Commit 33670fa2 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
Browse files

fuse: nfs export special lookups 



Implement the get_parent export operation by sending a LOOKUP request with
".." as the name.

Implement looking up an inode by node ID after it has been evicted from
the cache.  This is done by seding a LOOKUP request with "." as the name
(for all file types, not just directories).

The filesystem can set the FUSE_EXPORT_SUPPORT flag in the INIT reply, to
indicate that it supports these special lookups.

Thanks to John Muir for the original implementation of this feature.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: David Teigland <teigland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c180eebe

fs/fuse/fuse_i.h

+6 −0
Original line number Diff line number Diff line
@@ -363,6 +363,9 @@ struct fuse_conn { 
	/** Do not send separate SETATTR request before open(O_TRUNC)  */

	unsigned atomic_o_trunc : 1;



	/** Filesystem supports NFS exporting.  Only set in INIT */

	unsigned export_support : 1;



	/*

	 * The following bitfields are only for optimization purposes

	 * and hence races in setting them will not cause malfunction
@@ -473,6 +476,9 @@ struct inode *fuse_iget(struct super_block *sb, u64 nodeid, 
			int generation, struct fuse_attr *attr,

			u64 attr_valid, u64 attr_version);



int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,

		     struct fuse_entry_out *outarg, struct inode **inode);



/**

 * Send FORGET command

 */

fs/fuse/inode.c

+63 −3
Original line number Diff line number Diff line
@@ -562,6 +562,7 @@ struct fuse_inode_handle 
static struct dentry *fuse_get_dentry(struct super_block *sb,

				      struct fuse_inode_handle *handle)

{

	struct fuse_conn *fc = get_fuse_conn_super(sb);

	struct inode *inode;

	struct dentry *entry;

	int err = -ESTALE;
@@ -570,8 +571,27 @@ static struct dentry *fuse_get_dentry(struct super_block *sb, 
		goto out_err;



	inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);

	if (!inode)

	if (!inode) {

		struct fuse_entry_out outarg;

		struct qstr name;



		if (!fc->export_support)

			goto out_err;



		name.len = 1;

		name.name = ".";

		err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,

				       &inode);

		if (err && err != -ENOENT)

			goto out_err;

		if (err || !inode) {

			err = -ESTALE;

			goto out_err;

		}

		err = -EIO;

		if (get_node_id(inode) != handle->nodeid)

			goto out_iput;

	}

	err = -ESTALE;

	if (inode->i_generation != handle->generation)

		goto out_iput;
@@ -659,11 +679,46 @@ static struct dentry *fuse_fh_to_parent(struct super_block *sb, 
	return fuse_get_dentry(sb, &parent);

}



static struct dentry *fuse_get_parent(struct dentry *child)

{

	struct inode *child_inode = child->d_inode;

	struct fuse_conn *fc = get_fuse_conn(child_inode);

	struct inode *inode;

	struct dentry *parent;

	struct fuse_entry_out outarg;

	struct qstr name;

	int err;



	if (!fc->export_support)

		return ERR_PTR(-ESTALE);



	name.len = 2;

	name.name = "..";

	err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),

			       &name, &outarg, &inode);

	if (err && err != -ENOENT)

		return ERR_PTR(err);

	if (err || !inode)

		return ERR_PTR(-ESTALE);



	parent = d_alloc_anon(inode);

	if (!parent) {

		iput(inode);

		return ERR_PTR(-ENOMEM);

	}

	if (get_node_id(inode) != FUSE_ROOT_ID) {

		parent->d_op = &fuse_dentry_operations;

		fuse_invalidate_entry_cache(parent);

	}



	return parent;

}



static const struct export_operations fuse_export_operations = {

	.fh_to_dentry	= fuse_fh_to_dentry,

	.fh_to_parent	= fuse_fh_to_parent,

	.encode_fh	= fuse_encode_fh,

	.get_parent	= fuse_get_parent,

};



static const struct super_operations fuse_super_operations = {
@@ -695,6 +750,11 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req) 
				fc->no_lock = 1;

			if (arg->flags & FUSE_ATOMIC_O_TRUNC)

				fc->atomic_o_trunc = 1;

			if (arg->minor >= 9) {

				/* LOOKUP has dependency on proto version */

				if (arg->flags & FUSE_EXPORT_SUPPORT)

					fc->export_support = 1;

			}

			if (arg->flags & FUSE_BIG_WRITES)

				fc->big_writes = 1;

		} else {
@@ -721,7 +781,7 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req) 
	arg->minor = FUSE_KERNEL_MINOR_VERSION;

	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;

	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |

		FUSE_BIG_WRITES;

		FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES;

	req->in.h.opcode = FUSE_INIT;

	req->in.numargs = 1;

	req->in.args[0].size = sizeof(*arg);

include/linux/fuse.h

+3 −0
Original line number Diff line number Diff line
@@ -104,11 +104,14 @@ struct fuse_file_lock { 


/**

 * INIT request/reply flags

 *

 * FUSE_EXPORT_SUPPORT: filesystem handles lookups of "." and ".."

 */

#define FUSE_ASYNC_READ		(1 << 0)

#define FUSE_POSIX_LOCKS	(1 << 1)

#define FUSE_FILE_OPS		(1 << 2)

#define FUSE_ATOMIC_O_TRUNC	(1 << 3)

#define FUSE_EXPORT_SUPPORT	(1 << 4)

#define FUSE_BIG_WRITES		(1 << 5)



/**

CRA Git | Maintained and supported by SUSTech CRA and CCSE