diff options
| -rw-r--r-- | fs/fcntl.c | 66 | ||||
| -rw-r--r-- | fs/locks.c | 18 | ||||
| -rw-r--r-- | include/linux/fs.h | 5 |
3 files changed, 72 insertions, 17 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c index f8cc34f542c..dcdbc6f5c33 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -640,7 +640,7 @@ static void fasync_free_rcu(struct rcu_head *head) * match the state "is the filp on a fasync list". * */ -static int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) +int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) { struct fasync_struct *fa, **fp; int result = 0; @@ -666,21 +666,28 @@ static int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) return result; } +struct fasync_struct *fasync_alloc(void) +{ + return kmem_cache_alloc(fasync_cache, GFP_KERNEL); +} + /* - * Add a fasync entry. Return negative on error, positive if - * added, and zero if did nothing but change an existing one. - * - * NOTE! It is very important that the FASYNC flag always - * match the state "is the filp on a fasync list". + * NOTE! This can be used only for unused fasync entries: + * entries that actually got inserted on the fasync list + * need to be released by rcu - see fasync_remove_entry. */ -static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) +void fasync_free(struct fasync_struct *new) { - struct fasync_struct *new, *fa, **fp; - int result = 0; + kmem_cache_free(fasync_cache, new); +} - new = kmem_cache_alloc(fasync_cache, GFP_KERNEL); - if (!new) - return -ENOMEM; +/* + * Insert a new entry into the fasync list. Return the pointer to the + * old one if we didn't use the new one. + */ +struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) +{ + struct fasync_struct *fa, **fp; spin_lock(&filp->f_lock); spin_lock(&fasync_lock); @@ -691,8 +698,6 @@ static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fa spin_lock_irq(&fa->fa_lock); fa->fa_fd = fd; spin_unlock_irq(&fa->fa_lock); - - kmem_cache_free(fasync_cache, new); goto out; } @@ -702,13 +707,42 @@ static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fa new->fa_fd = fd; new->fa_next = *fapp; rcu_assign_pointer(*fapp, new); - result = 1; filp->f_flags |= FASYNC; out: spin_unlock(&fasync_lock); spin_unlock(&filp->f_lock); - return result; + return fa; +} + +/* + * Add a fasync entry. Return negative on error, positive if + * added, and zero if did nothing but change an existing one. + * + * NOTE! It is very important that the FASYNC flag always + * match the state "is the filp on a fasync list". + */ +static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) +{ + struct fasync_struct *new; + + new = fasync_alloc(); + if (!new) + return -ENOMEM; + + /* + * fasync_insert_entry() returns the old (update) entry if + * it existed. + * + * So free the (unused) new entry and return 0 to let the + * caller know that we didn't add any new fasync entries. + */ + if (fasync_insert_entry(fd, filp, fapp, new)) { + fasync_free(new); + return 0; + } + + return 1; } /* diff --git a/fs/locks.c b/fs/locks.c index 0391d2ff5a4..85fd9ce1aba 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1505,6 +1505,7 @@ EXPORT_SYMBOL_GPL(vfs_setlease); int fcntl_setlease(unsigned int fd, struct file *filp, long arg) { struct file_lock *fl; + struct fasync_struct *new; struct inode *inode = filp->f_path.dentry->d_inode; int error; @@ -1512,12 +1513,25 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg) if (IS_ERR(fl)) return PTR_ERR(fl); + new = fasync_alloc(); + if (!new) { + locks_free_lock(fl); + return -ENOMEM; + } lock_flocks(); error = __vfs_setlease(filp, arg, &fl); if (error || arg == F_UNLCK) goto out_unlock; - error = fasync_helper(fd, filp, 1, &fl->fl_fasync); + /* + * fasync_insert_entry() returns the old entry if any. + * If there was no old entry, then it used 'new' and + * inserted it into the fasync list. Clear new so that + * we don't release it here. + */ + if (!fasync_insert_entry(fd, filp, &fl->fl_fasync, new)) + new = NULL; + if (error < 0) { /* remove lease just inserted by setlease */ fl->fl_type = F_UNLCK | F_INPROGRESS; @@ -1529,6 +1543,8 @@ int fcntl_setlease(unsigned int fd, struct file *filp, long arg) error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); out_unlock: unlock_flocks(); + if (new) + fasync_free(new); return error; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 8d7de08ab54..56285e5e1de 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1302,6 +1302,11 @@ struct fasync_struct { /* SMP safe fasync helpers: */ extern int fasync_helper(int, struct file *, int, struct fasync_struct **); +extern struct fasync_struct *fasync_insert_entry(int, struct file *, struct fasync_struct **, struct fasync_struct *); +extern int fasync_remove_entry(struct file *, struct fasync_struct **); +extern struct fasync_struct *fasync_alloc(void); +extern void fasync_free(struct fasync_struct *); + /* can be called from interrupts */ extern void kill_fasync(struct fasync_struct **, int, int); |