[PATCH] fat: device-level-flush-after-sync

[PATCH] fat: device-level-flush-after-sync

[Gianfranco]

    This patch forces a device-level flush after the generic Linux
    code for sync has run.

    The kernel depends upon filesystem-specific code to flush when
    the filesystem itself thinks it is necessary, and otherwise
    does nothing.  Someone expecting sync to behave as expected
    might be in for a rude surprise.

    The usual caveats apply:  Devices that do not implement flush
    or whose implementation is buggy will not behave well.  IO
    that occurs after the sync will not be flushed.

Signed-off-by: Ken Kofman <gianfranco.dutka@arista.com>

---
 fs/fat/inode.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index a38238d75c08..ddaed94ee48f 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -823,6 +823,14 @@ static int fat_remount(struct super_block *sb, int *flags, char *data)
 	return 0;
 }
 
+static int fat_sync_fs(struct super_block *sb, int wait)
+{
+	if (wait)
+		return blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
+	else
+		return 0;
+}
+
 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
@@ -937,6 +945,7 @@ static const struct super_operations fat_sops = {
 	.put_super	= fat_put_super,
 	.statfs		= fat_statfs,
 	.remount_fs	= fat_remount,
+	.sync_fs        = fat_sync_fs,
 
 	.show_options	= fat_show_options,
 };
-- 
2.37.0

Re: [PATCH] fat: device-level-flush-after-sync

[OGAWA Hirofumi]

Gianfranco <gianfranco.dutka@arista.com> writes:

>     This patch forces a device-level flush after the generic Linux
>     code for sync has run.
>
>     The kernel depends upon filesystem-specific code to flush when
>     the filesystem itself thinks it is necessary, and otherwise
>     does nothing.  Someone expecting sync to behave as expected
>     might be in for a rude surprise.
>
>     The usual caveats apply:  Devices that do not implement flush
>     or whose implementation is buggy will not behave well.  IO
>     that occurs after the sync will not be flushed.

Does this patch fix the issue? After the ->sync_fs(), bdev page caches
including FAT data are still dirty, isn't it?

Thanks.

> Signed-off-by: Ken Kofman <gianfranco.dutka@arista.com>
>
> ---
>  fs/fat/inode.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index a38238d75c08..ddaed94ee48f 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -823,6 +823,14 @@ static int fat_remount(struct super_block *sb, int *flags, char *data)
>  	return 0;
>  }
>  
> +static int fat_sync_fs(struct super_block *sb, int wait)
> +{
> +	if (wait)
> +		return blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
> +	else
> +		return 0;
> +}
> +
>  static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
>  {
>  	struct super_block *sb = dentry->d_sb;
> @@ -937,6 +945,7 @@ static const struct super_operations fat_sops = {
>  	.put_super	= fat_put_super,
>  	.statfs		= fat_statfs,
>  	.remount_fs	= fat_remount,
> +	.sync_fs        = fat_sync_fs,
>  
>  	.show_options	= fat_show_options,
>  };

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

Re: [PATCH] fat: device-level-flush-after-sync

[kernel test robot]

Hi Gianfranco,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.0-rc5 next-20220915]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Gianfranco/fat-device-level-flush-after-sync/20220915-014337
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 3245cb65fd91cd514801bf91f5a3066d562f0ac4
config: x86_64-randconfig-a011 (https://download.01.org/0day-ci/archive/20220915/202209152048.xURrWxEC-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/b1130c74311f7b8c0713f373a8dc20b572883fca
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Gianfranco/fat-device-level-flush-after-sync/20220915-014337
        git checkout b1130c74311f7b8c0713f373a8dc20b572883fca
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   fs/fat/inode.c: In function 'fat_sync_fs':
>> fs/fat/inode.c:829:24: error: too many arguments to function 'blkdev_issue_flush'
     829 |                 return blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
         |                        ^~~~~~~~~~~~~~~~~~
   In file included from fs/fat/inode.c:21:
   include/linux/blkdev.h:1031:5: note: declared here
    1031 | int blkdev_issue_flush(struct block_device *bdev);
         |     ^~~~~~~~~~~~~~~~~~


vim +/blkdev_issue_flush +829 fs/fat/inode.c

   825	
   826	static int fat_sync_fs(struct super_block *sb, int wait)
   827	{
   828		if (wait)
 > 829			return blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
   830		else
   831			return 0;
   832	}
   833	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH] fat: device-level-flush-after-sync

[kernel test robot]

Hi Gianfranco,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.0-rc5 next-20220915]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Gianfranco/fat-device-level-flush-after-sync/20220915-014337
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 3245cb65fd91cd514801bf91f5a3066d562f0ac4
config: x86_64-randconfig-a012 (https://download.01.org/0day-ci/archive/20220916/202209160411.466veQ09-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/b1130c74311f7b8c0713f373a8dc20b572883fca
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Gianfranco/fat-device-level-flush-after-sync/20220915-014337
        git checkout b1130c74311f7b8c0713f373a8dc20b572883fca
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> fs/fat/inode.c:829:41: error: too many arguments to function call, expected single argument 'bdev', have 3 arguments
                   return blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
                          ~~~~~~~~~~~~~~~~~~             ^~~~~~~~~~~~~~~~
   include/linux/gfp_types.h:333:20: note: expanded from macro 'GFP_KERNEL'
   #define GFP_KERNEL      (__GFP_RECLAIM | __GFP_IO | __GFP_FS)
                           ^
   include/linux/blkdev.h:1031:5: note: 'blkdev_issue_flush' declared here
   int blkdev_issue_flush(struct block_device *bdev);
       ^
   1 error generated.


vim +/bdev +829 fs/fat/inode.c

   825	
   826	static int fat_sync_fs(struct super_block *sb, int wait)
   827	{
   828		if (wait)
 > 829			return blkdev_issue_flush(sb->s_bdev, GFP_KERNEL, NULL);
   830		else
   831			return 0;
   832	}
   833	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp