Commit e0cfc1c9 authored Jul 29, 2018 by Arnd Bergmann Committed by Greg Kroah-Hartman Sep 05, 2018

ext4: sysfs: print ext4_super_block fields as little-endian



commit a4d2aadca184ece182418950d45ba4ffc7b652d2 upstream.

While working on extended rand for last_error/first_error timestamps,
I noticed that the endianess is wrong; we access the little-endian
fields in struct ext4_super_block as native-endian when we print them.

This adds a special case in ext4_attr_show() and ext4_attr_store()
to byteswap the superblock fields if needed.

In older kernels, this code was part of super.c, it got moved to
sysfs.c in linux-4.4.

Cc: stable@vger.kernel.org
Fixes: 52c198c6 ("ext4: add sysfs entry showing whether the fs contains errors")
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9c2860f4

fs/ext4/sysfs.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -277,6 +277,10 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
		case attr_pointer_ui:
		if (!ptr)
		return 0;
		if (a->attr_ptr == ptr_ext4_super_block_offset)
		return snprintf(buf, PAGE_SIZE, "%u\n",
		le32_to_cpup(ptr));
		else
		return snprintf(buf, PAGE_SIZE, "%u\n",
		((unsigned int ) ptr));
		case attr_pointer_atomic:
		@@ -311,6 +315,9 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
		ret = kstrtoul(skip_spaces(buf), 0, &t);
		if (ret)
		return ret;
		if (a->attr_ptr == ptr_ext4_super_block_offset)
		((__le32 ) ptr) = cpu_to_le32(t);
		else
		((unsigned int ) ptr) = t;
		return len;
		case attr_inode_readahead: