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quota: Fix potential NULL pointer dereference
Below race may cause NULL pointer dereference P1 P2 dquot_free_inode quota_off drop_dquot_ref remove_dquot_ref dquots = i_dquot(inode) dquots = i_dquot(inode) srcu_read_lock dquots[cnt]) != NULL (1) dquots[type] = NULL (2) spin_lock(&dquots[cnt]->dq_dqb_lock) (3) .... If dquot_free_inode(or other routines) checks inode's quota pointers (1) before quota_off sets it to NULL(2) and use it (3) after that, NULL pointer dereference will be triggered. So let's fix it by using a temporary pointer to avoid this issue. Signed-off-by: Wang Jianjian <wangjianjian3@huawei.com> Signed-off-by: Jan Kara <jack@suse.cz> Message-Id: <20240202081852.2514092-1-wangjianjian3@huawei.com>
This commit is contained in:
Wang Jianjian
Jan Kara
parent
a1e1b2beca
commit
d0aa72604f
@ -399,15 +399,17 @@ int dquot_mark_dquot_dirty(struct dquot *dquot)
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EXPORT_SYMBOL(dquot_mark_dquot_dirty);
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/* Dirtify all the dquots - this can block when journalling */
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static inline int mark_all_dquot_dirty(struct dquot * const *dquot)
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static inline int mark_all_dquot_dirty(struct dquot * const *dquots)
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{
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int ret, err, cnt;
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struct dquot *dquot;
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ret = err = 0;
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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if (dquot[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (dquot)
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/* Even in case of error we have to continue */
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ret = mark_dquot_dirty(dquot[cnt]);
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ret = mark_dquot_dirty(dquot);
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if (!err)
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err = ret;
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}
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@ -1674,6 +1676,7 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
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struct dquot_warn warn[MAXQUOTAS];
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int reserve = flags & DQUOT_SPACE_RESERVE;
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struct dquot **dquots;
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struct dquot *dquot;
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if (!inode_quota_active(inode)) {
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if (reserve) {
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@ -1693,27 +1696,26 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
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index = srcu_read_lock(&dquot_srcu);
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spin_lock(&inode->i_lock);
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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if (!dquots[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (!dquot)
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continue;
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if (reserve) {
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ret = dquot_add_space(dquots[cnt], 0, number, flags,
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&warn[cnt]);
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ret = dquot_add_space(dquot, 0, number, flags, &warn[cnt]);
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} else {
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ret = dquot_add_space(dquots[cnt], number, 0, flags,
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&warn[cnt]);
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ret = dquot_add_space(dquot, number, 0, flags, &warn[cnt]);
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}
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if (ret) {
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/* Back out changes we already did */
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for (cnt--; cnt >= 0; cnt--) {
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if (!dquots[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (!dquot)
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continue;
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spin_lock(&dquots[cnt]->dq_dqb_lock);
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spin_lock(&dquot->dq_dqb_lock);
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if (reserve)
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dquot_free_reserved_space(dquots[cnt],
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number);
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dquot_free_reserved_space(dquot, number);
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else
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dquot_decr_space(dquots[cnt], number);
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spin_unlock(&dquots[cnt]->dq_dqb_lock);
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dquot_decr_space(dquot, number);
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spin_unlock(&dquot->dq_dqb_lock);
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}
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spin_unlock(&inode->i_lock);
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goto out_flush_warn;
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@ -1744,6 +1746,7 @@ int dquot_alloc_inode(struct inode *inode)
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int cnt, ret = 0, index;
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struct dquot_warn warn[MAXQUOTAS];
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struct dquot * const *dquots;
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struct dquot *dquot;
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if (!inode_quota_active(inode))
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return 0;
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@ -1754,17 +1757,19 @@ int dquot_alloc_inode(struct inode *inode)
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index = srcu_read_lock(&dquot_srcu);
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spin_lock(&inode->i_lock);
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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if (!dquots[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (!dquot)
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continue;
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ret = dquot_add_inodes(dquots[cnt], 1, &warn[cnt]);
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ret = dquot_add_inodes(dquot, 1, &warn[cnt]);
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if (ret) {
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for (cnt--; cnt >= 0; cnt--) {
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if (!dquots[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (!dquot)
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continue;
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/* Back out changes we already did */
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spin_lock(&dquots[cnt]->dq_dqb_lock);
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dquot_decr_inodes(dquots[cnt], 1);
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spin_unlock(&dquots[cnt]->dq_dqb_lock);
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spin_lock(&dquot->dq_dqb_lock);
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dquot_decr_inodes(dquot, 1);
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spin_unlock(&dquot->dq_dqb_lock);
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}
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goto warn_put_all;
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}
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@ -1786,6 +1791,7 @@ EXPORT_SYMBOL(dquot_alloc_inode);
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void dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
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{
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struct dquot **dquots;
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struct dquot *dquot;
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int cnt, index;
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if (!inode_quota_active(inode)) {
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@ -1801,9 +1807,8 @@ void dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
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spin_lock(&inode->i_lock);
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/* Claim reserved quotas to allocated quotas */
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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if (dquots[cnt]) {
