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Tue, 28 Jul 2026 19:30:32 -0700 (PDT) Received: from google.com ([2a00:79e0:2031:6:65c1:52a3:f6d3:37dc]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84ea02f8473sm611819b3a.31.2026.07.28.19.30.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jul 2026 19:30:31 -0700 (PDT) Date: Wed, 29 Jul 2026 11:30:28 +0900 From: Sergey Senozhatsky To: Haoqin Huang Cc: Minchan Kim , Sergey Senozhatsky , Jens Axboe , Nick Terrell , David Sterba , Andrew Morton , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Haoqin Huang , Rongwei Wang Subject: Re: [PATCH v2 2/5] zram: make dict update in comp_params_store() atomic Message-ID: References: <20260627070216.13511-1-haoqinhuang7@gmail.com> <20260728092935.31139-1-haoqinhuang7@gmail.com> <20260728092935.31139-2-haoqinhuang7@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260728092935.31139-2-haoqinhuang7@gmail.com> On (26/07/28 17:29), Haoqin Huang wrote: > comp_params_store() resets old parameters before reading a new dict, > so if kernel_read_file_from_path() fails the params are left broken > and the actual error is swallowed. Fix by reading into a temporary > buffer first, swapping only on success. Use sz <= 0 to also reject > zero-size dicts. > > Signed-off-by: Haoqin Huang > Signed-off-by: Rongwei Wang > --- > drivers/block/zram/zram_drv.c | 20 +++++++++++--------- > 1 file changed, 11 insertions(+), 9 deletions(-) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index ace65c586072..9ea7ba9d1ed0 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -1699,21 +1699,23 @@ static int comp_params_store(struct zram *zram, u32 prio, s32 level, > const char *dict_path, > struct deflate_params *deflate_params) > { > + void *new_dict = NULL; > ssize_t sz = 0; > > - comp_params_reset(zram, prio); I don't see why is that a problem. All you wanted to do here is to handle zero i_size. Why do we need dict setting to be atomic? > if (dict_path) { > - sz = kernel_read_file_from_path(dict_path, 0, > - &zram->params[prio].dict, > - INT_MAX, > - NULL, > - READING_POLICY); > - if (sz < 0) > - return -EINVAL; > + sz = kernel_read_file_from_path(dict_path, 0, &new_dict, > + INT_MAX, NULL, READING_POLICY); > + if (sz <= 0) { > + vfree(new_dict); > + if (sz == 0) > + return -EINVAL; > + return sz; > + } > } > > + comp_params_reset(zram, prio); > zram->params[prio].dict_sz = sz; > + zram->params[prio].dict = new_dict; > zram->params[prio].level = level; > zram->params[prio].deflate.winbits = deflate_params->winbits;