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    SubjectRe: [PATCH v20 03/32] splice: Make direct_read_splice() limit to eof where appropriate
    On Fri, May 19, 2023 at 11:27:51PM +0100, David Howells wrote:
    > ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
    > struct pipe_inode_info *pipe, size_t len,
    > unsigned int flags)
    > {
    > if (unlikely(*ppos >= in->f_mapping->host->i_sb->s_maxbytes))
    > return 0;
    > if (unlikely(!len))
    > return 0;
    > return filemap_splice_read(in, ppos, pipe, len, flags);
    > }
    >
    > so I wonder if the tests in generic_file_splice_read() can be folded into
    > vfs_splice_read(), pointers to generic_file_splice_read() be replaced with
    > pointers to filemap_splice_read() and generic_file_splice_read() just be
    > removed.
    >
    > I suspect we can't quite do this because of the *ppos check - but I wonder if
    > that's actually necessary since filemap_splice_read() checks against
    > i_size... or if the check can be moved there if we definitely want to do it.
    >
    > Certainly, the zero-length check can be done in vfs_splice_read().

    The zero length check makes sense in vfs_splice_read. The ppos check
    I think makes sense for filemap_splice_read - after all we're dealing
    with the page cache here, and the page cache needs a working maxbytes
    and i_size. What callers of filemap_splice_read that don't have the
    checks do you have in your tree right now and how did you end up with
    them?

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