Hmm, I can't find the email with this patch so I've just copied it from
some mail archive ;). Sorry if the CC's are wrong.
> quota: Add quota reservation claim and released operations
>
> Reserved quota will be claimed at the block allocation time. Over-booked
> quota could be returned back with the release callback function.
>
> Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
> ---
> fs/dquot.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/quota.h | 4 +-
> include/linux/quotaops.h | 55 +++++++++++++++++++++++++++++
> 3 files changed, 145 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.28-rc2/include/linux/quota.h
> ===================================================================
> --- linux-2.6.28-rc2.orig/include/linux/quota.h 2008-11-06 13:36:42.000000000 -0800
> +++ linux-2.6.28-rc2/include/linux/quota.h 2008-11-06 14:03:52.000000000 -0800
> @@ -292,7 +292,9 @@ struct dquot_operations {
> int (*release_dquot) (struct dquot *); /* Quota is going to be deleted from disk */
> int (*mark_dirty) (struct dquot *); /* Dquot is marked dirty */
> int (*write_info) (struct super_block *, int); /* Write of quota "superblock" */
> - int (*reserve_space) (struct inode *, qsize_t, int); /* reserve quota for delayed block allocation */
> + int (*reserve_space) (struct inode *, qsize_t, int); /* reserve quota for delayed alloc */
> + int (*claim_space) (struct inode *, qsize_t); /* claim reserved quota for delayed alloc */
> + void (*release_rsv) (struct inode *, qsize_t); /* release rsved quota for delayed alloc */
> };
>
> /* Operations handling requests from userspace */
> Index: linux-2.6.28-rc2/include/linux/quotaops.h
> ===================================================================
> --- linux-2.6.28-rc2.orig/include/linux/quotaops.h 2008-11-06 13:37:04.000000000 -0800
> +++ linux-2.6.28-rc2/include/linux/quotaops.h 2008-11-06 14:03:52.000000000 -0800
> @@ -28,6 +28,11 @@ int dquot_drop(struct inode *inode);
> int dquot_alloc_space(struct inode *inode, qsize_t number, int prealloc);
> int dquot_alloc_inode(const struct inode *inode, qsize_t number);
>
> +int dquot_reserve_space(struct inode *inode, qsize_t number, int prealloc);
> +int dquot_claim_space(struct inode *inode, qsize_t number);
> +void dquot_release_reserved_space(struct inode *inode, qsize_t number);
> +
> +
> int dquot_free_space(struct inode *inode, qsize_t number);
> int dquot_free_inode(const struct inode *inode, qsize_t number);
>
> @@ -196,6 +201,31 @@ static inline int vfs_dq_alloc_inode(str
> return 0;
> }
>
> +/*
> + * Convert in-memory reserved quotas to real consumed quotas
> + */
> +static inline int vfs_dq_claim_space(struct inode *inode, qsize_t nr)
> +{
> + if (sb_any_quota_active(inode->i_sb)) {
> + if (inode->i_sb->dq_op->claim_space(inode, nr) == NO_QUOTA)
> + return 1;
> + } else
> + inode_add_bytes(inode, nr);
> +
> + mark_inode_dirty(inode);
> + return 0;
> +}
> +
> +/*
> + * Release reserved (in-memory) quotas
> + */
> +static inline
> +void vfs_dq_release_reservation_space(struct inode *inode, qsize_t nr)
> +{
> + if (sb_any_quota_active(inode->i_sb))
> + inode->i_sb->dq_op->release_rsv(inode, nr);
> +}
> +
> static inline void vfs_dq_free_space_nodirty(struct inode *inode, qsize_t nr)
> {
> if (sb_any_quota_active(inode->i_sb))
> @@ -342,6 +372,17 @@ static inline int vfs_dq_reserve_space(s
> return 0;
> }
>
> +static inline int vfs_dq_claim_space(struct inode *inode, qsize_t nr)
> +{
> + return vfs_dq_alloc_space(inode, nr);
> +}
> +
> +static inline
> +int vfs_dq_release_reservation_space(struct inode *inode, qsize_t nr)
> +{
> + return 0;
> +}
> +
> static inline void vfs_dq_free_space_nodirty(struct inode *inode, qsize_t nr)
> {
> inode_sub_bytes(inode, nr);
> @@ -386,6 +427,18 @@ static inline int vfs_dq_reserve_block(s
> nr << inode->i_blkbits);
> }
>
> +static inline int vfs_dq_claim_block(struct inode *inode, qsize_t nr)
> +{
> + return vfs_dq_claim_space(inode,
> + nr << inode->i_blkbits);
> +}
> +
> +static inline
> +void vfs_dq_release_reservation(struct inode *inode, qsize_t nr)
> +{
> + vfs_dq_release_reservation_space(inode, nr << inode->i_blkbits);
> +}
> +
I guess the function should be called like vfs_dq_release_reservation_block().
It's ugly long but we should not omit the "block" part. Maybe we could shorten
reservation everywhere in function names to rsv?
