On Wed, Jun 26, 2019 at 03:23:33PM +0200, Andreas Gruenbacher wrote:
> Marking the inode dirty for each page copied into the page cache can be
> very inefficient for file systems that use the VFS dirty inode tracking,
> and is completely pointless for those that don't use the VFS dirty inode
> tracking. So instead, only set an iomap flag when changing the in-core
> inode size, and open code the rest of __generic_write_end.
>
> Partially based on code from Christoph Hellwig.
>
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/gfs2/bmap.c | 2 ++
> fs/iomap.c | 15 ++++++++++++++-
> include/linux/iomap.h | 1 +
> 3 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
> index 93ea1d529aa3..f4b895fc632d 100644
> --- a/fs/gfs2/bmap.c
> +++ b/fs/gfs2/bmap.c
> @@ -1182,6 +1182,8 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
>
> if (ip->i_qadata && ip->i_qadata->qa_qd_num)
> gfs2_quota_unlock(ip);
> + if (iomap->flags & IOMAP_F_SIZE_CHANGED)
> + mark_inode_dirty(inode);
> gfs2_write_unlock(inode);
>
> out:
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 12654c2e78f8..97569064faaa 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -777,6 +777,7 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
> unsigned copied, struct page *page, struct iomap *iomap)
> {
> const struct iomap_page_ops *page_ops = iomap->page_ops;
> + loff_t old_size = inode->i_size;
> int ret;
>
> if (iomap->type == IOMAP_INLINE) {
> @@ -788,7 +789,19 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
> ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
> }
>
> - __generic_write_end(inode, pos, ret, page);
> + /*
> + * Update the in-memory inode size after copying the data into the page
> + * cache. It's up to the file system to write the updated size to disk,
> + * preferably after I/O completion so that no stale data is exposed.
> + */
> + if (pos + ret > old_size) {
> + i_size_write(inode, pos + ret);
> + iomap->flags |= IOMAP_F_SIZE_CHANGED;
> + }
> + unlock_page(page);
> +
> + if (old_size < pos)
> + pagecache_isize_extended(inode, old_size, pos);
> if (page_ops && page_ops->page_done)
> page_ops->page_done(inode, pos, copied, page, iomap);
> put_page(page);
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 2103b94cb1bf..1df9ea187a9a 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -35,6 +35,7 @@ struct vm_fault;
> #define IOMAP_F_NEW 0x01 /* blocks have been newly allocated */
> #define IOMAP_F_DIRTY 0x02 /* uncommitted metadata */
> #define IOMAP_F_BUFFER_HEAD 0x04 /* file system requires buffer heads */
> +#define IOMAP_F_SIZE_CHANGED 0x08 /* file size has changed */
>
> /*
> * Flags that only need to be reported for IOMAP_REPORT requests:
> --
> 2.20.1
>
