From: Vivek Goyal <[email protected]> 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 <[email protected]> Signed-off-by: Miklos Szeredi <[email protected]> --- fs/fuse/cuse.c | 2 +- fs/fuse/dev.c | 2 +- fs/fuse/fuse_i.h | 4 +++- fs/fuse/inode.c | 25 +++++++++++++++++++++---- 4 files changed, 26 insertions(+), 7 deletions(-) diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index 7bad5d428ce1..c0204e3e811f 100644 --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -505,7 +505,7 @@ 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; diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 0bdb98a3b251..2df28ca7a654 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -2337,7 +2337,7 @@ 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; diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 617eca6046d2..21a2e86bbdf2 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1056,7 +1056,9 @@ 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, struct fuse_req *req); diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index e42e600e885b..a9e5b106e315 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1028,7 +1028,7 @@ 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; @@ -1044,16 +1044,33 @@ 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) { @@ -1115,7 +1132,7 @@ 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; -- 2.21.0
