On Thu, Mar 28, 2024 at 12:18:06PM +1100, Dave Chinner wrote:
> On Wed, Mar 27, 2024 at 05:45:09PM +0100, Christian Brauner wrote:
> > There's a bunch of flags that are purely based on what the file
> > operations support while also never being conditionally set or unset.
> > IOW, they're not subject to change for individual file opens. Imho, such
> > flags don't need to live in f_mode they might as well live in the fops
> > structs itself. And the fops struct already has that lonely
> > mmap_supported_flags member. We might as well turn that into a generic
> > fops_flags member and move a few flags from FMODE_* space into FOP_*
> > space. That gets us four FMODE_* bits back and the ability for new
> > static flags that are about file ops to not have to live in FMODE_*
> > space but in their own FOP_* space. It's not the most beautiful thing
> > ever but it gets the job done. Yes, there'll be an additional pointer
> > chase but hopefully that won't matter for these flags.
> >
> > If this is palatable I suspect there's a few more we can move into there
> > and that we can also redirect new flag suggestions that follow this
> > pattern into the fops_flags field instead of f_mode. As of yet untested.
> >
> > (Fwiw, FMODE_NOACCOUNT and FMODE_BACKING could live in fops_flags as
> > well because they're also completely static but they aren't really
> > about file operations so they're better suited for FMODE_* imho.)
> >
> > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
> .....
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index 632653e00906..d13e21eb9a3c 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -1230,8 +1230,7 @@ xfs_file_open(
> > {
> > if (xfs_is_shutdown(XFS_M(inode->i_sb)))
> > return -EIO;
> > - file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC |
> > - FMODE_DIO_PARALLEL_WRITE | FMODE_CAN_ODIRECT;
> > + file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
> > return generic_file_open(inode, file);
> > }
> >
> > @@ -1490,7 +1489,6 @@ const struct file_operations xfs_file_operations = {
> > .compat_ioctl = xfs_file_compat_ioctl,
> > #endif
> > .mmap = xfs_file_mmap,
> > - .mmap_supported_flags = MAP_SYNC,
> > .open = xfs_file_open,
> > .release = xfs_file_release,
> > .fsync = xfs_file_fsync,
> > @@ -1498,6 +1496,8 @@ const struct file_operations xfs_file_operations = {
> > .fallocate = xfs_file_fallocate,
> > .fadvise = xfs_file_fadvise,
> > .remap_file_range = xfs_file_remap_range,
> > + .fops_flags = FOP_MMAP_SYNC | FOP_BUF_RASYNC | FOP_BUF_WASYNC |
> > + FOP_DIO_PARALLEL_WRITE,
> > };
> >
> > const struct file_operations xfs_dir_file_operations = {
> > @@ -1510,4 +1510,6 @@ const struct file_operations xfs_dir_file_operations = {
> > .compat_ioctl = xfs_file_compat_ioctl,
> > #endif
> > .fsync = xfs_dir_fsync,
> > + .fops_flags = FOP_MMAP_SYNC | FOP_BUF_RASYNC | FOP_BUF_WASYNC |
> > + FOP_DIO_PARALLEL_WRITE,
> > };
>
> Why do we need to set any of these for directory operations now that
> we have a clear choice? i.e. we can't mmap directories, and the rest
> of these flags are for read() and write() operations which we also
> can't do on directories...
Yeah, I know but since your current implementation raises them for both
I just did it 1:1:
STATIC int
xfs_file_open(
struct inode *inode,
struct file *file)
{
if (xfs_is_shutdown(XFS_M(inode->i_sb)))
return -EIO;
file->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC | FMODE_BUF_WASYNC |
FMODE_DIO_PARALLEL_WRITE | FMODE_CAN_ODIRECT;
return generic_file_open(inode, file);
}
STATIC int
xfs_dir_open(
struct inode *inode,
struct file *file)
{
struct xfs_inode *ip = XFS_I(inode);
unsigned int mode;
int error;
error = xfs_file_open(inode, file);
if (error)
return error;
<snip>
}
>
> ....
>
> > @@ -1024,7 +1024,7 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags)
> >
> > /* File path supports NOWAIT for non-direct_IO only for block devices. */
> > if (!(kiocb->ki_flags & IOCB_DIRECT) &&
> > - !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) &&
> > + !fops_buf_wasync(kiocb->ki_filp) &&
> > (req->flags & REQ_F_ISREG))
> > goto copy_iov;
>
> You should probably also fix that comment - WASYNC is set when the
> filesystem supports NOWAIT for buffered writes.
>
> -Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
