在 2008-12-03三的 18:33 +0100，Jan Kara写道：
> Hi Mingming,
>
> On Thu 06-11-08 15:34:35, 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 allocation. Quota blocks
> > are reserved in memory, inode and quota won't gets dirtied until later
> > block allocation time.
> >
> > Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
> I've finally got to reading your patches (I hope this is the last version
> - at least it's the latest version I have ;). Sorry it took so long.
> Here are some comments:
>
> > Index: linux-2.6.28-rc2/fs/dquot.c
> > ===================================================================
> > --- linux-2.6.28-rc2.orig/fs/dquot.c 2008-11-06 13:36:21.000000000 -0800
> > +++ linux-2.6.28-rc2/fs/dquot.c 2008-11-06 14:04:10.000000000 -0800
> > @@ -841,6 +841,11 @@ 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 (dquot->dq_dqb.dqb_curinodes > number)
> > @@ -1069,13 +1074,18 @@ 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;
> > @@ -1083,7 +1093,7 @@ 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)
> > @@ -1092,7 +1102,7 @@ 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;
> > @@ -1227,49 +1237,85 @@ 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);
> > - ret = QUOTA_OK;
> > -warn_put_all:
> > +out_unlock:
> > + flush_warnings(inode->i_dquot, warntype);
> > spin_unlock(&dq_data_lock);
> > + 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;
> > +
> > + 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:
> > 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);
> > + inode_add_bytes(inode, number);
> > + return ret;
> > +}
> Doing inode_add_bytes() here can cause some trouble - we have to make
> sure that the amount of space quota knows (in dqb_space) about and the amount
> of space in i_blocks is always the same. We have to keep this invariant
> because of concurrent write() and chown/chgrp() calls. So we use dq_data_lock
> and make both the change to quota usage and i_blocks under that spinlock.
> And you've moved the change of i_blocks outside of dq_data_lock. In
> practice this need not be a problem since other locks (i_mutex) might
> provide enough synchronization but I'd rather see inode_add_bytes() inside
> the dq_data_lock together with the quota usage change.
>
> > +
> > +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;
> > }
> >
> > @@ -1958,7 +2004,7 @@ 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;
> OK, but you should probably subtract dqb_rsvspace from the amount
> provided by userspace in do_set_dqblk(). Setting usage is inherently
> dangerous thing if fs is used and admin should know what he's doing but
> I think setting it so that "total used space" is what admin meant is the
> way of the least surprise.
>
> > @@ -2297,6 +2343,7 @@ EXPORT_SYMBOL(dquot_alloc_space);
> > EXPORT_SYMBOL(dquot_alloc_inode);
> > EXPORT_SYMBOL(dquot_free_space);
> > EXPORT_SYMBOL(dquot_free_inode);
> > +EXPORT_SYMBOL(dquot_reserve_space);
> > EXPORT_SYMBOL(dquot_transfer);
> > EXPORT_SYMBOL(vfs_dq_transfer);
> > EXPORT_SYMBOL(vfs_dq_quota_on_remount);
> > Index: linux-2.6.28-rc2/include/linux/quota.h
> > ===================================================================
> > --- linux-2.6.28-rc2.orig/include/linux/quota.h 2008-11-06 13:36:21.000000000 -0800
> > +++ linux-2.6.28-rc2/include/linux/quota.h 2008-11-06 14:04:01.000000000 -0800
> > @@ -186,6 +186,7 @@ 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 */
> > @@ -291,6 +292,7 @@ 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 */
> > };
> >
> > /* 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 13:36:21.000000000 -0800
> > +++ linux-2.6.28-rc2/include/linux/quotaops.h 2008-11-06 14:04:10.000000000 -0800
> > @@ -176,6 +176,16 @@ 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)) {
> > @@ -327,6 +337,11 @@ 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);
> > @@ -358,12 +373,19 @@ static inline int vfs_dq_alloc_block_nod
> > nr << inode->i_sb->s_blocksize_bits);
> > }
> >
> > +
> > 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);
> > @@ -392,6 +414,7 @@ static inline void vfs_dq_free_block(str
> > #define DQUOT_ALLOC_BLOCK_NODIRTY(inode, nr) \
> > 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)
> These defines should go away as soon as I get to grepping all the
> filesystems and converting them to new lowercase function names. So there's
> no need of adding this one.
>
> > #define DQUOT_ALLOC_INODE(inode) vfs_dq_alloc_inode(inode)
> > #define DQUOT_FREE_SPACE_NODIRTY(inode, nr) \
> > vfs_dq_free_space_nodirty(inode, nr)
> >
>
> Honza
Attached is incremental fix for review, I will sent the updated patch
for Andrew shortly.
---
fs/dquot.c | 8 ++++----
include/linux/quotaops.h | 1 -
2 files changed, 4 insertions(+), 5 deletions(-)
Index: linux-2.6.28-rc2/fs/dquot.c
===================================================================
--- linux-2.6.28-rc2.orig/fs/dquot.c 2008-12-09 15:41:24.000000000 -0800
+++ linux-2.6.28-rc2/fs/dquot.c 2008-12-09 15:46:26.000000000 -0800
@@ -1261,8 +1261,10 @@ int __dquot_alloc_space(struct inode *in
continue;
if (reserve)
dquot_resv_space(inode->i_dquot[cnt], number);
- else
+ else{
dquot_incr_space(inode->i_dquot[cnt], number);
+ inode_add_bytes(inode, number);
+ }
}
out_unlock:
flush_warnings(inode->i_dquot, warntype);
@@ -1296,8 +1298,6 @@ int dquot_alloc_space(struct inode *inod
out_unlock:
up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
out:
- if (ret == QUOTA_OK)
- inode_add_bytes(inode, number);
return ret;
}
@@ -2046,7 +2046,7 @@ 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;
}
if (di->dqb_valid & QIF_BLIMITS) {
Index: linux-2.6.28-rc2/include/linux/quotaops.h
===================================================================
--- linux-2.6.28-rc2.orig/include/linux/quotaops.h 2008-12-09 15:46:42.000000000 -0800
+++ linux-2.6.28-rc2/include/linux/quotaops.h 2008-12-09 15:47:55.000000000 -0800
@@ -414,7 +414,6 @@ static inline void vfs_dq_free_block(str
#define DQUOT_ALLOC_BLOCK_NODIRTY(inode, nr) \
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_ALLOC_INODE(inode) vfs_dq_alloc_inode(inode)
#define DQUOT_FREE_SPACE_NODIRTY(inode, nr) \
vfs_dq_free_space_nodirty(inode, nr)
--
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