single_open_size() allocates the buffer itself because it does the single_open() too. A file whose seq_file is opened by somebody else, like procfs does now, needs to do that after the fact. Add seq_preallocate() for that and use it in single_open_size().
No functional changes. Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- fs/seq_file.c | 36 ++++++++++++++++++++++++++++-------- include/linux/seq_file.h | 1 + 2 files changed, 29 insertions(+), 8 deletions(-) diff --git a/fs/seq_file.c b/fs/seq_file.c index 456c78719fd0..a4644cdda7e6 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -590,21 +590,41 @@ int single_open(struct file *file, int (*show)(struct seq_file *, void *), } EXPORT_SYMBOL(single_open); -int single_open_size(struct file *file, int (*show)(struct seq_file *, void *), - void *data, size_t size) +/** + * seq_preallocate - start out with a buffer of @size + * @m: the seq_file, before it is first read + * @size: the size of the buffer + * + * For files whose records don't fit into a page, so that the first read + * doesn't have to work its way up to the right buffer size. + */ +int seq_preallocate(struct seq_file *m, size_t size) { char *buf = seq_buf_alloc(size); - int ret; + if (!buf) return -ENOMEM; + kvfree(m->buf); + m->buf = buf; + m->size = size; + return 0; +} +EXPORT_SYMBOL(seq_preallocate); + +int single_open_size(struct file *file, int (*show)(struct seq_file *, void *), + void *data, size_t size) +{ + int ret; + ret = single_open(file, show, data); - if (ret) { - kvfree(buf); + if (ret) return ret; + ret = seq_preallocate(file->private_data, size); + if (ret) { + single_release(file_inode(file), file); + file->private_data = NULL; } - ((struct seq_file *)file->private_data)->buf = buf; - ((struct seq_file *)file->private_data)->size = size; - return 0; + return ret; } EXPORT_SYMBOL(single_open_size); diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index b813b7e63d89..834daff48b7d 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -175,6 +175,7 @@ int seq_path_root(struct seq_file *m, const struct path *path, void *single_start(struct seq_file *, loff_t *); 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 seq_preallocate(struct seq_file *m, size_t size); 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); -- 2.53.0
