This patch brings ability to plug in auxiliary fdinfo providers. For example in further patches eventfd, evenpoll and fsnotify will print out information associated with files. This feature is CONFIG_CHECKPOINT_RESTORE guarded to eliminate overhead for those who don't need it at all (this unfortunately makes patch bigger than I wanted). The basic usage rule is the following - fdinfo provider should register own "show" method via proc_register_fdinfo_driver call, where "show" methods are rather well known seq-file operations - once the kernel opens /proc/$pid/fdinfo/$fd file it calls for ->probe() method in registered fdinfo drivers, and if probe success, then seq-file "show" operations will be called to provide out additional infomation Initially we considered to inject some "show" metod to file_operations but since there really a number of file_operations declared inside kernel (and in real the further patches cover onle eventfd/epoll/inotify) the waste of memory space will be inacceptable I think. Pavel, I've left seq_next memthod as it was simply because we can't leave seq_next() after calling extra->driver->ops->start without increasing "pos", thus we need to call for "show" manually once. Signed-off-by: Cyrill Gorcunov CC: Al Viro CC: Alexey Dobriyan CC: Andrew Morton CC: Pavel Emelyanov CC: James Bottomley --- fs/proc/fd.c | 198 ++++++++++++++++++++++++++++++++++++++++++++++-- include/linux/proc_fs.h | 26 ++++++ 2 files changed, 216 insertions(+), 8 deletions(-) Index: linux-2.6.git/fs/proc/fd.c =================================================================== --- linux-2.6.git.orig/fs/proc/fd.c +++ linux-2.6.git/fs/proc/fd.c @@ -8,18 +8,14 @@ #include #include #include +#include #include #include "internal.h" #include "fd.h" -struct proc_fdinfo { - loff_t f_pos; - int f_flags; -}; - -static int fdinfo_open_helper(struct inode *inode, int *f_flags, struct path *path) +static int fdinfo_open_helper(struct inode *inode, int *f_flags, struct file **f_file, struct path *path) { struct files_struct *files = NULL; struct task_struct *task; @@ -49,6 +45,10 @@ static int fdinfo_open_helper(struct ino *path = fd_file->f_path; path_get(&fd_file->f_path); } + if (f_file) { + *f_file = fd_file; + get_file(fd_file); + } ret = 0; } spin_unlock(&files->file_lock); @@ -58,6 +58,186 @@ static int fdinfo_open_helper(struct ino return ret; } +#ifdef CONFIG_CHECKPOINT_RESTORE + +static LIST_HEAD(fdinfo_drivers); +static DECLARE_RWSEM(fdinfo_drivers_sem); + +int proc_register_fdinfo_driver(struct proc_fdinfo_driver *s) +{ + struct proc_fdinfo_driver *i; + int ret = 0; + + if (!s->ops || !s->probe) + return -EINVAL; + + down_write(&fdinfo_drivers_sem); + list_for_each_entry(i, &fdinfo_drivers, list) { + if (i == s) { + WARN_ONCE("Trying reassign fdinfo driver `%s'\n", + i->name); + ret = -EINVAL; + break; + } + } + if (!ret) + list_add(&s->list, &fdinfo_drivers); + up_write(&fdinfo_drivers_sem); + + return ret; +} + +void proc_unregister_fdinfo_driver(struct proc_fdinfo_driver *s) +{ + struct proc_fdinfo_driver *i, *tmp; + + down_write(&fdinfo_drivers_sem); + list_for_each_entry_safe(i, tmp, &fdinfo_drivers, list) { + if (i == s) { + list_del(&i->list); + break; + } + } + up_write(&fdinfo_drivers_sem); +} + +static int prep_fdinfo_driver(struct proc_fdinfo_extra *extra) +{ + struct proc_fdinfo_driver *s; + + down_read(&fdinfo_drivers_sem); + list_for_each_entry(s, &fdinfo_drivers, list) { + if (s->probe(extra->f_file)) { + extra->driver = s; + break; + } + } + up_read(&fdinfo_drivers_sem); + + return 0; +} + +static void *seq_start(struct seq_file *m, loff_t *pos) +{ + struct proc_fdinfo_extra *extra = m->private; + + down_read(&fdinfo_drivers_sem); + extra->pos = *pos; + + return *pos == 0 ? extra : + (extra->driver ? extra->driver->ops->start(m, pos) : NULL); +} + +static void seq_stop(struct seq_file *m, void *v) +{ + struct proc_fdinfo_extra *extra = m->private; + + if (extra->driver && extra->pos > 0) + extra->driver->ops->stop(m, v); + up_read(&fdinfo_drivers_sem); +} + +static void *seq_next(struct seq_file *m, void *p, loff_t *pos) +{ + struct proc_fdinfo_extra *extra = m->private; + void *v = NULL; + + if (extra->driver) { + int