| Message ID | 20240124142645.9334-3-john.g.garry@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block atomic writes for XFS | expand |
On Wed, Jan 24, 2024 at 02:26:41PM +0000, John Garry wrote: > Add a flag indicating that a regular file is enabled for atomic writes. This is a file attribute that mirrors an ondisk inode flag. Actual support for untorn file writes (for now) depends on both the iflag and the underlying storage devices, which we can only really check at statx and pwrite time. This is the same story as FS_XFLAG_DAX, which signals to the fs that we should try to enable the fsdax IO path on the file (instead of the regular page cache), but applications have to query STAT_ATTR_DAX to find out if they really got that IO path. "try to enable atomic writes", perhaps? (and the comment for FS_XFLAG_DAX ought to read "try to use DAX for IO") --D > > Signed-off-by: John Garry <john.g.garry@oracle.com> > --- > include/uapi/linux/fs.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h > index a0975ae81e64..b5b4e1db9576 100644 > --- a/include/uapi/linux/fs.h > +++ b/include/uapi/linux/fs.h > @@ -140,6 +140,7 @@ struct fsxattr { > #define FS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */ > #define FS_XFLAG_DAX 0x00008000 /* use DAX for IO */ > #define FS_XFLAG_COWEXTSIZE 0x00010000 /* CoW extent size allocator hint */ > +#define FS_XFLAG_ATOMICWRITES 0x00020000 /* atomic writes enabled */ > #define FS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */ > > /* the read-only stuff doesn't really belong here, but any other place is > -- > 2.31.1 > >
On 02/02/2024 17:57, Darrick J. Wong wrote: > On Wed, Jan 24, 2024 at 02:26:41PM +0000, John Garry wrote: >> Add a flag indicating that a regular file is enabled for atomic writes. > > This is a file attribute that mirrors an ondisk inode flag. Actual > support for untorn file writes (for now) depends on both the iflag and > the underlying storage devices, which we can only really check at statx > and pwrite time. This is the same story as FS_XFLAG_DAX, which signals > to the fs that we should try to enable the fsdax IO path on the file > (instead of the regular page cache), but applications have to query > STAT_ATTR_DAX to find out if they really got that IO path. To be clear, are you suggesting to add this info to the commit message? > > "try to enable atomic writes", perhaps? > > (and the comment for FS_XFLAG_DAX ought to read "try to use DAX for IO") To me that sounds like "try to use DAX for IO, and, if not possible, fall back on some other method" - is that reality of what that flag does? Thanks, John > > --D > >> >> Signed-off-by: John Garry <john.g.garry@oracle.com> >> --- >> include/uapi/linux/fs.h | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h >> index a0975ae81e64..b5b4e1db9576 100644 >> --- a/include/uapi/linux/fs.h >> +++ b/include/uapi/linux/fs.h >> @@ -140,6 +140,7 @@ struct fsxattr { >> #define FS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */ >> #define FS_XFLAG_DAX 0x00008000 /* use DAX for IO */ >> #define FS_XFLAG_COWEXTSIZE 0x00010000 /* CoW extent size allocator hint */ >> +#define FS_XFLAG_ATOMICWRITES 0x00020000 /* atomic writes enabled */ >> #define FS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */ >> >> /* the read-only stuff doesn't really belong here, but any other place is >> -- >> 2.31.1 >> >>
On Mon, Feb 05, 2024 at 12:58:30PM +0000, John Garry wrote: > To me that sounds like "try to use DAX for IO, and, if not possible, fall > back on some other method" - is that reality of what that flag does? Yes. Of course for a fallback on XFS we need Darrick's swapext log item. Which would be good to have..
On Mon, Feb 05, 2024 at 12:58:30PM +0000, John Garry wrote: > On 02/02/2024 17:57, Darrick J. Wong wrote: > > On Wed, Jan 24, 2024 at 02:26:41PM +0000, John Garry wrote: > > > Add a flag indicating that a regular file is enabled for atomic writes. > > > > This is a file attribute that mirrors an ondisk inode flag. Actual > > support for untorn file writes (for now) depends on both the iflag and > > the underlying storage devices, which we can only really check at statx > > and pwrite time. This is the same story as FS_XFLAG_DAX, which signals > > to the fs that we should try to enable the fsdax IO path on the file > > (instead of the regular page cache), but applications have to query > > STAT_ATTR_DAX to find out if they really got that IO path. > > To be clear, are you suggesting to add this info to the commit message? That and a S_ATOMICW flag for the inode that triggers the proposed STAT_ATTR_ATOMICWRITES flag. > > "try to enable atomic writes", perhaps? > > > (and the comment for FS_XFLAG_DAX ought to read "try to use DAX for IO") > > To me that sounds like "try to use DAX for IO, and, if not possible, fall > back on some other method" - is that reality of what that flag does? As hch said, yes. --D > Thanks, > John > > > > > --D > > > > > > > > Signed-off-by: John Garry <john.g.garry@oracle.com> > > > --- > > > include/uapi/linux/fs.h | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h > > > index a0975ae81e64..b5b4e1db9576 100644 > > > --- a/include/uapi/linux/fs.h > > > +++ b/include/uapi/linux/fs.h > > > @@ -140,6 +140,7 @@ struct fsxattr { > > > #define FS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */ > > > #define FS_XFLAG_DAX 0x00008000 /* use DAX for IO */ > > > #define FS_XFLAG_COWEXTSIZE 0x00010000 /* CoW extent size allocator hint */ > > > +#define FS_XFLAG_ATOMICWRITES 0x00020000 /* atomic writes enabled */ > > > #define FS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */ > > > /* the read-only stuff doesn't really belong here, but any other place is > > > -- > > > 2.31.1 > > > > > > > >
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index a0975ae81e64..b5b4e1db9576 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -140,6 +140,7 @@ struct fsxattr { #define FS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */ #define FS_XFLAG_DAX 0x00008000 /* use DAX for IO */ #define FS_XFLAG_COWEXTSIZE 0x00010000 /* CoW extent size allocator hint */ +#define FS_XFLAG_ATOMICWRITES 0x00020000 /* atomic writes enabled */ #define FS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */ /* the read-only stuff doesn't really belong here, but any other place is
Add a flag indicating that a regular file is enabled for atomic writes. Signed-off-by: John Garry <john.g.garry@oracle.com> --- include/uapi/linux/fs.h | 1 + 1 file changed, 1 insertion(+)