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SubjectRe: [PATCH] f2fs: do not trim preallocated blocks when truncating after i_size
On Fri, Jun 05, 2015 at 06:34:02PM +0800, Chao Yu wrote:
> When we perform generic/092 in xfstests, output is like below:
>
> XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> 0: [0..10239]: data
> 0: [0..10239]: data
> -1: [10240..20479]: unwritten
> +1: [10240..14335]: unwritten
>
> This is because with this testcase, we redefine the regulation for
> truncate in perallocated space past i_size as below:
>
> "There was some confused about what the fs was supposed to do when you
> truncate at i_size with preallocated space past i_size. We decided on the
> following things.
>
> 1) truncate(i_size) will trim all blocks past i_size.
> 2) truncate(x) where x > i_size will not trim all blocks past i_size.
> "
>
> This method is used in xfs, and then ext4/btrfs will follow the rule.
>
> This patch fixes to follow the new rule for f2fs.
>
> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> ---
> fs/f2fs/file.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 4d42d66..85f97af 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -651,16 +651,16 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
> f2fs_get_encryption_info(inode))
> return -EACCES;
>
> - if (attr->ia_size != i_size_read(inode)) {
> + if (attr->ia_size <= i_size_read(inode)) {
> truncate_setsize(inode, attr->ia_size);
> f2fs_truncate(inode);
> f2fs_balance_fs(F2FS_I_SB(inode));
> } else {
> /*
> - * giving a chance to truncate blocks past EOF which
> - * are fallocated with FALLOC_FL_KEEP_SIZE.
> + * do not trim all blocks after i_size if target size is
> + * larger than i_size.
> */
> - f2fs_truncate(inode);
> + truncate_setsize(inode, attr->ia_size);

So, we can do:
truncate_setsize();

if (attr->ia_size <= i_size_read(inode)) {
f2fs_truncate(inode);
f2fs_balance_fs();
}

Right?

> }
> }
>
> --
> 2.4.2


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