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: Szymon Lukasz <noh4hss@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index b9ea99c..78fb7a0 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -35,7 +35,7 @@
{
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;
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index e9e9780..31d33b6 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -406,7 +406,7 @@
err_region:
unregister_chrdev_region(devt, 1);
err:
- fuse_abort_conn(fc);
+ fuse_abort_conn(fc, false);
goto out;
}
@@ -581,7 +581,7 @@
{
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);
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5d06384..78b6293 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1234,9 +1234,10 @@
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 @@
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 @@
* 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 @@
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 @@
/* 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);
}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index c4c093b..7d2e7de 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -515,6 +515,9 @@
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 @@
/** 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 @@
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
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 624f18b..3c9b675 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -371,7 +371,7 @@
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 @@
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 @@
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 @@
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);