Added modifications to s_errors in the modification framework of superblock's attrs. There is no lock protection when the user mode operates on the same block, so I modify the s_errors by the modification framework of superblock's attrs. The parameters passed in from the user mode will be checked by sb_attr_errors_check first, if the check is passed, It will call buffer_lock in ext4_update_superblocks_fn and use sb_attr_errors_set, so it can ensure the atomicity of a modification. Signed-off-by: zhanchengbin <zhanchengbin1@xxxxxxxxxx> Reported-by: kernel test robot <lkp@xxxxxxxxx> Closes: https://lore.kernel.org/oe-kbuild-all/202308021801.ieUVR2xl-lkp@xxxxxxxxx/ --- fs/ext4/ioctl.c | 22 ++++++++++++++++++++++ include/uapi/linux/ext4.h | 4 +++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 76653d855073..4053a038da0a 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -30,10 +30,32 @@ typedef void ext4_update_sb_callback(struct ext4_super_block *es, const void *arg); +static int sb_attr_errors_check(struct ext4_sbattr *p_sbattr) +{ + __u16 error_behavior = *(__u16 *)(p_sbattr->sba_value); + + if (p_sbattr->sba_len != EXT4_IOC_SUPERBLOCK_LEN_S_ERRORS) + return -EINVAL; + + if (error_behavior < EXT4_ERRORS_CONTINUE || + error_behavior > EXT4_ERRORS_PANIC) + return -EINVAL; + + return 0; +} + +static void sb_attr_errors_set(struct ext4_super_block *es, const void *arg) +{ + struct ext4_sbattr *p_sbattr = (struct ext4_sbattr *)arg; + + es->s_errors = cpu_to_le16(*(__u16 *)p_sbattr->sba_value); +} + /* * Check and modify functions for each superblock variable */ struct ext4_sbattr_operation ext4_sbattr_ops[] = { + {EXT4_IOC_SUPERBLOCK_KEY_S_ERRORS, sb_attr_errors_check, sb_attr_errors_set}, {EXT4_IOC_SUPERBLOCK_KEY_MAX, NULL, NULL}, }; diff --git a/include/uapi/linux/ext4.h b/include/uapi/linux/ext4.h index 79b5a751b83e..f5429630343e 100644 --- a/include/uapi/linux/ext4.h +++ b/include/uapi/linux/ext4.h @@ -90,8 +90,10 @@ struct ext4_sbattr { }; enum ext4_ioc_superblock_key { - EXT4_IOC_SUPERBLOCK_KEY_MAX = 0, + EXT4_IOC_SUPERBLOCK_KEY_S_ERRORS = 0, + EXT4_IOC_SUPERBLOCK_KEY_MAX, }; +#define EXT4_IOC_SUPERBLOCK_LEN_S_ERRORS 2 #define EXT4_SBATTR_MAX_COUNT 20 -- 2.31.1
