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gfs2: Move the inode glock locking to gfs2_file_buffered_write
So far, for buffered writes, we were taking the inode glock in gfs2_iomap_begin and dropping it in gfs2_iomap_end with the intention of not holding the inode glock while iomap_write_actor faults in user pages. It turns out that iomap_write_actor is called inside iomap_begin ... iomap_end, so the user pages were still faulted in while holding the inode glock and the locking code in iomap_begin / iomap_end was completely pointless. Move the locking into gfs2_file_buffered_write instead. We'll take care of the potential deadlocks due to faulting in user pages while holding a glock in a subsequent patch. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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dc732906c2
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b924bdab74
@ -961,46 +961,6 @@ hole_found:
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goto out;
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}
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static int gfs2_write_lock(struct inode *inode)
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{
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struct gfs2_inode *ip = GFS2_I(inode);
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struct gfs2_sbd *sdp = GFS2_SB(inode);
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int error;
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gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
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error = gfs2_glock_nq(&ip->i_gh);
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if (error)
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goto out_uninit;
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if (&ip->i_inode == sdp->sd_rindex) {
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struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
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error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
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GL_NOCACHE, &m_ip->i_gh);
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if (error)
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goto out_unlock;
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}
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return 0;
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out_unlock:
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gfs2_glock_dq(&ip->i_gh);
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out_uninit:
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gfs2_holder_uninit(&ip->i_gh);
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return error;
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}
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static void gfs2_write_unlock(struct inode *inode)
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{
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struct gfs2_inode *ip = GFS2_I(inode);
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struct gfs2_sbd *sdp = GFS2_SB(inode);
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if (&ip->i_inode == sdp->sd_rindex) {
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struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
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gfs2_glock_dq_uninit(&m_ip->i_gh);
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}
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gfs2_glock_dq_uninit(&ip->i_gh);
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}
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static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos,
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unsigned len)
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{
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@ -1118,11 +1078,6 @@ out_qunlock:
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return ret;
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}
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static inline bool gfs2_iomap_need_write_lock(unsigned flags)
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{
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return (flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT);
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}
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static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
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unsigned flags, struct iomap *iomap,
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struct iomap *srcmap)
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@ -1135,12 +1090,6 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
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iomap->flags |= IOMAP_F_BUFFER_HEAD;
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trace_gfs2_iomap_start(ip, pos, length, flags);
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if (gfs2_iomap_need_write_lock(flags)) {
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ret = gfs2_write_lock(inode);
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if (ret)
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goto out;
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}
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ret = __gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
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if (ret)
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goto out_unlock;
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@ -1168,10 +1117,7 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
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ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap, &mp);
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out_unlock:
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if (ret && gfs2_iomap_need_write_lock(flags))
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gfs2_write_unlock(inode);
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release_metapath(&mp);
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out:
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trace_gfs2_iomap_end(ip, iomap, ret);
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return ret;
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}
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@ -1219,15 +1165,11 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
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}
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if (unlikely(!written))
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goto out_unlock;
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return 0;
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if (iomap->flags & IOMAP_F_SIZE_CHANGED)
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mark_inode_dirty(inode);
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set_bit(GLF_DIRTY, &ip->i_gl->gl_flags);
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out_unlock:
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if (gfs2_iomap_need_write_lock(flags))
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gfs2_write_unlock(inode);
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return 0;
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}
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@ -880,13 +880,40 @@ static ssize_t gfs2_file_buffered_write(struct kiocb *iocb, struct iov_iter *fro
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{
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struct file *file = iocb->ki_filp;
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struct inode *inode = file_inode(file);
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struct gfs2_inode *ip = GFS2_I(inode);
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struct gfs2_sbd *sdp = GFS2_SB(inode);
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ssize_t ret;
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gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
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ret = gfs2_glock_nq(&ip->i_gh);
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if (ret)
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goto out_uninit;
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if (inode == sdp->sd_rindex) {
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struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
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ret = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
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GL_NOCACHE, &m_ip->i_gh);
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if (ret)
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goto out_unlock;
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}
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current->backing_dev_info = inode_to_bdi(inode);
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ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
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current->backing_dev_info = NULL;
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if (ret > 0)
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iocb->ki_pos += ret;
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if (inode == sdp->sd_rindex) {
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struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
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gfs2_glock_dq_uninit(&m_ip->i_gh);
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}
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out_unlock:
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gfs2_glock_dq(&ip->i_gh);
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out_uninit:
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gfs2_holder_uninit(&ip->i_gh);
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return ret;
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}
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