Re: [PATCH v2] zram: fix short reads from block_state

[Sergey Senozhatsky]

On (26/09/29 09:18), Pooyan Azad wrote:
> read_block_state() formats each entry directly into the buffer supplied
> by read(). If the remaining buffer is too small for one complete record,
> snprintf() returns the full record length and the function stops without
> copying data or advancing the file position. A read smaller than a record
> therefore returns zero at a non-EOF position and cannot make progress.
> 
> Convert block_state to seq_file so formatted records are buffered
> independently of the userspace read size. Keep dev_lock held across each
> seq_file iteration and continue to protect individual entries with their
> slot locks.
> 
> Fixes: c0265342bff4 ("zram: introduce zram memory tracking")
> Closes: https://lore.kernel.org/r/CANC3H+LdtoydSp+o2ecErAw7k6R2+gRf9LyxcaoHv_mGhJmyQQ@xxxxxxxxxxxxxx/
> Signed-off-by: Pooyan Azad <pooyan.azadparvar@xxxxxxxxx>

Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Tested-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>