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authorBob Peterson <rpeterso@redhat.com>2015-03-11 09:52:31 -0500
committerBob Peterson <rpeterso@redhat.com>2015-12-14 12:19:28 -0600
commit901c6c665b1024ea2bbabc24ba609a118459a2d8 (patch)
tree3142102b533bcab238ea38be2bf272f90575da75 /fs/gfs2
parentb58bf407ca4669a2dfcc00f5888ee719d9c34150 (diff)
GFS2: Update master statfs buffer with sd_statfs_spin locked
Before this patch, function update_statfs called gfs2_statfs_change_out to update the master statfs buffer without the sd_statfs_spin held. In theory, another process could call gfs2_statfs_sync, which takes the sd_statfs_spin lock and re-reads m_sc from the buffer. So there's a theoretical timing window in which one process could write the master statfs buffer, then another comes along and re-reads it, wiping out the changes. Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Diffstat (limited to 'fs/gfs2')
-rw-r--r--fs/gfs2/super.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 64f03c821b5d..03fa155f703e 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -556,6 +556,7 @@ void update_statfs(struct gfs2_sbd *sdp, struct buffer_head *m_bh,
struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
gfs2_trans_add_meta(l_ip->i_gl, l_bh);
+ gfs2_trans_add_meta(m_ip->i_gl, m_bh);
spin_lock(&sdp->sd_statfs_spin);
m_sc->sc_total += l_sc->sc_total;
@@ -564,10 +565,8 @@ void update_statfs(struct gfs2_sbd *sdp, struct buffer_head *m_bh,
memset(l_sc, 0, sizeof(struct gfs2_statfs_change));
memset(l_bh->b_data + sizeof(struct gfs2_dinode),
0, sizeof(struct gfs2_statfs_change));
- spin_unlock(&sdp->sd_statfs_spin);
-
- gfs2_trans_add_meta(m_ip->i_gl, m_bh);
gfs2_statfs_change_out(m_sc, m_bh->b_data + sizeof(struct gfs2_dinode));
+ spin_unlock(&sdp->sd_statfs_spin);
}
int gfs2_statfs_sync(struct super_block *sb, int type)