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From:   Anna Schumaker <anna@kernel.org>
To:     linux-nfs@vger.kernel.org, trond.myklebust@hammerspace.com
Cc:     anna@kernel.org, jlayton@kernel.org, tom@talpey.com
Subject: [PATCH] NFS: Allow very small rsize & wsize again
Date:   Wed, 30 Nov 2022 15:30:47 -0500
Message-Id: <20221130203047.1303804-1-anna@kernel.org>
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From: Anna Schumaker <Anna.Schumaker@Netapp.com>

940261a19508 introduced nfs_io_size() to clamp the iosize to a multiple
of PAGE_SIZE. This had the unintended side effect of no longer allowing
iosizes less than a page, which could be useful in some situations.

UDP already has an exception that causes it to fall back on the
power-of-two style sizes instead. This patch adds an additional
exception for very small iosizes.

Reported-by: Jeff Layton <jlayton@kernel.org>
Fixes: 940261a19508 ("NFS: Allow setting rsize / wsize to a multiple of PAGE_SIZE")
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 fs/nfs/internal.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 647fc3f547cb..ae7d4a8c728c 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -739,12 +739,10 @@ unsigned long nfs_io_size(unsigned long iosize, enum xprt_transports proto)
 		iosize = NFS_DEF_FILE_IO_SIZE;
 	else if (iosize >= NFS_MAX_FILE_IO_SIZE)
 		iosize = NFS_MAX_FILE_IO_SIZE;
-	else
-		iosize = iosize & PAGE_MASK;
 
-	if (proto == XPRT_TRANSPORT_UDP)
+	if (proto == XPRT_TRANSPORT_UDP || iosize < PAGE_SIZE)
 		return nfs_block_bits(iosize, NULL);
-	return iosize;
+	return iosize & PAGE_MASK;
 }
 
 /*
-- 
2.38.1