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Message-Id: <1228787422.6372.43.camel@mingming-laptop>
Date: Mon, 08 Dec 2008 17:50:22 -0800
From: Mingming Cao <cmm@...ibm.com>
To: Jan Kara <jack@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>, tytso <tytso@....edu>,
linux-ext4 <linux-ext4@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH V3 3/3]ext4: quota handling for delayed allocation
在 2008-12-03三的 21:11 +0100，Jan Kara写道：
> Hi,
>
> On Thu 06-11-08 15:39:05, Mingming Cao wrote:
> > ext4: quota reservation for delayed allocation
> >
> > Uses quota reservation/claim/release to handle quota properly for delayed
> > allocation in the three steps: 1) quotas are reserved when data being copied
> > to cache when block allocation is defered 2) when new blocks are allocated.
> > reserved quotas are converted to the real allocated quota, 2) over-booked
> > quotas for metadata blocks are released back.
> >
> >
> > Signed-off-by: Mingming Cao <cmm@...ibm.com>
> > ---
> > fs/ext4/inode.c | 29 ++++++++++++++++++++++++++---
> > fs/ext4/mballoc.c | 42 +++++++++++++++++++++++++-----------------
> > fs/ext4/super.c | 3 +++
> > 3 files changed, 54 insertions(+), 20 deletions(-)
> >
> > Index: linux-2.6.28-rc2/fs/ext4/inode.c
> > ===================================================================
> > --- linux-2.6.28-rc2.orig/fs/ext4/inode.c 2008-11-06 13:36:16.000000000 -0800
> > +++ linux-2.6.28-rc2/fs/ext4/inode.c 2008-11-06 14:03:35.000000000 -0800
> > @@ -994,7 +994,9 @@ static void ext4_da_update_reserve_space
> > {
> > struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> > int total, mdb, mdb_free;
> > + int claim_quota, free_quota = 0;
> >
> > + claim_quota = used;
> > spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
> > /* recalculate the number of metablocks still need to be reserved */
> > total = EXT4_I(inode)->i_reserved_data_blocks - used;
> > @@ -1007,6 +1009,8 @@ static void ext4_da_update_reserve_space
> > if (mdb_free) {
> > /* Account for allocated meta_blocks */
> > mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
> > + free_quota = mdb_free;
> > + claim_quota += EXT4_I(inode)->i_allocated_meta_blocks;
> >
> > /* update fs dirty blocks counter */
> > percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
> > @@ -1017,8 +1021,14 @@ static void ext4_da_update_reserve_space
> > /* update per-inode reservations */
> > BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks);
> > EXT4_I(inode)->i_reserved_data_blocks -= used;
> > -
> > spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
> > +
> > + /*
> > + * free those over-booking quota for metadata blocks
> > + */
> > +
> > + if (free_quota)
> > + DQUOT_RELEASE_RSV_BLOCK(inode, free_quota);
> claim_quota seems to be unused here and I'm not sure we need it for
> anything...
>
Thanks for catching this, I will remove that variable.
> > }
> >
> > /*
> > @@ -1514,8 +1524,8 @@ static int ext4_journalled_write_end(str
> > static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
> > {
> > int retries = 0;
> > - struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> > - unsigned long md_needed, mdblocks, total = 0;
> > + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> > + unsigned long md_needed, mdblocks, total = 0;
> >
> > /*
> > * recalculate the amount of metadata blocks to reserve
> > @@ -1531,12 +1541,23 @@ repeat:
> > md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
> > total = md_needed + nrblocks;
> >
> > + /*
> > + * Make quota reservation here to prevent quota overflow
> > + * later. Real quota accounting is done at pages writeout
> > + * time.
