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Message-Id: <20081104172309.b0abc24b.akpm@linux-foundation.org>
Date: Tue, 4 Nov 2008 17:23:09 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Mingming Cao <cmm@...ibm.com>
Cc: jack@...e.cz, tytso@....edu, linux-ext4@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH V2 2/3] quota: Add quota claim and release reserved
quota blocks operations
On Fri, 31 Oct 2008 14:27:26 -0700
Mingming Cao <cmm@...ibm.com> wrote:
> 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.
>
> --- linux-2.6.28-rc2.orig/include/linux/quotaops.h 2008-10-30 14:41:35.000000000 -0700
> +++ linux-2.6.28-rc2/include/linux/quotaops.h 2008-10-30 14:42:00.000000000 -0700
> @@ -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;
> +}
The amount of inlining in this code is, umm, suboptimal.
Thankfully there only appears to be a single DQUOT_CLAIM_BLOCK()
callsite at this stage.
I blame Jan ;)
> +/*
> + * 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 +372,16 @@ 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 +426,17 @@ static inline int vfs_dq_reserve_block(s
> nr << inode->i_sb->s_blocksize_bits);
> }
>
> +static inline int vfs_dq_claim_block(struct inode *inode, qsize_t nr)
> +{
> + return vfs_dq_claim_space(inode,
> + nr << inode->i_sb->s_blocksize_bits);
> +}
> +
> +static inline void vfs_dq_release_reservation(struct inode *inode, qsize_t nr)
> +{
> + vfs_dq_release_reservation_space(inode, nr << inode->i_sb->s_blocksize_bits);
I think you'll find that inode->i_blkbits contains the same
information. Accessing that is faster and will emit less code.
It appears that this optimisation can be made in several places in the
quota code.
> +}
> +
> 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 +466,8 @@ 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)
erk. I blame him for this too.
> #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 2008-10-30 14:41:50.000000000 -0700
> +++ linux-2.6.28-rc2/fs/dquot.c 2008-10-31 13:27:20.000000000 -0700
> @@ -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("WARNING: reserved quota %llu is not enough for"
> + "request %llu bytes\n",
> + dquot->dq_dqb.dqb_rsvspace, number);
Nope.
You cannot print a u64 - you do not know what type it has. It must be
typecast to a known type for printing purposes.
This mistake seems to be happening a lot in ext4 world. People, please
remember this! You might want to have a think about your compilation
test coverage also. powerpc and sparc64 are good ones to use.
> + return 1;
> + }
> +
> + dquot->dq_dqb.dqb_curspace += number;
> + dquot->dq_dqb.dqb_rsvspace -= number;
> + return 0;
> +}
> +
> static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number)
> {
> if (dquot->dq_dqb.dqb_curinodes > number)
> @@ -1325,6 +1343,71 @@ int dquot_reserve_space(struct inode *in
> 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;
> + }
> + /* 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);
> + return ret;
> +}
Didn't I just review that function? I might have got my patches confused.
> +/*
> + * Release reserved quota space
> + */
> +void dquot_release_reserved_space(struct inode *inode, qsize_t number)
> +{
> + int cnt;
> + struct dquot *dquot;
> +
> + if (IS_NOQUOTA(inode))
> + return;
> +
> + down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> + if (IS_NOQUOTA(inode)) {
> + up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> + return;
> + }
again, `goto out' will yield more maintainable and perhaps more
efficient code here.
> + /* 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;
> + }
> + }
> + up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
> +}
> +
> /*
> * This operation can block, but only after everything is updated
> */
> @@ -2350,6 +2433,8 @@ 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);
I blame him for that too.
> EXPORT_SYMBOL(dquot_transfer);
> EXPORT_SYMBOL(vfs_dq_transfer);
> EXPORT_SYMBOL(vfs_dq_quota_on_remount);
>
--
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