xfs, dax: introduce xfs_dax_aops

In preparation for the dax implementation to start associating dax pages
to inodes via page->mapping, we need to provide a 'struct
address_space_operations' instance for dax. Otherwise, direct-I/O
triggers incorrect page cache assumptions and warnings like the
following:

 WARNING: CPU: 27 PID: 1783 at fs/xfs/xfs_aops.c:1468
 xfs_vm_set_page_dirty+0xf3/0x1b0 [xfs]
 [..]
 CPU: 27 PID: 1783 Comm: dma-collision Tainted: G           O 4.15.0-rc2+ #984
 [..]
 Call Trace:
  set_page_dirty_lock+0x40/0x60
  bio_set_pages_dirty+0x37/0x50
  iomap_dio_actor+0x2b7/0x3b0
  ? iomap_dio_zero+0x110/0x110
  iomap_apply+0xa4/0x110
  iomap_dio_rw+0x29e/0x3b0
  ? iomap_dio_zero+0x110/0x110
  ? xfs_file_dio_aio_read+0x7c/0x1a0 [xfs]
  xfs_file_dio_aio_read+0x7c/0x1a0 [xfs]
  xfs_file_read_iter+0xa0/0xc0 [xfs]
  __vfs_read+0xf9/0x170
  vfs_read+0xa6/0x150
  SyS_pread64+0x93/0xb0
  entry_SYSCALL_64_fastpath+0x1f/0x96

...where the default set_page_dirty() handler assumes that dirty state
is being tracked in 'struct page' flags.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 9c6a830da0eec4663c04b5c58606962139598890..e7a56c4786ff41d7b19762b71df4d80a8d5d8c0e 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1194,16 +1194,22 @@ xfs_vm_writepages(
        int                     ret;
 
        xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
-       if (dax_mapping(mapping))
-               return dax_writeback_mapping_range(mapping,
-                               xfs_find_bdev_for_inode(mapping->host), wbc);
-
        ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc);
        if (wpc.ioend)
                ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
        return ret;
 }
 
+STATIC int
+xfs_dax_writepages(
+       struct address_space    *mapping,
+       struct writeback_control *wbc)
+{
+       xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+       return dax_writeback_mapping_range(mapping,
+                       xfs_find_bdev_for_inode(mapping->host), wbc);
+}
+
 /*
  * Called to move a page into cleanable state - and from there
  * to be released. The page should already be clean. We always
@@ -1367,17 +1373,6 @@ out_unlock:
        return error;
 }
 
-STATIC ssize_t
-xfs_vm_direct_IO(
-       struct kiocb            *iocb,
-       struct iov_iter         *iter)
-{
-       /*
-        * We just need the method present so that open/fcntl allow direct I/O.
-        */
-       return -EINVAL;
-}
-
 STATIC sector_t
 xfs_vm_bmap(
        struct address_space    *mapping,
@@ -1500,8 +1495,15 @@ const struct address_space_operations xfs_address_space_operations = {
        .releasepage            = xfs_vm_releasepage,
        .invalidatepage         = xfs_vm_invalidatepage,
        .bmap                   = xfs_vm_bmap,
-       .direct_IO              = xfs_vm_direct_IO,
+       .direct_IO              = noop_direct_IO,
        .migratepage            = buffer_migrate_page,
        .is_partially_uptodate  = block_is_partially_uptodate,
        .error_remove_page      = generic_error_remove_page,
 };
+
+const struct address_space_operations xfs_dax_aops = {
+       .writepages             = xfs_dax_writepages,
+       .direct_IO              = noop_direct_IO,
+       .set_page_dirty         = noop_set_page_dirty,
+       .invalidatepage         = noop_invalidatepage,
+};

diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
index 88c85ea63da030ce8d02629ad6aa1fe0bb3971ad..69346d460dfaf7c613c71f3c12326291c5f68033 100644 (file)
--- a/fs/xfs/xfs_aops.h
+++ b/fs/xfs/xfs_aops.h
@@ -54,6 +54,7 @@ struct xfs_ioend {
 };
 
 extern const struct address_space_operations xfs_address_space_operations;
+extern const struct address_space_operations xfs_dax_aops;
 
 int    xfs_setfilesize(struct xfs_inode *ip, xfs_off_t offset, size_t size);
 

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 56475fcd76f224216f89e4c0d3cead876d3b547c..951e84df557618dcd900fee2037bfa0eaf62ecdc 100644 (file)
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1272,7 +1272,10 @@ xfs_setup_iops(
        case S_IFREG:
                inode->i_op = &xfs_inode_operations;
                inode->i_fop = &xfs_file_operations;
-               inode->i_mapping->a_ops = &xfs_address_space_operations;
+               if (IS_DAX(inode))
+                       inode->i_mapping->a_ops = &xfs_dax_aops;
+               else
+                       inode->i_mapping->a_ops = &xfs_address_space_operations;
                break;
        case S_IFDIR:
                if (xfs_sb_version_hasasciici(&XFS_M(inode->i_sb)->m_sb))