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authorTrond Myklebust <Trond.Myklebust@netapp.com>2011-06-10 21:30:23 +0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2011-06-21 19:54:06 +0400
commit19982ba8562e33083cb5bbb59a74855d8a9624ea (patch)
tree51656f4ff6252a0207a0f42feea147c736474171 /fs/nfs
parent8f7d5efbef8718a774ac5e347b4ec069f17fd9b4 (diff)
downloadlinux-19982ba8562e33083cb5bbb59a74855d8a9624ea.tar.xz
NFSv4.1: Fix an off-by-one error in pnfs_generic_pg_test
And document what is going on there... Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/pnfs.c21
1 files changed, 16 insertions, 5 deletions
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 0f42e02436ee..29c0ca7fc347 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1078,11 +1078,22 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
return true;
}
- if (req_offset(req) > end_offset(pgio->pg_lseg->pls_range.offset,
- pgio->pg_lseg->pls_range.length))
- return false;
-
- return true;
+ /*
+ * 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.
+ *
+ * Please also note that 'end_offset' is actually the offset of the
+ * first byte that lies outside the pnfs_layout_range. FIXME?
+ *
+ */
+ return req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
+ pgio->pg_lseg->pls_range.length);
}
EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);