Commit 3d162688 authored Nov 06, 2012 by Benjamin Marzinski Committed by Steven Whitehouse Nov 07, 2012

GFS2: Don't call file_accessed() with a shared glock

file_accessed() was being called by gfs2_mmap() with a shared glock. If it
needed to update the atime, it was crashing because it dirtied the inode in
gfs2_dirty_inode() without holding an exclusive lock. gfs2_dirty_inode()
checked if the caller was already holding a glock, but it didn't make sure that
the glock was in the exclusive state. Now, instead of calling file_accessed()
while holding the shared lock in gfs2_mmap(), file_accessed() is called after
grabbing and releasing the glock to update the inode. If file_accessed() needs
to update the atime, it will grab an exclusive lock in gfs2_dirty_inode().

gfs2_dirty_inode() now also checks to make sure that if the calling process has
already locked the glock, it has an exclusive lock.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

parent 076f0faa

fs/gfs2/file.c

+5 −7

Original line number	Diff line number	Diff line
		@@ -516,15 +516,13 @@ static int gfs2_mmap(struct file file, struct vm_area_struct vma)
		struct gfs2_holder i_gh;
		int error;

		gfs2_holder_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
		error = gfs2_glock_nq(&i_gh);
		if (error == 0) {
		file_accessed(file);
		gfs2_glock_dq(&i_gh);
		}
		gfs2_holder_uninit(&i_gh);
		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
		&i_gh);
		if (error)
		return error;
		/* grab lock to update inode */
		gfs2_glock_dq_uninit(&i_gh);
		file_accessed(file);
		}
		vma->vm_ops = &gfs2_vm_ops;

fs/gfs2/super.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -810,7 +810,8 @@ static void gfs2_dirty_inode(struct inode *inode, int flags)
		return;
		}
		need_unlock = 1;
		}
		} else if (WARN_ON_ONCE(ip->i_gl->gl_state != LM_ST_EXCLUSIVE))
		return;

		if (current->journal_info == NULL) {
		ret = gfs2_trans_begin(sdp, RES_DINODE, 0);

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