[GFS2] Fix page lock/glock deadlock
This fixes a race between the glock and the page lock encountered
during truncate in gfs2_readpage and gfs2_prepare_write. The gfs2_readpages
function doesn't need the same fix since it only uses a try lock anyway, so
it will fail back to gfs2_readpage in the case of a potential deadlock.
This bug was spotted by Russell Cattelan.
Cc: Russell Cattelan <cattelan@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 5c3962c..3822189 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -230,7 +230,7 @@
/* gfs2_sharewrite_nopage has grabbed the ip->i_gl already */
goto skip_lock;
}
- gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|GL_AOP, &gh);
+ gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
do_unlock = 1;
error = gfs2_glock_nq_m_atime(1, &gh);
if (unlikely(error))
@@ -254,6 +254,8 @@
out:
return error;
out_unlock:
+ if (error == GLR_TRYFAILED)
+ error = AOP_TRUNCATED_PAGE;
unlock_page(page);
if (do_unlock)
gfs2_holder_uninit(&gh);
@@ -293,7 +295,7 @@
goto skip_lock;
}
gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
- LM_FLAG_TRY_1CB|GL_ATIME|GL_AOP, &gh);
+ LM_FLAG_TRY_1CB|GL_ATIME, &gh);
do_unlock = 1;
ret = gfs2_glock_nq_m_atime(1, &gh);
if (ret == GLR_TRYFAILED)
@@ -366,10 +368,13 @@
unsigned int write_len = to - from;
- gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|GL_AOP, &ip->i_gh);
+ gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|LM_FLAG_TRY_1CB, &ip->i_gh);
error = gfs2_glock_nq_m_atime(1, &ip->i_gh);
- if (error)
+ if (unlikely(error)) {
+ if (error == GLR_TRYFAILED)
+ error = AOP_TRUNCATED_PAGE;
goto out_uninit;
+ }
gfs2_write_calc_reserv(ip, write_len, &data_blocks, &ind_blocks);