From f6acf8bb6a40ba3bfcf542e4c4c9e8968c8cb57a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 28 Nov 2013 14:54:21 -0500 Subject: sysfs, kernfs: introduce kernfs_ops We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch introduces kernfs_ops which hosts methods kernfs users implement and updates fs/sysfs/file.c such that sysfs_kf_*() functions populate kernfs_ops and kernfs_file_*() functions call the matching entries from kernfs_ops. kernfs_ops contains the following groups of methods. * seq_show() - for kernfs files which use seq_file for reads. * read() - for direct read implementations. Used iff seq_show() is not implemented. * write() - for writes. * mmap() - for mmaps. Notes: * sysfs_elem_attr->ops is added so that kernfs_ops can be accessed from sysfs_dirent. kernfs_ops() helper is added to verify locking and access the field. * SYSFS_FLAG_HAS_(SEQ_SHOW|MMAP) added. sd->s_attr->ops is accessible only while holding active_ref and there are cases where we want to take different actions depending on which ops are implemented. These two flags cache whether the two ops are implemented for those. * kernfs_file_*() no longer test sysfs type but chooses different behaviors depending on which methods in kernfs_ops are implemented. The conversions are trivial except for the open path. As kernfs_file_open() now decides whether to allow read/write accesses depending on the kernfs_ops implemented, the presence of methods in kobjs and attribute_bin should be propagated to kernfs_ops. sysfs_add_file_mode_ns() is updated so that it propagates presence / absence of the callbacks through _empty, _ro, _wo, _rw kernfs_ops. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- include/linux/kernfs.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'include/linux/kernfs.h') diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index b923052c29d0..97c6c0f91325 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -33,6 +33,32 @@ struct sysfs_open_file { const struct vm_operations_struct *vm_ops; }; +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 + * associated sysfs_open_file. + * + * read() is bounced through kernel buffer and a read larger than + * PAGE_SIZE results in partial operation of PAGE_SIZE. + */ + int (*seq_show)(struct seq_file *sf, void *v); + + ssize_t (*read)(struct sysfs_open_file *of, char *buf, size_t bytes, + loff_t off); + + /* + * write() is bounced through kernel buffer and a write larger than + * PAGE_SIZE results in partial operation of PAGE_SIZE. + */ + ssize_t (*write)(struct sysfs_open_file *of, char *buf, size_t bytes, + loff_t off); + + int (*mmap)(struct sysfs_open_file *of, struct vm_area_struct *vma); +}; + #ifdef CONFIG_SYSFS struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent, -- cgit v1.2.2