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409e873ea3
There is a race between capsnaps flush and removing the inode from
'mdsc->snap_flush_list' list:
== Thread A == == Thread B ==
ceph_queue_cap_snap()
-> allocate 'capsnapA'
->ihold('&ci->vfs_inode')
->add 'capsnapA' to 'ci->i_cap_snaps'
->add 'ci' to 'mdsc->snap_flush_list'
...
== Thread C ==
ceph_flush_snaps()
->__ceph_flush_snaps()
->__send_flush_snap()
handle_cap_flushsnap_ack()
->iput('&ci->vfs_inode')
this also will release 'ci'
...
== Thread D ==
ceph_handle_snap()
->flush_snaps()
->iterate 'mdsc->snap_flush_list'
->get the stale 'ci'
->remove 'ci' from ->ihold(&ci->vfs_inode) this
'mdsc->snap_flush_list' will WARNING
To fix this we will increase the inode's i_count ref when adding 'ci'
to the 'mdsc->snap_flush_list' list.
[ idryomov: need_put int -> bool ]
Cc: stable@vger.kernel.org
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2209299
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.