[4.2.y-ckt stable] Patch "NFSv4.1/pNFS: Don't request a minimal read layout beyond the end of file" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    NFSv4.1/pNFS: Don't request a minimal read layout beyond the end of file

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 73a9184c44fb9d4d90ee73fcb9d9f3b14347ca3e Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust at primarydata.com>
Date: Mon, 31 Aug 2015 02:05:47 -0700
Subject: NFSv4.1/pNFS: Don't request a minimal read layout beyond the end of
 file

commit 2d89a1d3c9ff8ceb115f001e66cff9788338ca47 upstream.

If we have a read layout, then sanity check the minimal layout length
so that it does not extend beyond the end of file.

Signed-off-by: Trond Myklebust <trond.myklebust at primarydata.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/nfs/pnfs.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 70bf706..38b37d9 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -882,6 +882,7 @@ send_layoutget(struct pnfs_layout_hdr *lo,
 	struct nfs_server *server = NFS_SERVER(ino);
 	struct nfs4_layoutget *lgp;
 	struct pnfs_layout_segment *lseg;
+	loff_t i_size;

 	dprintk("--> %s\n", __func__);

@@ -889,9 +890,17 @@ send_layoutget(struct pnfs_layout_hdr *lo,
 	if (lgp == NULL)
 		return NULL;

+	i_size = i_size_read(ino);
+
 	lgp->args.minlength = PAGE_CACHE_SIZE;
 	if (lgp->args.minlength > range->length)
 		lgp->args.minlength = range->length;
+	if (range->iomode == IOMODE_READ) {
+		if (range->offset >= i_size)
+			lgp->args.minlength = 0;
+		else if (i_size - range->offset < lgp->args.minlength)
+			lgp->args.minlength = i_size - range->offset;
+	}
 	lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
 	lgp->args.range = *range;
 	lgp->args.type = server->pnfs_curr_ld->id;
--
1.9.1