From 2f0c6b7593a590eef7fa35344da57380fcee7581 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 1 Oct 2013 17:42:06 -0400 Subject: [PATCH] sysfs: add sysfs_bin_read() sysfs bin file handling will be merged into the regular file support. This patch prepares the read path. Copy fs/sysfs/bin.c::read() to fs/sysfs/file.c and make it use sysfs_open_file instead of bin_buffer. The function is identical copy except for the use of sysfs_open_file. The new function is added to sysfs_bin_operations. This isn't used yet but will eventually replace fs/sysfs/bin.c. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/file.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index b36473f21824..9ba492a3d932 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -139,6 +139,70 @@ static int sysfs_seq_show(struct seq_file *sf, void *v) return 0; } +/* + * Read method for bin files. As reading a bin file can have side-effects, + * the exact offset and bytes specified in read(2) call should be passed to + * the read callback making it difficult to use seq_file. Implement + * simplistic custom buffering for bin files. + */ +static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf, + size_t bytes, loff_t *off) +{ + struct sysfs_open_file *of = sysfs_of(file); + struct bin_attribute *battr = of->sd->s_bin_attr.bin_attr; + struct kobject *kobj = of->sd->s_parent->s_dir.kobj; + int size = file_inode(file)->i_size; + int count = min_t(size_t, bytes, PAGE_SIZE); + loff_t offs = *off; + char *buf; + + if (!bytes) + return 0; + + if (size) { + if (offs > size) + return 0; + if (offs + count > size) + count = size - offs; + } + + buf = kmalloc(count, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + /* need of->sd for battr, its parent for kobj */ + mutex_lock(&of->mutex); + if (!sysfs_get_active(of->sd)) { + count = -ENODEV; + mutex_unlock(&of->mutex); + goto out_free; + } + + if (battr->read) + count = battr->read(file, kobj, battr, buf, offs, count); + else + count = -EIO; + + sysfs_put_active(of->sd); + mutex_unlock(&of->mutex); + + if (count < 0) + goto out_free; + + if (copy_to_user(userbuf, buf, count)) { + count = -EFAULT; + goto out_free; + } + + pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count); + + *off = offs + count; + + out_free: + kfree(buf); + return count; +} + /** * flush_write_buffer - push buffer to kobject * @of: open file @@ -495,6 +559,7 @@ const struct file_operations sysfs_file_operations = { }; const struct file_operations sysfs_bin_operations = { + .read = sysfs_bin_read, .write = sysfs_write_file, .llseek = generic_file_llseek, }; -- 2.20.1