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Commit de0e8c20 authored by Dave Chinner's avatar Dave Chinner Committed by Dave Chinner
Browse files

xfs: use i_mmaplock on read faults 



Take the i_mmaplock over read page faults. These come through the
->fault callout, so we need to wrap the generic implementation
with the i_mmaplock. While there, add tracepoints for the read
fault as it passes through XFS.

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

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent 653c60b6

fs/xfs/xfs_file.c

+27 −1
Original line number Original line Diff line number Diff line
@@ -1379,6 +1379,32 @@ xfs_file_llseek( 
	}

	}

}

}





/*

 * Locking for serialisation of IO during page faults. This results in a lock

 * ordering of:

 *

 * mmap_sem (MM)

 *   i_mmap_lock (XFS - truncate serialisation)

 *     page_lock (MM)

 *       i_lock (XFS - extent map serialisation)

 */

STATIC int

xfs_filemap_fault(

	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_fault(ip);



	xfs_ilock(ip, XFS_MMAPLOCK_SHARED);

	error = filemap_fault(vma, vmf);

	xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);



	return error;

}



const struct file_operations xfs_file_operations = {

const struct file_operations xfs_file_operations = {

	.llseek		= xfs_file_llseek,

	.llseek		= xfs_file_llseek,

	.read		= new_sync_read,

	.read		= new_sync_read,
@@ -1411,7 +1437,7 @@ const struct file_operations xfs_dir_file_operations = { 
};

};





static const struct vm_operations_struct xfs_file_vm_ops = {

static const struct vm_operations_struct xfs_file_vm_ops = {

	.fault		= filemap_fault,

	.fault		= xfs_filemap_fault,

	.map_pages	= filemap_map_pages,

	.map_pages	= filemap_map_pages,

	.page_mkwrite	= xfs_vm_page_mkwrite,

	.page_mkwrite	= xfs_vm_page_mkwrite,

};
 
};

fs/xfs/xfs_trace.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -685,6 +685,8 @@ DEFINE_INODE_EVENT(xfs_inode_set_eofblocks_tag); 
DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);

DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);

DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);

DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);





DEFINE_INODE_EVENT(xfs_filemap_fault);



DECLARE_EVENT_CLASS(xfs_iref_class,

DECLARE_EVENT_CLASS(xfs_iref_class,

	TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),

	TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),

	TP_ARGS(ip, caller_ip),

	TP_ARGS(ip, caller_ip),