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Re: [PATCH v3 0/4] xfsprogs: v4 inode type in directory

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH v3 0/4] xfsprogs: v4 inode type in directory
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Fri, 18 Oct 2013 08:22:24 -0500
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20131018031950.GT4446@dastard>
References: <20131017152804.204045257@xxxxxxx> <52605FF8.2000301@xxxxxxx> <20131018031950.GT4446@dastard>
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120122 Thunderbird/9.0
On 10/17/13 22:19, Dave Chinner wrote:
On Thu, Oct 17, 2013 at 05:08:56PM -0500, Mark Tinguely wrote:
On 10/17/13 10:28, Mark Tinguely wrote:
Here are the patches that enable the inode in the directory
feature in v4 superblocks.

Unchanged
  patch 1: add the entries to xfs_sb.h (sync with kernel)
  patch 2: add the XFS_FSOP_GEOM_FLAGS_FTYPE to xfs_fs.h (sync with kernel)
          add the entry to repair so that xfs_info reports the feature
New
  patch 3: add feature to the xfs_db version command.

Fixed
  patch 4: add the feature to mkfs.xfs and manual page.
           note: this new feature is ignored for superblock v5
                automatically turns on this feature.

FYI.

I saw the request for adding the filetype entry to block/leaf after posting.

I have it displaying unconditionally, but am trying to figure out
how to make it display only for filesytems that support the ftype
feature. I am missing something in the field.count().

The count function only tells the code whether a structure is
present or not, but it does not tell you what the format of the
structure is.

if you look at db/dir2.c, you'll see that the difference between the
dir2_flds[] and the dir3_flds[] is mainly in the type, count and offset
fields. For example:

const field_t   dir2_flds[] = {
         { "bhdr", FLDT_DIR2_DATA_HDR, OI(BOFF(magic)), dir2_block_hdr_count,
           FLD_COUNT, TYP_NONE }
...

const field_t   dir3_flds[] = {
         { "bhdr", FLDT_DIR3_DATA_HDR, OI(B3OFF(hdr)), dir3_block_hdr_count,
           FLD_COUNT, TYP_NONE },
...

if you look at dir[23]_block_hdr_count(), you'll see that they
return a boolean value based on a magic number check. Hence when the
code is trying to determine the type of the block that has been read
(i.e. what the field definition is), if the magic number matches we
know exactly what type of contents they contain.

For decoding the dtype, you need too look at how to select the
correct structure for the FLDT_DIR2_DATA_UNION. If you don't have
the feature set, you need to select the FLDT_DIR2_DATA_UNION
structure type, and if it is set you need to select the
FLDT_DIR3_DATA_UNION type. Hence you need both these types defined
in the dir2_flds[] array, and some manner to ensure the correct
values are returned from the count functions.

And just to make it hard, both the dir2 and dir3 data union count
functions use the same function (dir2_data_u_count) so you're going
to have to be careful that you don't break the v5 superblock
directory decoding....

Cheers,

Dave.


Thanks Dave. I did some RTFS and found I was having problems with the field_t.flag.

Can't we add a filetype to the dir2 dir2_data_union_flds entry and use the count to turn it on/off? The problem I was having with this was the flag. Something like:

Add the directory field type information to xfs_db directory
displays.

---
 db/dir2.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Index: b/db/dir2.c
===================================================================
--- a/db/dir2.c
+++ b/db/dir2.c
@@ -52,6 +52,8 @@ static int    dir2_leaf_tail_count(void *ob
 static int     dir2_leaf_tail_offset(void *obj, int startoff, int idx);
 static int     dir2_node_btree_count(void *obj, int startoff);
 static int     dir2_node_hdr_count(void *obj, int startoff);
+static int     dir3_data_union_ftype_offset(void *obj, int startoff, int idx);
+static int     dir2_data_union_ftype_count(void *obj, int startoff);

 const field_t  dir2_hfld[] = {
        { "", FLDT_DIR2, OI(0), C1, 0, TYP_NONE },
@@ -130,6 +132,8 @@ const field_t       dir2_data_union_flds[] = {
          dir2_data_union_namelen_count, FLD_COUNT, TYP_NONE },
        { "name", FLDT_CHARNS, OI(DEOFF(name)), dir2_data_union_name_count,
          FLD_COUNT, TYP_NONE },
+       { "filetype", FLDT_UINT8D, dir3_data_union_ftype_offset,
+         dir2_data_union_ftype_count, FLD_OFFSET|FLD_COUNT, TYP_NONE },
        { "tag", FLDT_DIR2_DATA_OFF, dir2_data_union_tag_offset,
          dir2_data_union_tag_count, FLD_OFFSET|FLD_COUNT, TYP_NONE },
        { NULL }
@@ -454,6 +458,14 @@ dir2_data_union_name_count(
 }

 static int
+dir2_data_union_ftype_count(
+       void                    *obj,
+       int                     startoff)
+{
+       return xfs_sb_version_hasftype(&mp->m_sb);
+}
+
+static int
 dir2_data_union_namelen_count(
        void                    *obj,
        int                     startoff)


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