Reviewed-by: Sage Weil <sage@xxxxxxxxxxx> On Sat, 30 Mar 2013, Alex Elder wrote: > Currently ceph_msg_data_pages_advance() allows the page offset value > to be PAGE_SIZE, apparently assuming ceph_msg_data_pages_next() will > treat it as 0. But that doesn't happen, and the result led to a > helpful assertion failure. > > Change ceph_msg_data_pages_advance() to truncate the offset to 0 > before returning if it reaches PAGE_SIZE. > > Make a few other minor adjustments in this area (comments and a > better assertion) while modifying it. > > This resolves a second issue described in: > http://tracker.ceph.com/issues/4598 > > Signed-off-by: Alex Elder <elder@xxxxxxxxxxx> > --- > net/ceph/messenger.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c > index 24f3aba..198b902 100644 > --- a/net/ceph/messenger.c > +++ b/net/ceph/messenger.c > @@ -766,8 +766,8 @@ static struct page *ceph_msg_data_bio_next(struct > ceph_msg_data *data, > *length = cursor->resid; > else > *length = (size_t) (bio_vec->bv_len - cursor->vector_offset); > - BUG_ON(*length > PAGE_SIZE); > BUG_ON(*length > cursor->resid); > + BUG_ON(*page_offset + *length > PAGE_SIZE); > > return bio_vec->bv_page; > } > @@ -876,14 +876,13 @@ static bool ceph_msg_data_pages_advance(struct > ceph_msg_data *data, > /* Advance the cursor page offset */ > > cursor->resid -= bytes; > - cursor->page_offset += bytes; > - if (!bytes || cursor->page_offset & ~PAGE_MASK) > + cursor->page_offset = (cursor->page_offset + bytes) & ~PAGE_MASK; > + if (!bytes || cursor->page_offset) > return false; /* more bytes to process in the current page */ > > - /* Move on to the next page */ > + /* Move on to the next page; offset is already at 0 */ > > BUG_ON(cursor->page_index >= cursor->page_count); > - cursor->page_offset = 0; > cursor->page_index++; > cursor->last_piece = cursor->resid <= PAGE_SIZE; > > @@ -934,8 +933,9 @@ static struct page > *ceph_msg_data_pagelist_next(struct ceph_msg_data *data, > BUG_ON(!cursor->page); > BUG_ON(cursor->offset + cursor->resid != pagelist->length); > > + /* offset of first page in pagelist is always 0 */ > *page_offset = cursor->offset & ~PAGE_MASK; > - if (cursor->last_piece) /* pagelist offset is always 0 */ > + if (cursor->last_piece) > *length = cursor->resid; > else > *length = PAGE_SIZE - *page_offset; > @@ -961,7 +961,7 @@ static bool ceph_msg_data_pagelist_advance(struct > ceph_msg_data *data, > > cursor->resid -= bytes; > cursor->offset += bytes; > - /* pagelist offset is always 0 */ > + /* offset of first page in pagelist is always 0 */ > if (!bytes || cursor->offset & ~PAGE_MASK) > return false; /* more bytes to process in the current page */ > > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
