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fuse: separate fuse device allocation and installation in fuse_conn

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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: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Vivek Goyal 2019-03-06 16:51:40 -05:00 committed by Miklos Szeredi
parent ae3aad77f4
commit 0cd1eb9a41
4 changed files with 29 additions and 10 deletions
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2
fs/fuse/cuse.c
View File

@ -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;

2
fs/fuse/dev.c
View File

@ -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;

4
fs/fuse/fuse_i.h
View File

@ -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);

31
fs/fuse/inode.c
View File

@ -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;
@ -1061,17 +1061,34 @@ 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);
spin_lock(&fc->lock);
list_add_tail(&fud->entry, &fc->devices);
spin_unlock(&fc->lock);
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_install);
void fuse_dev_free(struct fuse_dev *fud)
{
struct fuse_conn *fc = fud->fc;
@ -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;