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From:   Benjamin Coddington <bcodding@redhat.com>
To:     trond.myklebust@hammerspace.com, anna@kernel.org
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH v2 1/2] pNFS: Fix the pnfs block driver's calculation of layoutget size
Date:   Fri, 17 Nov 2023 06:25:13 -0500
Message-ID: <21a1f2a6155398965f79ed64f0bd23bf38a50367.1700220277.git.bcodding@redhat.com>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

Instead of relying on the value of the 'bytes_left' field, we should
calculate the layout size based on the offset of the request that is
being written out.

Reported-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Fixes: 954998b60caa ("NFS: Fix error handling for O_DIRECT write scheduling")
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfs/blocklayout/blocklayout.c | 5 ++---
 fs/nfs/direct.c                  | 5 +++--
 fs/nfs/internal.h                | 2 +-
 fs/nfs/pnfs.c                    | 3 ++-
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 943aeea1eb16..c1cc9fe93dd4 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -893,10 +893,9 @@ bl_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
 	}
 
 	if (pgio->pg_dreq == NULL)
-		wb_size = pnfs_num_cont_bytes(pgio->pg_inode,
-					      req->wb_index);
+		wb_size = pnfs_num_cont_bytes(pgio->pg_inode, req->wb_index);
 	else
-		wb_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+		wb_size = nfs_dreq_bytes_left(pgio->pg_dreq, req_offset(req));
 
 	pnfs_generic_pg_init_write(pgio, req, wb_size);
 
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index f6c74f424691..5918c67dae0d 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -205,9 +205,10 @@ static void nfs_direct_req_release(struct nfs_direct_req *dreq)
 	kref_put(&dreq->kref, nfs_direct_req_free);
 }
 
-ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
+ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset)
 {
-	return dreq->bytes_left;
+	loff_t start = offset - dreq->io_start;
+	return dreq->max_count - start;
 }
 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
 
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 9c9cf764f600..b1fa81c9dff6 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -655,7 +655,7 @@ extern int nfs_sillyrename(struct inode *dir, struct dentry *dentry);
 /* direct.c */
 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
 			      struct nfs_direct_req *dreq);
-extern ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq);
+extern ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset);
 
 /* nfs4proc.c */
 extern struct nfs_client *nfs4_init_client(struct nfs_client *clp,
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 84343aefbbd6..9084f156d67b 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2729,7 +2729,8 @@ pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *r
 		if (pgio->pg_dreq == NULL)
 			rd_size = i_size_read(pgio->pg_inode) - req_offset(req);
 		else
-			rd_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+			rd_size = nfs_dreq_bytes_left(pgio->pg_dreq,
+						      req_offset(req));
 
 		pgio->pg_lseg =
 			pnfs_update_layout(pgio->pg_inode, nfs_req_openctx(req),
-- 
2.41.0