Re: [PATCH -V3 03/11] ext4: Retry block reservation

[Mingming Cao <cmm@us.ibm.com>]

在 2008-08-27三的 20:58 +0530，Aneesh Kumar K.V写道：
> During block reservation if we don't have enough
> blocks left, retry block reservation with smaller
> block count. This make sure we try fallocate
> and DIO with smaller request size and don't fail early.
> The delayed allocation reservation cannot try with smaller
> block count. So retry block reservation to handle temporary
> disk full conditions.  Also print free blocks details if we
> fail block allocation during writepages.
> 
Added to patch queue.
Reviewed-by: Mingming Cao <cmm@us.ibm.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  fs/ext4/balloc.c  |    8 +++++++-
>  fs/ext4/inode.c   |   14 +++++++++++---
>  fs/ext4/mballoc.c |    7 ++++++-
>  3 files changed, 24 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index dc10bfd..5767332 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -1738,10 +1738,16 @@ ext4_fsblk_t ext4_old_new_blocks(handle_t *handle, struct inode *inode,
>  		/*
>  		 * With delalloc we already reserved the blocks
>  		 */
> -		if (ext4_claim_free_blocks(sbi, *count)) {
> +		while (*count && ext4_claim_free_blocks(sbi, *count)) {
> +			/* let others to free the space */
> +			yield();
> +			*count = *count >> 1;
> +		}
> +		if (!*count) {
>  			*errp = -ENOSPC;
>  			return 0;	/*return with ENOSPC error */
>  		}
> +		num = *count;
>  	}
>  	/*
>  	 * Check quota for allocation of this block.
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index d965a05..98a998b 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1521,6 +1521,7 @@ static int ext4_journalled_write_end(struct file *file,
> 
>  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;
> 
> @@ -1529,6 +1530,7 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
>  	 * in order to allocate nrblocks
>  	 * worse case is one extent per block
>  	 */
> +repeat:
>  	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
>  	total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks;
>  	mdblocks = ext4_calc_metadata_amount(inode, total);
> @@ -1539,6 +1541,10 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
> 
>  	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;
> +		}
>  		return -ENOSPC;
>  	}
>  	EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
> @@ -1825,20 +1831,18 @@ static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
>  static int  mpage_da_map_blocks(struct mpage_da_data *mpd)
>  {
>  	int err = 0;
> +	struct buffer_head new;
>  	struct buffer_head *lbh = &mpd->lbh;
>  	sector_t next = lbh->b_blocknr;
> -	struct buffer_head new;
> 
>  	/*
>  	 * We consider only non-mapped and non-allocated blocks
>  	 */
>  	if (buffer_mapped(lbh) && !buffer_delay(lbh))
>  		return 0;
> -
>  	new.b_state = lbh->b_state;
>  	new.b_blocknr = 0;
>  	new.b_size = lbh->b_size;
> -
>  	/*
>  	 * If we didn't accumulate anything
>  	 * to write simply return
> @@ -1871,6 +1875,10 @@ static int  mpage_da_map_blocks(struct mpage_da_data *mpd)
>  				  lbh->b_size >> mpd->inode->i_blkbits, err);
>  		printk(KERN_EMERG "This should not happen.!! "
>  					"Data will be lost\n");
> +		if (err == -ENOSPC) {
> +			printk(KERN_CRIT "Total free blocks count %lld\n",
> +				ext4_count_free_blocks(mpd->inode->i_sb));
> +		}
>  		/* invlaidate all the pages */
>  		ext4_da_block_invalidatepages(mpd, next,
>  				lbh->b_size >> mpd->inode->i_blkbits);
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 4404b46..419009f 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -4397,7 +4397,12 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
>  		/*
>  		 * With delalloc we already reserved the blocks
>  		 */
> -		if (ext4_claim_free_blocks(sbi, ar->len)) {
> +		while (ar->len && ext4_claim_free_blocks(sbi, ar->len)) {
> +			/* let others to free the space */
> +			yield();
> +			ar->len = ar->len >> 1;
> +		}
> +		if (!ar->len) {
>  			*errp = -ENOSPC;
>  			return 0;
>  		}

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