diff options
| -rw-r--r-- | fs/fuse/dev.c | 88 | ||||
| -rw-r--r-- | fs/fuse/file.c | 13 | ||||
| -rw-r--r-- | fs/fuse/fuse_i.h | 12 |
3 files changed, 99 insertions, 14 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index fe3adf58917..ae26f37e53a 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -76,6 +76,13 @@ static void __fuse_put_request(struct fuse_req *req) atomic_dec(&req->count); } +static void fuse_req_init_context(struct fuse_req *req) +{ + req->in.h.uid = current->fsuid; + req->in.h.gid = current->fsgid; + req->in.h.pid = current->pid; +} + struct fuse_req *fuse_get_req(struct fuse_conn *fc) { struct fuse_req *req; @@ -100,9 +107,7 @@ struct fuse_req *fuse_get_req(struct fuse_conn *fc) if (!req) goto out; - req->in.h.uid = current->fsuid; - req->in.h.gid = current->fsgid; - req->in.h.pid = current->pid; + fuse_req_init_context(req); req->waiting = 1; return req; @@ -111,12 +116,87 @@ struct fuse_req *fuse_get_req(struct fuse_conn *fc) return ERR_PTR(err); } +/* + * Return request in fuse_file->reserved_req. However that may + * currently be in use. If that is the case, wait for it to become + * available. + */ +static struct fuse_req *get_reserved_req(struct fuse_conn *fc, + struct file *file) +{ + struct fuse_req *req = NULL; + struct fuse_file *ff = file->private_data; + + do { + wait_event(fc->blocked_waitq, ff->reserved_req); + spin_lock(&fc->lock); + if (ff->reserved_req) { + req = ff->reserved_req; + ff->reserved_req = NULL; + get_file(file); + req->stolen_file = file; + } + spin_unlock(&fc->lock); + } while (!req); + + return req; +} + +/* + * Put stolen request back into fuse_file->reserved_req + */ +static void put_reserved_req(struct fuse_conn *fc, struct fuse_req *req) +{ + struct file *file = req->stolen_file; + struct fuse_file *ff = file->private_data; + + spin_lock(&fc->lock); + fuse_request_init(req); + BUG_ON(ff->reserved_req); + ff->reserved_req = req; + wake_up(&fc->blocked_waitq); + spin_unlock(&fc->lock); + fput(file); +} + +/* + * Gets a requests for a file operation, always succeeds + * + * This is used for sending the FLUSH request, which must get to + * userspace, due to POSIX locks which may need to be unlocked. + * + * If allocation fails due to OOM, use the reserved request in + * fuse_file. + * + * This is very unlikely to deadlock accidentally, since the + * filesystem should not have it's own file open. If deadlock is + * intentional, it can still be broken by "aborting" the filesystem. + */ +struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file) +{ + struct fuse_req *req; + + atomic_inc(&fc->num_waiting); + wait_event(fc->blocked_waitq, !fc->blocked); + req = fuse_request_alloc(); + if (!req) + req = get_reserved_req(fc, file); + + fuse_req_init_context(req); + req->waiting = 1; + return req; +} + void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req) { if (atomic_dec_and_test(&req->count)) { if (req->waiting) atomic_dec(&fc->num_waiting); - fuse_request_free(req); + + if (req->stolen_file) + put_reserved_req(fc, req); + else + fuse_request_free(req); } } diff --git a/fs/fuse/file.c b/fs/fuse/file.c index d9a8289297c..ce759414cff 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -48,8 +48,8 @@ struct fuse_file *fuse_file_alloc(void) struct fuse_file *ff; ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL); if (ff) { - ff->release_req = fuse_request_alloc(); - if (!ff->release_req) { + ff->reserved_req = fuse_request_alloc(); + if (!ff->reserved_req) { kfree(ff); ff = NULL; } @@ -59,7 +59,7 @@ struct fuse_file *fuse_file_alloc(void) void fuse_file_free(struct fuse_file *ff) { - fuse_request_free(ff->release_req); + fuse_request_free(ff->reserved_req); kfree(ff); } @@ -115,7 +115,7 @@ int fuse_open_common(struct inode *inode, struct file *file, int isdir) struct fuse_req *fuse_release_fill(struct fuse_file *ff, u64 nodeid, int flags, int opcode) { - struct fuse_req *req = ff->release_req; + struct fuse_req *req = ff->reserved_req; struct fuse_release_in *inarg = &req->misc.release_in; inarg->fh = ff->fh; @@ -187,10 +187,7 @@ static int fuse_flush(struct file *file, fl_owner_t id) if (fc->no_flush) return 0; - req = fuse_get_req(fc); - if (IS_ERR(req)) - return PTR_ERR(req); - + req = fuse_get_req_nofail(fc, file); memset(&inarg, 0, sizeof(inarg)); inarg.fh = ff->fh; inarg.lock_owner = fuse_lock_owner_id(id); diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index eb3166625ca..f7c74516f3a 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -65,7 +65,7 @@ struct fuse_inode { /** FUSE specific file data */ struct fuse_file { /** Request reserved for flush and release */ - struct fuse_req *release_req; + struct fuse_req *reserved_req; /** File handle used by userspace */ u64 fh; @@ -213,6 +213,9 @@ struct fuse_req { /** Request completion callback */ void (*end)(struct fuse_conn *, struct fuse_req *); + + /** Request is stolen from fuse_file->reserved_req */ + struct file *stolen_file; }; /** @@ -456,11 +459,16 @@ struct fuse_req *fuse_request_alloc(void); void fuse_request_free(struct fuse_req *req); /** - * Reserve a preallocated request + * Get a request, may fail with -ENOMEM */ struct fuse_req *fuse_get_req(struct fuse_conn *fc); /** + * Gets a requests for a file operation, always succeeds + */ +struct fuse_req *fuse_get_req_nofail(struct fuse_conn *fc, struct file *file); + +/** * Decrement reference count of a request. If count goes to zero free * the request. */ |