Commit 44f52122 authored Jul 06, 2016 by Bob Peterson

GFS2: Check rs_free with rd_rsspin protection

For the last process to close a file opened for write, function
gfs2_rsqa_delete was deleting the file's inode's block reservation
out of the rgrp reservations tree. Then it was checking to make sure
rs_free was 0, but it was performing the check outside the protection
of rd_rsspin spin_lock. The rd_rsspin spin_lock protection is needed
to prevent a race between the process freeing the reservation and
another who is allocating a new set of blocks inside the same rgrp
for the same inode, thus changing its value.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>

parent fd4c5748

fs/gfs2/rgrp.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -658,6 +658,7 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
		if (rgd) {
		spin_lock(&rgd->rd_rsspin);
		__rs_deltree(rs);
		BUG_ON(rs->rs_free);
		spin_unlock(&rgd->rd_rsspin);
		}
		}
		@@ -671,10 +672,8 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
		void gfs2_rsqa_delete(struct gfs2_inode ip, atomic_t wcount)
		{
		down_write(&ip->i_rw_mutex);
		if ((wcount == NULL) \|\| (atomic_read(wcount) <= 1)) {
		if ((wcount == NULL) \|\| (atomic_read(wcount) <= 1))
		gfs2_rs_deltree(&ip->i_res);
		BUG_ON(ip->i_res.rs_free);
		}
		up_write(&ip->i_rw_mutex);
		gfs2_qa_delete(ip, wcount);
		}