Re: [LTP] [PATCH v4] readahead02.c: Fix check input fsize

[Wei Gao via ltp <ltp@lists.linux.it>]

On Mon, Jan 16, 2023 at 02:42:49PM +0100, Cyril Hrubis wrote:
> Hi!
> > diff --git a/include/tst_device.h b/include/tst_device.h
> > index 977427f1c..f03f17f7d 100644
> > --- a/include/tst_device.h
> > +++ b/include/tst_device.h
> > @@ -6,6 +6,8 @@
> >  #ifndef TST_DEVICE_H__
> >  #define TST_DEVICE_H__
> >  
> > +#define DEV_SIZE_MB 300u
> > +
> >  #include <unistd.h>
> >  #include <stdint.h>
> >  #include <sys/stat.h>
> > @@ -49,7 +51,7 @@ int tst_clear_device(const char *dev);
> >   * free loopdev). If path is non-NULL, it will be filled with free loopdev path.
> >   *
> >   */
> > -int tst_find_free_loopdev(const char *path, size_t path_len);
> > +int tst_find_free_loopdev(char *path, size_t path_len);
> >  
> >  /*
> >   * Attaches a file to a loop device.
> > diff --git a/lib/tst_device.c b/lib/tst_device.c
> > index 48d7e3ab6..b098fc80b 100644
> > --- a/lib/tst_device.c
> > +++ b/lib/tst_device.c
> > @@ -38,6 +38,7 @@
> >  #include "lapi/syscalls.h"
> >  #include "test.h"
> >  #include "safe_macros.h"
> > +#include "tst_device.h"
> >  
> >  #ifndef LOOP_CTL_GET_FREE
> >  # define LOOP_CTL_GET_FREE 0x4C82
> > @@ -46,7 +47,6 @@
> >  #define LOOP_CONTROL_FILE "/dev/loop-control"
> >  
> >  #define DEV_FILE "test_dev.img"
> > -#define DEV_SIZE_MB 300u
> >  #define UUID_STR_SZ 37
> >  #define UUID_FMT "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x"
> 
> These changes are useless now.
ack
> 
> > diff --git a/testcases/kernel/syscalls/readahead/readahead02.c b/testcases/kernel/syscalls/readahead/readahead02.c
> > index 7acf4bb18..5989c7cbf 100644
> > --- a/testcases/kernel/syscalls/readahead/readahead02.c
> > +++ b/testcases/kernel/syscalls/readahead/readahead02.c
> > @@ -33,6 +33,7 @@
> >  #include "tst_test.h"
> >  #include "tst_timer.h"
> >  #include "lapi/syscalls.h"
> > +#include "tst_device.h"
> >  
> >  static char testfile[PATH_MAX] = "testfile";
> >  #define DROP_CACHES_FNAME "/proc/sys/vm/drop_caches"
> > @@ -366,11 +367,24 @@ static void setup_readahead_length(void)
> >  
> >  static void setup(void)
> >  {
> > -	if (opt_fsizestr) {
> > -		testfile_size = SAFE_STRTOL(opt_fsizestr, 1, INT_MAX);
> > -		tst_set_max_runtime(1 + testfile_size / (DEFAULT_FILESIZE/32));
> > +	/*
> > +	 * Acutaly dev size will reduced after create filesystem,
> > +	 * so use dev_szie * 0.8 as dev real usage size, test case will
> > +	 * create two files within dev so we need div 2 get max file size
> > +	 */
> > +	size_t fsize_max = tst_device->size * 0.8 / 2 * 1024 * 1024;
> 
> I'm not entirely sure about the * 0.8 here. I suppose that we need some
> space for metadata and some manipulation space but 20% is probably way
> to much. What motivation is behind the exact number here?
> 

Acutaly dev size will reduced after create filesystem, for example
system set default dev size is 300M but acutal dev size is 280M

"df -h" example resulst in case dev size = 300M:
/dev/loop1      280M  272M     0 100% /tmp/LTP_reaNP2ElW/mntpoint

Around 7% space loss so we use dev_szie * 0.9 as dev real usage size
Test case will create two files within dev so we need div 2 to get
max file size

> > +	/* At least two pagesize for test case */
> > +	pagesize = getpagesize();
> > +	size_t fsize_min = pagesize * 2;
> > +
> > +	if (tst_parse_filesize(opt_fsizestr, (long long *)&testfile_size, fsize_min, fsize_max)) {
>                                               ^
> 					      This is wrong, as long as
> 					      size of size_t and long
> 					      long is different it will
> 					      either corrupt memory or
> 					      crash.
> 
> The testfile_size has to be defined long long there is no way around it.
ack
> 
> > +		tst_set_max_runtime(1 + DEFAULT_FILESIZE / (DEFAULT_FILESIZE/32));
> 
> Why do we even bother with setting runtime if we are doing
> tst_brk(TBROK, ...) on the next line?
ack
> 
> > +		tst_brk(TBROK, "invalid initial filesize '%s'", opt_fsizestr);
>                                              ^
> 					I do not understand what
> 					'initial' means in this context.
> >  	}
> >  
> > +	tst_set_max_runtime(1 + testfile_size / (DEFAULT_FILESIZE/32));
> > +
> >  	if (access(PROC_IO_FNAME, F_OK))
> >  		tst_brk(TCONF, "Requires " PROC_IO_FNAME);
> >  
> > @@ -380,7 +394,6 @@ static void setup(void)
> >  	/* check if readahead is supported */
> >  	tst_syscall(__NR_readahead, 0, 0, 0);
> >  
> > -	pagesize = getpagesize();
> >  
> >  	setup_readahead_length();
> >  	tst_res(TINFO, "readahead length: %d", readahead_length);
> > -- 
> > 2.35.3
> > 
> 
> -- 
> Cyril Hrubis
> chrubis@suse.cz

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