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Date: Wed, 09 Dec 2009 16:19:20 -0800
From: Mingming <cmm@...ibm.com>
To: Dmitry Monakhov <dmonakhov@...nvz.org>
Cc: linux-ext4@...r.kernel.org, aneesh.kumar@...ux.vnet.ibm.com,
jack@...e.cz
Subject: Re: [PATCH 2/3] quota: convert to generic reserved space management
On Wed, 2009-12-09 at 05:11 +0300, Dmitry Monakhov wrote:
> Before this patch fs_rsv_space must be always equals to
> quot_rsv_space all the time. Otherwise dquot_transfer()
> will result in incorrect quota(because fs_rsv_space is used
> on transfer).
By incorrect quota I assume you mean nagetive reserved quota?
I have asked Jan before whether we should transfer the reserved
quota...I still not quit sure..in fact the more I am thinking, I think
the reserved quota should not transfered until they are claimed.
I am going to cook a patch for this...
After that patch, we shall not see the negative quota reservation
values.
> This result in complex locking order issues
> aka http://bugzilla.kernel.org/show_bug.cgi?id=14739
> After this patch quot_rsv_space will be transferred on
> dquot_transfer(), this automatically solves locking issues.
>
This bug could be easily fixed by just drop the i_block_reservation lock
before release reserved quota.
> - Unify dquot_reserve_space() and dquot_reserve_space()
> - Unify dquot_release_reserved_space() and dquot_free_space()
> - Also this patch add missing warning update to release_rsv()
> dquot_release_reserved_space() must call flush_warnings() as
> dquot_free_space() does.
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> ---
> fs/quota/dquot.c | 169 +++++++++++++++++++++---------------------------
> include/linux/quota.h | 2 -
> 2 files changed, 74 insertions(+), 97 deletions(-)
>
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 39b49c4..4bc5ac8 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -1396,6 +1396,22 @@ EXPORT_SYMBOL(vfs_dq_drop);
> * inode write go into the same transaction.
> */
>
> +static void __inode_add_bytes(struct inode *inode, qsize_t number, int reserve)
> +{
> + if (reserve)
> + inode_add_rsv_blocks(inode, number >> 9);
> + else
> + inode_add_bytes(inode, number);
> +}
> +
> +static void __inode_sub_bytes(struct inode *inode, qsize_t number, int reserve)
> +{
> + if (reserve)
> + inode_sub_rsv_blocks(inode, number >> 9);
> + else
> + inode_sub_bytes(inode, number);
> +}
> +
> /*
> * This operation can block, but only after everything is updated
> */
> @@ -1405,6 +1421,21 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number,
> int cnt, ret = QUOTA_OK;
> char warntype[MAXQUOTAS];
>
> + /*
> + * First test before acquiring mutex - solves deadlocks when we
> + * re-enter the quota code and are already holding the mutex
> + */
> + if (IS_NOQUOTA(inode)) {
> + __inode_add_bytes(inode, number, reserve);
> + goto out;
> + }
> +
> + down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> + if (IS_NOQUOTA(inode)) {
> + __inode_add_bytes(inode, number, reserve);
> + goto out_unlock;
> + }
> +
> for (cnt = 0; cnt < MAXQUOTAS; cnt++)
> warntype[cnt] = QUOTA_NL_NOWARN;
>
> @@ -1415,7 +1446,7 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number,
> if (check_bdq(inode->i_dquot[cnt], number, warn, warntype+cnt)
> == NO_QUOTA) {
> ret = NO_QUOTA;
> - goto out_unlock;
> + goto out_data_unlock;
> }
> }
> for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
> @@ -1426,64 +1457,32 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number,
> else
> dquot_incr_space(inode->i_dquot[cnt], number);
