srcu,
+ lockdep_is_held(&dq_data_lock));
+ rcu_assign_pointer(dquots[cnt], NULL);
}
spin_unlock(&dq_data_lock);
dqput_all(put);
@@ -1612,7 +1621,7 @@ static void __dquot_drop(struct inode *inode)

void dquot_drop(struct inode *inode)
{
- struct dquot * const *dquots;
+ struct dquot __rcu * const *dquots;
int cnt;

if (IS_NOQUOTA(inode))
@@ -1685,7 +1694,7 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
int cnt, ret = 0, index;
struct dquot_warn warn[MAXQUOTAS];
int reserve = flags & DQUOT_SPACE_RESERVE;
- struct dquot **dquots;
+ struct dquot __rcu **dquots;
struct dquot *dquot;

if (!inode_quota_active(inode)) {
@@ -1755,7 +1764,7 @@ int dquot_alloc_inode(struct inode *inode)
{
int cnt, ret = 0, index;
struct dquot_warn warn[MAXQUOTAS];
- struct dquot * const *dquots;
+ struct dquot __rcu * const *dquots;
struct dquot *dquot;

if (!inode_quota_active(inode))
@@ -1800,7 +1809,7 @@ EXPORT_SYMBOL(dquot_alloc_inode);
*/
int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
{
- struct dquot **dquots;
+ struct dquot __rcu **dquots;
struct dquot *dquot;
int cnt, index;

@@ -1842,7 +1851,7 @@ EXPORT_SYMBOL(dquot_claim_space_nodirty);
*/
void dquot_reclaim_space_nodirty(struct inode *inode, qsize_t number)
{
- struct dquot **dquots;
+ struct dquot __rcu **dquots;
struct dquot *dquot;
int cnt, index;

@@ -1886,7 +1895,7 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
{
unsigned int cnt;
struct dquot_warn warn[MAXQUOTAS];
- struct dquot **dquots;
+ struct dquot __rcu **dquots;
struct dquot *dquot;
int reserve = flags & DQUOT_SPACE_RESERVE, index;

@@ -1943,7 +1952,7 @@ void dquot_free_inode(struct inode *inode)
{
unsigned int cnt;
struct dquot_warn warn[MAXQUOTAS];
- struct dquot * const *dquots;
+ struct dquot __rcu * const *dquots;
struct dquot *dquot;
int index;

@@ -1990,6 +1999,7 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
qsize_t cur_space;
qsize_t rsv_space = 0;
qsize_t inode_usage = 1;
+ struct dquot __rcu **dquots;
struct dquot *transfer_from[MAXQUOTAS] = {};
int cnt, index, ret = 0;
char is_valid[MAXQUOTAS] = {};
@@ -2022,6 +2032,7 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
}
cur_space = __inode_get_bytes(inode);
rsv_space = __inode_get_rsv_space(inode);
+ dquots = i_dquot(inode);
/*
* Build the transfer_from list, check limits, and update usage in
* the target structures.
@@ -2036,7 +2047,8 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
if (!sb_has_quota_active(inode->i_sb, cnt))
continue;
is_valid[cnt] = 1;
- transfer_from[cnt] = i_dquot(inode)[cnt];
+ transfer_from[cnt] = srcu_dereference_check(dquots[cnt],
+ &dquot_srcu, lockdep_is_held(&dq_data_lock));
ret = dquot_add_inodes(transfer_to[cnt], inode_usage,
&warn_to[cnt]);
if (ret)
@@ -2075,7 +2087,7 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
rsv_space);
spin_unlock(&transfer_from[cnt]->dq_dqb_lock);
}
- i_dquot(inode)[cnt] = transfer_to[cnt];
+ rcu_assign_pointer(dquots[cnt], transfer_to[cnt]);
}
spin_unlock(&inode->i_lock);
spin_unlock(&dq_data_lock);
@@ -2086,8 +2098,8 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
* mark_all_dquot_dirty().
*/
index = srcu_read_lock(&dquot_srcu);
- mark_all_dquot_dirty(transfer_from);
- mark_all_dquot_dirty(transfer_to);
+ mark_all_dquot_dirty((struct dquot __rcu **)transfer_from);
+ mark_all_dquot_dirty((struct dquot __rcu **)transfer_to);
srcu_read_unlock(&dquot_srcu, index);

flush_warnings(warn_to);
--
2.43.0