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Message-ID: <5F349211.1060508@cn.fujitsu.com> Date: Thu, 13 Aug 2020 09:06:25 +0800 From: Xiao Yang <yangx.jy@...fujitsu.com> To: Andreas Dilger <adilger@...ger.ca> CC: Ira Weiny <ira.weiny@...el.com>, "Darrick J. Wong" <darrick.wong@...cle.com>, Theodore Ts'o <tytso@....edu>, Eric Biggers <ebiggers@...nel.org>, Ext4 Developers List <linux-ext4@...r.kernel.org> Subject: Re: [PATCH v2] chattr/lsattr: Support dax attribute On 2020/8/13 7:25, Andreas Dilger wrote: > On Aug 7, 2020, at 10:03 AM, Ira Weiny<ira.weiny@...el.com> wrote: >> On Tue, Jul 28, 2020 at 01:33:21PM +0800, Xiao Yang wrote: >>> Use the letter 'x' to set/get dax attribute on a directory/file. >>> >>> Signed-off-by: Xiao Yang<yangx.jy@...fujitsu.com> >>> --- >>> >>> V1->V2: >>> 1) Define FS_DAX_FL in order and add missing 'x' letter in manpage. >>> 2) Add more detailed description about 'x' attribute. >>> 3) 'x' is a separate attribute and doesn't always affect S_DAX(i.e. >>> pagecache bypass) so remove the related info. >>> >>> lib/e2p/pf.c | 1 + >>> lib/ext2fs/ext2_fs.h | 1 + >>> misc/chattr.1.in | 15 ++++++++++++--- >>> misc/chattr.c | 3 ++- >>> 4 files changed, 16 insertions(+), 4 deletions(-) >>> >>> 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" }, >>> { 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 */ >> Per-file support is not supported on ext2... >> >> So I'm suspicious of this change. It is probably not an issue but I just >> wanted to check if you are trying to test on ext2? > It is up to the kernel to handle the various flags, definitely the chattr > command should not be trying to guess which flags are supported, since > this can definitely change between kernels and the underlying filesystems. Hi Andreas, Agreed, the various flags are handled by kernel instead of chattr command. :-) Best Regards, Xiao Yang > Note that the headers in e2fsprogs are all using "ext2" in the name, > regardless of the fact that the flags apply to ext3 and ext4. > > Cheers, Andreas > >>> #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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