From: Jan Kara Subject: Re: [PATCH V3 2/3] quota: Add quota claim and release reserved quota Date: Wed, 3 Dec 2008 20:06:46 +0100 Message-ID: <20081203190639.GD12803@duck.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org To: Mingming Cao Return-path: Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org 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 > --- > 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