The specs state that if you send a reserve down a path that is already the holder success must be returned and if it goes down a path that is not the holder reservation conflict must be returned. Windows failover clustering will send a second reservation and expects that a device returns success. The problem for multipathing is that for an All Registrants reservation, we can send the reserve down any path but for all other reservation types there is one path that is the holder. To handle this we could add PR state to dm but that can get nasty. Look at target_core_pr.c for an example of the type of things we'd have to track. It will also get more complicated because other initiators can change the state so we will have to add in async event/sense handling. This commit, and the 3 commits that follow, tries to keep dm simple and keep just doing passthrough. This commit modifies dm_call_pr to be able to find the first usable path that can execute our pr_op then return. When dm_pr_reserve is converted to dm_call_pr in the next commit for the normal case we will use the same path for every reserve. Signed-off-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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.
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