new helper: single_open_size()
Same as single_open(), but preallocates the buffer of given size.
Doesn't make any sense for sizes up to PAGE_SIZE and doesn't make
sense if output of show() exceeds PAGE_SIZE only rarely - seq_read()
will take care of growing the buffer and redoing show(). If you
_know_ that it will be large, it might make more sense to look into
saner iterator, rather than go with single-shot one. If that's
impossible, single_open_size() might be for you.
Again, don't use that without a good reason; occasionally that's really
the best way to go, but very often there are better solutions.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 38bb59f..774c1eb 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -599,6 +599,24 @@
}
EXPORT_SYMBOL(single_open);
+int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
+ void *data, size_t size)
+{
+ char *buf = kmalloc(size, GFP_KERNEL);
+ int ret;
+ if (!buf)
+ return -ENOMEM;
+ ret = single_open(file, show, data);
+ if (ret) {
+ kfree(buf);
+ return ret;
+ }
+ ((struct seq_file *)file->private_data)->buf = buf;
+ ((struct seq_file *)file->private_data)->size = size;
+ return 0;
+}
+EXPORT_SYMBOL(single_open_size);
+
int single_release(struct inode *inode, struct file *file)
{
const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 68a04a3..2da29ac 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -123,6 +123,7 @@
}
int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
+int single_open_size(struct file *, int (*)(struct seq_file *, void *), void *, size_t);
int single_release(struct inode *, struct file *);
void *__seq_open_private(struct file *, const struct seq_operations *, int);
int seq_open_private(struct file *, const struct seq_operations *, int);
