On Fri, Jun 17, 2022 at 11:04 AM Phillip Lougher
<phillip@xxxxxxxxxxxxxxx> wrote:
>
> This patch adds a function which can be used to read fragments in the
> readahead call.
>
> This function is necessary because filesystems built with the -tailends
> (or -always-use-fragments) option may have fragments present which
> cannot be currently handled.
>
> Signed-off-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
> ---
> fs/squashfs/file.c | 35 +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
> index f0c64ee272d5..3a4cce16d7da 100644
> --- a/fs/squashfs/file.c
> +++ b/fs/squashfs/file.c
> @@ -497,6 +497,41 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
> return res;
> }
>
> +static unsigned int squashfs_readahead_fragment(struct page **page,
hi Phillip,
Since the buffer->error is int, and also the variable to receive the
value is res, I modified it when sending it with the series, though it
won't affect the result.
> + unsigned int pages, unsigned int expected)
> +{
> + struct inode *inode = page[0]->mapping->host;
> + struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
> + squashfs_i(inode)->fragment_block,
> + squashfs_i(inode)->fragment_size);
> + struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> + unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
> +
> + if (buffer->error)
> + goto out;
> +
> + expected += squashfs_i(inode)->fragment_offset;
> +
> + for (n = 0; n < pages; n++) {
> + unsigned int base = (page[n]->index & mask) << PAGE_SHIFT;
> + unsigned int offset = base + squashfs_i(inode)->fragment_offset;
> +
> + if (expected > offset) {
> + unsigned int avail = min_t(unsigned int, expected -
> + offset, PAGE_SIZE);
> +
> + squashfs_fill_page(page[n], buffer, offset, avail);
> + }
> +
> + unlock_page(page[n]);
> + put_page(page[n]);
> + }
> +
> +out:
> + squashfs_cache_put(buffer);
> + return buffer->error;
> +}
> +
> static void squashfs_readahead(struct readahead_control *ractl)
> {
> struct inode *inode = ractl->mapping->host;
> --
> 2.34.1
>
