On Fri, Jan 11, 2013 at 08:57:22PM -0600, Eric Sandeen
wrote:> truncate() vs. ftruncate() differ in the VFS; truncate()
> doesn''t set (ATTR_CTIME | ATTR_MTIME), and it''s up to the
> fs to do the timestamp updates if the size changes.
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> Hm, am I breaking the rules by updating the vfs inode fields
> before the transaction starts?
IMO it is ok since we''ll modify these info in btree during a
transaction.
thanks,
liubo
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 16d9e8e..af1ab2d 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -88,7 +88,7 @@ static unsigned char btrfs_type_by_mode[S_IFMT >>
S_SHIFT] = {
> [S_IFLNK >> S_SHIFT] = BTRFS_FT_SYMLINK,
> };
>
> -static int btrfs_setsize(struct inode *inode, loff_t newsize);
> +static int btrfs_setsize(struct inode *inode, struct iattr *attr);
> static int btrfs_truncate(struct inode *inode);
> static int btrfs_finish_ordered_io(struct btrfs_ordered_extent
*ordered_extent);
> static noinline int cow_file_range(struct inode *inode,
> @@ -3748,16 +3748,27 @@ next:
> return err;
> }
>
> -static int btrfs_setsize(struct inode *inode, loff_t newsize)
> +static int btrfs_setsize(struct inode *inode, struct iattr *attr)
> {
> struct btrfs_root *root = BTRFS_I(inode)->root;
> struct btrfs_trans_handle *trans;
> loff_t oldsize = i_size_read(inode);
> + loff_t newsize = attr->ia_size;
> + int mask = attr->ia_valid;
> int ret;
>
> if (newsize == oldsize)
> return 0;
>
> + /*
> + * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a
> + * special case where we need to update the times despite not having
> + * these flags set. For all other operations the VFS set these flags
> + * explicitly if it wants a timestamp update.
> + */
> + if (newsize != oldsize && (!(mask & (ATTR_CTIME |
ATTR_MTIME))))
> + inode->i_ctime = inode->i_mtime = current_fs_time(inode->i_sb);
> +
> if (newsize > oldsize) {
> truncate_pagecache(inode, oldsize, newsize);
> ret = btrfs_cont_expand(inode, oldsize, newsize);
> @@ -3805,7 +3816,7 @@ static int btrfs_setattr(struct dentry *dentry,
struct iattr *attr)
> return err;
>
> if (S_ISREG(inode->i_mode) && (attr->ia_valid &
ATTR_SIZE)) {
> - err = btrfs_setsize(inode, attr->ia_size);
> + err = btrfs_setsize(inode, attr);
> if (err)
> return err;
> }
>
> --
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