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Commit 24ab59f6 authored by Daniel Rosenberg's avatar Daniel Rosenberg Committed by Greg Kroah-Hartman
Browse files

ANDROID: fuse: Add support for d_canonical_path 



Allows FUSE to report to inotify that it is acting
as a layered filesystem. The userspace component
returns a string representing the location of the
underlying file. If the string cannot be resolved
into a path, the top level path is returned instead.

Bug: 23904372
Bug: 171780975
Test: inotify on cuttlefish
Change-Id: Iabdca0bbedfbff59e9c820c58636a68ef9683d9f
Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
Signed-off-by: default avatarAlessio Balsini <balsini@google.com>
parent 854f3806

fs/fuse/dev.c

+7 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/sched/signal.h>

#include <linux/uio.h>

#include <linux/miscdevice.h>

#include <linux/namei.h>

#include <linux/pagemap.h>

#include <linux/file.h>

#include <linux/slab.h>
@@ -1899,6 +1900,12 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud, 
		err = copy_out_args(cs, req->args, nbytes);

	fuse_copy_finish(cs);



	if (!err && req->in.h.opcode == FUSE_CANONICAL_PATH) {

		char *path = (char *)req->args->out_args[0].value;

		path[req->args->out_args[0].size - 1] = 0;

		req->out.h.error = kern_path(path, 0, req->args->canonical_path);

	}



	spin_lock(&fpq->lock);

	clear_bit(FR_LOCKED, &req->flags);

	if (!fpq->connected)

fs/fuse/dir.c

+37 −0
Original line number Diff line number Diff line
@@ -298,6 +298,42 @@ static int fuse_dentry_delete(const struct dentry *dentry) 
	return time_before64(fuse_dentry_time(dentry), get_jiffies_64());

}



/*

 * Get the canonical path. Since we must translate to a path, this must be done

 * in the context of the userspace daemon, however, the userspace daemon cannot

 * look up paths on its own. Instead, we handle the lookup as a special case

 * inside of the write request.

 */

static void fuse_dentry_canonical_path(const struct path *path, struct path *canonical_path) {

	struct inode *inode = d_inode(path->dentry);

	struct fuse_conn *fc = get_fuse_conn(inode);

	FUSE_ARGS(args);

	char *path_name;

	int err;



	path_name = (char*)__get_free_page(GFP_KERNEL);

	if (!path_name)

		goto default_path;



	args.opcode = FUSE_CANONICAL_PATH;

	args.nodeid = get_node_id(inode);

	args.in_numargs = 0;

	args.out_numargs = 1;

	args.out_args[0].size = PATH_MAX;

	args.out_args[0].value = path_name;

	args.canonical_path = canonical_path;

	args.out_argvar = 1;



	err = fuse_simple_request(fc, &args);

	free_page((unsigned long)path_name);

	if (err > 0)

		return;

default_path:

	canonical_path->dentry = path->dentry;

	canonical_path->mnt = path->mnt;

	path_get(canonical_path);

}



const struct dentry_operations fuse_dentry_operations = {

	.d_revalidate	= fuse_dentry_revalidate,

	.d_delete	= fuse_dentry_delete,
@@ -305,6 +341,7 @@ const struct dentry_operations fuse_dentry_operations = { 
	.d_init		= fuse_dentry_init,

	.d_release	= fuse_dentry_release,

#endif

	.d_canonical_path = fuse_dentry_canonical_path,

};



const struct dentry_operations fuse_root_dentry_operations = {

fs/fuse/fuse_i.h

+3 −0
Original line number Diff line number Diff line
@@ -253,6 +253,9 @@ struct fuse_args { 
	struct fuse_in_arg in_args[3];

	struct fuse_arg out_args[2];

	void (*end)(struct fuse_conn *fc, struct fuse_args *args, int error);



	/* Path used for completing d_canonical_path */

	struct path *canonical_path;

};



struct fuse_args_pages {

include/uapi/linux/fuse.h

+1 −0
Original line number Diff line number Diff line
@@ -465,6 +465,7 @@ enum fuse_opcode { 
	FUSE_COPY_FILE_RANGE	= 47,

	FUSE_SETUPMAPPING	= 48,

	FUSE_REMOVEMAPPING	= 49,

	FUSE_CANONICAL_PATH	= 2016,



	/* CUSE specific operations */

	CUSE_INIT		= 4096,