| Message ID | 20190109135606.15401-1-pagupta@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | kvm "virtio pmem" device | expand |
On Wed 09-01-19 19:26:05, Pankaj Gupta wrote: > Virtio pmem provides asynchronous host page cache flush > mechanism. We don't support 'MAP_SYNC' with virtio pmem > and ext4. > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> ... > @@ -371,6 +373,13 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) > if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC)) > return -EOPNOTSUPP; > > + /* We don't support synchronous mappings with guest direct access > + * and virtio based host page cache flush mechanism. > + */ > + if (IS_DAX(file_inode(file)) && virtio_pmem_host_cache_enabled(dax_dev) > + && (vma->vm_flags & VM_SYNC)) > + return -EOPNOTSUPP; > + Shouldn't there rather be some generic way of doing this? Having virtio_pmem_host_cache_enabled() check in filesystem code just looks like filesystem sniffing into details is should not care about... Maybe just naming this (or having a wrapper) dax_dev_map_sync_supported()? Honza
> > On Wed 09-01-19 19:26:05, Pankaj Gupta wrote: > > Virtio pmem provides asynchronous host page cache flush > > mechanism. We don't support 'MAP_SYNC' with virtio pmem > > and ext4. > > > > Signed-off-by: Pankaj Gupta <pagupta@redhat.com> > ... > > @@ -371,6 +373,13 @@ static int ext4_file_mmap(struct file *file, struct > > vm_area_struct *vma) > > if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC)) > > return -EOPNOTSUPP; > > > > + /* We don't support synchronous mappings with guest direct access > > + * and virtio based host page cache flush mechanism. > > + */ > > + if (IS_DAX(file_inode(file)) && virtio_pmem_host_cache_enabled(dax_dev) > > + && (vma->vm_flags & VM_SYNC)) > > + return -EOPNOTSUPP; > > + > > Shouldn't there rather be some generic way of doing this? Having > virtio_pmem_host_cache_enabled() check in filesystem code just looks like > filesystem sniffing into details is should not care about... Maybe just > naming this (or having a wrapper) dax_dev_map_sync_supported()? Thanks for the feedback. Just wanted to avoid 'dax' in function name just to differentiate this with real dax. But yes can add a wrapper: dax_dev_map_sync_supported() Thanks, Pankaj
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 69d65d4..e54f48b 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -360,8 +360,10 @@ static const struct vm_operations_struct ext4_file_vm_ops = { static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) { struct inode *inode = file->f_mapping->host; + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); + struct dax_device *dax_dev = sbi->s_daxdev; - if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) + if (unlikely(ext4_forced_shutdown(sbi))) return -EIO; /* @@ -371,6 +373,13 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma) if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC)) return -EOPNOTSUPP; + /* We don't support synchronous mappings with guest direct access + * and virtio based host page cache flush mechanism. + */ + if (IS_DAX(file_inode(file)) && virtio_pmem_host_cache_enabled(dax_dev) + && (vma->vm_flags & VM_SYNC)) + return -EOPNOTSUPP; + file_accessed(file); if (IS_DAX(file_inode(file))) { vma->vm_ops = &ext4_dax_vm_ops;
Virtio pmem provides asynchronous host page cache flush mechanism. We don't support 'MAP_SYNC' with virtio pmem and ext4. Signed-off-by: Pankaj Gupta <pagupta@redhat.com> --- fs/ext4/file.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)