Commit 0cd1eb9a authored by Vivek Goyal's avatar Vivek Goyal Committed by Miklos Szeredi
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fuse: separate fuse device allocation and installation in fuse_conn 



As of now fuse_dev_alloc() both allocates a fuse device and installs it in
fuse_conn list.  fuse_dev_alloc() can fail if fuse_device allocation fails.

virtio-fs needs to initialize multiple fuse devices (one per virtio queue).
It initializes one fuse device as part of call to fuse_fill_super_common()
and rest of the devices are allocated and installed after that.

But, we can't afford to fail after calling fuse_fill_super_common() as we
don't have a way to undo all the actions done by fuse_fill_super_common().
So to avoid failures after the call to fuse_fill_super_common(),
pre-allocate all fuse devices early and install them into fuse connection
later.

This patch provides two separate helpers for fuse device allocation and
fuse device installation in fuse_conn.

Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent ae3aad77

fs/fuse/cuse.c

+1 −1
Original line number Diff line number Diff line
@@ -508,7 +508,7 @@ static int cuse_channel_open(struct inode *inode, struct file *file) 
	 */

	fuse_conn_init(&cc->fc, file->f_cred->user_ns, &fuse_dev_fiq_ops, NULL);



	fud = fuse_dev_alloc(&cc->fc);

	fud = fuse_dev_alloc_install(&cc->fc);

	if (!fud) {

		kfree(cc);

		return -ENOMEM;

fs/fuse/dev.c

+1 −1
Original line number Diff line number Diff line
@@ -2203,7 +2203,7 @@ static int fuse_device_clone(struct fuse_conn *fc, struct file *new) 
	if (new->private_data)

		return -EINVAL;



	fud = fuse_dev_alloc(fc);

	fud = fuse_dev_alloc_install(fc);

	if (!fud)

		return -ENOMEM;

fs/fuse/fuse_i.h

+3 −1
Original line number Diff line number Diff line
@@ -929,7 +929,9 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns, 
 */

void fuse_conn_put(struct fuse_conn *fc);



struct fuse_dev *fuse_dev_alloc(struct fuse_conn *fc);

struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc);

struct fuse_dev *fuse_dev_alloc(void);

void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc);

void fuse_dev_free(struct fuse_dev *fud);

void fuse_send_init(struct fuse_conn *fc);

fs/fuse/inode.c

+21 −4
Original line number Diff line number Diff line
@@ -1045,7 +1045,7 @@ static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb) 
	return 0;

}



struct fuse_dev *fuse_dev_alloc(struct fuse_conn *fc)

struct fuse_dev *fuse_dev_alloc(void)

{

	struct fuse_dev *fud;

	struct list_head *pq;
@@ -1061,16 +1061,33 @@ struct fuse_dev *fuse_dev_alloc(struct fuse_conn *fc) 
	}



	fud->pq.processing = pq;

	fud->fc = fuse_conn_get(fc);

	fuse_pqueue_init(&fud->pq);



	return fud;

}

EXPORT_SYMBOL_GPL(fuse_dev_alloc);



void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)

{

	fud->fc = fuse_conn_get(fc);

	spin_lock(&fc->lock);

	list_add_tail(&fud->entry, &fc->devices);

	spin_unlock(&fc->lock);

}

EXPORT_SYMBOL_GPL(fuse_dev_install);



struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc)

{

	struct fuse_dev *fud;



	fud = fuse_dev_alloc();

	if (!fud)

		return NULL;



	fuse_dev_install(fud, fc);

	return fud;

}

EXPORT_SYMBOL_GPL(fuse_dev_alloc);

EXPORT_SYMBOL_GPL(fuse_dev_alloc_install);



void fuse_dev_free(struct fuse_dev *fud)

{
@@ -1132,7 +1149,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx) 
	if (sb->s_user_ns != &init_user_ns)

		sb->s_xattr = fuse_no_acl_xattr_handlers;



	fud = fuse_dev_alloc(fc);

	fud = fuse_dev_alloc_install(fc);

	if (!fud)

		goto err;

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