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Message-ID: <20080621104814.GB9584@skywalker>
Date: Sat, 21 Jun 2008 16:18:14 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: Mingming <cmm@...ibm.com>
Cc: linux-ext4@...r.kernel.org
Subject: Re: [PATCH] delalloc: add quota handling
On Fri, Jun 20, 2008 at 06:14:38PM -0700, Mingming wrote:
> Correct quota handling in delayed allocation. With this patch,
> the quota for blocks are counted at block reservation time when
> the fs free blocks counter are updated, instead of at later
> block allocation time.
>
> Signed-off-by: Mingming Cao <cmm@...ibm.com>
> ---
> fs/ext4/balloc.c | 8 +++++---
> fs/ext4/inode.c | 5 +++++
> fs/ext4/mballoc.c | 22 ++++++++++++----------
> 3 files changed, 22 insertions(+), 13 deletions(-)
>
> Index: linux-2.6.26-rc6/fs/ext4/balloc.c
> ===================================================================
> --- linux-2.6.26-rc6.orig/fs/ext4/balloc.c 2008-06-20 18:06:02.000000000 -0700
> +++ linux-2.6.26-rc6/fs/ext4/balloc.c 2008-06-20 18:06:05.000000000 -0700
> @@ -1716,7 +1716,8 @@ ext4_fsblk_t ext4_old_new_blocks(handle_
> /*
> * Check quota for allocation of this block.
> */
> - if (DQUOT_ALLOC_BLOCK(inode, num)) {
> + if (!EXT4_I(inode)->i_delalloc_reserved_flag &&
> + DQUOT_ALLOC_BLOCK(inode, num)) {
> *errp = -EDQUOT;
> return 0;
> }
> @@ -1928,7 +1929,8 @@ allocated:
>
> *errp = 0;
> brelse(bitmap_bh);
> - DQUOT_FREE_BLOCK(inode, *count-num);
> + if (!EXT4_I(inode)->i_delalloc_reserved_flag)
> + DQUOT_FREE_BLOCK(inode, *count-num);
> *count = num;
> return ret_block;
>
> @@ -1942,7 +1944,7 @@ out:
> /*
> * Undo the block allocation
> */
> - if (!performed_allocation)
> + if (!EXT4_I(inode)->i_delalloc_reserved_flag && !performed_allocation)
> DQUOT_FREE_BLOCK(inode, *count);
> brelse(bitmap_bh);
> return 0;
> Index: linux-2.6.26-rc6/fs/ext4/inode.c
> ===================================================================
> --- linux-2.6.26-rc6.orig/fs/ext4/inode.c 2008-06-20 18:06:02.000000000 -0700
> +++ linux-2.6.26-rc6/fs/ext4/inode.c 2008-06-20 18:06:05.000000000 -0700
> @@ -1450,6 +1450,9 @@ static int ext4_da_reserve_space(struct
> return -ENOSPC;
> }
>
> + if (DQUOT_ALLOC_BLOCK(inode, total))
> + return -EDQUOT;
> +
We should not be counting meta-data blocks for quota. I guess this
should be
if (DQUOT_ALLOC_BLOCK(inode, nrblocks))
return -EDQUOT;
Also i think we should be doing quota check first. In mballoc we request
for less number of blocks if quota is limited. In case of
ext4_da_reserve_space even though we get called only with one block
reservation request to make the code correct i guess we should do the
mballoc equivalent.
while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
ar->flags |= EXT4_MB_HINT_NOPREALLOC;
ar->len--;
}
Also in mballoc we should do some test for free quota blocks and
should set the EXT4_MB_HINT_NOPREALLOC even for delalloc.
> /* reduce fs free blocks counter */
> percpu_counter_sub(&sbi->s_freeblocks_counter, total);
>
> @@ -1479,6 +1482,8 @@ void ext4_da_release_space(struct inode
>
> release = to_free + mdb_free;
>
> + DQUOT_FREE_BLOCK(inode, release);
This should be
DQUOT_FREE_BLOCK(inode, to_free);
> +
> /* update fs free blocks counter for truncate case */
> percpu_counter_add(&sbi->s_freeblocks_counter, release);
>
> Index: linux-2.6.26-rc6/fs/ext4/mballoc.c
> ===================================================================
> --- linux-2.6.26-rc6.orig/fs/ext4/mballoc.c 2008-06-20 18:06:01.000000000 -0700
> +++ linux-2.6.26-rc6/fs/ext4/mballoc.c 2008-06-20 18:06:05.000000000 -0700
> @@ -4037,7 +4037,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t
> struct super_block *sb;
> ext4_fsblk_t block = 0;
> int freed;
> - int inquota;
> + int inquota = 0;
>
> sb = ar->inode->i_sb;
> sbi = EXT4_SB(sb);
> @@ -4059,15 +4059,17 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t
> return 0;
> }
>
> - 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;
> + if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag) {
> + while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
> + ar->flags |= EXT4_MB_HINT_NOPREALLOC;
> + ar->len--;
> + }
We need to set ar->flags even for delalloc. Otherwise we will try to
normalize the request in mballoc.
> + if (ar->len == 0) {
> + *errp = -EDQUOT;
> + return 0;
> + }
> + inquota = ar->len;
> }
> - inquota = ar->len;
>
> if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
> ar->flags |= EXT4_MB_DELALLOC_RESERVED;
> @@ -4134,7 +4136,7 @@ repeat:
> out2:
> kmem_cache_free(ext4_ac_cachep, ac);
> out1:
> - if (ar->len < inquota)
> + if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag && ar->len < inquota)
> DQUOT_FREE_BLOCK(ar->inode, inquota - ar->len);
>
> return block;
>
>
-aneesh
--
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