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struct dquot *dquot = dquots[cnt];
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (dquot) {
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spin_lock(&dquot->dq_dqb_lock);
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if (WARN_ON_ONCE(dquot->dq_dqb.dqb_rsvspace < number))
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number = dquot->dq_dqb.dqb_rsvspace;
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@ -1828,6 +1833,7 @@ EXPORT_SYMBOL(dquot_claim_space_nodirty);
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void dquot_reclaim_space_nodirty(struct inode *inode, qsize_t number)
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{
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struct dquot **dquots;
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struct dquot *dquot;
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int cnt, index;
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if (!inode_quota_active(inode)) {
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@ -1843,9 +1849,8 @@ void dquot_reclaim_space_nodirty(struct inode *inode, qsize_t number)
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spin_lock(&inode->i_lock);
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/* Claim reserved quotas to allocated quotas */
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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if (dquots[cnt]) {
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struct dquot *dquot = dquots[cnt];
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (dquot) {
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spin_lock(&dquot->dq_dqb_lock);
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if (WARN_ON_ONCE(dquot->dq_dqb.dqb_curspace < number))
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number = dquot->dq_dqb.dqb_curspace;
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@ -1872,6 +1877,7 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
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unsigned int cnt;
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struct dquot_warn warn[MAXQUOTAS];
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struct dquot **dquots;
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struct dquot *dquot;
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int reserve = flags & DQUOT_SPACE_RESERVE, index;
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if (!inode_quota_active(inode)) {
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@ -1892,17 +1898,18 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
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int wtype;
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warn[cnt].w_type = QUOTA_NL_NOWARN;
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if (!dquots[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (!dquot)
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continue;
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spin_lock(&dquots[cnt]->dq_dqb_lock);
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wtype = info_bdq_free(dquots[cnt], number);
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spin_lock(&dquot->dq_dqb_lock);
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wtype = info_bdq_free(dquot, number);
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if (wtype != QUOTA_NL_NOWARN)
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prepare_warning(&warn[cnt], dquots[cnt], wtype);
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prepare_warning(&warn[cnt], dquot, wtype);
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if (reserve)
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dquot_free_reserved_space(dquots[cnt], number);
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dquot_free_reserved_space(dquot, number);
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else
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dquot_decr_space(dquots[cnt], number);
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spin_unlock(&dquots[cnt]->dq_dqb_lock);
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dquot_decr_space(dquot, number);
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spin_unlock(&dquot->dq_dqb_lock);
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}
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if (reserve)
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*inode_reserved_space(inode) -= number;
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@ -1927,6 +1934,7 @@ void dquot_free_inode(struct inode *inode)
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unsigned int cnt;
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struct dquot_warn warn[MAXQUOTAS];
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struct dquot * const *dquots;
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struct dquot *dquot;
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int index;
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if (!inode_quota_active(inode))
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@ -1937,16 +1945,16 @@ void dquot_free_inode(struct inode *inode)
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spin_lock(&inode->i_lock);
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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int wtype;
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warn[cnt].w_type = QUOTA_NL_NOWARN;
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if (!dquots[cnt])
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dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
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if (!dquot)
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continue;
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spin_lock(&dquots[cnt]->dq_dqb_lock);
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wtype = info_idq_free(dquots[cnt], 1);
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spin_lock(&dquot->dq_dqb_lock);
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wtype = info_idq_free(dquot, 1);
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if (wtype != QUOTA_NL_NOWARN)
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prepare_warning(&warn[cnt], dquots[cnt], wtype);
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dquot_decr_inodes(dquots[cnt], 1);
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spin_unlock(&dquots[cnt]->dq_dqb_lock);
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prepare_warning(&warn[cnt], dquot, wtype);
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dquot_decr_inodes(dquot, 1);
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spin_unlock(&dquot->dq_dqb_lock);
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}
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spin_unlock(&inode->i_lock);
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mark_all_dquot_dirty(dquots);
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@ -1973,7 +1981,7 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
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qsize_t rsv_space = 0;
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qsize_t inode_usage = 1;
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struct dquot *transfer_from[MAXQUOTAS] = {};
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int cnt, ret = 0;
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int cnt, index, ret = 0;
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char is_valid[MAXQUOTAS] = {};
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struct dquot_warn warn_to[MAXQUOTAS];
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struct dquot_warn warn_from_inodes[MAXQUOTAS];
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@ -2062,8 +2070,16 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
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spin_unlock(&inode->i_lock);
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spin_unlock(&dq_data_lock);
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/*
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* These arrays are local and we hold dquot references so we don't need
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* the srcu protection but still take dquot_srcu to avoid warning in
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* mark_all_dquot_dirty().
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*/
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index = srcu_read_lock(&dquot_srcu);
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mark_all_dquot_dirty(transfer_from);
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mark_all_dquot_dirty(transfer_to);
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srcu_read_unlock(&dquot_srcu, index);
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flush_warnings(warn_to);
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flush_warnings(warn_from_inodes);
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flush_warnings(warn_from_space);
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