Commit 1cef2184 authored Feb 21, 2020 by Scott Mayhew Committed by Anna Schumaker Feb 21, 2020

NFS: Ensure the fs_context has the correct fs_type before mounting



This is necessary because unless userspace explicitly requests fstype
"nfs4" (either via "mount -t nfs4" or by calling the "mount.nfs4" helper
directly), the fstype will default to "nfs".

This was fine on older kernels because the super_block->s_type was set
via mount_info->nfs_mod->nfs_fs, which was set when parsing the mount
options and subsequently passed in the "type" argument of sget().

After commit f2aedb71 ("NFS: Add fs_context support."), sget_fc(),
which has no "type" argument, is called instead.  In sget_fc(), the
super_block->s_type is set via fs_context->fs_type, which was set when
the filesystem context was initially created.

Reported-by: Patrick Steinhardt <ps@pks.im>
Fixes: f2aedb71 ("NFS: Add fs_context support.")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

parent 5d63944f

fs/nfs/fs_context.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -1240,6 +1240,13 @@ static int nfs_fs_context_validate(struct fs_context *fc)
		}
		ctx->nfs_mod = nfs_mod;
		}

		/* Ensure the filesystem context has the correct fs_type */
		if (fc->fs_type != ctx->nfs_mod->nfs_fs) {
		module_put(fc->fs_type->owner);
		__module_get(ctx->nfs_mod->nfs_fs->owner);
		fc->fs_type = ctx->nfs_mod->nfs_fs;
		}
		return 0;

		out_no_device_name:

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