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Originally, the logic of handling config_llog_data::cld_refcount is some confusing, it may cause the cld_refcount to be leaked or trigger "LASSERT(atomic_read(&cld->cld_refcount) > 0);" when put the reference. This patch clean related logic as following: 1) When the 'cld' is created, its reference is set as 1. 2) No need additional reference when add the 'cld' into the list 'config_llog_list'. 3) Inrease 'cld_refcount' when set lock data after mgc_enqueue() done successfully by mgc_process_log(). 4) When mgc_requeue_thread() traversals the 'config_llog_list', it needs to take additional reference on each 'cld' to avoid being freed during subsequent processing. The reference also prevents the 'cld' to be dropped from the 'config_llog_list', then the mgc_requeue_thread() can safely locate next 'cld', and then decrease the 'cld_refcount' for previous one. 5) mgc_blocking_ast() will drop the reference of 'cld_refcount' that is taken in mgc_process_log(). 6) The others need to call config_log_find() to find the 'cld' if want to access related config log data. That will increase the 'cld_refcount' to avoid being freed during accessing. The sponsor needs to call config_log_put() after using the 'cld'. 7) Other confused or redundant logic are dropped. On the other hand, the patch also enhances the protection for 'config_llog_data' flags, such as 'cld_stopping'/'cld_lostlock' as following. a) Use 'config_list_lock' (spinlock) to handle the possible parallel accessing of these flags among mgc_requeue_thread() and others config llog data visitors, such as mount/umount, blocking_ast, and so on. b) Use 'config_llog_data::cld_lock' (mutex) to pretect other parallel accessing of these flags among kinds of blockable operations, such as mount, umount, and blocking ast. The 'config_llog_data::cld_lock' is also used for protecting the sub-cld members, such as 'cld_sptlrpc'/'cld_params', and so on. Signed-off-by: Fan Yong <fan.yong@intel.com> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8408 Reviewed-on: http://review.whamcloud.com/21616 Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com> Reviewed-by: Hongchao Zhang <hongchao.zhang@intel.com> Reviewed-by: Oleg Drokin <oleg.drokin@intel.com> Signed-off-by: James Simmons <jsimmons@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.