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Date: Mon, 07 Dec 2009 16:00:33 -0800
From: Mingming <cmm@...ibm.com>
To: Dmitry Monakhov <dmonakhov@...nvz.org>
Cc: linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/4] ext4: delalloc quota fixes
On Tue, 2009-11-24 at 01:58 +0300, Dmitry Monakhov wrote:
> This patch fix most visible problems with delalloc+quota issues
> - ext4_get_reserved_space() must return bytes instead of blocks.
> - Claim allocated meta blocks. Do it as we do for data blocks
> but delay it untill proper moment.
> - Move space claiming to ext4_da_update_reserve_space()
> Only here we do know what we are dealing with data or metadata
>
Thanks for sending the first fix, I am actually surprisely to know the
fix didn't get merged before, as Jan has pointed this out when he review
the original patch and I have get this fixed...somehow the latest patch
wasn't being picked at the end.
here it is.
http://marc.info/?l=linux-ext4&m=123185939602949&w=2
About the second and third issue you are trying to fix here... I think
the current code does what you want already.
The current code does reserve quota for metadata blocks at
ext4_da_update_reserve_space() already and delay the quota claim at the
later time when metadata blocks are really allocated (via
ext4_mb_mark_diskspace_used), extra reserved quota for metadata blocks
will get freed at ext4_da_update_reserve_space().
ext4_mb_mark_diskspace_used() is called for every block allocation
including medatadata allocation, so we won't miss quota claim for
metadata there.
The reason that I keep all quota claim immediately at the block
allocation time via ext4_mb_mark_diskspace_used() is to keep the block
allocation space accounting/dirty/delayed block space accounting/quota
accounting in the same place; Plus, when ext4_da_update_reserve_space()
called, the number of blocks passed is the number of blocks mapped, may
not necessarilly the the number of blocks just new allocated.
cheers,
Mingming
put the space claiming under
> The most useful test case for delalloc+quota is concurent tasks
> with write+truncate vs chown for a same file.
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> ---
> fs/ext4/inode.c | 12 ++++++++----
> fs/ext4/mballoc.c | 6 ------
> 2 files changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index ab22297..e642cdb 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1057,7 +1057,7 @@ qsize_t ext4_get_reserved_space(struct inode *inode)
> EXT4_I(inode)->i_reserved_meta_blocks;
> spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
>
> - return total;
> + return (total << inode->i_blkbits);
> }
> /*
> * Calculate the number of metadata blocks need to reserve
> @@ -1096,7 +1096,7 @@ static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
> static void ext4_da_update_reserve_space(struct inode *inode, int used)
> {
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> - int total, mdb, mdb_free;
> + int total, mdb, mdb_free, mdb_claim = 0;
>
> spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
> /* recalculate the number of metablocks still need to be reserved */
> @@ -1109,7 +1109,9 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
>
> if (mdb_free) {
> /* Account for allocated meta_blocks */
> - mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
> + mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks;
> + BUG_ON(mdb_free < mdb_claim);
> + mdb_free -= mdb_claim;
>
> /* update fs dirty blocks counter */
> percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
> @@ -1119,7 +1121,9 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
>
> /* update per-inode reservations */
> BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks);
> - EXT4_I(inode)->i_reserved_data_blocks -= used;
> + EXT4_I(inode)->i_reserved_data_blocks -= used;
> + percpu_counter_sub(&sbi->s_dirtyblocks_counter, used + mdb_claim);
> + vfs_dq_claim_block(inode, used + mdb_claim);
> spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
>
> /*
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index bba1282..d4c52db 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2750,12 +2750,6 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
> 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 {
> - percpu_counter_sub(&sbi->s_dirtyblocks_counter,
> - ac->ac_b_ex.fe_len);
> - /* convert reserved quota blocks to real quota blocks */
> - vfs_dq_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,
--
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