On Mon 26-04-21 06:40:27, Damien Le Moal wrote:
> On 2021/04/24 2:30, Jan Kara wrote:
> > Use invalidate_lock instead of zonefs' private i_mmap_sem. The intended
> > purpose is exactly the same. By this conversion we also fix a race
> > between hole punching and read(2) / readahead(2) paths that can lead to
> > stale page cache contents.
>
> zonefs does not support hole punching since the blocks of a file are determined
> by the device zone configuration and cannot change, ever. So I think you can
> remove the second sentence above.
Sure, thanks for correction. Updated.
Honza
>
> >
> > CC: Damien Le Moal <damien.lemoal@xxxxxxx>
> > CC: Johannes Thumshirn <jth@xxxxxxxxxx>
> > CC: <linux-fsdevel@xxxxxxxxxxxxxxx>
> > Signed-off-by: Jan Kara <jack@xxxxxxx>
> > ---
> > fs/zonefs/super.c | 23 +++++------------------
> > fs/zonefs/zonefs.h | 7 +++----
> > 2 files changed, 8 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> > index 049e36c69ed7..60ac5587c880 100644
> > --- a/fs/zonefs/super.c
> > +++ b/fs/zonefs/super.c
> > @@ -462,7 +462,7 @@ static int zonefs_file_truncate(struct inode *inode, loff_t isize)
> > inode_dio_wait(inode);
> >
> > /* Serialize against page faults */
> > - down_write(&zi->i_mmap_sem);
> > + down_write(&inode->i_mapping->invalidate_lock);
> >
> > /* Serialize against zonefs_iomap_begin() */
> > mutex_lock(&zi->i_truncate_mutex);
> > @@ -500,7 +500,7 @@ static int zonefs_file_truncate(struct inode *inode, loff_t isize)
> >
> > unlock:
> > mutex_unlock(&zi->i_truncate_mutex);
> > - up_write(&zi->i_mmap_sem);
> > + up_write(&inode->i_mapping->invalidate_lock);
> >
> > return ret;
> > }
> > @@ -575,18 +575,6 @@ static int zonefs_file_fsync(struct file *file, loff_t start, loff_t end,
> > return ret;
> > }
> >
> > -static vm_fault_t zonefs_filemap_fault(struct vm_fault *vmf)
> > -{
> > - struct zonefs_inode_info *zi = ZONEFS_I(file_inode(vmf->vma->vm_file));
> > - vm_fault_t ret;
> > -
> > - down_read(&zi->i_mmap_sem);
> > - ret = filemap_fault(vmf);
> > - up_read(&zi->i_mmap_sem);
> > -
> > - return ret;
> > -}
> > -
> > static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
> > {
> > struct inode *inode = file_inode(vmf->vma->vm_file);
> > @@ -607,16 +595,16 @@ static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
> > file_update_time(vmf->vma->vm_file);
> >
> > /* Serialize against truncates */
> > - down_read(&zi->i_mmap_sem);
> > + down_read(&inode->i_mapping->invalidate_lock);
> > ret = iomap_page_mkwrite(vmf, &zonefs_iomap_ops);
> > - up_read(&zi->i_mmap_sem);
> > + up_read(&inode->i_mapping->invalidate_lock);
> >
> > sb_end_pagefault(inode->i_sb);
> > return ret;
> > }
> >
> > static const struct vm_operations_struct zonefs_file_vm_ops = {
> > - .fault = zonefs_filemap_fault,
> > + .fault = filemap_fault,
> > .map_pages = filemap_map_pages,
> > .page_mkwrite = zonefs_filemap_page_mkwrite,
> > };
> > @@ -1158,7 +1146,6 @@ static struct inode *zonefs_alloc_inode(struct super_block *sb)
> >
> > inode_init_once(&zi->i_vnode);
> > mutex_init(&zi->i_truncate_mutex);
> > - init_rwsem(&zi->i_mmap_sem);
> > zi->i_wr_refcnt = 0;
> >
> > return &zi->i_vnode;
> > diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
> > index 51141907097c..7b147907c328 100644
> > --- a/fs/zonefs/zonefs.h
> > +++ b/fs/zonefs/zonefs.h
> > @@ -70,12 +70,11 @@ struct zonefs_inode_info {
> > * and changes to the inode private data, and in particular changes to
> > * a sequential file size on completion of direct IO writes.
> > * Serialization of mmap read IOs with truncate and syscall IO
> > - * operations is done with i_mmap_sem in addition to i_truncate_mutex.
> > - * Only zonefs_seq_file_truncate() takes both lock (i_mmap_sem first,
> > - * i_truncate_mutex second).
> > + * operations is done with invalidate_lock in addition to
> > + * i_truncate_mutex. Only zonefs_seq_file_truncate() takes both lock
> > + * (invalidate_lock first, i_truncate_mutex second).
> > */
> > struct mutex i_truncate_mutex;
> > - struct rw_semaphore i_mmap_sem;
> >
> > /* guarded by i_truncate_mutex */
> > unsigned int i_wr_refcnt;
> >
>
>
> --
> Damien Le Moal
> Western Digital Research
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
