f2fs: fix to avoid potential memory corruption in __update_iostat_latency()

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to avoid potential memory corruption in __update_iostat_latency()

Add iotype sanity check to avoid potential memory corruption.
This is to fix the compile error below:

fs/f2fs/iostat.c:231 __update_iostat_latency() error: buffer overflow
'io_lat->peak_lat[type]' 3 <= 3

vim +228 fs/f2fs/iostat.c

211 static inline void __update_iostat_latency(struct bio_iostat_ctx
*iostat_ctx,
212 enum iostat_lat_type type)
213 {
214 unsigned long ts_diff;
215 unsigned int page_type = iostat_ctx->type;
216 struct f2fs_sb_info *sbi = iostat_ctx->sbi;
217 struct iostat_lat_info *io_lat = sbi->iostat_io_lat;
218 unsigned long flags;
219
220 if (!sbi->iostat_enable)
221 return;
222
223 ts_diff = jiffies - iostat_ctx->submit_ts;
224 if (page_type >= META_FLUSH)
^^^^^^^^^^

225 page_type = META;
226
227 spin_lock_irqsave(&sbi->iostat_lat_lock, flags);
@228 io_lat->sum_lat[type][page_type] += ts_diff;
^^^^^^^^^
Mixup between META_FLUSH and NR_PAGE_TYPE leads to memory corruption.