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Commit e89a5a43 authored by Trond Myklebust's avatar Trond Myklebust Committed by Linus Torvalds
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NFS: Fix the mount regression 



This avoids the recent NFS mount regression (returning EBUSY when
mounting the same filesystem twice with different parameters).

The best I can do given the constraints appears to be to have the kernel
first look for a superblock that matches both the fsid and the
user-specified mount options, and then spawn off a new superblock if
that search fails.

Note that this is not the same as specifying nosharecache everywhere
since nosharecache will never attempt to match an existing superblock.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Tested-by: default avatarHua Zhong <hzhong@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 36ad4885

fs/nfs/super.c

+64 −46
Original line number Diff line number Diff line
@@ -1303,34 +1303,6 @@ static void nfs_clone_super(struct super_block *sb, 
 	nfs_initialise_sb(sb);

}



static int nfs_set_super(struct super_block *s, void *_server)

{

	struct nfs_server *server = _server;

	int ret;



	s->s_fs_info = server;

	ret = set_anon_super(s, server);

	if (ret == 0)

		server->s_dev = s->s_dev;

	return ret;

}



static int nfs_compare_super(struct super_block *sb, void *data)

{

	struct nfs_server *server = data, *old = NFS_SB(sb);



	if (memcmp(&old->nfs_client->cl_addr,

				&server->nfs_client->cl_addr,

				sizeof(old->nfs_client->cl_addr)) != 0)

		return 0;

	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */

	if (old->flags & NFS_MOUNT_UNSHARED)

		return 0;

	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)

		return 0;

	return 1;

}



#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)



static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
@@ -1359,9 +1331,46 @@ static int nfs_compare_mount_options(const struct super_block *s, const struct n 
		goto Ebusy;

	if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)

		goto Ebusy;

	return 0;

	return 1;

Ebusy:

	return -EBUSY;

	return 0;

}



struct nfs_sb_mountdata {

	struct nfs_server *server;

	int mntflags;

};



static int nfs_set_super(struct super_block *s, void *data)

{

	struct nfs_sb_mountdata *sb_mntdata = data;

	struct nfs_server *server = sb_mntdata->server;

	int ret;



	s->s_flags = sb_mntdata->mntflags;

	s->s_fs_info = server;

	ret = set_anon_super(s, server);

	if (ret == 0)

		server->s_dev = s->s_dev;

	return ret;

}



static int nfs_compare_super(struct super_block *sb, void *data)

{

	struct nfs_sb_mountdata *sb_mntdata = data;

	struct nfs_server *server = sb_mntdata->server, *old = NFS_SB(sb);

	int mntflags = sb_mntdata->mntflags;



	if (memcmp(&old->nfs_client->cl_addr,

				&server->nfs_client->cl_addr,

				sizeof(old->nfs_client->cl_addr)) != 0)

		return 0;

	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */

	if (old->flags & NFS_MOUNT_UNSHARED)

		return 0;

	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)

		return 0;

	return nfs_compare_mount_options(sb, server, mntflags);

}



static int nfs_get_sb(struct file_system_type *fs_type,
@@ -1373,6 +1382,9 @@ static int nfs_get_sb(struct file_system_type *fs_type, 
	struct nfs_mount_data *data = raw_data;

	struct dentry *mntroot;

	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;

	struct nfs_sb_mountdata sb_mntdata = {

		.mntflags = flags,

	};

	int error;



	/* Validate the mount data */
@@ -1386,28 +1398,25 @@ static int nfs_get_sb(struct file_system_type *fs_type, 
		error = PTR_ERR(server);

		goto out;

	}

	sb_mntdata.server = server;



	if (server->flags & NFS_MOUNT_UNSHARED)

		compare_super = NULL;



	/* Get a superblock - note that we may end up sharing one that already exists */

	s = sget(fs_type, compare_super, nfs_set_super, server);

	s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);

	if (IS_ERR(s)) {

		error = PTR_ERR(s);

		goto out_err_nosb;

	}



	if (s->s_fs_info != server) {

		error = nfs_compare_mount_options(s, server, flags);

		nfs_free_server(server);

		server = NULL;

		if (error < 0)

			goto error_splat_super;

	}



	if (!s->s_root) {

		/* initial superblock/root creation */

		s->s_flags = flags;

		nfs_fill_super(s, data);

	}
@@ -1460,6 +1469,9 @@ static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags, 
	struct nfs_server *server;

	struct dentry *mntroot;

