linux-kernel - [PATCH 01/13] NFS: move generic_write_checks() call from nfs_file_direct_write() to nfs_file

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Date:   Tue, 16 Nov 2021 13:44:04 +1100
From:   NeilBrown <neilb@...e.de>
To:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Chuck Lever <chuck.lever@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>
Cc:     linux-nfs@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 01/13] NFS: move generic_write_checks() call from
 nfs_file_direct_write() to nfs_file_write()

generic_write_checks() is not needed for swap-out writes, and fails if
they are attempted.
nfs_file_direct_write() currently calls generic_write_checks() and is in
turn called from:
  nfs_direct_IO  - only for swap-out
  nfs_file_write - for normal O_DIRECT write

So move the generic_write_checks() call into nfs_file_write().  This
allows NFS swap-out writes to complete.

Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
Signed-off-by: NeilBrown <neilb@...e.de>
---
 fs/nfs/direct.c |    5 +----
 fs/nfs/file.c   |    6 +++++-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 9cff8709c80a..1e80d243ba25 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -905,10 +905,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 	dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
 		file, iov_iter_count(iter), (long long) iocb->ki_pos);
 
-	result = generic_write_checks(iocb, iter);
-	if (result <= 0)
-		return result;
-	count = result;
+	count = iov_iter_count(iter);
 	nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 
 	pos = iocb->ki_pos;
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 24e7dccce355..45d8180b7be3 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -615,8 +615,12 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
 	if (result)
 		return result;
 
-	if (iocb->ki_flags & IOCB_DIRECT)
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		result = generic_write_checks(iocb, from);
+		if (result <= 0)
+			return result;
 		return nfs_file_direct_write(iocb, from);
+	}
 
 	dprintk("NFS: write(%pD2, %zu@%Ld)\n",
 		file, iov_iter_count(from), (long long) iocb->ki_pos);