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

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Hi,

Is there any comment on the patch? :-)

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@xxxxxxxxxxxxxx>  wrote:
Use the letter 'x' to set/get dax attribute on a directory/file.

Signed-off-by: Xiao Yang<yangx.jy@xxxxxxxxxxxxxx>
One minor nit below, but otherwise looks OK.

Reviewed-by: Andreas Dilger<adilger@xxxxxxxxx>

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












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