> > + */
> > + if (DQUOT_RESERVE_BLOCK(inode, total)) {
> > + spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
> > + return -EDQUOT;
> > + }
> > +
> > if (ext4_claim_free_blocks(sbi, total)) {
> > spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
> > if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
> > yield();
> > goto repeat;
> > }
> > + DQUOT_RELEASE_RSV_BLOCK(inode, total);
> > return -ENOSPC;
> > }
> > EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
> > @@ -1590,6 +1611,8 @@ static void ext4_da_release_space(struct
> > BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
> > EXT4_I(inode)->i_reserved_meta_blocks = mdb;
> > spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
> > +
> > + DQUOT_RELEASE_RSV_BLOCK(inode, release);
> > }
> >
> > static void ext4_da_page_release_reservation(struct page *page,
> > Index: linux-2.6.28-rc2/fs/ext4/super.c
> > ===================================================================
> > --- linux-2.6.28-rc2.orig/fs/ext4/super.c 2008-11-06 13:36:16.000000000 -0800
> > +++ linux-2.6.28-rc2/fs/ext4/super.c 2008-11-06 14:02:57.000000000 -0800
> > @@ -795,6 +795,9 @@ static struct dquot_operations ext4_quot
> > .initialize = ext4_dquot_initialize,
> > .drop = ext4_dquot_drop,
> > .alloc_space = dquot_alloc_space,
> > + .reserve_space = dquot_reserve_space,
> > + .claim_space = dquot_claim_space,
> > + .release_rsv = dquot_release_reserved_space,
> > .alloc_inode = dquot_alloc_inode,
> > .free_space = dquot_free_space,
> > .free_inode = dquot_free_inode,
> > Index: linux-2.6.28-rc2/fs/ext4/mballoc.c
> > ===================================================================
> > --- linux-2.6.28-rc2.orig/fs/ext4/mballoc.c 2008-11-06 13:36:16.000000000 -0800
> > +++ linux-2.6.28-rc2/fs/ext4/mballoc.c 2008-11-06 14:03:35.000000000 -0800
> > @@ -2887,9 +2887,11 @@ ext4_mb_mark_diskspace_used(struct ext4_
> > if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED))
> > /* release all the reserved blocks if non delalloc */
> > percpu_counter_sub(&sbi->s_dirtyblocks_counter, reserv_blks);
> > - else
> > + else {
> > percpu_counter_sub(&sbi->s_dirtyblocks_counter,
> > ac->ac_b_ex.fe_len);
> > + DQUOT_CLAIM_BLOCK(ac->ac_inode, ac->ac_b_ex.fe_len);
> > + }
> >
> > if (sbi->s_log_groups_per_flex) {
> > ext4_group_t flex_group = ext4_flex_group(sbi,
> > @@ -4286,15 +4288,24 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t
> > struct ext4_sb_info *sbi;
> > struct super_block *sb;
> > ext4_fsblk_t block = 0;
> > - unsigned long inquota;
> > + unsigned long inquota = 0;
> > unsigned long reserv_blks = 0;
> >
> > sb = ar->inode->i_sb;
> > sbi = EXT4_SB(sb);
> >
> > - if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag) {
> > + /*
> > + * For delayed allocation, we could skip the ENOSPC and
> > + * EDQUOT check, as blocks and quotas have been already
> > + * reserved when data being copied into pagecache.
> > + */
> > + if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
> > + ar->flags |= EXT4_MB_DELALLOC_RESERVED;
> > + else {
> > /*
> > - * With delalloc we already reserved the blocks
> > + * Without delayed allocation we need to verify
> > + * there is enough free blocks to do block allocation
> > + * and verify allocation doesn't exceed the quota limits.
> > */
> > while (ar->len && ext4_claim_free_blocks(sbi, ar->len)) {
> > /* let others to free the space */
> > @@ -4306,19 +4317,16 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t
> > return 0;
> > }
> > reserv_blks = ar->len;
> > + while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
> > + ar->flags |= EXT4_MB_HINT_NOPREALLOC;
> > + ar->len--;
> > + }
> > + if (ar->len == 0) {
> > + *errp = -EDQUOT;
> > + return 0;
> > + }
> > + inquota = ar->len;
> > }
> > - while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
> > - ar->flags |= EXT4_MB_HINT_NOPREALLOC;
> > - ar->len--;
> > - }
> > - if (ar->len == 0) {
> > - *errp = -EDQUOT;
> > - return 0;
> > - }
> > - inquota = ar->len;
> > -
> > - if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
> > - ar->flags |= EXT4_MB_DELALLOC_RESERVED;
> >
> > ac = kmem_cache_alloc(ext4_ac_cachep, GFP_NOFS);
> > if (!ac) {
> > @@ -4380,7 +4388,7 @@ repeat:
> > out2:
> > kmem_cache_free(ext4_ac_cachep, ac);
> > out1:
> > - if (ar->len < inquota)
> > + if (inquota && ar->len < inquota)
> > DQUOT_FREE_BLOCK(ar->inode, inquota - ar->len);
> >
> > return block;
> >
> >
>
> Honza
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