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    SubjectRe: [PATCH 3.2 39/79] ocfs2: should wait dio before inode lock in ocfs2_setattr()
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    On Sun, 2018-02-11 at 15:39 +0800, alex chen wrote:
    > Hi Ben,
    >
    > ocfs2_dio_end_io_write() was introduced in 4.6 and the problem this patch
    > fixes is only exist in the kernel 4.6 and above 4.6.

    Thanks for the reminder. I'll drop this from the 3.2 and 3.16 patch
    queues.

    Ben.

    > Thanks,
    > Alex
    >
    > On 2018/2/11 12:20, Ben Hutchings wrote:
    > > 3.2.99-rc1 review patch. If anyone has any objections, please let me know.
    > >
    > > ------------------
    > >
    > > From: alex chen <alex.chen@huawei.com>
    > >
    > > commit 28f5a8a7c033cbf3e32277f4cc9c6afd74f05300 upstream.
    > >
    > > we should wait dio requests to finish before inode lock in
    > > ocfs2_setattr(), otherwise the following deadlock will happen:
    > >
    > > process 1 process 2 process 3
    > > truncate file 'A' end_io of writing file 'A' receiving the bast messages
    > > ocfs2_setattr
    > > ocfs2_inode_lock_tracker
    > > ocfs2_inode_lock_full
    > > inode_dio_wait
    > > __inode_dio_wait
    > > -->waiting for all dio
    > > requests finish
    > > dlm_proxy_ast_handler
    > > dlm_do_local_bast
    > > ocfs2_blocking_ast
    > > ocfs2_generic_handle_bast
    > > set OCFS2_LOCK_BLOCKED flag
    > > dio_end_io
    > > dio_bio_end_aio
    > > dio_complete
    > > ocfs2_dio_end_io
    > > ocfs2_dio_end_io_write
    > > ocfs2_inode_lock
    > > __ocfs2_cluster_lock
    > > ocfs2_wait_for_mask
    > > -->waiting for OCFS2_LOCK_BLOCKED
    > > flag to be cleared, that is waiting
    > > for 'process 1' unlocking the inode lock
    > > inode_dio_end
    > > -->here dec the i_dio_count, but will never
    > > be called, so a deadlock happened.
    > >
    > > Link: http://lkml.kernel.org/r/59F81636.70508@huawei.com
    > > Signed-off-by: Alex Chen <alex.chen@huawei.com>
    > > Reviewed-by: Jun Piao <piaojun@huawei.com>
    > > Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
    > > Acked-by: Changwei Ge <ge.changwei@h3c.com>
    > > Cc: Mark Fasheh <mfasheh@versity.com>
    > > Cc: Joel Becker <jlbec@evilplan.org>
    > > Cc: Junxiao Bi <junxiao.bi@oracle.com>
    > > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    > > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    > > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    > > ---
    > > fs/ocfs2/file.c | 9 +++++++--
    > > 1 file changed, 7 insertions(+), 2 deletions(-)
    > >
    > > --- a/fs/ocfs2/file.c
    > > +++ b/fs/ocfs2/file.c
    > > @@ -1130,6 +1130,13 @@ int ocfs2_setattr(struct dentry *dentry,
    > > dquot_initialize(inode);
    > > size_change = S_ISREG(inode->i_mode) && attr->ia_valid & ATTR_SIZE;
    > > if (size_change) {
    > > + /*
    > > + * Here we should wait dio to finish before inode lock
    > > + * to avoid a deadlock between ocfs2_setattr() and
    > > + * ocfs2_dio_end_io_write()
    > > + */
    > > + inode_dio_wait(inode);
    > > +
    > > status = ocfs2_rw_lock(inode, 1);
    > > if (status < 0) {
    > > mlog_errno(status);
    > > @@ -1149,8 +1156,6 @@ int ocfs2_setattr(struct dentry *dentry,
    > > if (status)
    > > goto bail_unlock;
    > >
    > > - inode_dio_wait(inode);
    > > -
    > > if (i_size_read(inode) >= attr->ia_size) {
    > > if (ocfs2_should_order_data(inode)) {
    > > status = ocfs2_begin_ordered_truncate(inode,
    > >
    > >
    > > .
    > >
    >
    >
    --
    Ben Hutchings
    Sturgeon's Law: Ninety percent of everything is crap.

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