Re: [PATCH v2] chattr/lsattr: Support dax attribute

[Andreas Dilger <adilger@dilger.ca>]

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On Aug 27, 2020, at 7:33 PM, Xiao Yang <yangx.jy@cn.fujitsu.com> wrote:
> 
> Hi,
> 
> Is there any comment on the patch? :-)

I don't need a v3 for the Dax vs. DAX case, though I think DAX would be
better.  The decision is up to Ted.

Cheers, Andreas

> 
> Thanks,
> Xiao Yang
> On 2020/8/13 9:42, Xiao Yang wrote:
>> On 2020/8/13 7:29, Andreas Dilger wrote:
>>> On Jul 27, 2020, at 11:33 PM, Xiao Yang<yangx.jy@cn.fujitsu.com>  wrote:
>>>> Use the letter 'x' to set/get dax attribute on a directory/file.
>>>> 
>>>> Signed-off-by: Xiao Yang<yangx.jy@cn.fujitsu.com>
>>> One minor nit below, but otherwise looks OK.
>>> 
>>> Reviewed-by: Andreas Dilger<adilger@dilger.ca>
>>> 
>>>> diff --git a/lib/e2p/pf.c b/lib/e2p/pf.c
>>>> index 0c6998c4..e59cccff 100644
>>>> --- a/lib/e2p/pf.c
>>>> +++ b/lib/e2p/pf.c
>>>> @@ -44,6 +44,7 @@ static struct flags_name flags_array[] = {
>>>>    { EXT2_TOPDIR_FL, "T", "Top_of_Directory_Hierarchies" },
>>>>    { EXT4_EXTENTS_FL, "e", "Extents" },
>>>>    { FS_NOCOW_FL, "C", "No_COW" },
>>>> +    { FS_DAX_FL, "x", "Dax" },
>>> Should this be "DAX" ?  That is how it is commonly used in the kernel.
>> Hi Andreas,
>> 
>> Thanks a lot for your review.
>> 
>> Either 'Dax' or 'DAX' is fine to me because it is just the output of lsattr -v.
>> For example, xfs_io shows 'dax' instead of 'DAX':
>> # xfs_io -c "lsattr -v" file
>> [dax] file
>> 
>> BTW:
>> I just used 'Dax' to follow the current format of output(i.e. capitalize the first letter).
>> 
>> Do you want me to send v3 patch with the 'DAX'? :-)
>> 
>> Best Regards,
>> Xiao Yang
>>>>    { EXT4_CASEFOLD_FL, "F", "Casefold" },
>>>>    { EXT4_INLINE_DATA_FL, "N", "Inline_Data" },
>>>>    { EXT4_PROJINHERIT_FL, "P", "Project_Hierarchy" },
>>>> diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
>>>> index 6c20ea77..88f510a3 100644
>>>> --- a/lib/ext2fs/ext2_fs.h
>>>> +++ b/lib/ext2fs/ext2_fs.h
>>>> @@ -335,6 +335,7 @@ struct ext2_dx_tail {
>>>> /* EXT4_EOFBLOCKS_FL 0x00400000 was here */
>>>> #define FS_NOCOW_FL            0x00800000 /* Do not cow file */
>>>> #define EXT4_SNAPFILE_FL        0x01000000  /* Inode is a snapshot */
>>>> +#define FS_DAX_FL            0x02000000 /* Inode is DAX */
>>>> #define EXT4_SNAPFILE_DELETED_FL    0x04000000  /* Snapshot is being deleted */
>>>> #define EXT4_SNAPFILE_SHRUNK_FL        0x08000000  /* Snapshot shrink has completed */
>>>> #define EXT4_INLINE_DATA_FL        0x10000000 /* Inode has inline data */
>>>> diff --git a/misc/chattr.1.in b/misc/chattr.1.in
>>>> index ff2fcf00..5a4928a5 100644
>>>> --- a/misc/chattr.1.in
>>>> +++ b/misc/chattr.1.in
>>>> @@ -23,13 +23,13 @@ chattr \- change file attributes on a Linux file system
>>>> .B chattr
>>>> changes the file attributes on a Linux file system.
>>>> .PP
>>>> -The format of a symbolic mode is +-=[aAcCdDeFijPsStTu].
>>>> +The format of a symbolic mode is +-=[aAcCdDeFijPsStTux].
>>>> .PP
>>>> The operator '+' causes the selected attributes to be added to the
>>>> existing attributes of the files; '-' causes them to be removed; and '='
>>>> causes them to be the only attributes that the files have.
>>>> .PP
>>>> -The letters 'aAcCdDeFijPsStTu' select the new attributes for the files:
>>>> +The letters 'aAcCdDeFijPsStTux' select the new attributes for the files:
>>>> append only (a),
>>>> no atime updates (A),
>>>> compressed (c),
>>>> @@ -45,7 +45,8 @@ secure deletion (s),
>>>> synchronous updates (S),
>>>> no tail-merging (t),
>>>> top of directory hierarchy (T),
>>>> -and undeletable (u).
>>>> +undeletable (u),
>>>> +and direct access for files (x).
>>>> .PP
>>>> The following attributes are read-only, and may be listed by
>>>> .BR lsattr (1)
>>>> @@ -210,6 +211,14 @@ saved.  This allows the user to ask for its undeletion.  Note: please
>>>> make sure to read the bugs and limitations section at the end of this
>>>> document.
>>>> .TP
>>>> +.B x
>>>> +The 'x' attribute can be set on a directory or file.  If the attribute
>>>> +is set on an existing directory, it will be inherited by all files and
>>>> +subdirectories that are subsequently created in the directory.  If an
>>>> +existing directory has contained some files and subdirectories, modifying
>>>> +the attribute on the parent directory doesn't change the attributes on
>>>> +these files and subdirectories.
>>>> +.TP
>>>> .B V
>>>> A file with the 'V' attribute set has fs-verity enabled.  It cannot be
>>>> written to, and the filesystem will automatically verify all data read
>>>> diff --git a/misc/chattr.c b/misc/chattr.c
>>>> index a5d60170..c0337f86 100644
>>>> --- a/misc/chattr.c
>>>> +++ b/misc/chattr.c
>>>> @@ -86,7 +86,7 @@ static unsigned long sf;
>>>> static void usage(void)
>>>> {
>>>>    fprintf(stderr,
>>>> -        _("Usage: %s [-pRVf] [-+=aAcCdDeijPsStTuF] [-v version] files...\n"),
>>>> +        _("Usage: %s [-pRVf] [-+=aAcCdDeijPsStTuFx] [-v version] files...\n"),
>>>>        program_name);
>>>>    exit(1);
>>>> }
>>>> @@ -112,6 +112,7 @@ static const struct flags_char flags_array[] = {
>>>>    { EXT2_NOTAIL_FL, 't' },
>>>>    { EXT2_TOPDIR_FL, 'T' },
>>>>    { FS_NOCOW_FL, 'C' },
>>>> +    { FS_DAX_FL, 'x' },
>>>>    { EXT4_CASEFOLD_FL, 'F' },
>>>>    { 0, 0 }
>>>> };
>>>> --
>>>> 2.21.0
>>>> 
>>>> 
>>>> 
>>> 
>>> Cheers, Andreas


Cheers, Andreas






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