2013/1/22, Jan Kara <jack@xxxxxxx>: > On Tue 22-01-13 09:45:09, Namjae Jeon wrote: >> 2013/1/21, Jan Kara <jack@xxxxxxx>: >> > @@ -2222,6 +2219,8 @@ int udf_read_extent_cache(struct inode *inode, >> > loff_t >> > bcount, >> > *lbcount = iinfo->cached_extent.lstart; >> > memcpy(pos, &iinfo->cached_extent.epos, >> > sizeof(struct extent_position)); >> > + if (pos->bh) >> > + get_bh(pos->bh); >> > spin_unlock(&iinfo->i_extent_cache_lock); >> > return 1; >> > } else >> > This is the most important - we should give buffer reference to >> > pos->bh. >> > Caller will eventually free it right? >> This change is not required as we give buffer reference to pos->bh at >> the time of cache update. >> When we start reading a file, first we try to read the cache which >> will lead to cache miss. >> So, we would really access the pos->bh in udf_update_extent_cache for >> the first time, and this is where the buffer reference is incremented. >> Calling get_bh at 2 places will eventually lead to mem leak. >> Let me know your opinion. > Yes, udf_update_extent_cache() gets its own reference to bh but that is > dropped in udf_clear_extent_cache(). So I think udf_read_extent_cache() > needs to get a reference to the caller (as the caller will eventually free > the bh via brelse(epos.bh) e.g. in udf_extend_file(). Also I realized > udf_update_extent_cache() needs to first clear the cache if it is valid. > Otherwise it just overwrites bh pointer and reference is leaked. Is it > clearer now? Yes, you're right. Also, this patch looks good to me. > > I've also changed locking of udf_clear_extent_cache() so that > i_extent_cache_lock is always taken for that function - it makes the > locking rules obvious at the first sight. Yes, right. it is needed. When we test with this patch, working fine. Thanks Jan! > > Attached is the patch I currently carry. > > Honza > > -- > Jan Kara <jack@xxxxxxx> > SUSE Labs, CR > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
