Messages in this thread Patch in this message | | | Date | Mon, 28 Oct 2013 09:04:14 -0400 | From | Tejun Heo <> | Subject | [PATCH v2 25/34] sysfs, kernfs: add kernfs_ops->seq_{start|next|stop}() |
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kernfs_ops currently only supports single_open() behavior which is pretty restrictive. Add optional callbacks ->seq_{start|next|stop}() which, when implemented, are invoked for seq_file traversal. This allows full seq_file functionality for kernfs users. This currently doesn't have any user and doesn't change any behavior.
v2: Refreshed on top of the updated "sysfs, kernfs: prepare read path for kernfs".
Signed-off-by: Tejun Heo <tj@kernel.org> --- fs/sysfs/file.c | 39 ++++++++++++++++++++++++++++----------- include/linux/kernfs.h | 9 +++++++-- 2 files changed, 35 insertions(+), 13 deletions(-)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index 971f1d8..9b79160 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -146,6 +146,7 @@ static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf, static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos) { struct sysfs_open_file *of = sf->private; + const struct kernfs_ops *ops; /* * @of->mutex nests outside active ref and is just to ensure that @@ -157,26 +158,42 @@ static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos) return ERR_PTR(-ENODEV); } - /* - * The same behavior and code as single_open(). Returns !NULL if - * pos is at the beginning; otherwise, NULL. - */ - return NULL + !*ppos; + ops = kernfs_ops(of->sd); + if (ops->seq_start) { + return ops->seq_start(sf, ppos); + } else { + /* + * The same behavior and code as single_open(). Returns + * !NULL if pos is at the beginning; otherwise, NULL. + */ + return NULL + !*ppos; + } } static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos) { - /* - * The same behavior and code as single_open(), always terminate - * after the initial read. - */ - ++*ppos; - return NULL; + struct sysfs_open_file *of = sf->private; + const struct kernfs_ops *ops = kernfs_ops(of->sd); + + if (ops->seq_next) { + return ops->seq_next(sf, v, ppos); + } else { + /* + * The same behavior and code as single_open(), always + * terminate after the initial read. + */ + ++*ppos; + return NULL; + } } static void kernfs_seq_stop(struct seq_file *sf, void *v) { struct sysfs_open_file *of = sf->private; + const struct kernfs_ops *ops = kernfs_ops(of->sd); + + if (ops->seq_stop) + ops->seq_stop(sf, v); sysfs_put_active(of->sd); mutex_unlock(&of->mutex); diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index a1b94b7..222040c 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -36,8 +36,9 @@ struct kernfs_ops { /* * Read is handled by either seq_file or raw_read(). * - * If seq_show() is present, seq_file path is active. The behavior - * is equivalent to single_open(). @sf->private points to the + * If seq_show() is present, seq_file path is active. Other seq + * operations are optional and if not implemented, the behavior is + * equivalent to single_open(). @sf->private points to the * associated sysfs_open_file. * * read() is bounced through kernel buffer and a read larger than @@ -45,6 +46,10 @@ struct kernfs_ops { */ int (*seq_show)(struct seq_file *sf, void *v); + void *(*seq_start)(struct seq_file *sf, loff_t *ppos); + void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); + void (*seq_stop)(struct seq_file *sf, void *v); + ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes, loff_t off); -- 1.8.3.1
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