Instead of appending new text attribute data at the offset specified by the
write() system call, only pass the newly written data to the .store()
callback.

Reported-by: Bodo Stroesser <bostroesser@gmail.com>
Tested-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Commit 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter
methods") changed the simple_read_from_buffer() calls into copy_to_iter()
calls and the simple_write_to_buffer() calls into copy_from_iter() calls.
The simple*buffer() methods update the file offset (*ppos) but the read
and write iterators not yet. Make the read and write iterators update the
file offset (iocb->ki_pos).

This patch has been tested as follows:

 # modprobe target_core_user
 # dd if=/sys/kernel/config/target/dbroot bs=1
/var/target
12+0 records in
12+0 records out
12 bytes copied, 9.5539e-05 s, 126 kB/s

 # cd /sys/kernel/config/acpi/table
 # mkdir test
 # cd test
 # dmesg -c >/dev/null; printf 'SSDT\x8\0\0\0abcdefghijklmnopqrstuvwxyz' | dd of=aml bs=1; dmesg -c
34+0 records in
34+0 records out
34 bytes copied, 0.010627 s, 3.2 kB/s
[  261.056551] ACPI configfs: invalid table length

Reported-by: Yanko Kaneti <yaneti@declera.com>
Cc: Yanko Kaneti <yaneti@declera.com>
Fixes: 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter methods")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Pull configfs updates from Christoph Hellwig:

 - fix a memleak in configfs_release_bin_file (Chung-Chiang Cheng)

 - implement the .read_iter and .write_iter (Bart Van Assche)

 - minor cleanups (Bart Van Assche, me)

* tag 'configfs-5.13' of git://git.infradead.org/users/hch/configfs:
  configfs: simplify configfs_release_bin_file
  configfs: fix memleak in configfs_release_bin_file
  configfs: implement the .read_iter and .write_iter methods
  configfs: drop pointless kerneldoc comments
  configfs: fix the kerneldoc comment for configfs_create_bin_file

Move the ramfs aops to libfs and reuse them for kernfs and configfs.
Thosw two did not wire up ->set_page_dirty before and now get
__set_page_dirty_no_writeback, which is the right one for no-writeback
address_space usage.

Drop the now unused exports of the libfs helpers only used for ramfs-style
pagecache usage.

Link: https://lkml.kernel.org/r/20210614061512.3966143-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Remove the clearing of various fields just before freeing the
buffer structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>

When reading binary attributes in progress, buffer->bin_buffer is setup in
configfs_read_bin_file() but never freed.

Fixes: 03607ace807b4 ("configfs: implement binary attributes")
Signed-off-by: Chung-Chiang Cheng <cccheng@synology.com>
[hch: move the vfree rather than duplicating it]
Signed-off-by: Christoph Hellwig <hch@lst.de>

Configfs is one of the few filesystems that does not yet support the
.read_iter and .write_iter callbacks. This patch adds support for these
methods in configfs.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[hch: split out a separate fix]
Signed-off-by: Christoph Hellwig <hch@lst.de>

file.c has a bunch of kerneldoc comments for static functions that do not
document any API but just list what is done.  Drop them.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Mention the correct argument name.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>

The section "19) Editor modelines and other cruft" in
Documentation/process/coding-style.rst clearly says, "Do not include any
of these in source files."

I recently receive a patch to explicitly add a new one.

Let's do treewide cleanups, otherwise some people follow the existing code
and attempt to upstream their favoriate editor setups.

It is even nicer if scripts/checkpatch.pl can check it.

If we like to impose coding style in an editor-independent manner, I think
editorconfig (patch [1]) is a saner solution.

[1] https://lore.kernel.org/lkml/20200703073143.423557-1-danny@kdrag0n.dev/

Link: https://lkml.kernel.org/r/20210324054457.1477489-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>	[auxdisplay]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>