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    Subject[PATCH v2] netfs: Miscellaneous fixes
    Date
    Okay, how about the attached, then?

    David
    ---
    netfs: Miscellaneous fixes

    Fix some miscellaneous things in the new netfs lib[1]:

    (1) The kerneldoc for netfs_readpage() shouldn't say netfs_page().

    (2) netfs_readpage() can get an integer overflow on 32-bit when it
    multiplies page_index(page) by PAGE_SIZE. It should use
    page_file_offset() instead.

    (3) netfs_write_begin() should use page_offset() to avoid the same
    overflow.

    Note that netfs_readpage() needs to use page_file_offset() rather than
    page_offset() as it may see swap-over-NFS.

    Reported-by: Matthew Wilcox <willy@infradead.org>
    Signed-off-by: David Howells <dhowells@redhat.com>
    Link: https://lore.kernel.org/r/161789062190.6155.12711584466338493050.stgit@warthog.procyon.org.uk/ [1]
    ---
    fs/netfs/read_helper.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
    index 1d3b50c5db6d..193841d03de0 100644
    --- a/fs/netfs/read_helper.c
    +++ b/fs/netfs/read_helper.c
    @@ -933,7 +933,7 @@ void netfs_readahead(struct readahead_control *ractl,
    EXPORT_SYMBOL(netfs_readahead);

    /**
    - * netfs_page - Helper to manage a readpage request
    + * netfs_readpage - Helper to manage a readpage request
    * @file: The file to read from
    * @page: The page to read
    * @ops: The network filesystem's operations for the helper to use
    @@ -968,7 +968,7 @@ int netfs_readpage(struct file *file,
    return -ENOMEM;
    }
    rreq->mapping = page_file_mapping(page);
    - rreq->start = page_index(page) * PAGE_SIZE;
    + rreq->start = page_file_offset(page);
    rreq->len = thp_size(page);

    if (ops->begin_cache_operation) {
    @@ -1106,7 +1106,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
    if (!rreq)
    goto error;
    rreq->mapping = page->mapping;
    - rreq->start = page->index * PAGE_SIZE;
    + rreq->start = page_offset(page);
    rreq->len = thp_size(page);
    rreq->no_unlock_page = page->index;
    __set_bit(NETFS_RREQ_NO_UNLOCK_PAGE, &rreq->flags);
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