Hi Christoph,
On Thu, Aug 21, 2014 at 11:07 AM, Christoph Hellwig <hch@xxxxxx> wrote:
> The VFS handles attributes on truncate in a strange way, fix NFS to handle
> it properly by copying a small code sniplet from XFS.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/nfs/inode.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 577a36f..5bbd991 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -505,8 +505,28 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr)
> attr->ia_valid &= ~ATTR_MODE;
>
> if (attr->ia_valid & ATTR_SIZE) {
> - if (!S_ISREG(inode->i_mode) || attr->ia_size == i_size_read(inode))
> + if (!S_ISREG(inode->i_mode) ||
> + attr->ia_size == i_size_read(inode))
> attr->ia_valid &= ~ATTR_SIZE;
> +
> + /*
> + * Only change the c/mtime if we are changing the size or we
> + * are explicitly asked to change it. This handles the
> + * semantic difference between truncate() and ftruncate() as
> + * implemented in the VFS.
> + *
> + * 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 (attr->ia_size != i_size_read(inode) &&
> + !(attr->ia_valid & (ATTR_CTIME | ATTR_MTIME))) {
> + attr->ia_ctime = attr->ia_mtime =
> + current_fs_time(inode->i_sb);
> + attr->ia_valid |= ATTR_CTIME | ATTR_MTIME;
> + }
> }
>
We shouldn't need to set attr->ia_ctime/ia_mtime above. We should set
the file time to the server clock time.
Also note that instead of checking attr->ia_size !=
i_size_read(inode), the above should check attr->ia_valid & ATTR_SIZE
due to the optimisation above.
--
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@xxxxxxxxxxxxxxx
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