ret = 0; + + if (*pos == 0) { + v = extra->driver->ops->start(m, pos); + if (v) { + ret = extra->driver->ops->show(m, v); + p = v; + } else + ret = -1; + } + + if (!ret) + v = extra->driver->ops->next(m, p, pos); + } else + ++*pos; + + extra->pos = *pos; + return v; +} + +static int seq_show(struct seq_file *m, void *v) +{ + struct proc_fdinfo_extra *extra = m->private; + + if (extra->driver && extra->pos > 0) + return extra->driver->ops->show(m, v); + + seq_printf(m, "pos:\t%lli\nflags:\t0%o\n", + (long long)extra->f_file->f_pos, + extra->f_flags); + return 0; +} + +static const struct seq_operations fdinfo_seq_ops = { + .start = seq_start, + .next = seq_next, + .stop = seq_stop, + .show = seq_show, +}; + +static int seq_fdinfo_open(struct inode *inode, struct file *file) +{ + struct proc_fdinfo_extra *extra; + struct seq_file *m; + int ret; + + extra = kzalloc(sizeof(*extra), GFP_KERNEL); + if (!extra) + return -ENOMEM; + + ret = seq_open(file, &fdinfo_seq_ops); + if (!ret) { + ret = -ENOENT; + m = file->private_data; + m->private = extra; + + ret = fdinfo_open_helper(inode, &extra->f_flags, + &extra->f_file, NULL); + if (!ret) + ret = prep_fdinfo_driver(extra); + } + + if (ret) { + if (extra->f_file) + put_filp(extra->f_file); + kfree(extra); + } + return ret; +} + +static int seq_fdinfo_release(struct inode *inode, struct file *file) +{ + struct seq_file *m = file->private_data; + struct proc_fdinfo_extra *extra = m->private; + + put_filp(extra->f_file); + kfree(m->private); + + return seq_release(inode, file); +} + +static const struct file_operations proc_fdinfo_file_operations = { + .open = seq_fdinfo_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_fdinfo_release, +}; + +#else /* CONFIG_CHECKPOINT_RESTORE */ + +struct proc_fdinfo { + loff_t f_pos; + int f_flags; +}; + static int seq_show(struct seq_file *m, void *v) { struct proc_fdinfo *fdinfo = m->private; @@ -76,7 +256,7 @@ static int seq_fdinfo_open(struct inode if (!fdinfo) return -ENOMEM; - ret = fdinfo_open_helper(inode, &fdinfo->f_flags, NULL); + ret = fdinfo_open_helper(inode, &fdinfo->f_flags, NULL, NULL); if (!ret) { ret = single_open(file, seq_show, fdinfo); if (!ret) @@ -104,6 +284,8 @@ static const struct file_operations proc .release = seq_fdinfo_release, }; +#endif /* CONFIG_CHECKPOINT_RESTORE */ + static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) { struct files_struct *files; @@ -173,7 +355,7 @@ static const struct dentry_operations ti static int proc_fd_link(struct dentry *dentry, struct path *path) { - return fdinfo_open_helper(dentry->d_inode, NULL, path); + return fdinfo_open_helper(dentry->d_inode, NULL, NULL, path); } static struct dentry * Index: linux-2.6.git/include/linux/proc_fs.h =================================================================== --- linux-2.6.git.orig/include/linux/proc_fs.h +++ linux-2.6.git/include/linux/proc_fs.h @@ -100,6 +100,24 @@ struct vmcore { loff_t offset; }; +struct seq_operations; + +/* fdinfo auxiliary information drivers */ +struct proc_fdinfo_driver { + struct list_head list; + const char *name; + const struct seq_operations *ops; + int (*probe)(struct file *file); +}; + +/* auxiliary data allocated per fdinfo reader */ +struct proc_fdinfo_extra { + struct proc_fdinfo_driver *driver; + loff_t pos; + struct file *f_file; + unsigned int f_flags; +}; + #ifdef CONFIG_PROC_FS extern void proc_root_init(void); @@ -175,6 +193,11 @@ extern struct proc_dir_entry *proc_net_m extern struct file *proc_ns_fget(int fd); +#ifdef CONFIG_CHECKPOINT_RESTORE +extern int proc_register_fdinfo_driver(struct proc_fdinfo_driver *s); +extern void proc_unregister_fdinfo_driver(struct proc_fdinfo_driver *s); +#endif /* CONFIG_CHECKPOINT_RESTORE */ + #else #define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; }) @@ -229,6 +252,9 @@ static inline struct file *proc_ns_fget( return ERR_PTR(-EINVAL); } +static inline int proc_register_fdinfo_driver(struct proc_fdinfo_driver *s) { return -EINVAL; } +static inline void proc_unregister_fdinfo_driver(struct proc_fdinfo_driver *s) { } + #endif /* CONFIG_PROC_FS */ #if !defined(CONFIG_PROC_KCORE) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/