> }
> - if (!reserve)
> - inode_add_bytes(inode, number);
> -out_unlock:
> - spin_unlock(&dq_data_lock);
> - flush_warnings(inode->i_dquot, warntype);
> - return ret;
> -}
> -
> -int dquot_alloc_space(struct inode *inode, qsize_t number, int warn)
> -{
> - int cnt, ret = QUOTA_OK;
> -
> - /*
> - * First test before acquiring mutex - solves deadlocks when we
> - * re-enter the quota code and are already holding the mutex
> - */
> - if (IS_NOQUOTA(inode)) {
> - inode_add_bytes(inode, number);
> - goto out;
> - }
> -
> - down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> - if (IS_NOQUOTA(inode)) {
> - inode_add_bytes(inode, number);
> - goto out_unlock;
> - }
> -
> - ret = __dquot_alloc_space(inode, number, warn, 0);
> - if (ret == NO_QUOTA)
> - goto out_unlock;
> + __inode_add_bytes(inode, number, reserve);
>
> + if (reserve)
> + goto out_data_unlock;
> /* Dirtify all the dquots - this can block when journalling */
> for (cnt = 0; cnt < MAXQUOTAS; cnt++)
> if (inode->i_dquot[cnt])
> mark_dquot_dirty(inode->i_dquot[cnt]);
> +out_data_unlock:
> + spin_unlock(&dq_data_lock);
> + flush_warnings(inode->i_dquot, warntype);
> out_unlock:
> up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> out:
> return ret;
> }
> +
> +int dquot_alloc_space(struct inode *inode, qsize_t number, int warn)
> +{
> + return __dquot_alloc_space(inode, number, warn, 0);
> +}
> EXPORT_SYMBOL(dquot_alloc_space);
>
> int dquot_reserve_space(struct inode *inode, qsize_t number, int warn)
> {
> - int ret = QUOTA_OK;
> -
> - if (IS_NOQUOTA(inode))
> - goto out;
> -
> - down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> - if (IS_NOQUOTA(inode))
> - goto out_unlock;
> -
> - ret = __dquot_alloc_space(inode, number, warn, 1);
> -out_unlock:
> - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> -out:
> - return ret;
> + return __dquot_alloc_space(inode, number, warn, 1);
> }
> EXPORT_SYMBOL(dquot_reserve_space);
>
> @@ -1540,14 +1539,14 @@ int dquot_claim_space(struct inode *inode, qsize_t number)
> int ret = QUOTA_OK;
>
> if (IS_NOQUOTA(inode)) {
> - inode_add_bytes(inode, number);
> + inode_claim_rsv_blocks(inode, number >> 9);
> goto out;
> }
>
> down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> if (IS_NOQUOTA(inode)) {
> up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> - inode_add_bytes(inode, number);
> + inode_claim_rsv_blocks(inode, number >> 9);
> goto out;
> }
>
> @@ -1559,7 +1558,7 @@ int dquot_claim_space(struct inode *inode, qsize_t number)
> number);
> }
> /* Update inode bytes */
> - inode_add_bytes(inode, number);
> + inode_claim_rsv_blocks(inode, number >> 9);
> spin_unlock(&dq_data_lock);
> /* Dirtify all the dquots - this can block when journalling */
> for (cnt = 0; cnt < MAXQUOTAS; cnt++)
> @@ -1572,38 +1571,9 @@ out:
> EXPORT_SYMBOL(dquot_claim_space);
>
> /*
> - * Release reserved quota space
> - */
> -void dquot_release_reserved_space(struct inode *inode, qsize_t number)
> -{
> - int cnt;
> -
> - if (IS_NOQUOTA(inode))
> - goto out;
> -
> - down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> - if (IS_NOQUOTA(inode))
> - goto out_unlock;
> -
> - spin_lock(&dq_data_lock);
> - /* Release reserved dquots */
> - for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
> - if (inode->i_dquot[cnt])
> - dquot_free_reserved_space(inode->i_dquot[cnt], number);
> - }
> - spin_unlock(&dq_data_lock);
> -
> -out_unlock:
> - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> -out:
> - return;
> -}
> -EXPORT_SYMBOL(dquot_release_reserved_space);
