Before this patch, the inode glock's gl_object was set after a reference was acquired, but before the block type was verified. In cases where the block was unlinked, then freed and reused on another node, a residule delete callback (delete_work) would try to look up the inode, eventually failing the block check, but only after it overwrites gl_object with a pointer to the wrong inode. This patch moves the assignment of gl_object after the block check so it won't be improperly overwritten.
Likewise, at the end of the function, gfs2_inode_lookup was clearing gl_object after it unlocked the glock, which meant another process might free the glock in the meantime. This patch guards against that case. Signed-off-by: Bob Peterson <[email protected]> Reviewed-by: Andreas Gruenbacher <[email protected]> --- fs/gfs2/inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index 2578bd824e34..fd6e1da3c5ab 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -145,7 +145,6 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, if (unlikely(error)) goto fail; flush_delayed_work(&ip->i_gl->gl_work); - glock_set_object(ip->i_gl, ip); error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl); if (unlikely(error)) @@ -170,6 +169,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, } } + glock_set_object(ip->i_gl, ip); set_bit(GIF_INVALID, &ip->i_flags); error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh); if (unlikely(error)) @@ -206,9 +206,9 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, fail_put: if (io_gl) gfs2_glock_put(io_gl); + glock_clear_object(ip->i_gl, ip); if (gfs2_holder_initialized(&i_gh)) gfs2_glock_dq_uninit(&i_gh); - glock_clear_object(ip->i_gl, ip); fail: iget_failed(inode); return ERR_PTR(error); -- 2.13.5