	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;

	struct nfs_sb_mountdata sb_mntdata = {

		.mntflags = flags,

	};

	int error;



	dprintk("--> nfs_xdev_get_sb()\n");
@@ -1470,28 +1482,25 @@ static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags, 
		error = PTR_ERR(server);

		goto out_err_noserver;

	}

	sb_mntdata.server = server;



	if (server->flags & NFS_MOUNT_UNSHARED)

		compare_super = NULL;



	/* Get a superblock - note that we may end up sharing one that already exists */

	s = sget(&nfs_fs_type, compare_super, nfs_set_super, server);

	s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);

	if (IS_ERR(s)) {

		error = PTR_ERR(s);

		goto out_err_nosb;

	}



	if (s->s_fs_info != server) {

		error = nfs_compare_mount_options(s, server, flags);

		nfs_free_server(server);

		server = NULL;

		if (error < 0)

			goto error_splat_super;

	}



	if (!s->s_root) {

		/* initial superblock/root creation */

		s->s_flags = flags;

		nfs_clone_super(s, data->sb);

	}
@@ -1729,6 +1738,9 @@ static int nfs4_get_sb(struct file_system_type *fs_type, 
	struct dentry *mntroot;

	char *mntpath = NULL, *hostname = NULL, *ip_addr = NULL;

	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;

	struct nfs_sb_mountdata sb_mntdata = {

		.mntflags = flags,

	};

	int error;



	/* Validate the mount data */
@@ -1744,12 +1756,13 @@ static int nfs4_get_sb(struct file_system_type *fs_type, 
		error = PTR_ERR(server);

		goto out;

	}

	sb_mntdata.server = server;



	if (server->flags & NFS4_MOUNT_UNSHARED)

		compare_super = NULL;



	/* Get a superblock - note that we may end up sharing one that already exists */

	s = sget(fs_type, compare_super, nfs_set_super, server);

	s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);

	if (IS_ERR(s)) {

		error = PTR_ERR(s);

		goto out_free;
@@ -1762,7 +1775,6 @@ static int nfs4_get_sb(struct file_system_type *fs_type, 


	if (!s->s_root) {

		/* initial superblock/root creation */

		s->s_flags = flags;

		nfs4_fill_super(s);

	}
@@ -1816,6 +1828,9 @@ static int nfs4_xdev_get_sb(struct file_system_type *fs_type, int flags, 
	struct nfs_server *server;

	struct dentry *mntroot;

	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;

	struct nfs_sb_mountdata sb_mntdata = {

		.mntflags = flags,

	};

	int error;



	dprintk("--> nfs4_xdev_get_sb()\n");
@@ -1826,12 +1841,13 @@ static int nfs4_xdev_get_sb(struct file_system_type *fs_type, int flags, 
		error = PTR_ERR(server);

		goto out_err_noserver;

	}

	sb_mntdata.server = server;



	if (server->flags & NFS4_MOUNT_UNSHARED)

		compare_super = NULL;



	/* Get a superblock - note that we may end up sharing one that already exists */

	s = sget(&nfs_fs_type, compare_super, nfs_set_super, server);

	s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);

	if (IS_ERR(s)) {

		error = PTR_ERR(s);

		goto out_err_nosb;
@@ -1844,7 +1860,6 @@ static int nfs4_xdev_get_sb(struct file_system_type *fs_type, int flags, 


	if (!s->s_root) {

		/* initial superblock/root creation */

		s->s_flags = flags;

		nfs4_clone_super(s, data->sb);

	}
@@ -1887,6 +1902,9 @@ static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags, 
	struct dentry *mntroot;

	struct nfs_fh mntfh;

	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;

	struct nfs_sb_mountdata sb_mntdata = {

		.mntflags = flags,

	};

	int error;



	dprintk("--> nfs4_referral_get_sb()\n");
@@ -1897,12 +1915,13 @@ static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags, 
		error = PTR_ERR(server);

		goto out_err_noserver;

	}

	sb_mntdata.server = server;



	if (server->flags & NFS4_MOUNT_UNSHARED)

		compare_super = NULL;



	/* Get a superblock - note that we may end up sharing one that already exists */

	s = sget(&nfs_fs_type, compare_super, nfs_set_super, server);

	s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata);

	if (IS_ERR(s)) {

		error = PTR_ERR(s);

		goto out_err_nosb;
@@ -1915,7 +1934,6 @@ static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags, 


	if (!s->s_root) {

		/* initial superblock/root creation */

		s->s_flags = flags;

		nfs4_fill_super(s);

	}