> -
> -/*
> * This operation can block, but only after everything is updated
> */
> -int dquot_free_space(struct inode *inode, qsize_t number)
> +int __dquot_free_space(struct inode *inode, qsize_t number, int reserve)
> {
> unsigned int cnt;
> char warntype[MAXQUOTAS];
> @@ -1612,7 +1582,7 @@ int dquot_free_space(struct inode *inode, qsize_t number)
> * re-enter the quota code and are already holding the mutex */
> if (IS_NOQUOTA(inode)) {
> out_sub:
> - inode_sub_bytes(inode, number);
> + __inode_sub_bytes(inode, number, reserve);
> return QUOTA_OK;
> }
>
> @@ -1627,21 +1597,43 @@ out_sub:
> if (!inode->i_dquot[cnt])
> continue;
> warntype[cnt] = info_bdq_free(inode->i_dquot[cnt], number);
> - dquot_decr_space(inode->i_dquot[cnt], number);
> + if (reserve)
> + dquot_free_reserved_space(inode->i_dquot[cnt], number);
> + else
> + dquot_decr_space(inode->i_dquot[cnt], number);
> }
> - inode_sub_bytes(inode, number);
> + __inode_sub_bytes(inode, number, reserve);
> spin_unlock(&dq_data_lock);
> +
> + if (reserve)
> + goto out_unlock;
> /* Dirtify all the dquots - this can block when journalling */
> for (cnt = 0; cnt < MAXQUOTAS; cnt++)
> if (inode->i_dquot[cnt])
> mark_dquot_dirty(inode->i_dquot[cnt]);
> +out_unlock:
> flush_warnings(inode->i_dquot, warntype);
> up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> return QUOTA_OK;
> }
> +
> +int dquot_free_space(struct inode *inode, qsize_t number)
> +{
> + return __dquot_free_space(inode, number, 0);
> +}
> EXPORT_SYMBOL(dquot_free_space);
>
> /*
> + * Release reserved quota space
> + */
> +void dquot_release_reserved_space(struct inode *inode, qsize_t number)
> +{
> + return (void )__dquot_free_space(inode, number, 1);
> +
> +}
> +EXPORT_SYMBOL(dquot_release_reserved_space);
> +
> +/*
> * This operation can block, but only after everything is updated
> */
> int dquot_free_inode(const struct inode *inode, qsize_t number)
> @@ -1679,19 +1671,6 @@ int dquot_free_inode(const struct inode *inode, qsize_t number)
> EXPORT_SYMBOL(dquot_free_inode);
>
> /*
> - * call back function, get reserved quota space from underlying fs
> - */
> -qsize_t dquot_get_reserved_space(struct inode *inode)
> -{
> - qsize_t reserved_space = 0;
> -
> - if (sb_any_quota_active(inode->i_sb) &&
> - inode->i_sb->dq_op->get_reserved_space)
> - reserved_space = inode->i_sb->dq_op->get_reserved_space(inode);
> - return reserved_space;
> -}
> -
> -/*
> * Transfer the number of inode and blocks from one diskquota to an other.
> *
> * This operation can block, but only after everything is updated
> @@ -1734,7 +1713,7 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
> }
> spin_lock(&dq_data_lock);
> cur_space = inode_get_bytes(inode);
> - rsv_space = dquot_get_reserved_space(inode);
> + rsv_space = inode_get_rsv_blocks(inode) << 9;
> space = cur_space + rsv_space;
> /* Build the transfer_from list and check the limits */
> for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
> diff --git a/include/linux/quota.h b/include/linux/quota.h
> index 78c4889..daa6274 100644
> --- a/include/linux/quota.h
> +++ b/include/linux/quota.h
> @@ -313,8 +313,6 @@ struct dquot_operations {
> int (*claim_space) (struct inode *, qsize_t);
> /* release rsved quota for delayed alloc */
> void (*release_rsv) (struct inode *, qsize_t);
> - /* get reserved quota for delayed alloc */
> - qsize_t (*get_reserved_space) (struct inode *);
> };
>
> /* Operations handling requests from userspace */
--
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