2019-01-09 14:23:52

by Pankaj Gupta

Subject: [PATCH v3 4/5] ext4: disable map_sync for virtio pmem

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 <[email protected]>
---
fs/ext4/file.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

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;
--
2.9.3

2019-01-09 13:58:14

by Pankaj Gupta

Subject: [PATCH v3 5/5] xfs: disable map_sync for virtio pmem

Virtio pmem provides asynchronous host page cache flush
mechanism. we don't support 'MAP_SYNC' with virtio pmem
and xfs.

Signed-off-by: Pankaj Gupta <[email protected]>
---
fs/xfs/xfs_file.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index e474250..eae4aa4 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1190,6 +1190,14 @@ xfs_file_mmap(
if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
return -EOPNOTSUPP;

+ /* We don't support synchronous mappings with guest direct access
+ * and virtio based host page cache mechanism.
+ */
+ if (IS_DAX(file_inode(filp)) && virtio_pmem_host_cache_enabled(
+ xfs_find_daxdev_for_inode(file_inode(filp))) &&
+ (vma->vm_flags & VM_SYNC))
+ return -EOPNOTSUPP;
+
file_accessed(filp);
vma->vm_ops = &xfs_file_vm_ops;
if (IS_DAX(file_inode(filp)))
--
2.9.3

2019-01-09 16:29:18

by Jan Kara

Subject: Re: [PATCH v3 4/5] ext4: disable map_sync for virtio pmem

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 <[email protected]>
...
> @@ -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
--
Jan Kara <[email protected]>
SUSE Labs, CR