On Fri 26-04-19 15:11:25, Andreas Gruenbacher wrote:
> In iomap_write_end, we are not holding a page reference anymore when
> calling the page_done callback, but the callback needs that reference to
> access the page.
>
> To fix that, move the put_page call in __generic_write_end into the
> callers of __generic_write_end. Then, in iomap_write_end, put the page
> after calling the page_done callback.
>
> Reported-by: Jan Kara <jack@xxxxxxx>
> Fixes: 63899c6f8851 ("iomap: add a page_done callback")
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/buffer.c | 5 +++--
> fs/iomap.c | 12 ++++++++++--
> 2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index ce357602f471..6e2c95160ce3 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2104,7 +2104,6 @@ int __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
> }
>
> unlock_page(page);
> - put_page(page);
>
> if (old_size < pos)
> pagecache_isize_extended(inode, old_size, pos);
> @@ -2160,7 +2159,9 @@ int generic_write_end(struct file *file, struct address_space *mapping,
> struct page *page, void *fsdata)
> {
> copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
> - return __generic_write_end(mapping->host, pos, copied, page);
> + copied = __generic_write_end(mapping->host, pos, copied, page);
> + put_page(page);
> + return copied;
> }
> EXPORT_SYMBOL(generic_write_end);
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 97cb9d486a7d..3e4652dac9d9 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -765,6 +765,14 @@ iomap_write_end_inline(struct inode *inode, struct page *page,
> return copied;
> }
>
> +static int
> +buffer_write_end(struct address_space *mapping, loff_t pos, loff_t len,
> + unsigned copied, struct page *page)
> +{
> + copied = block_write_end(NULL, mapping, pos, len, copied, page, NULL);
> + return __generic_write_end(mapping->host, pos, copied, page);
> +}
> +
> static int
> iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
> unsigned copied, struct page *page, struct iomap *iomap)
> @@ -774,14 +782,14 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
> if (iomap->type == IOMAP_INLINE) {
> ret = iomap_write_end_inline(inode, page, iomap, pos, copied);
> } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) {
> - ret = generic_write_end(NULL, inode->i_mapping, pos, len,
> - copied, page, NULL);
> + ret = buffer_write_end(inode->i_mapping, pos, len, copied, page);
> } else {
> ret = __iomap_write_end(inode, pos, len, copied, page, iomap);
> }
>
> if (iomap->page_done)
> iomap->page_done(inode, pos, copied, page, iomap);
> + put_page(page);
>
> if (ret < len)
> iomap_write_failed(inode, pos, len);
> --
> 2.20.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
