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| author | Bob Peterson <rpeterso@redhat.com> | 2015-03-11 09:52:31 -0500 |
|---|---|---|
| committer | Bob Peterson <rpeterso@redhat.com> | 2015-12-14 12:19:28 -0600 |
| commit | 901c6c665b1024ea2bbabc24ba609a118459a2d8 (patch) | |
| tree | 3142102b533bcab238ea38be2bf272f90575da75 /fs/gfs2 | |
| parent | b58bf407ca4669a2dfcc00f5888ee719d9c34150 (diff) | |
| download | blackbird-obmc-linux-901c6c665b1024ea2bbabc24ba609a118459a2d8.tar.gz blackbird-obmc-linux-901c6c665b1024ea2bbabc24ba609a118459a2d8.zip | |
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.c | 5 |
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) |
