diff options
| -rw-r--r-- | fs/nfs/pnfs.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index ce46a417e500..ee60c42b72b3 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -1433,33 +1433,37 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev, struct nfs_page *req) { unsigned int size; - u64 end; + u64 seg_end, req_start, seg_left; size = nfs_generic_pg_test(pgio, prev, req); if (!size) return 0; /* - * Test if a nfs_page is fully contained in the pnfs_layout_range. - * Note that this test makes several assumptions: - * - that the previous nfs_page in the struct nfs_pageio_descriptor - * is known to lie within the range. - * - that the nfs_page being tested is known to be contiguous with the - * previous nfs_page. - * - Layout ranges are page aligned, so we only have to test the - * start offset of the request. + * 'size' contains the number of bytes left in the current page (up + * to the original size asked for in @req->wb_bytes). + * + * Calculate how many bytes are left in the layout segment + * and if there are less bytes than 'size', return that instead. * * Please also note that 'end_offset' is actually the offset of the * first byte that lies outside the pnfs_layout_range. FIXME? * */ if (pgio->pg_lseg) { - end = end_offset(pgio->pg_lseg->pls_range.offset, - pgio->pg_lseg->pls_range.length); - WARN_ON_ONCE(req_offset(req) > end); - if (req_offset(req) >= end) + seg_end = end_offset(pgio->pg_lseg->pls_range.offset, + pgio->pg_lseg->pls_range.length); + req_start = req_offset(req); + WARN_ON_ONCE(req_start > seg_end); + /* start of request is past the last byte of this segment */ + if (req_start >= seg_end) return 0; - size = min((unsigned int)(end - req_offset(req)), size); + + /* adjust 'size' iff there are fewer bytes left in the + * segment than what nfs_generic_pg_test returned */ + seg_left = seg_end - req_start; + if (seg_left < size) + size = (unsigned int)seg_left; } return size; |