linux/fs/sysfs
Valentine Sinitsyn 0fedefd4c4 kernfs: sysfs: support custom llseek method for sysfs entries
As of now, seeking in sysfs files is handled by generic_file_llseek().
There are situations where one may want to customize seeking logic:

- Many sysfs entries are fixed files while generic_file_llseek() accepts
  past-the-end positions. Not only being useless by itself, this
  also means a bug in userspace code will trigger not at lseek(), but at
  some later point making debugging harder.
- generic_file_llseek() relies on f_mapping->host to get the file size
  which might not be correct for all sysfs entries.
  See commit 636b21b501 ("PCI: Revoke mappings like devmem") as an example.

Implement llseek method to override this behavior at sysfs attribute
level. The method is optional, and if it is absent,
generic_file_llseek() is called to preserve backwards compatibility.

Signed-off-by: Valentine Sinitsyn <valesini@yandex-team.ru>
Link: https://lore.kernel.org/r/20230925084013.309399-1-valesini@yandex-team.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-05 13:42:11 +02:00
..
dir.c fs/sysfs/dir.c: replace S_IRWXU|S_IRUGO|S_IXUGO with 0755 sysfs_create_dir_ns() 2021-10-05 16:35:05 +02:00
file.c kernfs: sysfs: support custom llseek method for sysfs entries 2023-10-05 13:42:11 +02:00
group.c sysfs: Skip empty folders creation 2023-06-15 13:37:53 +02:00
Kconfig
Makefile
mount.c kernfs: move struct kernfs_root out of the public view. 2022-02-23 15:46:34 +01:00
symlink.c
sysfs.h sysfs: split out binary attribute handling from sysfs_add_file_mode_ns 2021-09-14 16:59:46 +02:00