| From a4d2aadca184ece182418950d45ba4ffc7b652d2 Mon Sep 17 00:00:00 2001 |
| From: Arnd Bergmann <arnd@arndb.de> |
| Date: Sun, 29 Jul 2018 15:48:00 -0400 |
| Subject: ext4: sysfs: print ext4_super_block fields as little-endian |
| |
| 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 |
| @@ -278,8 +278,12 @@ 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; |
| @@ -312,7 +316,10 @@ 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); |
