From: Jan Kara Subject: Re: [PATCH V5 1/5] quota: Add reservation support for delayed block allocation Date: Tue, 6 Jan 2009 11:06:46 +0100 Message-ID: <20090106100645.GH10705@duck.suse.cz> References: <1231216808.9267.22.camel@mingming-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Jan Kara , tytso , linux-ext4 , linux-fsdevel To: Mingming Cao Return-path: Received: from styx.suse.cz ([82.119.242.94]:55418 "EHLO mail.suse.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752613AbZAFKGs (ORCPT ); Tue, 6 Jan 2009 05:06:48 -0500 Content-Disposition: inline In-Reply-To: <1231216808.9267.22.camel@mingming-laptop> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 05-01-09 20:40:08, Mingming Cao wrote: > Quota: Add quota reservation support > > Delayed allocation defers the block allocation at the dirty pages > flush-out time, doing quota charge/check at that time is too late. > But we can't charge the quota blocks until blocks are really allocated, > otherwise users could get overcharged after reboot from system crash. > > This patch adds quota reservation for delayed llocation. Quota blocks > are reserved in memory, inode and quota won't gets dirtied until later > block allocation time. > > Signed-off-by: Mingming Cao Just a few comments below: > --- > fs/dquot.c | 111 +++++++++++++++++++++++++++++++++-------------- > include/linux/quota.h | 3 + > include/linux/quotaops.h | 22 +++++++++ > 3 files changed, 105 insertions(+), 31 deletions(-) > > Index: linux-2.6.28-git7/fs/dquot.c > =================================================================== > --- linux-2.6.28-git7.orig/fs/dquot.c 2009-01-05 17:09:50.000000000 -0800 > +++ linux-2.6.28-git7/fs/dquot.c 2009-01-05 20:07:08.000000000 -0800 > @@ -898,6 +898,11 @@ static inline void dquot_incr_space(stru > dquot->dq_dqb.dqb_curspace += number; > } > > +static inline void dquot_resv_space(struct dquot *dquot, qsize_t number) > +{ > + dquot->dq_dqb.dqb_rsvspace += number; > +} > + > static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number) > { > if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE || > @@ -1067,7 +1072,9 @@ err_out: > kfree_skb(skb); > } > #endif > - > +/* > + * Should called with dq_data_lock dropped, this function could sleep. > + */ If you want to add a comment here I'd add something like: /* * Write warnings to the console and send warning messages over netlink. * * Note that this function can sleep. */ Because you cannot hold *any* spinlock when calling a function that can sleep... > static inline void flush_warnings(struct dquot * const *dquots, char *warntype) > { > int i; > @@ -1128,13 +1135,18 @@ static int check_idq(struct dquot *dquot > /* needs dq_data_lock */ > static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *warntype) > { > + qsize_t tspace; > + > *warntype = QUOTA_NL_NOWARN; > if (!sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_type) || > test_bit(DQ_FAKE_B, &dquot->dq_flags)) > return QUOTA_OK; > > + tspace = dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace > + + space; > + > if (dquot->dq_dqb.dqb_bhardlimit && > - dquot->dq_dqb.dqb_curspace + space > dquot->dq_dqb.dqb_bhardlimit && > + tspace > dquot->dq_dqb.dqb_bhardlimit && > !ignore_hardlimit(dquot)) { > if (!prealloc) > *warntype = QUOTA_NL_BHARDWARN; > @@ -1142,7 +1154,7 @@ static int check_bdq(struct dquot *dquot > } > > if (dquot->dq_dqb.dqb_bsoftlimit && > - dquot->dq_dqb.dqb_curspace + space > dquot->dq_dqb.dqb_bsoftlimit && > + tspace > dquot->dq_dqb.dqb_bsoftlimit && > dquot->dq_dqb.dqb_btime && get_seconds() >= dquot->dq_dqb.dqb_btime && > !ignore_hardlimit(dquot)) { > if (!prealloc) > @@ -1151,7 +1163,7 @@ static int check_bdq(struct dquot *dquot > } > > if (dquot->dq_dqb.dqb_bsoftlimit && > - dquot->dq_dqb.dqb_curspace + space > dquot->dq_dqb.dqb_bsoftlimit && > + tspace > dquot->dq_dqb.dqb_bsoftlimit && > dquot->dq_dqb.dqb_btime == 0) { > if (!prealloc) { > *warntype = QUOTA_NL_BSOFTWARN; > @@ -1292,51 +1304,88 @@ void vfs_dq_drop(struct inode *inode) > /* > * This operation can block, but only after everything is updated > */ > -int dquot_alloc_space(struct inode *inode, qsize_t number, int warn) > +int __dquot_alloc_space(struct inode *inode, qsize_t number, > + int warn, int reserve) > { > - int cnt, ret = NO_QUOTA; > + 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)) { > -out_add: > - inode_add_bytes(inode, number); > - return QUOTA_OK; > - } > for (cnt = 0; cnt < MAXQUOTAS; cnt++) > warntype[cnt] = QUOTA_NL_NOWARN; > > - down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); > - if (IS_NOQUOTA(inode)) { /* Now we can do reliable test... */ > - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); > - goto out_add; > - } > spin_lock(&dq_data_lock); > for (cnt = 0; cnt < MAXQUOTAS; cnt++) { > if (inode->i_dquot[cnt] == NODQUOT) > continue; > - if (check_bdq(inode->i_dquot[cnt], number, warn, warntype+cnt) == NO_QUOTA) > - goto warn_put_all; > + if (check_bdq(inode->i_dquot[cnt], number, warn, warntype+cnt) > + == NO_QUOTA) { > + ret = NO_QUOTA; > + goto out_unlock; > + } > } > for (cnt = 0; cnt < MAXQUOTAS; cnt++) { > if (inode->i_dquot[cnt] == NODQUOT) > continue; > - dquot_incr_space(inode->i_dquot[cnt], number); > + if (reserve) > + dquot_resv_space(inode->i_dquot[cnt], number); > + else { > + dquot_incr_space(inode->i_dquot[cnt], number); > + inode_add_bytes(inode, number); > + } > } > - inode_add_bytes(inode, number); > - ret = QUOTA_OK; > -warn_put_all: > +out_unlock: > spin_unlock(&dq_data_lock); > - if (ret == QUOTA_OK) > - /* 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]); > 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)) > + goto out; > + > + down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); > + if (IS_NOQUOTA(inode)) > + goto out_unlock; We need to call inode_add_bytes(inode, number) even for IS_NOQUOTA() inodes (but we don't have to hold dq_data_lock for such inodes). Your rewrite has removed this call... > + > + ret = __dquot_alloc_space(inode, number, warn, 0); > + if (ret == NO_QUOTA) > + 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: > up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); > +out: > + return ret; > +} > + > +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; > } > +EXPORT_SYMBOL(dquot_reserve_space); > > /* > * This operation can block, but only after everything is updated > @@ -2025,7 +2074,7 @@ static void do_get_dqblk(struct dquot *d > spin_lock(&dq_data_lock); > di->dqb_bhardlimit = stoqb(dm->dqb_bhardlimit); > di->dqb_bsoftlimit = stoqb(dm->dqb_bsoftlimit); > - di->dqb_curspace = dm->dqb_curspace; > + di->dqb_curspace = dm->dqb_curspace + dm->dqb_rsvspace; > di->dqb_ihardlimit = dm->dqb_ihardlimit; > di->dqb_isoftlimit = dm->dqb_isoftlimit; > di->dqb_curinodes = dm->dqb_curinodes; > @@ -2067,7 +2116,7 @@ static int do_set_dqblk(struct dquot *dq > > spin_lock(&dq_data_lock); > if (di->dqb_valid & QIF_SPACE) { > - dm->dqb_curspace = di->dqb_curspace; > + dm->dqb_curspace = di->dqb_curspace - dm->dqb_rsvspace; > check_blim = 1; > __set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags); > } > Index: linux-2.6.28-git7/include/linux/quota.h > =================================================================== > --- linux-2.6.28-git7.orig/include/linux/quota.h 2009-01-05 17:09:37.000000000 -0800 > +++ linux-2.6.28-git7/include/linux/quota.h 2009-01-05 20:07:08.000000000 -0800 > @@ -198,6 +198,7 @@ struct mem_dqblk { > qsize_t dqb_bhardlimit; /* absolute limit on disk blks alloc */ > qsize_t dqb_bsoftlimit; /* preferred limit on disk blks */ > qsize_t dqb_curspace; /* current used space */ > + qsize_t dqb_rsvspace; /* current reserved space for delalloc*/ > qsize_t dqb_ihardlimit; /* absolute limit on allocated inodes */ > qsize_t dqb_isoftlimit; /* preferred inode limit */ > qsize_t dqb_curinodes; /* current # allocated inodes */ > @@ -308,6 +309,8 @@ 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" */ > + /* reserve quota for delayed block allocation */ > + int (*reserve_space) (struct inode *, qsize_t, int); > }; > > /* Operations handling requests from userspace */ > Index: linux-2.6.28-git7/include/linux/quotaops.h > =================================================================== > --- linux-2.6.28-git7.orig/include/linux/quotaops.h 2009-01-05 17:09:37.000000000 -0800 > +++ linux-2.6.28-git7/include/linux/quotaops.h 2009-01-05 20:07:08.000000000 -0800 > @@ -185,6 +185,16 @@ static inline int vfs_dq_alloc_space(str > return ret; > } > > +static inline int vfs_dq_reserve_space(struct inode *inode, qsize_t nr) > +{ > + if (sb_any_quota_active(inode->i_sb)) { > + /* Used space is updated in alloc_space() */ > + if (inode->i_sb->dq_op->reserve_space(inode, nr, 0) == NO_QUOTA) > + return 1; > + } > + return 0; > +} > + > static inline int vfs_dq_alloc_inode(struct inode *inode) > { > if (sb_any_quota_active(inode->i_sb)) { > @@ -341,6 +351,11 @@ static inline int vfs_dq_alloc_space(str > return 0; > } > > +static inline int vfs_dq_reserve_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); > @@ -372,12 +387,19 @@ static inline int vfs_dq_alloc_block_nod > nr << inode->i_sb->s_blocksize_bits); > } > > + ^^ This empty line was added by accident I guess... > static inline int vfs_dq_alloc_block(struct inode *inode, qsize_t nr) > { > return vfs_dq_alloc_space(inode, > nr << inode->i_sb->s_blocksize_bits); > } > > +static inline int vfs_dq_reserve_block(struct inode *inode, qsize_t nr) > +{ > + return vfs_dq_reserve_space(inode, > + nr << inode->i_blkbits); > +} > + > 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); > > -- Jan Kara SUSE Labs, CR