4.9-stable review patch. If anyone has any objections, please let me know.
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From: Arnd Bergmann arnd@arndb.de
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: 52c198c6820f ("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
--- fs/ext4/sysfs.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/fs/ext4/sysfs.c +++ b/fs/ext4/sysfs.c @@ -277,8 +277,12 @@ static ssize_t ext4_attr_show(struct kob case attr_pointer_ui: if (!ptr) return 0; - return snprintf(buf, PAGE_SIZE, "%u\n", - *((unsigned int *) ptr)); + 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: if (!ptr) return 0; @@ -311,7 +315,10 @@ static ssize_t ext4_attr_store(struct ko ret = kstrtoul(skip_spaces(buf), 0, &t); if (ret) return ret; - *((unsigned int *) ptr) = t; + 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: return inode_readahead_blks_store(a, sbi, buf, len);