xfs: use i_mmaplock on write faults

commit 075a924d45cc69c75a35f20b4912b85aa98b180a upstream.

Take the i_mmaplock over write page faults. These come through the
->page_mkwrite callout, so we need to wrap that calls with the
i_mmaplock.

This gives us a lock order of mmap_sem -> i_mmaplock -> page_lock
-> i_lock.

Also, move the page_mkwrite wrapper to the same region of xfs_file.c
as the read fault wrappers and add a tracepoint.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Jan Kara <jack@suse.cz>
Cc: xfs@oss.sgi.com

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 878ca2a03dd8a282296e15753b08db740d3b5476..e9ae58e33c6cfe9964cf94c625dde7b4af783844 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -956,20 +956,6 @@ xfs_file_mmap(
        return 0;
 }
 
-/*
- * mmap()d file has taken write protection fault and is being made
- * writable. We can set the page state up correctly for a writable
- * page, which means we can do correct delalloc accounting (ENOSPC
- * checking!) and unwritten extent mapping.
- */
-STATIC int
-xfs_vm_page_mkwrite(
-       struct vm_area_struct   *vma,
-       struct vm_fault         *vmf)
-{
-       return block_page_mkwrite(vma, vmf, xfs_get_blocks);
-}
-
 /*
  * This type is designed to indicate the type of offset we would like
  * to search from page cache for either xfs_seek_data() or xfs_seek_hole().
@@ -1443,6 +1429,29 @@ xfs_filemap_fault(
        return error;
 }
 
+/*
+ * mmap()d file has taken write protection fault and is being made writable. We
+ * can set the page state up correctly for a writable page, which means we can
+ * do correct delalloc accounting (ENOSPC checking!) and unwritten extent
+ * mapping.
+ */
+STATIC int
+xfs_filemap_page_mkwrite(
+       struct vm_area_struct   *vma,
+       struct vm_fault         *vmf)
+{
+       struct xfs_inode        *ip = XFS_I(vma->vm_file->f_mapping->host);
+       int                     error;
+
+       trace_xfs_filemap_page_mkwrite(ip);
+
+       xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
+       error = block_page_mkwrite(vma, vmf, xfs_get_blocks);
+       xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
+
+       return error;
+}
+
 const struct file_operations xfs_file_operations = {
        .llseek         = xfs_file_llseek,
        .read           = new_sync_read,
@@ -1477,6 +1486,6 @@ const struct file_operations xfs_dir_file_operations = {
 static const struct vm_operations_struct xfs_file_vm_ops = {
        .fault          = xfs_filemap_fault,
        .map_pages      = filemap_map_pages,
-       .page_mkwrite   = xfs_vm_page_mkwrite,
+       .page_mkwrite   = xfs_filemap_page_mkwrite,
        .remap_pages    = generic_file_remap_pages,
 };

diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 389e1f16c220752e3b373c80e09b246cdce41fdc..24799bb4373994022aab75caf17e486b0e2de37d 100644 (file)
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -685,6 +685,7 @@ DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);
 DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);
 
 DEFINE_INODE_EVENT(xfs_filemap_fault);
+DEFINE_INODE_EVENT(xfs_filemap_page_mkwrite);
 
 DECLARE_EVENT_CLASS(xfs_iref_class,
        TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),