From 385a17bfc3cb035333c8a91eddc78a6e04c4625e Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Mon, 10 Apr 2006 22:54:52 -0700 Subject: [PATCH] fuse: add O_ASYNC support to FUSE device This adds asynchronous notification to FUSE - a FUSE server can request O_ASYNC on a /dev/fuse file descriptor and receive SIGIO when there is input available. One subtlety - fuse_dev_fasync, which is called when O_ASYNC is requested, does no locking, unlink the other methods. I think it's unnecessary, as the fuse_conn.fasync list is manipulated only by fasync_helper and kill_fasync, which provide their own locking. It would also be wrong to use the fuse_lock, as it's a spin lock and fasync_helper can sleep. My one concern with this is the fuse_conn going away underneath fuse_dev_fasync - sys_fcntl takes a reference on the file struct, so this seems not to be a problem. Signed-off-by: Jeff Dike Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/fuse_i.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index a16a04fcf41e..e5cb46b78437 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -318,6 +318,9 @@ struct fuse_conn { /** kobject */ struct kobject kobj; + + /** O_ASYNC requests */ + struct fasync_struct *fasync; }; static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb) -- cgit v1.2.1 From d713311464bcca73c990d1a1b5c9467eae87f5b4 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 10 Apr 2006 22:54:55 -0700 Subject: [PATCH] fuse: use a per-mount spinlock Remove the global spinlock in favor of a per-mount one. This patch is basically find & replace. The difficult part has already been done by the previous patch. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/fuse_i.h | 24 ++++++------------------ 1 file changed, 6 insertions(+), 18 deletions(-) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index e5cb46b78437..6ed812fd6200 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1,6 +1,6 @@ /* FUSE: Filesystem in Userspace - Copyright (C) 2001-2005 Miklos Szeredi + Copyright (C) 2001-2006 Miklos Szeredi This program can be distributed under the terms of the GNU GPL. See the file COPYING. @@ -144,7 +144,7 @@ struct fuse_req { /* * The following bitfields are either set once before the * request is queued or setting/clearing them is protected by - * fuse_lock + * fuse_conn->lock */ /** True if the request has reply */ @@ -213,6 +213,9 @@ struct fuse_req { * unmounted. */ struct fuse_conn { + /** Lock protecting accessess to members of this structure */ + spinlock_t lock; + /** The user id for this mount */ uid_t user_id; @@ -351,21 +354,6 @@ static inline u64 get_node_id(struct inode *inode) /** Device operations */ extern const struct file_operations fuse_dev_operations; -/** - * This is the single global spinlock which protects FUSE's structures - * - * The following data is protected by this lock: - * - * - the private_data field of the device file - * - the s_fs_info field of the super block - * - unused_list, pending, processing lists in fuse_conn - * - background list in fuse_conn - * - the unique request ID counter reqctr in fuse_conn - * - the sb (super_block) field in fuse_conn - * - the file (device file) field in fuse_conn - */ -extern spinlock_t fuse_lock; - /** * Get a filled in inode */ @@ -490,7 +478,7 @@ void request_send_background(struct fuse_conn *fc, struct fuse_req *req); /** * Release inodes and file associated with background request */ -void fuse_release_background(struct fuse_req *req); +void fuse_release_background(struct fuse_conn *fc, struct fuse_req *req); /* Abort all requests */ void fuse_abort_conn(struct fuse_conn *fc); -- cgit v1.2.1 From ce1d5a491f0ee50560416a73faa5e4ddbab074bd Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 10 Apr 2006 22:54:58 -0700 Subject: [PATCH] fuse: clean up request accounting FUSE allocated most requests from a fixed size pool filled at mount time. However in some cases (release/forget) non-pool requests were used. File locking operations aren't well served by the request pool, since they may block indefinetly thus exhausting the pool. This patch removes the request pool and always allocates requests on demand. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/fuse_i.h | 26 +++++--------------------- 1 file changed, 5 insertions(+), 21 deletions(-) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 6ed812fd6200..242e69cb1251 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -18,9 +18,6 @@ /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 -/** If more requests are outstanding, then the operation will block */ -#define FUSE_MAX_OUTSTANDING 10 - /** It could be as large as PATH_MAX, but would that have any uses? */ #define FUSE_NAME_MAX 1024 @@ -131,8 +128,8 @@ struct fuse_conn; * A request to the client */ struct fuse_req { - /** This can be on either unused_list, pending processing or - io lists in fuse_conn */ + /** This can be on either pending processing or io lists in + fuse_conn */ struct list_head list; /** Entry on the background list */ @@ -150,9 +147,6 @@ struct fuse_req { /** True if the request has reply */ unsigned isreply:1; - /** The request is preallocated */ - unsigned preallocated:1; - /** The request was interrupted */ unsigned interrupted:1; @@ -247,19 +241,9 @@ struct fuse_conn { interrupted request) */ struct list_head background; - /** Controls the maximum number of outstanding requests */ - struct semaphore outstanding_sem; - - /** This counts the number of outstanding requests if - outstanding_sem would go negative */ - unsigned outstanding_debt; - /** RW semaphore for exclusion with fuse_put_super() */ struct rw_semaphore sbput_sem; - /** The list of unused requests */ - struct list_head unused_list; - /** The next unique request id */ u64 reqctr; @@ -452,11 +436,11 @@ void fuse_reset_request(struct fuse_req *req); /** * Reserve a preallocated request */ -struct fuse_req *fuse_get_request(struct fuse_conn *fc); +struct fuse_req *fuse_get_req(struct fuse_conn *fc); /** - * Decrement reference count of a request. If count goes to zero put - * on unused list (preallocated) or free request (not preallocated). + * Decrement reference count of a request. If count goes to zero free + * the request. */ void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req); -- cgit v1.2.1 From 08a53cdce62d37d918530bbbf726cc01b21dc3d1 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 10 Apr 2006 22:54:59 -0700 Subject: [PATCH] fuse: account background requests The previous patch removed limiting the number of outstanding requests. This patch adds a much simpler limiting, that is also compatible with file locking operations. A task may have at most one synchronous request allocated. So these requests need not be otherwise limited. However the number of background requests (release, forget, asynchronous reads, interrupted requests) can grow indefinitely. This can be used by a malicous user to cause FUSE to allocate arbitrary amounts of unswappable kernel memory, denying service. For this reason add a limit for the number of background requests, and block allocations of new requests until the number goes bellow the limit. Also use this mechanism to block all requests until the INIT reply is received. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/fuse_i.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'fs/fuse/fuse_i.h') diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 242e69cb1251..19c7185a7546 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -18,6 +18,9 @@ /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 +/** Maximum number of outstanding background requests */ +#define FUSE_MAX_BACKGROUND 10 + /** It could be as large as PATH_MAX, but would that have any uses? */ #define FUSE_NAME_MAX 1024 @@ -241,6 +244,17 @@ struct fuse_conn { interrupted request) */ struct list_head background; + /** Number of requests currently in the background */ + unsigned num_background; + + /** Flag indicating if connection is blocked. This will be + the case before the INIT reply is received, and if there + are too many outstading backgrounds requests */ + int blocked; + + /** waitq for blocked connection */ + wait_queue_head_t blocked_waitq; + /** RW semaphore for exclusion with fuse_put_super() */ struct rw_semaphore sbput_sem; -- cgit v1.2.1