MFC: r290970

mnt_stat.f_iosize (which is used to set bo_bsize) must be set to
the largest size of buffer cache block or the mapping of the buffer
is bogus. When a mount with rsize=4096,wsize=4096 was done, f_iosize
would be set to 4096. This resulted in corrupted directory data, since
the buffer cache block size for directories is NFS_DIRBLKSIZ (8192).
This patch fixes the code so that it always sets f_iosize to at least
NFS_DIRBLKSIZ.

1 files changed, 3 insertions, 1 deletions

diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c
index 0f8c36a..b8aa2fd 100644
--- a/sys/fs/nfsclient/nfs_clvfsops.c
+++ b/sys/fs/nfsclient/nfs_clvfsops.c
@@ -211,10 +211,12 @@ newnfs_iosize(struct nfsmount *nmp)
 	 * Calculate the size used for io buffers.  Use the larger
 	 * of the two sizes to minimise nfs requests but make sure
 	 * that it is at least one VM page to avoid wasting buffer
-	 * space.
+	 * space.  It must also be at least NFS_DIRBLKSIZ, since
+	 * that is the buffer size used for directories.
 	 */
 	iosize = imax(nmp->nm_rsize, nmp->nm_wsize);
 	iosize = imax(iosize, PAGE_SIZE);
+	iosize = imax(iosize, NFS_DIRBLKSIZ);
 	nmp->nm_mountp->mnt_stat.f_iosize = iosize;
 	return (iosize);
 }