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Commit 93a8614e authored by Dave Chinner's avatar Dave Chinner Committed by Dave Chinner
Browse files

xfs: fix directory inode iolock lockdep false positive 



The change to add the IO lock to protect the directory extent map
during readdir operations has cause lockdep to have a heart attack
as it now sees a different locking order on inodes w.r.t. the
mmap_sem because readdir has a different ordering to write().

Add a new lockdep class for directory inodes to avoid this false
positive.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent a1358aa3

fs/xfs/xfs_iops.c

+14 −0
Original line number Diff line number Diff line
@@ -48,6 +48,18 @@ 
#include <linux/fiemap.h>

#include <linux/slab.h>



/*

 * Directories have different lock order w.r.t. mmap_sem compared to regular

 * files. This is due to readdir potentially triggering page faults on a user

 * buffer inside filldir(), and this happens with the ilock on the directory

 * held. For regular files, the lock order is the other way around - the

 * mmap_sem is taken during the page fault, and then we lock the ilock to do

 * block mapping. Hence we need a different class for the directory ilock so

 * that lockdep can tell them apart.

 */

static struct lock_class_key xfs_nondir_ilock_class;

static struct lock_class_key xfs_dir_ilock_class;



static int

xfs_initxattrs(

	struct inode		*inode,
@@ -1191,6 +1203,7 @@ xfs_setup_inode( 
	xfs_diflags_to_iflags(inode, ip);



	ip->d_ops = ip->i_mount->m_nondir_inode_ops;

	lockdep_set_class(&ip->i_lock.mr_lock, &xfs_nondir_ilock_class);

	switch (inode->i_mode & S_IFMT) {

	case S_IFREG:

		inode->i_op = &xfs_inode_operations;
@@ -1198,6 +1211,7 @@ xfs_setup_inode( 
		inode->i_mapping->a_ops = &xfs_address_space_operations;

		break;

	case S_IFDIR:

		lockdep_set_class(&ip->i_lock.mr_lock, &xfs_dir_ilock_class);

		if (xfs_sb_version_hasasciici(&XFS_M(inode->i_sb)->m_sb))

			inode->i_op = &xfs_dir_ci_inode_operations;

		else