On Thu, 23 May 2013 17:53:41 -0400
Scott Mayhew <smayhew@xxxxxxxxxx> wrote:
> Currently nfs_updatepage allows a write to be extended to cover a full
> page only if we don't have a byte range lock on the file... but if we've
> got the whole file locked, then we should be allowed to extend the
> write.
>
> Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx>
> ---
> fs/nfs/write.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index a2c7c28..f35fb4f 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -908,13 +908,16 @@ int nfs_updatepage(struct file *file, struct page *page,
> file->f_path.dentry->d_name.name, count,
> (long long)(page_file_offset(page) + offset));
>
> - /* If we're not using byte range locks, and we know the page
> + /* If we're not using byte range locks (or if the range of the
> + * lock covers the entire file), and we know the page
> * is up to date, it may be more efficient to extend the write
> * to cover the entire page in order to avoid fragmentation
> * inefficiencies.
> */
> if (nfs_write_pageuptodate(page, inode) &&
> - inode->i_flock == NULL &&
> + (inode->i_flock == NULL ||
> + (inode->i_flock->fl_start == 0 &&
> + inode->i_flock->fl_end == OFFSET_MAX)) &&
> !(file->f_flags & O_DSYNC)) {
> count = max(count + offset, nfs_page_length(page));
> offset = 0;
Sounds like a reasonable proposition, but I think you might need to do
more vetting of the locks...
For instance, does it make sense to do this if it's a F_RDLCK? Also,
you're only looking at the first lock in the i_flock list. Might it
make more sense to walk the list and see whether the page might be
entirely covered by a lock that doesn't extend over the whole file?
--
Jeff Layton <jlayton@xxxxxxxxxx>
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