NFS: Allow very small rsize & wsize again

[ Upstream commit a60214c2465493aac0b014d87ee19327b6204c42 ]

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>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 647fc3f..ae7d4a8 100644 (file)
--- 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;
 }
 
 /*