Re: [PATCH -v2] btrfs: Use correct values when updating inode i_size on fallocate

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

Hi Chris,

I see that you merged an older version of this patch. But i guess it
still have some issues.

-anesh
On Fri, 22 Jan 2010 11:02:45 +0530, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:
> Even though we allocate more, we should be updating inode i_size
> as per the arguments passed
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
> Changes from V1:
>  We should update i_size only if actual_len and cur_offset are both
>  larger than i_size. Otherwise if actual_len is < i_size and cur_offset > i_size
>  we may end up setting wrong i_size value
> 
>  fs/btrfs/inode.c |   17 ++++++++++++-----
>  1 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 5440bab..ac4cb6b 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -5789,7 +5789,7 @@ out_fail:
>  }
> 
>  static int prealloc_file_range(struct inode *inode, u64 start, u64 end,
> -			       u64 alloc_hint, int mode)
> +			u64 alloc_hint, int mode, loff_t actual_len)
>  {
>  	struct btrfs_trans_handle *trans;
>  	struct btrfs_root *root = BTRFS_I(inode)->root;
> @@ -5798,6 +5798,7 @@ static int prealloc_file_range(struct inode *inode, u64 start, u64 end,
>  	u64 cur_offset = start;
>  	u64 num_bytes = end - start;
>  	int ret = 0;
> +	u64 i_size;
> 
>  	while (num_bytes > 0) {
>  		alloc_size = min(num_bytes, root->fs_info->max_extent);
> @@ -5835,9 +5836,15 @@ static int prealloc_file_range(struct inode *inode, u64 start, u64 end,
>  		inode->i_ctime = CURRENT_TIME;
>  		BTRFS_I(inode)->flags |= BTRFS_INODE_PREALLOC;
>  		if (!(mode & FALLOC_FL_KEEP_SIZE) &&
> -		    cur_offset > inode->i_size) {
> -			i_size_write(inode, cur_offset);
> -			btrfs_ordered_update_i_size(inode, cur_offset, NULL);
> +			(actual_len > inode->i_size) &&
> +			(cur_offset > inode->i_size)) {
> +
> +			if (cur_offset > actual_len)
> +				i_size  = actual_len;
> +			else
> +				i_size = cur_offset;
> +			i_size_write(inode, i_size);
> +			btrfs_ordered_update_i_size(inode, i_size, NULL);
>  		}
> 
>  		ret = btrfs_update_inode(trans, root, inode);
> @@ -5930,7 +5937,7 @@ static long btrfs_fallocate(struct inode *inode, int mode,
>  		     !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
>  			ret = prealloc_file_range(inode,
>  						  cur_offset, last_byte,
> -						  alloc_hint, mode);
> +						alloc_hint, mode, offset+len);
>  			if (ret < 0) {
>  				free_extent_map(em);
>  				break;
> -- 
> 1.6.6.1.383.g5a9f
> 
> --
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