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Commit 3b7008b2 authored by Szymon Lukasz's avatar Szymon Lukasz Committed by Miklos Szeredi
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fuse: return -ECONNABORTED on /dev/fuse read after abort 



Currently the userspace has no way of knowing whether the fuse
connection ended because of umount or abort via sysfs. It makes it hard
for filesystems to free the mountpoint after abort without worrying
about removing some new mount.

The patch fixes it by returning different errors when userspace reads
from /dev/fuse (-ENODEV for umount and -ECONNABORTED for abort).

Add a new capability flag FUSE_ABORT_ERROR. If set and the connection is
gone because of sysfs abort, reading from the device will return
-ECONNABORTED.

Signed-off-by: default avatarSzymon Lukasz <noh4hss@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent df0e91d4

fs/fuse/control.c

+1 −1
Original line number Diff line number Diff line
@@ -35,7 +35,7 @@ static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf, 
{

	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);

	if (fc) {

		fuse_abort_conn(fc);

		fuse_abort_conn(fc, true);

		fuse_conn_put(fc);

	}

	return count;

fs/fuse/cuse.c

+2 −2
Original line number Diff line number Diff line
@@ -406,7 +406,7 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req) 
err_region:

	unregister_chrdev_region(devt, 1);

err:

	fuse_abort_conn(fc);

	fuse_abort_conn(fc, false);

	goto out;

}
@@ -581,7 +581,7 @@ static ssize_t cuse_class_abort_store(struct device *dev, 
{

	struct cuse_conn *cc = dev_get_drvdata(dev);



	fuse_abort_conn(&cc->fc);

	fuse_abort_conn(&cc->fc, false);

	return count;

}

static DEVICE_ATTR(abort, 0200, NULL, cuse_class_abort_store);

fs/fuse/dev.c

+7 −5
Original line number Diff line number Diff line
@@ -1234,9 +1234,10 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file, 
	if (err)

		goto err_unlock;



	err = -ENODEV;

	if (!fiq->connected)

	if (!fiq->connected) {

		err = (fc->aborted && fc->abort_err) ? -ECONNABORTED : -ENODEV;

		goto err_unlock;

	}



	if (!list_empty(&fiq->interrupts)) {

		req = list_entry(fiq->interrupts.next, struct fuse_req,
@@ -1287,7 +1288,7 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file, 
	spin_lock(&fpq->lock);

	clear_bit(FR_LOCKED, &req->flags);

	if (!fpq->connected) {

		err = -ENODEV;

		err = (fc->aborted && fc->abort_err) ? -ECONNABORTED : -ENODEV;

		goto out_end;

	}

	if (err) {
@@ -2076,7 +2077,7 @@ static void end_polls(struct fuse_conn *fc) 
 * is OK, the request will in that case be removed from the list before we touch

 * it.

 */

void fuse_abort_conn(struct fuse_conn *fc)

void fuse_abort_conn(struct fuse_conn *fc, bool is_abort)

{

	struct fuse_iqueue *fiq = &fc->iq;
@@ -2089,6 +2090,7 @@ void fuse_abort_conn(struct fuse_conn *fc) 


		fc->connected = 0;

		fc->blocked = 0;

		fc->aborted = is_abort;

		fuse_set_initialized(fc);

		list_for_each_entry(fud, &fc->devices, entry) {

			struct fuse_pqueue *fpq = &fud->pq;
@@ -2151,7 +2153,7 @@ int fuse_dev_release(struct inode *inode, struct file *file) 
		/* Are we the last open device? */

		if (atomic_dec_and_test(&fc->dev_count)) {

			WARN_ON(fc->iq.fasync != NULL);

			fuse_abort_conn(fc);

			fuse_abort_conn(fc, false);

		}

		fuse_dev_free(fud);

	}

fs/fuse/fuse_i.h

+7 −1
Original line number Diff line number Diff line
@@ -515,6 +515,9 @@ struct fuse_conn { 
	    abort and device release */

	unsigned connected;



	/** Connection aborted via sysfs */

	bool aborted;



	/** Connection failed (version mismatch).  Cannot race with

	    setting other bitfields since it is only set once in INIT

	    reply, before any other request, and never cleared */
@@ -526,6 +529,9 @@ struct fuse_conn { 
	/** Do readpages asynchronously?  Only set in INIT */

	unsigned async_read:1;



	/** Return an unique read error after abort.  Only set in INIT */

	unsigned abort_err:1;



	/** Do not send separate SETATTR request before open(O_TRUNC)  */

	unsigned atomic_o_trunc:1;
@@ -851,7 +857,7 @@ void fuse_request_send_background_locked(struct fuse_conn *fc, 
					 struct fuse_req *req);



/* Abort all requests */

void fuse_abort_conn(struct fuse_conn *fc);

void fuse_abort_conn(struct fuse_conn *fc, bool is_abort);



/**

 * Invalidate inode attributes

fs/fuse/inode.c

+6 −3
Original line number Diff line number Diff line
@@ -371,7 +371,7 @@ void fuse_unlock_inode(struct inode *inode) 


static void fuse_umount_begin(struct super_block *sb)

{

	fuse_abort_conn(get_fuse_conn_super(sb));

	fuse_abort_conn(get_fuse_conn_super(sb), false);

}



static void fuse_send_destroy(struct fuse_conn *fc)
@@ -393,7 +393,7 @@ static void fuse_put_super(struct super_block *sb) 


	fuse_send_destroy(fc);



	fuse_abort_conn(fc);

	fuse_abort_conn(fc, false);

	mutex_lock(&fuse_mutex);

	list_del(&fc->entry);

	fuse_ctl_remove_conn(fc);
@@ -918,6 +918,8 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req) 
				fc->posix_acl = 1;

				fc->sb->s_xattr = fuse_acl_xattr_handlers;

			}

			if (arg->flags & FUSE_ABORT_ERROR)

				fc->abort_err = 1;

		} else {

			ra_pages = fc->max_read / PAGE_SIZE;

			fc->no_lock = 1;
@@ -948,7 +950,8 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req) 
		FUSE_FLOCK_LOCKS | FUSE_HAS_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |

		FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |

		FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |

		FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL;

		FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |

		FUSE_ABORT_ERROR;

	req->in.h.opcode = FUSE_INIT;

	req->in.numargs = 1;

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