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gfs2: Add missing else in trans_add_meta/data 

This patch fixes a timing window that causes a segfault.
The problem is that bd can remain NULL throughout the function
and then reference that NULL pointer if the bh->b_private starts
out NULL, then someone sets it to non-NULL inside the locking.
In that case, bd still needs to be set.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
This commit is contained in:
Bob Peterson 2015-10-01 11:47:31 -05:00
parent 6de20eb0de
commit 491e94f790
1 changed files with 4 additions and 0 deletions
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4
fs/gfs2/trans.c
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@ -176,6 +176,8 @@ void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
unlock_buffer(bh);
if (bh->b_private == NULL)
bd = gfs2_alloc_bufdata(gl, bh, &gfs2_databuf_lops);
else
bd = bh->b_private;
lock_buffer(bh);
gfs2_log_lock(sdp);
}
@ -236,6 +238,8 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
lock_page(bh->b_page);
if (bh->b_private == NULL)
bd = gfs2_alloc_bufdata(gl, bh, &gfs2_buf_lops);
else
bd = bh->b_private;
unlock_page(bh->b_page);
lock_buffer(bh);
gfs2_log_lock(sdp);