> static inline void vfs_dq_free_block_nodirty(struct inode *inode, qsize_t nr)
> {
> vfs_dq_free_space_nodirty(inode, nr << inode->i_sb->s_blocksize_bits);
> @@ -415,6 +468,8 @@ static inline void vfs_dq_free_block(str
> vfs_dq_alloc_block_nodirty(inode, nr)
> #define DQUOT_ALLOC_BLOCK(inode, nr) vfs_dq_alloc_block(inode, nr)
> #define DQUOT_RESERVE_BLOCK(inode, nr) vfs_dq_reserve_block(inode, nr)
> +#define DQUOT_CLAIM_BLOCK(inode, nr) vfs_dq_claim_block(inode, nr)
> +#define DQUOT_RELEASE_RSV_BLOCK(inode, nr) vfs_dq_release_reservation(inode, nr)
Please call lowercase variants from ext4 and don't define these functions.
> #define DQUOT_ALLOC_INODE(inode) vfs_dq_alloc_inode(inode)
> #define DQUOT_FREE_SPACE_NODIRTY(inode, nr) \
> vfs_dq_free_space_nodirty(inode, nr)
> Index: linux-2.6.28-rc2/fs/dquot.c
> ===================================================================
> --- linux-2.6.28-rc2.orig/fs/dquot.c 2008-11-06 13:37:04.000000000 -0800
> +++ linux-2.6.28-rc2/fs/dquot.c 2008-11-06 14:03:52.000000000 -0800
> @@ -846,6 +846,24 @@ static inline void dquot_resv_space(stru
> dquot->dq_dqb.dqb_rsvspace += number;
> }
>
> +/*
> + * Claim reserved quota space
> + */
> +static int dquot_claim_reserved_space(struct dquot *dquot,
> + qsize_t number)
> +{
> + if (dquot->dq_dqb.dqb_rsvspace < number) {
> + printk(KERN_WARNING "Reserved quota %llu is not enough for"
> + "request %llu bytes\n",
> + (unsigned long long)dquot->dq_dqb.dqb_rsvspace, number);
> + return 1;
Wouldn't a WARN_ON here be more appropriate? It's a filesystem bug to cause
this AFAICS.
> + }
> +
> + dquot->dq_dqb.dqb_curspace += number;
> + dquot->dq_dqb.dqb_rsvspace -= number;
> + return 0;
> +}
You should use dq_data_lock to protect these operations...
> +
> static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number)
> {
> if (dquot->dq_dqb.dqb_curinodes > number)
> @@ -1319,6 +1337,73 @@ out:
> return ret;
> }
>
> +int dquot_claim_space(struct inode *inode, qsize_t number)
> +{
> + int cnt;
> + int ret = QUOTA_OK;
> +
> + if (IS_NOQUOTA(inode)) {
> + inode_add_bytes(inode, number);
> + return ret;
> + }
> +
> + 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);
> + return ret;
> + }
> +
> + /* Claim reserved quotas to allocated quotas */
> + for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
> + if (inode->i_dquot[cnt] != NODQUOT)
> + ret = dquot_claim_reserved_space(inode->i_dquot[cnt],
> + number);
> + }
> + if (ret == NO_QUOTA) {
> + up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> + return ret;
> + }
It seems a bit silly to try to recover here from filesystem bugs. I'd just
make dquot_claim_reserved_space() void and ignore possible failure here.
We won't do anything harmful like loosing data. Just counters might become
out of sync but given there's a bug in fs anyway it does not matter much.
> + /* 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]);
> + up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> +
> + /* Update inode bytes */
> + inode_add_bytes(inode, number);
And this should be called from under dq_data_lock from
dquot_claim_reserved_space().
BTW: This reminds me that you should also modify dquot_transfer() function.
Because that should not only transfer i_blocks sectors from one user
to another but it has to also transfer the amount reserved for that inode...
I think the easiest way around this would be to change i_blocks already when
reservation is acquired (and than substract it when some of it is given back).
> + return ret;
> +}
> +
> +/*
> + * Release reserved quota space
> + */
> +void dquot_release_reserved_space(struct inode *inode, qsize_t number)
> +{
> + int cnt;
> + struct dquot *dquot;
> +
> + if (IS_NOQUOTA(inode))
> + goto out;
> +
> + down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> + if (IS_NOQUOTA(inode))
> + goto out_unlock;
> +
> + /* Release reserved dquots */
> + for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
> + if (inode->i_dquot[cnt] != NODQUOT) {
> + dquot = inode->i_dquot[cnt];
> + dquot->dq_dqb.dqb_rsvspace -= number;
> + }
> + }
Again dq_data_lock...
> +
> +out_unlock:
> + up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> +out:
> + return;
> +}
> +
> /*
> * This operation can block, but only after everything is updated
> */
> @@ -2344,6 +2429,8 @@ EXPORT_SYMBOL(dquot_alloc_inode);
> EXPORT_SYMBOL(dquot_free_space);
> EXPORT_SYMBOL(dquot_free_inode);
> EXPORT_SYMBOL(dquot_reserve_space);
> +EXPORT_SYMBOL(dquot_claim_space);
> +EXPORT_SYMBOL(dquot_release_reserved_space);
> EXPORT_SYMBOL(dquot_transfer);
> EXPORT_SYMBOL(vfs_dq_transfer);
> EXPORT_SYMBOL(vfs_dq_quota_on_remount);
Honza
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